2008-02-05 09:28:20 +03:00
# include <linux/kernel.h>
# include <linux/module.h>
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# include <linux/interrupt.h>
2008-02-05 09:28:20 +03:00
# include <linux/irq.h>
# include <linux/spinlock.h>
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
# include <linux/device.h>
# include <linux/err.h>
# include <linux/debugfs.h>
# include <linux/seq_file.h>
# include <linux/gpio.h>
2010-06-08 17:48:17 +04:00
# include <linux/of_gpio.h>
2009-09-23 03:46:38 +04:00
# include <linux/idr.h>
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 11:04:11 +03:00
# include <linux/slab.h>
2008-02-05 09:28:20 +03:00
/* Optional implementation infrastructure for GPIO interfaces.
*
* Platforms may want to use this if they tend to use very many GPIOs
* that aren ' t part of a System - On - Chip core ; or across I2C / SPI / etc .
*
* When kernel footprint or instruction count is an issue , simpler
* implementations may be preferred . The GPIO programming interface
* allows for inlining speed - critical get / set operations for common
* cases , so that access to SOC - integrated GPIOs can sometimes cost
* only an instruction or two per bit .
*/
/* When debugging, extend minimal trust to callers and platform code.
* Also emit diagnostic messages that may help initial bringup , when
* board setup or driver bugs are most common .
*
* Otherwise , minimize overhead in what may be bitbanging codepaths .
*/
# ifdef DEBUG
# define extra_checks 1
# else
# define extra_checks 0
# endif
/* gpio_lock prevents conflicts during gpio_desc[] table updates.
* While any GPIO is requested , its gpio_chip is not removable ;
* each GPIO ' s " requested " flag serves as a lock and refcount .
*/
static DEFINE_SPINLOCK ( gpio_lock ) ;
struct gpio_desc {
struct gpio_chip * chip ;
unsigned long flags ;
/* flag symbols are bit numbers */
# define FLAG_REQUESTED 0
# define FLAG_IS_OUT 1
2008-04-28 13:14:47 +04:00
# define FLAG_RESERVED 2
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
# define FLAG_EXPORT 3 /* protected by sysfs_lock */
# define FLAG_SYSFS 4 /* exported via /sys/class/gpio/control */
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# define FLAG_TRIG_FALL 5 /* trigger on falling edge */
# define FLAG_TRIG_RISE 6 /* trigger on rising edge */
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# define FLAG_ACTIVE_LOW 7 /* sysfs value has active low */
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2010-08-11 05:02:25 +04:00
# define ID_SHIFT 16 /* add new flags before this one */
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2010-08-11 05:02:25 +04:00
# define GPIO_FLAGS_MASK ((1 << ID_SHIFT) - 1)
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# define GPIO_TRIGGER_MASK (BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE))
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# ifdef CONFIG_DEBUG_FS
const char * label ;
# endif
} ;
static struct gpio_desc gpio_desc [ ARCH_NR_GPIOS ] ;
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# ifdef CONFIG_GPIO_SYSFS
2010-08-11 05:02:25 +04:00
static DEFINE_IDR ( dirent_idr ) ;
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# endif
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static inline void desc_set_label ( struct gpio_desc * d , const char * label )
{
# ifdef CONFIG_DEBUG_FS
d - > label = label ;
# endif
}
/* Warn when drivers omit gpio_request() calls -- legal but ill-advised
* when setting direction , and otherwise illegal . Until board setup code
* and drivers use explicit requests everywhere ( which won ' t happen when
* those calls have no teeth ) we can ' t avoid autorequesting . This nag
2008-10-16 09:03:16 +04:00
* message should motivate switching to explicit requests . . . so should
* the weaker cleanup after faults , compared to gpio_request ( ) .
2009-04-03 03:57:06 +04:00
*
* NOTE : the autorequest mechanism is going away ; at this point it ' s
* only " legal " in the sense that ( old ) code using it won ' t break yet ,
* but instead only triggers a WARN ( ) stack dump .
2008-02-05 09:28:20 +03:00
*/
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static int gpio_ensure_requested ( struct gpio_desc * desc , unsigned offset )
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{
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const struct gpio_chip * chip = desc - > chip ;
const int gpio = chip - > base + offset ;
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2009-04-03 03:57:06 +04:00
if ( WARN ( test_and_set_bit ( FLAG_REQUESTED , & desc - > flags ) = = 0 ,
" autorequest GPIO-%d \n " , gpio ) ) {
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if ( ! try_module_get ( chip - > owner ) ) {
pr_err ( " GPIO-%d: module can't be gotten \n " , gpio ) ;
clear_bit ( FLAG_REQUESTED , & desc - > flags ) ;
/* lose */
return - EIO ;
}
2008-02-05 09:28:20 +03:00
desc_set_label ( desc , " [auto] " ) ;
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/* caller must chip->request() w/o spinlock */
if ( chip - > request )
return 1 ;
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}
2008-10-16 09:03:16 +04:00
return 0 ;
2008-02-05 09:28:20 +03:00
}
/* caller holds gpio_lock *OR* gpio is marked as requested */
static inline struct gpio_chip * gpio_to_chip ( unsigned gpio )
{
return gpio_desc [ gpio ] . chip ;
}
2008-04-28 13:14:46 +04:00
/* dynamic allocation of GPIOs, e.g. on a hotplugged device */
static int gpiochip_find_base ( int ngpio )
{
int i ;
int spare = 0 ;
int base = - ENOSPC ;
for ( i = ARCH_NR_GPIOS - 1 ; i > = 0 ; i - - ) {
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struct gpio_desc * desc = & gpio_desc [ i ] ;
struct gpio_chip * chip = desc - > chip ;
2008-04-28 13:14:46 +04:00
2008-04-28 13:14:47 +04:00
if ( ! chip & & ! test_bit ( FLAG_RESERVED , & desc - > flags ) ) {
2008-04-28 13:14:46 +04:00
spare + + ;
if ( spare = = ngpio ) {
base = i ;
break ;
}
} else {
spare = 0 ;
2008-04-28 13:14:47 +04:00
if ( chip )
i - = chip - > ngpio - 1 ;
2008-04-28 13:14:46 +04:00
}
}
if ( gpio_is_valid ( base ) )
pr_debug ( " %s: found new base at %d \n " , __func__ , base ) ;
return base ;
}
2008-04-28 13:14:47 +04:00
/**
* gpiochip_reserve ( ) - reserve range of gpios to use with platform code only
* @ start : starting gpio number
* @ ngpio : number of gpios to reserve
* Context : platform init , potentially before irqs or kmalloc will work
*
* Returns a negative errno if any gpio within the range is already reserved
* or registered , else returns zero as a success code . Use this function
* to mark a range of gpios as unavailable for dynamic gpio number allocation ,
* for example because its driver support is not yet loaded .
*/
int __init gpiochip_reserve ( int start , int ngpio )
{
int ret = 0 ;
unsigned long flags ;
int i ;
2008-05-24 00:04:44 +04:00
if ( ! gpio_is_valid ( start ) | | ! gpio_is_valid ( start + ngpio - 1 ) )
2008-04-28 13:14:47 +04:00
return - EINVAL ;
spin_lock_irqsave ( & gpio_lock , flags ) ;
for ( i = start ; i < start + ngpio ; i + + ) {
struct gpio_desc * desc = & gpio_desc [ i ] ;
if ( desc - > chip | | test_bit ( FLAG_RESERVED , & desc - > flags ) ) {
ret = - EBUSY ;
goto err ;
}
set_bit ( FLAG_RESERVED , & desc - > flags ) ;
}
pr_debug ( " %s: reserved gpios from %d to %d \n " ,
__func__ , start , start + ngpio - 1 ) ;
err :
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
return ret ;
}
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
# ifdef CONFIG_GPIO_SYSFS
/* lock protects against unexport_gpio() being called while
* sysfs files are active .
*/
static DEFINE_MUTEX ( sysfs_lock ) ;
/*
* / sys / class / gpio / gpioN . . . only for GPIOs that are exported
* / direction
* * MAY BE OMITTED if kernel won ' t allow direction changes
* * is read / write as " in " or " out "
* * may also be written as " high " or " low " , initializing
* output value as specified ( " out " implies " low " )
* / value
* * always readable , subject to hardware behavior
* * may be writable , as zero / nonzero
2009-09-23 03:46:38 +04:00
* / edge
* * configures behavior of poll ( 2 ) on / value
* * available only if pin can generate IRQs on input
* * is read / write as " none " , " falling " , " rising " , or " both "
2009-12-16 03:46:20 +03:00
* / active_low
* * configures polarity of / value
* * is read / write as zero / nonzero
* * also affects existing and subsequent " falling " and " rising "
* / edge configuration
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
*/
static ssize_t gpio_direction_show ( struct device * dev ,
struct device_attribute * attr , char * buf )
{
const struct gpio_desc * desc = dev_get_drvdata ( dev ) ;
ssize_t status ;
mutex_lock ( & sysfs_lock ) ;
if ( ! test_bit ( FLAG_EXPORT , & desc - > flags ) )
status = - EIO ;
else
status = sprintf ( buf , " %s \n " ,
test_bit ( FLAG_IS_OUT , & desc - > flags )
? " out " : " in " ) ;
mutex_unlock ( & sysfs_lock ) ;
return status ;
}
static ssize_t gpio_direction_store ( struct device * dev ,
struct device_attribute * attr , const char * buf , size_t size )
{
const struct gpio_desc * desc = dev_get_drvdata ( dev ) ;
unsigned gpio = desc - gpio_desc ;
ssize_t status ;
mutex_lock ( & sysfs_lock ) ;
if ( ! test_bit ( FLAG_EXPORT , & desc - > flags ) )
status = - EIO ;
else if ( sysfs_streq ( buf , " high " ) )
status = gpio_direction_output ( gpio , 1 ) ;
else if ( sysfs_streq ( buf , " out " ) | | sysfs_streq ( buf , " low " ) )
status = gpio_direction_output ( gpio , 0 ) ;
else if ( sysfs_streq ( buf , " in " ) )
status = gpio_direction_input ( gpio ) ;
else
status = - EINVAL ;
mutex_unlock ( & sysfs_lock ) ;
return status ? : size ;
}
2009-12-16 03:46:20 +03:00
static /* const */ DEVICE_ATTR ( direction , 0644 ,
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
gpio_direction_show , gpio_direction_store ) ;
static ssize_t gpio_value_show ( struct device * dev ,
struct device_attribute * attr , char * buf )
{
const struct gpio_desc * desc = dev_get_drvdata ( dev ) ;
unsigned gpio = desc - gpio_desc ;
ssize_t status ;
mutex_lock ( & sysfs_lock ) ;
2009-12-16 03:46:20 +03:00
if ( ! test_bit ( FLAG_EXPORT , & desc - > flags ) ) {
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
status = - EIO ;
2009-12-16 03:46:20 +03:00
} else {
int value ;
value = ! ! gpio_get_value_cansleep ( gpio ) ;
if ( test_bit ( FLAG_ACTIVE_LOW , & desc - > flags ) )
value = ! value ;
status = sprintf ( buf , " %d \n " , value ) ;
}
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
mutex_unlock ( & sysfs_lock ) ;
return status ;
}
static ssize_t gpio_value_store ( struct device * dev ,
struct device_attribute * attr , const char * buf , size_t size )
{
const struct gpio_desc * desc = dev_get_drvdata ( dev ) ;
unsigned gpio = desc - gpio_desc ;
ssize_t status ;
mutex_lock ( & sysfs_lock ) ;
if ( ! test_bit ( FLAG_EXPORT , & desc - > flags ) )
status = - EIO ;
else if ( ! test_bit ( FLAG_IS_OUT , & desc - > flags ) )
status = - EPERM ;
else {
long value ;
status = strict_strtol ( buf , 0 , & value ) ;
if ( status = = 0 ) {
2009-12-16 03:46:20 +03:00
if ( test_bit ( FLAG_ACTIVE_LOW , & desc - > flags ) )
value = ! value ;
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
gpio_set_value_cansleep ( gpio , value ! = 0 ) ;
status = size ;
}
}
mutex_unlock ( & sysfs_lock ) ;
return status ;
}
2009-12-16 03:46:20 +03:00
static const DEVICE_ATTR ( value , 0644 ,
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
gpio_value_show , gpio_value_store ) ;
2009-09-23 03:46:38 +04:00
static irqreturn_t gpio_sysfs_irq ( int irq , void * priv )
{
2010-08-11 05:02:25 +04:00
struct sysfs_dirent * value_sd = priv ;
2009-09-23 03:46:38 +04:00
2010-08-11 05:02:25 +04:00
sysfs_notify_dirent ( value_sd ) ;
2009-09-23 03:46:38 +04:00
return IRQ_HANDLED ;
}
static int gpio_setup_irq ( struct gpio_desc * desc , struct device * dev ,
unsigned long gpio_flags )
{
2010-08-11 05:02:25 +04:00
struct sysfs_dirent * value_sd ;
2009-09-23 03:46:38 +04:00
unsigned long irq_flags ;
int ret , irq , id ;
if ( ( desc - > flags & GPIO_TRIGGER_MASK ) = = gpio_flags )
return 0 ;
irq = gpio_to_irq ( desc - gpio_desc ) ;
if ( irq < 0 )
return - EIO ;
2010-08-11 05:02:25 +04:00
id = desc - > flags > > ID_SHIFT ;
value_sd = idr_find ( & dirent_idr , id ) ;
if ( value_sd )
free_irq ( irq , value_sd ) ;
2009-09-23 03:46:38 +04:00
desc - > flags & = ~ GPIO_TRIGGER_MASK ;
if ( ! gpio_flags ) {
ret = 0 ;
2010-08-11 05:02:25 +04:00
goto free_id ;
2009-09-23 03:46:38 +04:00
}
irq_flags = IRQF_SHARED ;
if ( test_bit ( FLAG_TRIG_FALL , & gpio_flags ) )
2009-12-16 03:46:20 +03:00
irq_flags | = test_bit ( FLAG_ACTIVE_LOW , & desc - > flags ) ?
IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING ;
2009-09-23 03:46:38 +04:00
if ( test_bit ( FLAG_TRIG_RISE , & gpio_flags ) )
2009-12-16 03:46:20 +03:00
irq_flags | = test_bit ( FLAG_ACTIVE_LOW , & desc - > flags ) ?
IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING ;
2009-09-23 03:46:38 +04:00
2010-08-11 05:02:25 +04:00
if ( ! value_sd ) {
value_sd = sysfs_get_dirent ( dev - > kobj . sd , NULL , " value " ) ;
if ( ! value_sd ) {
ret = - ENODEV ;
2009-09-23 03:46:38 +04:00
goto err_out ;
}
do {
ret = - ENOMEM ;
2010-08-11 05:02:25 +04:00
if ( idr_pre_get ( & dirent_idr , GFP_KERNEL ) )
ret = idr_get_new_above ( & dirent_idr , value_sd ,
1 , & id ) ;
2009-09-23 03:46:38 +04:00
} while ( ret = = - EAGAIN ) ;
if ( ret )
2010-08-11 05:02:25 +04:00
goto free_sd ;
2009-09-23 03:46:38 +04:00
desc - > flags & = GPIO_FLAGS_MASK ;
2010-08-11 05:02:25 +04:00
desc - > flags | = ( unsigned long ) id < < ID_SHIFT ;
2009-09-23 03:46:38 +04:00
2010-08-11 05:02:25 +04:00
if ( desc - > flags > > ID_SHIFT ! = id ) {
2009-09-23 03:46:38 +04:00
ret = - ERANGE ;
goto free_id ;
}
}
ret = request_irq ( irq , gpio_sysfs_irq , irq_flags ,
2010-08-11 05:02:25 +04:00
" gpiolib " , value_sd ) ;
2009-09-23 03:46:38 +04:00
if ( ret )
2010-08-11 05:02:25 +04:00
goto free_id ;
2009-09-23 03:46:38 +04:00
desc - > flags | = gpio_flags ;
return 0 ;
free_id :
2010-08-11 05:02:25 +04:00
idr_remove ( & dirent_idr , id ) ;
2009-09-23 03:46:38 +04:00
desc - > flags & = GPIO_FLAGS_MASK ;
2010-08-11 05:02:25 +04:00
free_sd :
if ( value_sd )
sysfs_put ( value_sd ) ;
2009-09-23 03:46:38 +04:00
err_out :
return ret ;
}
static const struct {
const char * name ;
unsigned long flags ;
} trigger_types [ ] = {
{ " none " , 0 } ,
{ " falling " , BIT ( FLAG_TRIG_FALL ) } ,
{ " rising " , BIT ( FLAG_TRIG_RISE ) } ,
{ " both " , BIT ( FLAG_TRIG_FALL ) | BIT ( FLAG_TRIG_RISE ) } ,
} ;
static ssize_t gpio_edge_show ( struct device * dev ,
struct device_attribute * attr , char * buf )
{
const struct gpio_desc * desc = dev_get_drvdata ( dev ) ;
ssize_t status ;
mutex_lock ( & sysfs_lock ) ;
if ( ! test_bit ( FLAG_EXPORT , & desc - > flags ) )
status = - EIO ;
else {
int i ;
status = 0 ;
for ( i = 0 ; i < ARRAY_SIZE ( trigger_types ) ; i + + )
if ( ( desc - > flags & GPIO_TRIGGER_MASK )
= = trigger_types [ i ] . flags ) {
status = sprintf ( buf , " %s \n " ,
trigger_types [ i ] . name ) ;
break ;
}
}
mutex_unlock ( & sysfs_lock ) ;
return status ;
}
static ssize_t gpio_edge_store ( struct device * dev ,
struct device_attribute * attr , const char * buf , size_t size )
{
struct gpio_desc * desc = dev_get_drvdata ( dev ) ;
ssize_t status ;
int i ;
for ( i = 0 ; i < ARRAY_SIZE ( trigger_types ) ; i + + )
if ( sysfs_streq ( trigger_types [ i ] . name , buf ) )
goto found ;
return - EINVAL ;
found :
mutex_lock ( & sysfs_lock ) ;
if ( ! test_bit ( FLAG_EXPORT , & desc - > flags ) )
status = - EIO ;
else {
status = gpio_setup_irq ( desc , dev , trigger_types [ i ] . flags ) ;
if ( ! status )
status = size ;
}
mutex_unlock ( & sysfs_lock ) ;
return status ;
}
static DEVICE_ATTR ( edge , 0644 , gpio_edge_show , gpio_edge_store ) ;
2009-12-16 03:46:20 +03:00
static int sysfs_set_active_low ( struct gpio_desc * desc , struct device * dev ,
int value )
{
int status = 0 ;
if ( ! ! test_bit ( FLAG_ACTIVE_LOW , & desc - > flags ) = = ! ! value )
return 0 ;
if ( value )
set_bit ( FLAG_ACTIVE_LOW , & desc - > flags ) ;
else
clear_bit ( FLAG_ACTIVE_LOW , & desc - > flags ) ;
/* reconfigure poll(2) support if enabled on one edge only */
if ( dev ! = NULL & & ( ! ! test_bit ( FLAG_TRIG_RISE , & desc - > flags ) ^
! ! test_bit ( FLAG_TRIG_FALL , & desc - > flags ) ) ) {
unsigned long trigger_flags = desc - > flags & GPIO_TRIGGER_MASK ;
gpio_setup_irq ( desc , dev , 0 ) ;
status = gpio_setup_irq ( desc , dev , trigger_flags ) ;
}
return status ;
}
static ssize_t gpio_active_low_show ( struct device * dev ,
struct device_attribute * attr , char * buf )
{
const struct gpio_desc * desc = dev_get_drvdata ( dev ) ;
ssize_t status ;
mutex_lock ( & sysfs_lock ) ;
if ( ! test_bit ( FLAG_EXPORT , & desc - > flags ) )
status = - EIO ;
else
status = sprintf ( buf , " %d \n " ,
! ! test_bit ( FLAG_ACTIVE_LOW , & desc - > flags ) ) ;
mutex_unlock ( & sysfs_lock ) ;
return status ;
}
static ssize_t gpio_active_low_store ( struct device * dev ,
struct device_attribute * attr , const char * buf , size_t size )
{
struct gpio_desc * desc = dev_get_drvdata ( dev ) ;
ssize_t status ;
mutex_lock ( & sysfs_lock ) ;
if ( ! test_bit ( FLAG_EXPORT , & desc - > flags ) ) {
status = - EIO ;
} else {
long value ;
status = strict_strtol ( buf , 0 , & value ) ;
if ( status = = 0 )
status = sysfs_set_active_low ( desc , dev , value ! = 0 ) ;
}
mutex_unlock ( & sysfs_lock ) ;
return status ? : size ;
}
static const DEVICE_ATTR ( active_low , 0644 ,
gpio_active_low_show , gpio_active_low_store ) ;
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
static const struct attribute * gpio_attrs [ ] = {
& dev_attr_value . attr ,
2009-12-16 03:46:20 +03:00
& dev_attr_active_low . attr ,
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
NULL ,
} ;
static const struct attribute_group gpio_attr_group = {
. attrs = ( struct attribute * * ) gpio_attrs ,
} ;
/*
* / sys / class / gpio / gpiochipN /
* / base . . . matching gpio_chip . base ( N )
* / label . . . matching gpio_chip . label
* / ngpio . . . matching gpio_chip . ngpio
*/
static ssize_t chip_base_show ( struct device * dev ,
struct device_attribute * attr , char * buf )
{
const struct gpio_chip * chip = dev_get_drvdata ( dev ) ;
return sprintf ( buf , " %d \n " , chip - > base ) ;
}
static DEVICE_ATTR ( base , 0444 , chip_base_show , NULL ) ;
static ssize_t chip_label_show ( struct device * dev ,
struct device_attribute * attr , char * buf )
{
const struct gpio_chip * chip = dev_get_drvdata ( dev ) ;
return sprintf ( buf , " %s \n " , chip - > label ? : " " ) ;
}
static DEVICE_ATTR ( label , 0444 , chip_label_show , NULL ) ;
static ssize_t chip_ngpio_show ( struct device * dev ,
struct device_attribute * attr , char * buf )
{
const struct gpio_chip * chip = dev_get_drvdata ( dev ) ;
return sprintf ( buf , " %u \n " , chip - > ngpio ) ;
}
static DEVICE_ATTR ( ngpio , 0444 , chip_ngpio_show , NULL ) ;
static const struct attribute * gpiochip_attrs [ ] = {
& dev_attr_base . attr ,
& dev_attr_label . attr ,
& dev_attr_ngpio . attr ,
NULL ,
} ;
static const struct attribute_group gpiochip_attr_group = {
. attrs = ( struct attribute * * ) gpiochip_attrs ,
} ;
/*
* / sys / class / gpio / export . . . write - only
* integer N . . . number of GPIO to export ( full access )
* / sys / class / gpio / unexport . . . write - only
* integer N . . . number of GPIO to unexport
*/
2010-01-05 14:48:07 +03:00
static ssize_t export_store ( struct class * class ,
struct class_attribute * attr ,
const char * buf , size_t len )
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
{
long gpio ;
int status ;
status = strict_strtol ( buf , 0 , & gpio ) ;
if ( status < 0 )
goto done ;
/* No extra locking here; FLAG_SYSFS just signifies that the
* request and export were done by on behalf of userspace , so
* they may be undone on its behalf too .
*/
status = gpio_request ( gpio , " sysfs " ) ;
if ( status < 0 )
goto done ;
status = gpio_export ( gpio , true ) ;
if ( status < 0 )
gpio_free ( gpio ) ;
else
set_bit ( FLAG_SYSFS , & gpio_desc [ gpio ] . flags ) ;
done :
if ( status )
pr_debug ( " %s: status %d \n " , __func__ , status ) ;
return status ? : len ;
}
2010-01-05 14:48:07 +03:00
static ssize_t unexport_store ( struct class * class ,
struct class_attribute * attr ,
const char * buf , size_t len )
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
{
long gpio ;
int status ;
status = strict_strtol ( buf , 0 , & gpio ) ;
if ( status < 0 )
goto done ;
status = - EINVAL ;
/* reject bogus commands (gpio_unexport ignores them) */
if ( ! gpio_is_valid ( gpio ) )
goto done ;
/* No extra locking here; FLAG_SYSFS just signifies that the
* request and export were done by on behalf of userspace , so
* they may be undone on its behalf too .
*/
if ( test_and_clear_bit ( FLAG_SYSFS , & gpio_desc [ gpio ] . flags ) ) {
status = 0 ;
gpio_free ( gpio ) ;
}
done :
if ( status )
pr_debug ( " %s: status %d \n " , __func__ , status ) ;
return status ? : len ;
}
static struct class_attribute gpio_class_attrs [ ] = {
__ATTR ( export , 0200 , NULL , export_store ) ,
__ATTR ( unexport , 0200 , NULL , unexport_store ) ,
__ATTR_NULL ,
} ;
static struct class gpio_class = {
. name = " gpio " ,
. owner = THIS_MODULE ,
. class_attrs = gpio_class_attrs ,
} ;
/**
* gpio_export - export a GPIO through sysfs
* @ gpio : gpio to make available , already requested
* @ direction_may_change : true if userspace may change gpio direction
* Context : arch_initcall or later
*
* When drivers want to make a GPIO accessible to userspace after they
* have requested it - - perhaps while debugging , or as part of their
* public interface - - they may use this routine . If the GPIO can
* change direction ( some can ' t ) and the caller allows it , userspace
* will see " direction " sysfs attribute which may be used to change
* the gpio ' s direction . A " value " attribute will always be provided .
*
* Returns zero on success , else an error .
*/
int gpio_export ( unsigned gpio , bool direction_may_change )
{
unsigned long flags ;
struct gpio_desc * desc ;
int status = - EINVAL ;
2010-05-27 01:42:17 +04:00
const char * ioname = NULL ;
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
/* can't export until sysfs is available ... */
if ( ! gpio_class . p ) {
pr_debug ( " %s: called too early! \n " , __func__ ) ;
return - ENOENT ;
}
if ( ! gpio_is_valid ( gpio ) )
goto done ;
mutex_lock ( & sysfs_lock ) ;
spin_lock_irqsave ( & gpio_lock , flags ) ;
desc = & gpio_desc [ gpio ] ;
if ( test_bit ( FLAG_REQUESTED , & desc - > flags )
& & ! test_bit ( FLAG_EXPORT , & desc - > flags ) ) {
status = 0 ;
if ( ! desc - > chip - > direction_input
| | ! desc - > chip - > direction_output )
direction_may_change = false ;
}
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
2009-04-03 03:57:05 +04:00
if ( desc - > chip - > names & & desc - > chip - > names [ gpio - desc - > chip - > base ] )
ioname = desc - > chip - > names [ gpio - desc - > chip - > base ] ;
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
if ( status = = 0 ) {
struct device * dev ;
dev = device_create ( & gpio_class , desc - > chip - > dev , MKDEV ( 0 , 0 ) ,
2010-05-27 01:42:18 +04:00
desc , ioname ? ioname : " gpio%u " , gpio ) ;
2009-11-12 01:26:50 +03:00
if ( ! IS_ERR ( dev ) ) {
2009-12-16 03:46:20 +03:00
status = sysfs_create_group ( & dev - > kobj ,
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
& gpio_attr_group ) ;
2009-12-16 03:46:20 +03:00
if ( ! status & & direction_may_change )
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
status = device_create_file ( dev ,
2009-12-16 03:46:20 +03:00
& dev_attr_direction ) ;
2009-09-23 03:46:38 +04:00
if ( ! status & & gpio_to_irq ( gpio ) > = 0
& & ( direction_may_change
| | ! test_bit ( FLAG_IS_OUT ,
& desc - > flags ) ) )
status = device_create_file ( dev ,
& dev_attr_edge ) ;
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
if ( status ! = 0 )
device_unregister ( dev ) ;
} else
2009-11-12 01:26:50 +03:00
status = PTR_ERR ( dev ) ;
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
if ( status = = 0 )
set_bit ( FLAG_EXPORT , & desc - > flags ) ;
}
mutex_unlock ( & sysfs_lock ) ;
done :
if ( status )
pr_debug ( " %s: gpio%d status %d \n " , __func__ , gpio , status ) ;
return status ;
}
EXPORT_SYMBOL_GPL ( gpio_export ) ;
static int match_export ( struct device * dev , void * data )
{
return dev_get_drvdata ( dev ) = = data ;
}
2009-09-23 03:46:33 +04:00
/**
* gpio_export_link - create a sysfs link to an exported GPIO node
* @ dev : device under which to create symlink
* @ name : name of the symlink
* @ gpio : gpio to create symlink to , already exported
*
* Set up a symlink from / sys / . . . / dev / name to / sys / class / gpio / gpioN
* node . Caller is responsible for unlinking .
*
* Returns zero on success , else an error .
*/
int gpio_export_link ( struct device * dev , const char * name , unsigned gpio )
{
struct gpio_desc * desc ;
int status = - EINVAL ;
if ( ! gpio_is_valid ( gpio ) )
goto done ;
mutex_lock ( & sysfs_lock ) ;
desc = & gpio_desc [ gpio ] ;
if ( test_bit ( FLAG_EXPORT , & desc - > flags ) ) {
struct device * tdev ;
tdev = class_find_device ( & gpio_class , NULL , desc , match_export ) ;
if ( tdev ! = NULL ) {
status = sysfs_create_link ( & dev - > kobj , & tdev - > kobj ,
name ) ;
} else {
status = - ENODEV ;
}
}
mutex_unlock ( & sysfs_lock ) ;
done :
if ( status )
pr_debug ( " %s: gpio%d status %d \n " , __func__ , gpio , status ) ;
return status ;
}
EXPORT_SYMBOL_GPL ( gpio_export_link ) ;
2009-12-16 03:46:20 +03:00
/**
* gpio_sysfs_set_active_low - set the polarity of gpio sysfs value
* @ gpio : gpio to change
* @ value : non - zero to use active low , i . e . inverted values
*
* Set the polarity of / sys / class / gpio / gpioN / value sysfs attribute .
* The GPIO does not have to be exported yet . If poll ( 2 ) support has
* been enabled for either rising or falling edge , it will be
* reconfigured to follow the new polarity .
*
* Returns zero on success , else an error .
*/
int gpio_sysfs_set_active_low ( unsigned gpio , int value )
{
struct gpio_desc * desc ;
struct device * dev = NULL ;
int status = - EINVAL ;
if ( ! gpio_is_valid ( gpio ) )
goto done ;
mutex_lock ( & sysfs_lock ) ;
desc = & gpio_desc [ gpio ] ;
if ( test_bit ( FLAG_EXPORT , & desc - > flags ) ) {
dev = class_find_device ( & gpio_class , NULL , desc , match_export ) ;
if ( dev = = NULL ) {
status = - ENODEV ;
goto unlock ;
}
}
status = sysfs_set_active_low ( desc , dev , value ) ;
unlock :
mutex_unlock ( & sysfs_lock ) ;
done :
if ( status )
pr_debug ( " %s: gpio%d status %d \n " , __func__ , gpio , status ) ;
return status ;
}
EXPORT_SYMBOL_GPL ( gpio_sysfs_set_active_low ) ;
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
/**
* gpio_unexport - reverse effect of gpio_export ( )
* @ gpio : gpio to make unavailable
*
* This is implicit on gpio_free ( ) .
*/
void gpio_unexport ( unsigned gpio )
{
struct gpio_desc * desc ;
2010-07-28 00:18:06 +04:00
int status = 0 ;
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
2010-07-28 00:18:06 +04:00
if ( ! gpio_is_valid ( gpio ) ) {
status = - EINVAL ;
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
goto done ;
2010-07-28 00:18:06 +04:00
}
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
mutex_lock ( & sysfs_lock ) ;
desc = & gpio_desc [ gpio ] ;
2009-04-03 03:57:05 +04:00
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
if ( test_bit ( FLAG_EXPORT , & desc - > flags ) ) {
struct device * dev = NULL ;
dev = class_find_device ( & gpio_class , NULL , desc , match_export ) ;
if ( dev ) {
2009-09-23 03:46:38 +04:00
gpio_setup_irq ( desc , dev , 0 ) ;
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
clear_bit ( FLAG_EXPORT , & desc - > flags ) ;
put_device ( dev ) ;
device_unregister ( dev ) ;
} else
status = - ENODEV ;
}
mutex_unlock ( & sysfs_lock ) ;
done :
if ( status )
pr_debug ( " %s: gpio%d status %d \n " , __func__ , gpio , status ) ;
}
EXPORT_SYMBOL_GPL ( gpio_unexport ) ;
static int gpiochip_export ( struct gpio_chip * chip )
{
int status ;
struct device * dev ;
/* Many systems register gpio chips for SOC support very early,
* before driver model support is available . In those cases we
* export this later , in gpiolib_sysfs_init ( ) . . . here we just
* verify that _some_ field of gpio_class got initialized .
*/
if ( ! gpio_class . p )
return 0 ;
/* use chip->base for the ID; it's already known to be unique */
mutex_lock ( & sysfs_lock ) ;
dev = device_create ( & gpio_class , chip - > dev , MKDEV ( 0 , 0 ) , chip ,
" gpiochip%d " , chip - > base ) ;
2009-11-12 01:26:50 +03:00
if ( ! IS_ERR ( dev ) ) {
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
status = sysfs_create_group ( & dev - > kobj ,
& gpiochip_attr_group ) ;
} else
2009-11-12 01:26:50 +03:00
status = PTR_ERR ( dev ) ;
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
chip - > exported = ( status = = 0 ) ;
mutex_unlock ( & sysfs_lock ) ;
if ( status ) {
unsigned long flags ;
unsigned gpio ;
spin_lock_irqsave ( & gpio_lock , flags ) ;
gpio = chip - > base ;
while ( gpio_desc [ gpio ] . chip = = chip )
gpio_desc [ gpio + + ] . chip = NULL ;
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
pr_debug ( " %s: chip %s status %d \n " , __func__ ,
chip - > label , status ) ;
}
return status ;
}
static void gpiochip_unexport ( struct gpio_chip * chip )
{
int status ;
struct device * dev ;
mutex_lock ( & sysfs_lock ) ;
dev = class_find_device ( & gpio_class , NULL , chip , match_export ) ;
if ( dev ) {
put_device ( dev ) ;
device_unregister ( dev ) ;
chip - > exported = 0 ;
status = 0 ;
} else
status = - ENODEV ;
mutex_unlock ( & sysfs_lock ) ;
if ( status )
pr_debug ( " %s: chip %s status %d \n " , __func__ ,
chip - > label , status ) ;
}
static int __init gpiolib_sysfs_init ( void )
{
int status ;
unsigned long flags ;
unsigned gpio ;
status = class_register ( & gpio_class ) ;
if ( status < 0 )
return status ;
/* Scan and register the gpio_chips which registered very
* early ( e . g . before the class_register above was called ) .
*
* We run before arch_initcall ( ) so chip - > dev nodes can have
* registered , and so arch_initcall ( ) can always gpio_export ( ) .
*/
spin_lock_irqsave ( & gpio_lock , flags ) ;
for ( gpio = 0 ; gpio < ARCH_NR_GPIOS ; gpio + + ) {
struct gpio_chip * chip ;
chip = gpio_desc [ gpio ] . chip ;
if ( ! chip | | chip - > exported )
continue ;
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
status = gpiochip_export ( chip ) ;
spin_lock_irqsave ( & gpio_lock , flags ) ;
}
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
return status ;
}
postcore_initcall ( gpiolib_sysfs_init ) ;
# else
static inline int gpiochip_export ( struct gpio_chip * chip )
{
return 0 ;
}
static inline void gpiochip_unexport ( struct gpio_chip * chip )
{
}
# endif /* CONFIG_GPIO_SYSFS */
2008-02-05 09:28:20 +03:00
/**
* gpiochip_add ( ) - register a gpio_chip
* @ chip : the chip to register , with chip - > base initialized
* Context : potentially before irqs or kmalloc will work
*
* Returns a negative errno if the chip can ' t be registered , such as
* because the chip - > base is invalid or already associated with a
* different chip . Otherwise it returns zero as a success code .
2008-04-28 13:14:46 +04:00
*
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
* When gpiochip_add ( ) is called very early during boot , so that GPIOs
* can be freely used , the chip - > dev device must be registered before
* the gpio framework ' s arch_initcall ( ) . Otherwise sysfs initialization
* for GPIOs will fail rudely .
*
2008-04-28 13:14:46 +04:00
* If chip - > base is negative , this requests dynamic assignment of
* a range of valid GPIOs .
2008-02-05 09:28:20 +03:00
*/
int gpiochip_add ( struct gpio_chip * chip )
{
unsigned long flags ;
int status = 0 ;
unsigned id ;
2008-04-28 13:14:46 +04:00
int base = chip - > base ;
2008-02-05 09:28:20 +03:00
2008-05-24 00:04:44 +04:00
if ( ( ! gpio_is_valid ( base ) | | ! gpio_is_valid ( base + chip - > ngpio - 1 ) )
2008-04-28 13:14:46 +04:00
& & base > = 0 ) {
2008-02-05 09:28:20 +03:00
status = - EINVAL ;
goto fail ;
}
spin_lock_irqsave ( & gpio_lock , flags ) ;
2008-04-28 13:14:46 +04:00
if ( base < 0 ) {
base = gpiochip_find_base ( chip - > ngpio ) ;
if ( base < 0 ) {
status = base ;
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
goto unlock ;
2008-04-28 13:14:46 +04:00
}
chip - > base = base ;
}
2008-02-05 09:28:20 +03:00
/* these GPIO numbers must not be managed by another gpio_chip */
2008-04-28 13:14:46 +04:00
for ( id = base ; id < base + chip - > ngpio ; id + + ) {
2008-02-05 09:28:20 +03:00
if ( gpio_desc [ id ] . chip ! = NULL ) {
status = - EBUSY ;
break ;
}
}
if ( status = = 0 ) {
2008-04-28 13:14:46 +04:00
for ( id = base ; id < base + chip - > ngpio ; id + + ) {
2008-02-05 09:28:20 +03:00
gpio_desc [ id ] . chip = chip ;
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
/* REVISIT: most hardware initializes GPIOs as
* inputs ( often with pullups enabled ) so power
* usage is minimized . Linux code should set the
* gpio direction first thing ; but until it does ,
* we may expose the wrong direction in sysfs .
*/
gpio_desc [ id ] . flags = ! chip - > direction_input
? ( 1 < < FLAG_IS_OUT )
: 0 ;
2008-02-05 09:28:20 +03:00
}
}
2010-06-08 17:48:17 +04:00
of_gpiochip_add ( chip ) ;
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
unlock :
2008-02-05 09:28:20 +03:00
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
2010-06-08 17:48:15 +04:00
if ( status )
goto fail ;
status = gpiochip_export ( chip ) ;
if ( status )
goto fail ;
return 0 ;
2008-02-05 09:28:20 +03:00
fail :
/* failures here can mean systems won't boot... */
2010-06-08 17:48:15 +04:00
pr_err ( " gpiochip_add: gpios %d..%d (%s) failed to register \n " ,
chip - > base , chip - > base + chip - > ngpio - 1 ,
chip - > label ? : " generic " ) ;
2008-02-05 09:28:20 +03:00
return status ;
}
EXPORT_SYMBOL_GPL ( gpiochip_add ) ;
/**
* gpiochip_remove ( ) - unregister a gpio_chip
* @ chip : the chip to unregister
*
* A gpio_chip with any GPIOs still requested may not be removed .
*/
int gpiochip_remove ( struct gpio_chip * chip )
{
unsigned long flags ;
int status = 0 ;
unsigned id ;
spin_lock_irqsave ( & gpio_lock , flags ) ;
2010-06-08 17:48:17 +04:00
of_gpiochip_remove ( chip ) ;
2008-02-05 09:28:20 +03:00
for ( id = chip - > base ; id < chip - > base + chip - > ngpio ; id + + ) {
if ( test_bit ( FLAG_REQUESTED , & gpio_desc [ id ] . flags ) ) {
status = - EBUSY ;
break ;
}
}
if ( status = = 0 ) {
for ( id = chip - > base ; id < chip - > base + chip - > ngpio ; id + + )
gpio_desc [ id ] . chip = NULL ;
}
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
if ( status = = 0 )
gpiochip_unexport ( chip ) ;
2008-02-05 09:28:20 +03:00
return status ;
}
EXPORT_SYMBOL_GPL ( gpiochip_remove ) ;
2010-06-08 17:48:16 +04:00
/**
* gpiochip_find ( ) - iterator for locating a specific gpio_chip
* @ data : data to pass to match function
* @ callback : Callback function to check gpio_chip
*
* Similar to bus_find_device . It returns a reference to a gpio_chip as
* determined by a user supplied @ match callback . The callback should return
* 0 if the device doesn ' t match and non - zero if it does . If the callback is
* non - zero , this function will return to the caller and not iterate over any
* more gpio_chips .
*/
struct gpio_chip * gpiochip_find ( void * data ,
int ( * match ) ( struct gpio_chip * chip , void * data ) )
{
struct gpio_chip * chip = NULL ;
unsigned long flags ;
int i ;
spin_lock_irqsave ( & gpio_lock , flags ) ;
for ( i = 0 ; i < ARCH_NR_GPIOS ; i + + ) {
if ( ! gpio_desc [ i ] . chip )
continue ;
if ( match ( gpio_desc [ i ] . chip , data ) ) {
chip = gpio_desc [ i ] . chip ;
break ;
}
}
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
return chip ;
}
2008-02-05 09:28:20 +03:00
/* These "optional" allocation calls help prevent drivers from stomping
* on each other , and help provide better diagnostics in debugfs .
* They ' re called even less than the " set direction " calls .
*/
int gpio_request ( unsigned gpio , const char * label )
{
struct gpio_desc * desc ;
2008-10-16 09:03:16 +04:00
struct gpio_chip * chip ;
2008-02-05 09:28:20 +03:00
int status = - EINVAL ;
unsigned long flags ;
spin_lock_irqsave ( & gpio_lock , flags ) ;
2008-04-28 13:14:46 +04:00
if ( ! gpio_is_valid ( gpio ) )
2008-02-05 09:28:20 +03:00
goto done ;
desc = & gpio_desc [ gpio ] ;
2008-10-16 09:03:16 +04:00
chip = desc - > chip ;
if ( chip = = NULL )
2008-02-05 09:28:20 +03:00
goto done ;
2008-10-16 09:03:16 +04:00
if ( ! try_module_get ( chip - > owner ) )
2008-04-28 13:14:44 +04:00
goto done ;
2008-02-05 09:28:20 +03:00
/* NOTE: gpio_request() can be called in early boot,
2008-10-16 09:03:16 +04:00
* before IRQs are enabled , for non - sleeping ( SOC ) GPIOs .
2008-02-05 09:28:20 +03:00
*/
if ( test_and_set_bit ( FLAG_REQUESTED , & desc - > flags ) = = 0 ) {
desc_set_label ( desc , label ? : " ? " ) ;
status = 0 ;
2008-04-28 13:14:44 +04:00
} else {
2008-02-05 09:28:20 +03:00
status = - EBUSY ;
2008-10-16 09:03:16 +04:00
module_put ( chip - > owner ) ;
2009-01-30 01:25:12 +03:00
goto done ;
2008-10-16 09:03:16 +04:00
}
if ( chip - > request ) {
/* chip->request may sleep */
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
status = chip - > request ( chip , gpio - chip - > base ) ;
spin_lock_irqsave ( & gpio_lock , flags ) ;
if ( status < 0 ) {
desc_set_label ( desc , NULL ) ;
module_put ( chip - > owner ) ;
clear_bit ( FLAG_REQUESTED , & desc - > flags ) ;
}
2008-04-28 13:14:44 +04:00
}
2008-02-05 09:28:20 +03:00
done :
if ( status )
pr_debug ( " gpio_request: gpio-%d (%s) status %d \n " ,
gpio , label ? : " ? " , status ) ;
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
return status ;
}
EXPORT_SYMBOL_GPL ( gpio_request ) ;
void gpio_free ( unsigned gpio )
{
unsigned long flags ;
struct gpio_desc * desc ;
2008-10-16 09:03:16 +04:00
struct gpio_chip * chip ;
2008-02-05 09:28:20 +03:00
2008-10-16 09:03:12 +04:00
might_sleep ( ) ;
2008-04-28 13:14:46 +04:00
if ( ! gpio_is_valid ( gpio ) ) {
2008-02-05 09:28:20 +03:00
WARN_ON ( extra_checks ) ;
return ;
}
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
gpio_unexport ( gpio ) ;
2008-02-05 09:28:20 +03:00
spin_lock_irqsave ( & gpio_lock , flags ) ;
desc = & gpio_desc [ gpio ] ;
2008-10-16 09:03:16 +04:00
chip = desc - > chip ;
if ( chip & & test_bit ( FLAG_REQUESTED , & desc - > flags ) ) {
if ( chip - > free ) {
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
2010-08-11 05:02:24 +04:00
might_sleep_if ( chip - > can_sleep ) ;
2008-10-16 09:03:16 +04:00
chip - > free ( chip , gpio - chip - > base ) ;
spin_lock_irqsave ( & gpio_lock , flags ) ;
}
2008-02-05 09:28:20 +03:00
desc_set_label ( desc , NULL ) ;
2008-04-28 13:14:44 +04:00
module_put ( desc - > chip - > owner ) ;
2009-12-16 03:46:20 +03:00
clear_bit ( FLAG_ACTIVE_LOW , & desc - > flags ) ;
2008-10-16 09:03:16 +04:00
clear_bit ( FLAG_REQUESTED , & desc - > flags ) ;
2008-04-28 13:14:44 +04:00
} else
2008-02-05 09:28:20 +03:00
WARN_ON ( extra_checks ) ;
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
}
EXPORT_SYMBOL_GPL ( gpio_free ) ;
2010-03-06 00:44:35 +03:00
/**
* gpio_request_one - request a single GPIO with initial configuration
* @ gpio : the GPIO number
* @ flags : GPIO configuration as specified by GPIOF_ *
* @ label : a literal description string of this GPIO
*/
int gpio_request_one ( unsigned gpio , unsigned long flags , const char * label )
{
int err ;
err = gpio_request ( gpio , label ) ;
if ( err )
return err ;
if ( flags & GPIOF_DIR_IN )
err = gpio_direction_input ( gpio ) ;
else
err = gpio_direction_output ( gpio ,
( flags & GPIOF_INIT_HIGH ) ? 1 : 0 ) ;
return err ;
}
EXPORT_SYMBOL_GPL ( gpio_request_one ) ;
/**
* gpio_request_array - request multiple GPIOs in a single call
* @ array : array of the ' struct gpio '
* @ num : how many GPIOs in the array
*/
int gpio_request_array ( struct gpio * array , size_t num )
{
int i , err ;
for ( i = 0 ; i < num ; i + + , array + + ) {
err = gpio_request_one ( array - > gpio , array - > flags , array - > label ) ;
if ( err )
goto err_free ;
}
return 0 ;
err_free :
while ( i - - )
gpio_free ( ( - - array ) - > gpio ) ;
return err ;
}
EXPORT_SYMBOL_GPL ( gpio_request_array ) ;
/**
* gpio_free_array - release multiple GPIOs in a single call
* @ array : array of the ' struct gpio '
* @ num : how many GPIOs in the array
*/
void gpio_free_array ( struct gpio * array , size_t num )
{
while ( num - - )
gpio_free ( ( array + + ) - > gpio ) ;
}
EXPORT_SYMBOL_GPL ( gpio_free_array ) ;
2008-02-05 09:28:20 +03:00
/**
* gpiochip_is_requested - return string iff signal was requested
* @ chip : controller managing the signal
* @ offset : of signal within controller ' s 0. . ( ngpio - 1 ) range
*
* Returns NULL if the GPIO is not currently requested , else a string .
* If debugfs support is enabled , the string returned is the label passed
* to gpio_request ( ) ; otherwise it is a meaningless constant .
*
* This function is for use by GPIO controller drivers . The label can
* help with diagnostics , and knowing that the signal is used as a GPIO
* can help avoid accidentally multiplexing it to another controller .
*/
const char * gpiochip_is_requested ( struct gpio_chip * chip , unsigned offset )
{
unsigned gpio = chip - > base + offset ;
2008-04-28 13:14:46 +04:00
if ( ! gpio_is_valid ( gpio ) | | gpio_desc [ gpio ] . chip ! = chip )
2008-02-05 09:28:20 +03:00
return NULL ;
if ( test_bit ( FLAG_REQUESTED , & gpio_desc [ gpio ] . flags ) = = 0 )
return NULL ;
# ifdef CONFIG_DEBUG_FS
return gpio_desc [ gpio ] . label ;
# else
return " ? " ;
# endif
}
EXPORT_SYMBOL_GPL ( gpiochip_is_requested ) ;
/* Drivers MUST set GPIO direction before making get/set calls. In
* some cases this is done in early boot , before IRQs are enabled .
*
* As a rule these aren ' t called more than once ( except for drivers
* using the open - drain emulation idiom ) so these are natural places
* to accumulate extra debugging checks . Note that we can ' t ( yet )
* rely on gpio_request ( ) having been called beforehand .
*/
int gpio_direction_input ( unsigned gpio )
{
unsigned long flags ;
struct gpio_chip * chip ;
struct gpio_desc * desc = & gpio_desc [ gpio ] ;
int status = - EINVAL ;
spin_lock_irqsave ( & gpio_lock , flags ) ;
2008-04-28 13:14:46 +04:00
if ( ! gpio_is_valid ( gpio ) )
2008-02-05 09:28:20 +03:00
goto fail ;
chip = desc - > chip ;
if ( ! chip | | ! chip - > get | | ! chip - > direction_input )
goto fail ;
gpio - = chip - > base ;
if ( gpio > = chip - > ngpio )
goto fail ;
2008-10-16 09:03:16 +04:00
status = gpio_ensure_requested ( desc , gpio ) ;
if ( status < 0 )
goto fail ;
2008-02-05 09:28:20 +03:00
/* now we know the gpio is valid and chip won't vanish */
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
2010-08-11 05:02:24 +04:00
might_sleep_if ( chip - > can_sleep ) ;
2008-02-05 09:28:20 +03:00
2008-10-16 09:03:16 +04:00
if ( status ) {
status = chip - > request ( chip , gpio ) ;
if ( status < 0 ) {
pr_debug ( " GPIO-%d: chip request fail, %d \n " ,
chip - > base + gpio , status ) ;
/* and it's not available to anyone else ...
* gpio_request ( ) is the fully clean solution .
*/
goto lose ;
}
}
2008-02-05 09:28:20 +03:00
status = chip - > direction_input ( chip , gpio ) ;
if ( status = = 0 )
clear_bit ( FLAG_IS_OUT , & desc - > flags ) ;
2008-10-16 09:03:16 +04:00
lose :
2008-02-05 09:28:20 +03:00
return status ;
fail :
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
if ( status )
pr_debug ( " %s: gpio-%d status %d \n " ,
2008-04-30 11:54:57 +04:00
__func__ , gpio , status ) ;
2008-02-05 09:28:20 +03:00
return status ;
}
EXPORT_SYMBOL_GPL ( gpio_direction_input ) ;
int gpio_direction_output ( unsigned gpio , int value )
{
unsigned long flags ;
struct gpio_chip * chip ;
struct gpio_desc * desc = & gpio_desc [ gpio ] ;
int status = - EINVAL ;
spin_lock_irqsave ( & gpio_lock , flags ) ;
2008-04-28 13:14:46 +04:00
if ( ! gpio_is_valid ( gpio ) )
2008-02-05 09:28:20 +03:00
goto fail ;
chip = desc - > chip ;
if ( ! chip | | ! chip - > set | | ! chip - > direction_output )
goto fail ;
gpio - = chip - > base ;
if ( gpio > = chip - > ngpio )
goto fail ;
2008-10-16 09:03:16 +04:00
status = gpio_ensure_requested ( desc , gpio ) ;
if ( status < 0 )
goto fail ;
2008-02-05 09:28:20 +03:00
/* now we know the gpio is valid and chip won't vanish */
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
2010-08-11 05:02:24 +04:00
might_sleep_if ( chip - > can_sleep ) ;
2008-02-05 09:28:20 +03:00
2008-10-16 09:03:16 +04:00
if ( status ) {
status = chip - > request ( chip , gpio ) ;
if ( status < 0 ) {
pr_debug ( " GPIO-%d: chip request fail, %d \n " ,
chip - > base + gpio , status ) ;
/* and it's not available to anyone else ...
* gpio_request ( ) is the fully clean solution .
*/
goto lose ;
}
}
2008-02-05 09:28:20 +03:00
status = chip - > direction_output ( chip , gpio , value ) ;
if ( status = = 0 )
set_bit ( FLAG_IS_OUT , & desc - > flags ) ;
2008-10-16 09:03:16 +04:00
lose :
2008-02-05 09:28:20 +03:00
return status ;
fail :
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
if ( status )
pr_debug ( " %s: gpio-%d status %d \n " ,
2008-04-30 11:54:57 +04:00
__func__ , gpio , status ) ;
2008-02-05 09:28:20 +03:00
return status ;
}
EXPORT_SYMBOL_GPL ( gpio_direction_output ) ;
2010-05-27 01:42:23 +04:00
/**
* gpio_set_debounce - sets @ debounce time for a @ gpio
* @ gpio : the gpio to set debounce time
* @ debounce : debounce time is microseconds
*/
int gpio_set_debounce ( unsigned gpio , unsigned debounce )
{
unsigned long flags ;
struct gpio_chip * chip ;
struct gpio_desc * desc = & gpio_desc [ gpio ] ;
int status = - EINVAL ;
spin_lock_irqsave ( & gpio_lock , flags ) ;
if ( ! gpio_is_valid ( gpio ) )
goto fail ;
chip = desc - > chip ;
if ( ! chip | | ! chip - > set | | ! chip - > set_debounce )
goto fail ;
gpio - = chip - > base ;
if ( gpio > = chip - > ngpio )
goto fail ;
status = gpio_ensure_requested ( desc , gpio ) ;
if ( status < 0 )
goto fail ;
/* now we know the gpio is valid and chip won't vanish */
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
2010-08-11 05:02:24 +04:00
might_sleep_if ( chip - > can_sleep ) ;
2010-05-27 01:42:23 +04:00
return chip - > set_debounce ( chip , gpio , debounce ) ;
fail :
spin_unlock_irqrestore ( & gpio_lock , flags ) ;
if ( status )
pr_debug ( " %s: gpio-%d status %d \n " ,
__func__ , gpio , status ) ;
return status ;
}
EXPORT_SYMBOL_GPL ( gpio_set_debounce ) ;
2008-02-05 09:28:20 +03:00
/* I/O calls are only valid after configuration completed; the relevant
* " is this a valid GPIO " error checks should already have been done .
*
* " Get " operations are often inlinable as reading a pin value register ,
* and masking the relevant bit in that register .
*
* When " set " operations are inlinable , they involve writing that mask to
* one register to set a low value , or a different register to set it high .
* Otherwise locking is needed , so there may be little value to inlining .
*
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
*
* IMPORTANT ! ! ! The hot paths - - get / set value - - assume that callers
* have requested the GPIO . That can include implicit requesting by
* a direction setting call . Marking a gpio as requested locks its chip
* in memory , guaranteeing that these table lookups need no more locking
* and that gpiochip_remove ( ) will fail .
*
* REVISIT when debugging , consider adding some instrumentation to ensure
* that the GPIO was actually requested .
*/
/**
* __gpio_get_value ( ) - return a gpio ' s value
* @ gpio : gpio whose value will be returned
* Context : any
*
* This is used directly or indirectly to implement gpio_get_value ( ) .
* It returns the zero or nonzero value provided by the associated
* gpio_chip . get ( ) method ; or zero if no such method is provided .
*/
int __gpio_get_value ( unsigned gpio )
{
struct gpio_chip * chip ;
chip = gpio_to_chip ( gpio ) ;
2010-08-11 05:02:24 +04:00
WARN_ON ( chip - > can_sleep ) ;
2008-02-05 09:28:20 +03:00
return chip - > get ? chip - > get ( chip , gpio - chip - > base ) : 0 ;
}
EXPORT_SYMBOL_GPL ( __gpio_get_value ) ;
/**
* __gpio_set_value ( ) - assign a gpio ' s value
* @ gpio : gpio whose value will be assigned
* @ value : value to assign
* Context : any
*
* This is used directly or indirectly to implement gpio_set_value ( ) .
* It invokes the associated gpio_chip . set ( ) method .
*/
void __gpio_set_value ( unsigned gpio , int value )
{
struct gpio_chip * chip ;
chip = gpio_to_chip ( gpio ) ;
2010-08-11 05:02:24 +04:00
WARN_ON ( chip - > can_sleep ) ;
2008-02-05 09:28:20 +03:00
chip - > set ( chip , gpio - chip - > base , value ) ;
}
EXPORT_SYMBOL_GPL ( __gpio_set_value ) ;
/**
* __gpio_cansleep ( ) - report whether gpio value access will sleep
* @ gpio : gpio in question
* Context : any
*
* This is used directly or indirectly to implement gpio_cansleep ( ) . It
* returns nonzero if access reading or writing the GPIO value can sleep .
*/
int __gpio_cansleep ( unsigned gpio )
{
struct gpio_chip * chip ;
/* only call this on GPIOs that are valid! */
chip = gpio_to_chip ( gpio ) ;
return chip - > can_sleep ;
}
EXPORT_SYMBOL_GPL ( __gpio_cansleep ) ;
2008-10-16 09:03:14 +04:00
/**
* __gpio_to_irq ( ) - return the IRQ corresponding to a GPIO
* @ gpio : gpio whose IRQ will be returned ( already requested )
* Context : any
*
* This is used directly or indirectly to implement gpio_to_irq ( ) .
* It returns the number of the IRQ signaled by this ( input ) GPIO ,
* or a negative errno .
*/
int __gpio_to_irq ( unsigned gpio )
{
struct gpio_chip * chip ;
chip = gpio_to_chip ( gpio ) ;
return chip - > to_irq ? chip - > to_irq ( chip , gpio - chip - > base ) : - ENXIO ;
}
EXPORT_SYMBOL_GPL ( __gpio_to_irq ) ;
2008-02-05 09:28:20 +03:00
/* There's no value in making it easy to inline GPIO calls that may sleep.
* Common examples include ones connected to I2C or SPI chips .
*/
int gpio_get_value_cansleep ( unsigned gpio )
{
struct gpio_chip * chip ;
might_sleep_if ( extra_checks ) ;
chip = gpio_to_chip ( gpio ) ;
2008-10-19 07:27:49 +04:00
return chip - > get ? chip - > get ( chip , gpio - chip - > base ) : 0 ;
2008-02-05 09:28:20 +03:00
}
EXPORT_SYMBOL_GPL ( gpio_get_value_cansleep ) ;
void gpio_set_value_cansleep ( unsigned gpio , int value )
{
struct gpio_chip * chip ;
might_sleep_if ( extra_checks ) ;
chip = gpio_to_chip ( gpio ) ;
chip - > set ( chip , gpio - chip - > base , value ) ;
}
EXPORT_SYMBOL_GPL ( gpio_set_value_cansleep ) ;
# ifdef CONFIG_DEBUG_FS
static void gpiolib_dbg_show ( struct seq_file * s , struct gpio_chip * chip )
{
unsigned i ;
unsigned gpio = chip - > base ;
struct gpio_desc * gdesc = & gpio_desc [ gpio ] ;
int is_out ;
for ( i = 0 ; i < chip - > ngpio ; i + + , gpio + + , gdesc + + ) {
if ( ! test_bit ( FLAG_REQUESTED , & gdesc - > flags ) )
continue ;
is_out = test_bit ( FLAG_IS_OUT , & gdesc - > flags ) ;
2008-11-20 02:36:17 +03:00
seq_printf ( s , " gpio-%-3d (%-20.20s) %s %s " ,
2008-02-05 09:28:20 +03:00
gpio , gdesc - > label ,
is_out ? " out " : " in " ,
chip - > get
? ( chip - > get ( chip , i ) ? " hi " : " lo " )
: " ? " ) ;
if ( ! is_out ) {
int irq = gpio_to_irq ( gpio ) ;
2008-08-20 07:50:05 +04:00
struct irq_desc * desc = irq_to_desc ( irq ) ;
2008-02-05 09:28:20 +03:00
/* This races with request_irq(), set_irq_type(),
* and set_irq_wake ( ) . . . but those are " rare " .
*
* More significantly , trigger type flags aren ' t
* currently maintained by genirq .
*/
if ( irq > = 0 & & desc - > action ) {
char * trigger ;
switch ( desc - > status & IRQ_TYPE_SENSE_MASK ) {
case IRQ_TYPE_NONE :
trigger = " (default) " ;
break ;
case IRQ_TYPE_EDGE_FALLING :
trigger = " edge-falling " ;
break ;
case IRQ_TYPE_EDGE_RISING :
trigger = " edge-rising " ;
break ;
case IRQ_TYPE_EDGE_BOTH :
trigger = " edge-both " ;
break ;
case IRQ_TYPE_LEVEL_HIGH :
trigger = " level-high " ;
break ;
case IRQ_TYPE_LEVEL_LOW :
trigger = " level-low " ;
break ;
default :
trigger = " ?trigger? " ;
break ;
}
seq_printf ( s , " irq-%d %s%s " ,
irq , trigger ,
( desc - > status & IRQ_WAKEUP )
? " wakeup " : " " ) ;
}
}
seq_printf ( s , " \n " ) ;
}
}
static int gpiolib_show ( struct seq_file * s , void * unused )
{
struct gpio_chip * chip = NULL ;
unsigned gpio ;
int started = 0 ;
/* REVISIT this isn't locked against gpio_chip removal ... */
2008-04-28 13:14:46 +04:00
for ( gpio = 0 ; gpio_is_valid ( gpio ) ; gpio + + ) {
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
struct device * dev ;
2008-02-05 09:28:20 +03:00
if ( chip = = gpio_desc [ gpio ] . chip )
continue ;
chip = gpio_desc [ gpio ] . chip ;
if ( ! chip )
continue ;
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
seq_printf ( s , " %sGPIOs %d-%d " ,
2008-02-05 09:28:20 +03:00
started ? " \n " : " " ,
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
chip - > base , chip - > base + chip - > ngpio - 1 ) ;
dev = chip - > dev ;
if ( dev )
seq_printf ( s , " , %s/%s " ,
dev - > bus ? dev - > bus - > name : " no-bus " ,
2009-01-06 21:44:42 +03:00
dev_name ( dev ) ) ;
gpio: sysfs interface
This adds a simple sysfs interface for GPIOs.
/sys/class/gpio
/export ... asks the kernel to export a GPIO to userspace
/unexport ... to return a GPIO to the kernel
/gpioN ... for each exported GPIO #N
/value ... always readable, writes fail for input GPIOs
/direction ... r/w as: in, out (default low); write high, low
/gpiochipN ... for each gpiochip; #N is its first GPIO
/base ... (r/o) same as N
/label ... (r/o) descriptive, not necessarily unique
/ngpio ... (r/o) number of GPIOs; numbered N .. N+(ngpio - 1)
GPIOs claimed by kernel code may be exported by its owner using a new
gpio_export() call, which should be most useful for driver debugging.
Such exports may optionally be done without a "direction" attribute.
Userspace may ask to take over a GPIO by writing to a sysfs control file,
helping to cope with incomplete board support or other "one-off"
requirements that don't merit full kernel support:
echo 23 > /sys/class/gpio/export
... will gpio_request(23, "sysfs") and gpio_export(23);
use /sys/class/gpio/gpio-23/direction to (re)configure it,
when that GPIO can be used as both input and output.
echo 23 > /sys/class/gpio/unexport
... will gpio_free(23), when it was exported as above
The extra D-space footprint is a few hundred bytes, except for the sysfs
resources associated with each exported GPIO. The additional I-space
footprint is about two thirds of the current size of gpiolib (!). Since
no /dev node creation is involved, no "udev" support is needed.
Related changes:
* This adds a device pointer to "struct gpio_chip". When GPIO
providers initialize that, sysfs gpio class devices become children of
that device instead of being "virtual" devices.
* The (few) gpio_chip providers which have such a device node have
been updated.
* Some gpio_chip drivers also needed to update their module "owner"
field ... for which missing kerneldoc was added.
* Some gpio_chips don't support input GPIOs. Those GPIOs are now
flagged appropriately when the chip is registered.
Based on previous patches, and discussion both on and off LKML.
A Documentation/ABI/testing/sysfs-gpio update is ready to submit once this
merges to mainline.
[akpm@linux-foundation.org: a few maintenance build fixes]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 12:46:07 +04:00
if ( chip - > label )
seq_printf ( s , " , %s " , chip - > label ) ;
if ( chip - > can_sleep )
seq_printf ( s , " , can sleep " ) ;
seq_printf ( s , " : \n " ) ;
2008-02-05 09:28:20 +03:00
started = 1 ;
if ( chip - > dbg_show )
chip - > dbg_show ( s , chip ) ;
else
gpiolib_dbg_show ( s , chip ) ;
}
return 0 ;
}
static int gpiolib_open ( struct inode * inode , struct file * file )
{
return single_open ( file , gpiolib_show , NULL ) ;
}
2009-10-02 02:43:56 +04:00
static const struct file_operations gpiolib_operations = {
2008-02-05 09:28:20 +03:00
. open = gpiolib_open ,
. read = seq_read ,
. llseek = seq_lseek ,
. release = single_release ,
} ;
static int __init gpiolib_debugfs_init ( void )
{
/* /sys/kernel/debug/gpio */
( void ) debugfs_create_file ( " gpio " , S_IFREG | S_IRUGO ,
NULL , NULL , & gpiolib_operations ) ;
return 0 ;
}
subsys_initcall ( gpiolib_debugfs_init ) ;
# endif /* DEBUG_FS */