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gpio: sysfs interface

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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>
This commit is contained in:
David Brownell 2008-07-25 01:46:07 -07:00 committed by Linus Torvalds
parent 8b6dd98682
commit d8f388d8dc
12 changed files with 712 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

123
Documentation/gpio.txt
View File

@ -347,15 +347,12 @@ necessarily be nonportable.
Dynamic definition of GPIOs is not currently standard; for example, as
a side effect of configuring an add-on board with some GPIO expanders.
These calls are purely for kernel space, but a userspace API could be built
on top of them.
GPIO implementor's framework (OPTIONAL)
=======================================
As noted earlier, there is an optional implementation framework making it
easier for platforms to support different kinds of GPIO controller using
the same programming interface.
the same programming interface. This framework is called "gpiolib".
As a debugging aid, if debugfs is available a /sys/kernel/debug/gpio file
will be found there. That will list all the controllers registered through
@ -439,4 +436,120 @@ becomes available. That may mean the device should not be registered until
calls for that GPIO can work. One way to address such dependencies is for
such gpio_chip controllers to provide setup() and teardown() callbacks to
board specific code; those board specific callbacks would register devices
once all the necessary resources are available.
once all the necessary resources are available, and remove them later when
the GPIO controller device becomes unavailable.
Sysfs Interface for Userspace (OPTIONAL)
========================================
Platforms which use the "gpiolib" implementors framework may choose to
configure a sysfs user interface to GPIOs. This is different from the
debugfs interface, since it provides control over GPIO direction and
value instead of just showing a gpio state summary. Plus, it could be
present on production systems without debugging support.
Given approprate hardware documentation for the system, userspace could
know for example that GPIO #23 controls the write protect line used to
protect boot loader segments in flash memory. System upgrade procedures
may need to temporarily remove that protection, first importing a GPIO,
then changing its output state, then updating the code before re-enabling
the write protection. In normal use, GPIO #23 would never be touched,
and the kernel would have no need to know about it.
Again depending on appropriate hardware documentation, on some systems
userspace GPIO can be used to determine system configuration data that
standard kernels won't know about. And for some tasks, simple userspace
GPIO drivers could be all that the system really needs.
Note that standard kernel drivers exist for common "LEDs and Buttons"
GPIO tasks: "leds-gpio" and "gpio_keys", respectively. Use those
instead of talking directly to the GPIOs; they integrate with kernel
frameworks better than your userspace code could.
Paths in Sysfs
--------------
There are three kinds of entry in /sys/class/gpio:
- Control interfaces used to get userspace control over GPIOs;
- GPIOs themselves; and
- GPIO controllers ("gpio_chip" instances).
That's in addition to standard files including the "device" symlink.
The control interfaces are write-only:
/sys/class/gpio/
"export" ... Userspace may ask the kernel to export control of
a GPIO to userspace by writing its number to this file.
Example: "echo 19 > export" will create a "gpio19" node
for GPIO #19, if that's not requested by kernel code.
"unexport" ... Reverses the effect of exporting to userspace.
Example: "echo 19 > unexport" will remove a "gpio19"
node exported using the "export" file.
GPIO signals have paths like /sys/class/gpio/gpio42/ (for GPIO #42)
and have the following read/write attributes:
/sys/class/gpio/gpioN/
"direction" ... reads as either "in" or "out". This value may
normally be written. Writing as "out" defaults to
initializing the value as low. To ensure glitch free
operation, values "low" and "high" may be written to
configure the GPIO as an output with that initial value.
Note that this attribute *will not exist* if the kernel
doesn't support changing the direction of a GPIO, or
it was exported by kernel code that didn't explicitly
allow userspace to reconfigure this GPIO's direction.
"value" ... reads as either 0 (low) or 1 (high). If the GPIO
is configured as an output, this value may be written;
any nonzero value is treated as high.
GPIO controllers have paths like /sys/class/gpio/chipchip42/ (for the
controller implementing GPIOs starting at #42) and have the following
read-only attributes:
/sys/class/gpio/gpiochipN/
"base" ... same as N, the first GPIO managed by this chip
"label" ... provided for diagnostics (not always unique)
"ngpio" ... how many GPIOs this manges (N to N + ngpio - 1)
Board documentation should in most cases cover what GPIOs are used for
what purposes. However, those numbers are not always stable; GPIOs on
a daughtercard might be different depending on the base board being used,
or other cards in the stack. In such cases, you may need to use the
gpiochip nodes (possibly in conjunction with schematics) to determine
the correct GPIO number to use for a given signal.
Exporting from Kernel code
--------------------------
Kernel code can explicitly manage exports of GPIOs which have already been
requested using gpio_request():
/* export the GPIO to userspace */
int gpio_export(unsigned gpio, bool direction_may_change);
/* reverse gpio_export() */
void gpio_unexport();
After a kernel driver requests a GPIO, it may only be made available in
the sysfs interface by gpio_export(). The driver can control whether the
signal direction may change. This helps drivers prevent userspace code
from accidentally clobbering important system state.
This explicit exporting can help with debugging (by making some kinds
of experiments easier), or can provide an always-there interface that's
suitable for documenting as part of a board support package.

3
arch/arm/plat-omap/gpio.c
View File

@ -1488,6 +1488,9 @@ static int __init _omap_gpio_init(void)
bank->chip.set = gpio_set;
if (bank_is_mpuio(bank)) {
bank->chip.label = "mpuio";
#ifdef CONFIG_ARCH_OMAP1
bank->chip.dev = &omap_mpuio_device.dev;
#endif
bank->chip.base = OMAP_MPUIO(0);
} else {
bank->chip.label = "gpio";

2
arch/avr32/mach-at32ap/pio.c
View File

@ -360,6 +360,8 @@ static int __init pio_probe(struct platform_device *pdev)
pio->chip.label = pio->name;
pio->chip.base = pdev->id * 32;
pio->chip.ngpio = 32;
pio->chip.dev = &pdev->dev;
pio->chip.owner = THIS_MODULE;
pio->chip.direction_input = direction_input;
pio->chip.get = gpio_get;

15
drivers/gpio/Kconfig
View File

@ -23,6 +23,21 @@ config DEBUG_GPIO
slower. The diagnostics help catch the type of setup errors
that are most common when setting up new platforms or boards.
config GPIO_SYSFS
bool "/sys/class/gpio/... (sysfs interface)"
depends on SYSFS && EXPERIMENTAL
help
Say Y here to add a sysfs interface for GPIOs.
This is mostly useful to work around omissions in a system's
kernel support. Those are common in custom and semicustom
hardware assembled using standard kernels with a minimum of
custom patches. In those cases, userspace code may import
a given GPIO from the kernel, if no kernel driver requested it.
Kernel drivers may also request that a particular GPIO be
exported to userspace; this can be useful when debugging.
# put expanders in the right section, in alphabetical order
comment "I2C GPIO expanders:"

536
drivers/gpio/gpiolib.c
View File

@ -2,8 +2,11 @@
#include <linux/module.h>
#include <linux/irq.h>
#include <linux/spinlock.h>
#include <asm/gpio.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/gpio.h>
/* Optional implementation infrastructure for GPIO interfaces.
@ -44,6 +47,8 @@ struct gpio_desc {
#define FLAG_REQUESTED 0
#define FLAG_IS_OUT 1
#define FLAG_RESERVED 2
#define FLAG_EXPORT 3 /* protected by sysfs_lock */
#define FLAG_SYSFS 4 /* exported via /sys/class/gpio/control */
#ifdef CONFIG_DEBUG_FS
const char *label;
@ -151,6 +156,482 @@ err:
return ret;
}
#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
*
* REVISIT there will likely be an attribute for configuring async
* notifications, e.g. to specify polling interval or IRQ trigger type
* that would for example trigger a poll() on the "value".
*/
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;
}
static const DEVICE_ATTR(direction, 0644,
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);
if (!test_bit(FLAG_EXPORT, &desc->flags))
status = -EIO;
else
status = sprintf(buf, "%d\n", gpio_get_value_cansleep(gpio));
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) {
gpio_set_value_cansleep(gpio, value != 0);
status = size;
}
}
mutex_unlock(&sysfs_lock);
return status;
}
static /*const*/ DEVICE_ATTR(value, 0644,
gpio_value_show, gpio_value_store);
static const struct attribute *gpio_attrs[] = {
&dev_attr_direction.attr,
&dev_attr_value.attr,
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
*/
static ssize_t export_store(struct class *class, const char *buf, size_t len)
{
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;
}
static ssize_t unexport_store(struct class *class, const char *buf, size_t len)
{
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;
/* 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);
if (status == 0) {
struct device *dev;
dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
desc, "gpio%d", gpio);
if (dev) {
if (direction_may_change)
status = sysfs_create_group(&dev->kobj,
&gpio_attr_group);
else
status = device_create_file(dev,
&dev_attr_value);
if (status != 0)
device_unregister(dev);
} else
status = -ENODEV;
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;
}
/**
* 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;
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 *dev = NULL;
dev = class_find_device(&gpio_class, NULL, desc, match_export);
if (dev) {
clear_bit(FLAG_EXPORT, &desc->flags);
put_device(dev);
device_unregister(dev);
status = 0;
} 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);
if (dev) {
status = sysfs_create_group(&dev->kobj,
&gpiochip_attr_group);
} else
status = -ENODEV;
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 */
/**
* gpiochip_add() - register a gpio_chip
* @chip: the chip to register, with chip->base initialized
@ -160,6 +641,11 @@ err:
* because the chip->base is invalid or already associated with a
* different chip. Otherwise it returns zero as a success code.
*
* 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.
*
* If chip->base is negative, this requests dynamic assignment of
* a range of valid GPIOs.
*/
@ -182,7 +668,7 @@ int gpiochip_add(struct gpio_chip *chip)
base = gpiochip_find_base(chip->ngpio);
if (base < 0) {
status = base;
goto fail_unlock;
goto unlock;
}
chip->base = base;
}
@ -197,12 +683,23 @@ int gpiochip_add(struct gpio_chip *chip)
if (status == 0) {
for (id = base; id < base + chip->ngpio; id++) {
gpio_desc[id].chip = chip;
gpio_desc[id].flags = 0;
/* 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;
}
}
fail_unlock:
unlock:
spin_unlock_irqrestore(&gpio_lock, flags);
if (status == 0)
status = gpiochip_export(chip);
fail:
/* failures here can mean systems won't boot... */
if (status)
@ -239,6 +736,10 @@ int gpiochip_remove(struct gpio_chip *chip)
}
spin_unlock_irqrestore(&gpio_lock, flags);
if (status == 0)
gpiochip_unexport(chip);
return status;
}
EXPORT_SYMBOL_GPL(gpiochip_remove);
@ -296,6 +797,8 @@ void gpio_free(unsigned gpio)
return;
}
gpio_unexport(gpio);
spin_lock_irqsave(&gpio_lock, flags);
desc = &gpio_desc[gpio];
@ -534,10 +1037,6 @@ EXPORT_SYMBOL_GPL(gpio_set_value_cansleep);
#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>
#include <linux/seq_file.h>
static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
{
unsigned i;
@ -614,17 +1113,28 @@ static int gpiolib_show(struct seq_file *s, void *unused)
/* REVISIT this isn't locked against gpio_chip removal ... */
for (gpio = 0; gpio_is_valid(gpio); gpio++) {
struct device *dev;
if (chip == gpio_desc[gpio].chip)
continue;
chip = gpio_desc[gpio].chip;
if (!chip)
continue;
seq_printf(s, "%sGPIOs %d-%d, %s%s:\n",
seq_printf(s, "%sGPIOs %d-%d",
started ? "\n" : "",
chip->base, chip->base + chip->ngpio - 1,
chip->label ? : "generic",
chip->can_sleep ? ", can sleep" : "");
chip->base, chip->base + chip->ngpio - 1);
dev = chip->dev;
if (dev)
seq_printf(s, ", %s/%s",
dev->bus ? dev->bus->name : "no-bus",
dev->bus_id);
if (chip->label)
seq_printf(s, ", %s", chip->label);
if (chip->can_sleep)
seq_printf(s, ", can sleep");
seq_printf(s, ":\n");
started = 1;
if (chip->dbg_show)
chip->dbg_show(s, chip);

1
drivers/gpio/mcp23s08.c
View File

@ -239,6 +239,7 @@ static int mcp23s08_probe(struct spi_device *spi)
mcp->chip.base = pdata->base;
mcp->chip.ngpio = 8;
mcp->chip.can_sleep = 1;
mcp->chip.dev = &spi->dev;
mcp->chip.owner = THIS_MODULE;
spi_set_drvdata(spi, mcp);

1
drivers/gpio/pca953x.c
View File

@ -188,6 +188,7 @@ static void pca953x_setup_gpio(struct pca953x_chip *chip, int gpios)
gc->base = chip->gpio_start;
gc->ngpio = gpios;
gc->label = chip->client->name;
gc->dev = &chip->client->dev;
gc->owner = THIS_MODULE;
}

1
drivers/gpio/pcf857x.c
View File

@ -200,6 +200,7 @@ static int pcf857x_probe(struct i2c_client *client,
gpio->chip.base = pdata->gpio_base;
gpio->chip.can_sleep = 1;
gpio->chip.dev = &client->dev;
gpio->chip.owner = THIS_MODULE;
/* NOTE: the OnSemi jlc1562b is also largely compatible with

2
drivers/i2c/chips/tps65010.c
View File

@ -636,6 +636,8 @@ static int tps65010_probe(struct i2c_client *client,
tps->outmask = board->outmask;
tps->chip.label = client->name;
tps->chip.dev = &client->dev;
tps->chip.owner = THIS_MODULE;
tps->chip.set = tps65010_gpio_set;
tps->chip.direction_output = tps65010_output;

2
drivers/mfd/htc-egpio.c
View File

@ -318,6 +318,8 @@ static int __init egpio_probe(struct platform_device *pdev)
ei->chip[i].dev = &(pdev->dev);
chip = &(ei->chip[i].chip);
chip->label = "htc-egpio";
chip->dev = &pdev->dev;
chip->owner = THIS_MODULE;
chip->get = egpio_get;
chip->set = egpio_set;
chip->direction_input = egpio_direction_input;

33
include/asm-generic/gpio.h
View File

@ -32,6 +32,8 @@ struct module;
/**
* struct gpio_chip - abstract a GPIO controller
* @label: for diagnostics
* @dev: optional device providing the GPIOs
* @owner: helps prevent removal of modules exporting active GPIOs
* @direction_input: configures signal "offset" as input, or returns error
* @get: returns value for signal "offset"; for output signals this
* returns either the value actually sensed, or zero
@ -59,6 +61,7 @@ struct module;
*/
struct gpio_chip {
char *label;
struct device *dev;
struct module *owner;
int (*direction_input)(struct gpio_chip *chip,
@ -74,6 +77,7 @@ struct gpio_chip {
int base;
u16 ngpio;
unsigned can_sleep:1;
unsigned exported:1;
};
extern const char *gpiochip_is_requested(struct gpio_chip *chip,
@ -108,7 +112,18 @@ extern void __gpio_set_value(unsigned gpio, int value);
extern int __gpio_cansleep(unsigned gpio);
#else
#ifdef CONFIG_GPIO_SYSFS
/*
* A sysfs interface can be exported by individual drivers if they want,
* but more typically is configured entirely from userspace.
*/
extern int gpio_export(unsigned gpio, bool direction_may_change);
extern void gpio_unexport(unsigned gpio);
#endif /* CONFIG_GPIO_SYSFS */
#else /* !CONFIG_HAVE_GPIO_LIB */
static inline int gpio_is_valid(int number)
{
@ -137,6 +152,20 @@ static inline void gpio_set_value_cansleep(unsigned gpio, int value)
gpio_set_value(gpio, value);
}
#endif
#endif /* !CONFIG_HAVE_GPIO_LIB */
#ifndef CONFIG_GPIO_SYSFS
/* sysfs support is only available with gpiolib, where it's optional */
static inline int gpio_export(unsigned gpio, bool direction_may_change)
{
return -ENOSYS;
}
static inline void gpio_unexport(unsigned gpio)
{
}
#endif /* CONFIG_GPIO_SYSFS */
#endif /* _ASM_GENERIC_GPIO_H */

13
include/linux/gpio.h
View File

@ -79,6 +79,19 @@ static inline void gpio_set_value_cansleep(unsigned gpio, int value)
WARN_ON(1);
}
static inline int gpio_export(unsigned gpio, bool direction_may_change)
{
/* GPIO can never have been requested or set as {in,out}put */
WARN_ON(1);
return -EINVAL;
}
static inline void gpio_unexport(unsigned gpio)
{
/* GPIO can never have been exported */
WARN_ON(1);
}
static inline int gpio_to_irq(unsigned gpio)
{
/* GPIO can never have been requested or set as input */