837 Commits

Author SHA1 Message Date
Andy Shevchenko
8ae438f5ff gpiolib: Deduplicate cleanup for-loop in gpiochip_add_data_with_key()
There is no need to repeat for-loop twice in the error path in
gpiochip_add_data_with_key(). Deduplicate it. While at it,
rename loop variable to be more specific and avoid ambguity.

It also properly unwinds the SRCU, i.e. in reversed order of allocating.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-03-05 19:24:58 +01:00
Bartosz Golaszewski
e9c717bee8 Linux 6.8-rc7
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Merge tag 'v6.8-rc7' into gpio/for-next

Linux 6.8-rc7
2024-03-05 19:24:34 +01:00
Bartosz Golaszewski
ec5c54a9d3 gpio: fix resource unwinding order in error path
Hogs are added *after* ACPI so should be removed *before* in error path.

Fixes: a411e81e61df ("gpiolib: add hogs support for machine code")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-03-01 09:33:30 +01:00
Andy Shevchenko
8122c7c625 gpio: acpi: Make acpi_gpio_count() take firmware node as a parameter
Make acpi_gpio_count() take firmware node as a parameter in order
to be aligned with other functions and decouple from unused device
pointer. The latter helps to create a common fwnode_gpio_count()
in the future.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-03-01 09:08:34 +01:00
Andy Shevchenko
adcad5364a gpio: of: Make of_gpio_get_count() take firmware node as a parameter
Make of_gpio_get_count() take firmware node as a parameter in order
to be aligned with other functions and decouple from unused device
pointer. The latter helps to create a common fwnode_gpio_count()
in the future.

While at it, rename to be of_gpio_count() to be aligned with the others.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-03-01 09:07:21 +01:00
Andy Shevchenko
e4aec4daa8 gpiolib: Fix the error path order in gpiochip_add_data_with_key()
After shuffling the code, error path wasn't updated correctly.
Fix it here.

Fixes: 2f4133bb5f14 ("gpiolib: No need to call gpiochip_remove_pin_ranges() twice")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-03-01 08:36:53 +01:00
Stephen Boyd
0d776cfd5e gpiolib: Pass consumer device through to core in devm_fwnode_gpiod_get_index()
This devm API takes a consumer device as an argument to setup the devm
action, but throws it away when calling further into gpiolib. This leads
to odd debug messages like this:

 (NULL device *): using DT '/gpio-keys/switch-pen-insert' for '(null)' GPIO lookup

Let's pass the consumer device down, by directly calling what
fwnode_gpiod_get_index() calls but pass the device used for devm. This
changes the message to look like this instead:

 gpio-keys gpio-keys: using DT '/gpio-keys/switch-pen-insert' for '(null)' GPIO lookup

Note that callers of fwnode_gpiod_get_index() will still see the NULL
device pointer debug message, but there's not much we can do about that
because the API doesn't take a struct device.

Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Fixes: 8eb1f71e7acc ("gpiolib: consolidate GPIO lookups")
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-02-27 14:17:38 +01:00
Bartosz Golaszewski
5d60c1e61f gpio: don't warn about removing GPIO chips with active users anymore
With SRCU we can now correctly handle the situation when a GPIO provider
is removed while having users still holding references to GPIO
descriptors. Remove all warnings emitted in this situation.

Suggested-by: Kent Gibson <warthog618@gmail.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Herve Codina <herve.codina@bootlin.com>
2024-02-26 16:43:51 +01:00
Emil Renner Berthing
ae366ba857 gpiolib: Handle no pin_ranges in gpiochip_generic_config()
Similar to gpiochip_generic_request() and gpiochip_generic_free() the
gpiochip_generic_config() function needs to handle the case where there
are no pinctrl pins mapped to the GPIOs, usually through the gpio-ranges
device tree property.

Commit f34fd6ee1be8 ("gpio: dwapb: Use generic request, free and
set_config") set the .set_config callback to gpiochip_generic_config()
in the dwapb GPIO driver so the GPIO API can set pinctrl configuration
for the corresponding pins. Most boards using the dwapb driver do not
set the gpio-ranges device tree property though, and in this case
gpiochip_generic_config() would return -EPROPE_DEFER rather than the
previous -ENOTSUPP return value. This in turn makes
gpio_set_config_with_argument_optional() fail and propagate the error to
any driver requesting GPIOs.

Fixes: 2956b5d94a76 ("pinctrl / gpio: Introduce .set_config() callback for GPIO chips")
Reported-by: Jisheng Zhang <jszhang@kernel.org>
Closes: https://lore.kernel.org/linux-gpio/ZdC_g3U4l0CJIWzh@xhacker/
Tested-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-02-20 12:49:14 +01:00
Xiaolei Wang
24ba441d2b gpio: fix memory leak in gpiod_request_commit()
Since commit 1f2bcb8c8ccd ("gpio: protect the descriptor label with
SRCU"), desc_set_label() already allocates memory for the label, so there
is no need to allocate it again. If we do, we leak it.

unreferenced object 0xffff0000c3e4d0c0 (size 32):
  comm "kworker/u16:4", pid 60, jiffies 4294894555
  hex dump (first 32 bytes):
    72 65 67 75 6c 61 74 6f 72 2d 63 61 6e 32 2d 73  regulator-can2-s
    74 62 79 00 00 00 ff ff ff ff ff ff eb db ff ff  tby.............
  backtrace (crc 2c3a0350):
    [<00000000e93c5cf4>] kmemleak_alloc+0x34/0x40
    [<0000000097a2657f>] __kmalloc_node_track_caller+0x2c4/0x524
    [<000000000dd1c057>] kstrdup+0x4c/0x98
    [<00000000b513a96a>] kstrdup_const+0x34/0x40
    [<000000008a7f0feb>] gpiod_request_commit+0xdc/0x358
    [<00000000fc71ad64>] gpiod_request+0xd8/0x204
    [<00000000fa24b091>] gpiod_find_and_request+0x170/0x780
    [<0000000086ecf92d>] gpiod_get_index+0x70/0xe0
    [<000000004aef97f9>] gpiod_get_optional+0x18/0x30
    [<00000000312f1b25>] reg_fixed_voltage_probe+0x58c/0xad8
    [<00000000e6f47635>] platform_probe+0xc4/0x198
    [<00000000cf78fbdb>] really_probe+0x204/0x5a8
    [<00000000e28d05ec>] __driver_probe_device+0x158/0x2c4
    [<00000000e4fe452b>] driver_probe_device+0x60/0x18c
    [<00000000479fcf5d>] __device_attach_driver+0x168/0x208
    [<000000007d389f38>] bus_for_each_drv+0x104/0x190

Fixes: 1f2bcb8c8ccd ("gpio: protect the descriptor label with SRCU")
Signed-off-by: Xiaolei Wang <xiaolei.wang@windriver.com>
[Bartosz: tweaked the commit message]
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-02-19 08:46:23 +01:00
Krzysztof Kozlowski
4a92857d6e gpio: constify opaque pointer "data" in gpio_device_find()
The opaque pointer "data" in each match function used by
gpio_device_find() is a pointer to const, thus the same argument passed
to gpio_device_find() can adjusted similarly.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-02-17 20:02:22 +01:00
Bartosz Golaszewski
0d7fa0eda4 gpio: don't let lockdep complain about inherently dangerous RCU usage
There are two legacy, deprecated functions - gpiod_to_chip() and
gpio_device_get_chip() - that still have users in tree. They return the
address of the SRCU-protected chip outside of the read-only critical
sections. They are inherently dangerous and the users should convert to
safer alternatives. Let's explicitly silence lockdep warnings by using
rcu_dereference_check(ptr, 1). While at it: reuse
gpio_device_get_chip() in gpiod_to_chip().

Fixes: d83cee3d2bb1 ("gpio: protect the pointer to gpio_chip in gpio_device with SRCU")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202402122234.d85cca9b-lkp@intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-02-15 08:39:29 +01:00
Bartosz Golaszewski
d82b9e0887 gpio: use srcu_dereference() with SRCU-protected pointers
Lockdep with CONFIG_PROVE_RCU enabled reports false positives about
suspicious rcu_dereference() usage. Let's silence it by using
srcu_dereference() which is the correct helper with SRCU.

Fixes: d83cee3d2bb1 ("gpio: protect the pointer to gpio_chip in gpio_device with SRCU")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202402122234.d85cca9b-lkp@intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
2024-02-15 08:39:25 +01:00
Bartosz Golaszewski
815a1b5a6d gpio: take the SRCU read lock in gpiod_hog()
gpiod_hog() may be called without the gpio_device SRCU read lock taken
so we need to do it here as well. It's alright if someone else is
already holding the lock as SRCU read critical sections can be nested.

Fixes: d83cee3d2bb1 ("gpio: protect the pointer to gpio_chip in gpio_device with SRCU")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202402122234.d85cca9b-lkp@intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
2024-02-15 08:39:13 +01:00
Bartosz Golaszewski
ba5c5effe0 gpio: initialize descriptor SRCU structure before adding OF-based chips
In certain situations we may end up taking the GPIO descriptor SRCU read
lock in of_gpiochip_add() before the SRCU struct is initialized. Move
the initialization before the call to of_gpiochip_add().

Fixes: be711caa87c5 ("gpio: add SRCU infrastructure to struct gpio_desc")
Fixes: 1f2bcb8c8ccd ("gpio: protect the descriptor label with SRCU")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202402122228.e607a080-lkp@intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-02-14 09:34:03 +01:00
Bartosz Golaszewski
5e62844440 gpio: mark unsafe gpio_chip manipulators as deprecated
We still have some functions that return the address of the GPIO chip
associated with the GPIO device. This is dangerous and the users should
find a better solution. Let's add appropriate comments to the kernel
docs.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 11:00:55 +01:00
Bartosz Golaszewski
f067372c6a gpio: remove the RW semaphore from the GPIO device
With all accesses to gdev->chip being protected with SRCU, we can now
remove the RW-semaphore specific to the character device which
fulfilled the same role up to this point.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 11:00:55 +01:00
Bartosz Golaszewski
d83cee3d2b gpio: protect the pointer to gpio_chip in gpio_device with SRCU
Ensure we cannot crash if the GPIO device gets unregistered (and the
chip pointer set to NULL) during any of the API calls.

To that end: wait for all users of gdev->chip to exit their read-only
SRCU critical sections in gpiochip_remove().

For brevity: add a guard class which can be instantiated at the top of
every function requiring read-only access to the chip pointer and use it
in all API calls taking a GPIO descriptor as argument. In places where
we only deal with the GPIO device - use regular guard() helpers and
rcu_dereference() for chip access. Do the same in API calls taking a
const pointer to gpio_desc.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 11:00:31 +01:00
Bartosz Golaszewski
47d8b4c1d8 gpio: add SRCU infrastructure to struct gpio_device
Add the SRCU struct to GPIO device. It will be used to serialize access
to the GPIO chip pointer. Initialize and clean it up where applicable.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:51:29 +01:00
Bartosz Golaszewski
8a5b477bb3 gpio: add the can_sleep flag to struct gpio_device
Duplicating the can_sleep value in GPIO device will allow us to not
needlessly dereference the chip pointer in several places and reduce the
number of SRCU read-only critical sections.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:51:26 +01:00
Bartosz Golaszewski
c5cf334dcc gpio: remove unnecessary checks from gpiod_to_chip()
We don't need to check the gdev pointer in struct gpio_desc - it's
always assigned and never cleared. It's also pointless to check
gdev->chip before we actually serialize access to it.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:51:23 +01:00
Bartosz Golaszewski
6c82e737ab gpio: reduce the functionality of validate_desc()
Checking desc->gdev->chip for NULL without holding it in place with some
serializing mechanism is pointless. Remove this check. Also don't check
desc->gdev for NULL as it can never happen. We'll be protecting
gdev->chip with SRCU soon but we will provide a dedicated, automatic
class for that.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:51:20 +01:00
Bartosz Golaszewski
7fe595b3c3 gpio: don't dereference gdev->chip in gpiochip_setup_dev()
We don't need to dereference gdev->chip in gpiochip_setup_dev() as at
the time it's called, the label in the associated struct gpio_device is
already set.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:51:17 +01:00
Bartosz Golaszewski
b6f87adbac gpio: remove unneeded code from gpio_device_get_desc()
The GPIO chip pointer is unused. Let's remove it.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:50:52 +01:00
Bartosz Golaszewski
2559f2e092 gpio: reinforce desc->flags handling
We now removed the gpio_lock spinlock and modified the places
previously protected by it to handle desc->flags access in a consistent
way. Let's improve other places that were previously unprotected by
reading the flags field of gpio_desc once and using the stored value for
logic consistency. If we need to modify the field, let's also write it
back once with a consistent value resulting from the function's logic.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:50:49 +01:00
Bartosz Golaszewski
35b545332b gpio: remove gpio_lock
The "multi-function" gpio_lock is pretty much useless with how it's used
in GPIOLIB currently. Because many GPIO API calls can be called from all
contexts but may also call into sleeping driver callbacks, there are
many places with utterly broken workarounds like yielding the lock to
call a possibly sleeping function and then re-acquiring it again without
taking into account that the protected state may have changed.

It was also used to protect several unrelated things: like individual
descriptors AND the GPIO device list. We now serialize access to these
two with SRCU and so can finally remove the spinlock.

There is of course the question of consistency of lockless access to
GPIO descriptors. Because we only support exclusive access to GPIOs
(officially anyway, I'm looking at you broken
GPIOD_FLAGS_BIT_NONEXCLUSIVE bit...) and the API contract with providers
does not guarantee serialization, it's enough to ensure we cannot
accidentally dereference an invalid pointer and that the state we present
to both users and providers remains consistent. To achieve that: read the
flags field atomically except for a few special cases. Read their current
value before executing callback code and use this value for any subsequent
logic. Modifying the flags depends on the particular use-case and can
differ. For instance: when requesting a GPIO, we need to set the
REQUESTED bit immediately so that the next user trying to request the
same line sees -EBUSY.

While at it: the allocations that used GFP_ATOMIC until this point can
now switch to GFP_KERNEL.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:50:45 +01:00
Bartosz Golaszewski
2a9101e875 gpio: sysfs: use gpio_device_find() to iterate over existing devices
With the list of GPIO devices now protected with SRCU we can use
gpio_device_find() to traverse it from sysfs.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:50:42 +01:00
Bartosz Golaszewski
1f2bcb8c8c gpio: protect the descriptor label with SRCU
In order to ensure that the label is not freed while it's being
accessed, let's protect it with SRCU and synchronize it everytime it's
changed.

Let's modify desc_set_label() to manage the memory used for the label as
it can only be freed once synchronize_srcu() returns.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:50:40 +01:00
Bartosz Golaszewski
be711caa87 gpio: add SRCU infrastructure to struct gpio_desc
Extend the GPIO descriptor with an SRCU structure in order to serialize
the access to the label. Initialize and clean it up where applicable.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:50:37 +01:00
Bartosz Golaszewski
ccfb6ff4f6 gpio: don't set label from irq helpers
We will soon serialize access to the descriptor label using SRCU. The
write-side of the protection will require calling synchronize_srcu()
which must not be called from atomic context. We have two irq helpers:
gpiochip_lock_as_irq() and gpiochip_unlock_as_irq() that set the label
if the GPIO is not requested but is being used as interrupt. They are
called with a spinlock held from the interrupt subsystem.

They must not do it if we are to use SRCU so instead let's move the
special corner case to a dedicated getter.

Don't actually set the label to "interrupt" in the above case but rather
use the newly added gpiod_get_label() helper to hide the logic that
atomically checks the descriptor flags and returns the address of a
static "interrupt" string.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:50:34 +01:00
Bartosz Golaszewski
d23dc4a9a8 gpio: provide and use gpiod_get_label()
We will soon serialize access to the descriptor label using SRCU. The
write-side of the protection will require calling synchronize_srcu()
which must not be called from atomic context. We have two irq helpers:
gpiochip_lock_as_irq() and gpiochip_unlock_as_irq() that set the label
if the GPIO is not requested but is being used as interrupt. They are
called with a spinlock held from the interrupt subsystem.

They must not do it if we are to use SRCU so instead let's move the
special corner case to a dedicated getter.

First: let's implement and use the getter where it's applicable.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:50:30 +01:00
Bartosz Golaszewski
8ce6fd81a4 gpio: of: assign and read the hog pointer atomically
The device nodes representing GPIO hogs cannot be deleted without
unregistering the GPIO chip so there's no need to serialize their access.
However we must ensure that users can get the right address so write and
read it atomically.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:50:24 +01:00
Bartosz Golaszewski
e348544f79 gpio: protect the list of GPIO devices with SRCU
We're working towards removing the "multi-function" GPIO spinlock that's
implemented terribly wrong. We tried using an RW-semaphore to protect
the list of GPIO devices but it turned out that we still have old code
using legacy GPIO calls that need to translate the global GPIO number to
the address of the associated descriptor and - to that end - traverse
the list while holding the lock. If we change the spinlock to a sleeping
lock then we'll end up with "scheduling while atomic" bugs.

Let's allow lockless traversal of the list using SRCU and only use the
mutex when modyfing the list.

While at it: let's protect the period between when we start the lookup
and when we finally request the descriptor (increasing the reference
count of the GPIO device) with the SRCU read lock.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2024-02-12 10:50:20 +01:00
Krzysztof Kozlowski
faf6efd2e5 gpio: constify opaque pointer in gpio_device_find() match function
The match function used in gpio_device_find() should not modify the
contents of passed opaque pointer, because such modification would not
be necessary for actual matching and it could lead to quite unreadable,
spaghetti code.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
[Bartosz: fix coding style in header]
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-02-12 10:18:31 +01:00
Bartosz Golaszewski
104e00bbc7 Linux 6.8-rc4
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Merge tag 'v6.8-rc4' into gpio/for-next

Linux 6.8-rc4

Pulling this for a bugfix upstream with which the gpio/for-next branch
conflicts.
2024-02-12 10:12:41 +01:00
Bartosz Golaszewski
aab5c6f200 gpio: set device type for GPIO chips
It's useful to have the device type information for those sub-devices
that are actually GPIO chips registered with GPIOLIB. While at it: use
the device type struct to setup the release callback which is the
preferred way to use the device API.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-02-08 10:35:59 +01:00
Bartosz Golaszewski
2526dffc6d gpio: remove GPIO device from the list unconditionally in error path
Since commit 48e1b4d369cf ("gpiolib: remove the GPIO device from the list
when it's unregistered") we remove the GPIO device entry from the global
list (used to order devices by their GPIO ranges) when unregistering the
chip, not when releasing the device. It will not happen when the last
reference is put anymore. This means, we need to remove it in error path
in gpiochip_add_data_with_key() unconditionally, without checking if the
device's .release() callback is set.

Fixes: 48e1b4d369cf ("gpiolib: remove the GPIO device from the list when it's unregistered")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-02-08 10:33:03 +01:00
Ricardo B. Marliere
a875746f60 gpio: gpiolib: make gpio_bus_type const
Now that the driver core can properly handle constant struct bus_type,
move the gpio_bus_type variable to be a constant structure as well,
placing it into read-only memory which can not be modified at runtime.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-02-05 09:42:21 +01:00
Bartosz Golaszewski
88b7049635 gpio: unexport GPIO irq domain functions only used internally
There are no external users for the irq domain helpers so unexport them
and remove the prototypes from the driver header.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-01-29 11:45:49 +01:00
Bartosz Golaszewski
efb8235bfd gpiolib: revert the attempt to protect the GPIO device list with an rwsem
This reverts commits 1979a2807547 ("gpiolib: replace the GPIO device
mutex with a read-write semaphore") and 65a828bab158 ("gpiolib: use
a mutex to protect the list of GPIO devices").

Unfortunately the legacy GPIO API that's still used in older code has to
translate numbers from the global GPIO numberspace to descriptors. This
results in a GPIO device lookup in every call to legacy functions. Some
of those functions - like gpio_set/get_value() - can be called from
atomic context so taking a sleeping lock that is an RW semaphore results
in an error.

We'll probably have to protect this list with SRCU.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-wireless/f7b5ff1e-8f34-4d98-a7be-b826cb897dc8@moroto.mountain/
Fixes: 1979a2807547 ("gpiolib: replace the GPIO device mutex with a read-write semaphore")
Fixes: 65a828bab158 ("gpiolib: use a mutex to protect the list of GPIO devices")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-01-17 09:52:37 +01:00
Bartosz Golaszewski
1979a28075 gpiolib: replace the GPIO device mutex with a read-write semaphore
There are only two spots where we modify (add to or remove objects from)
the GPIO device list. Readers should be able to access it concurrently.
Replace the mutex with a read-write semaphore and adjust the locking
operations accordingly.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
2024-01-04 10:29:16 +01:00
Bartosz Golaszewski
48e1b4d369 gpiolib: remove the GPIO device from the list when it's unregistered
If we wait until the GPIO device's .release() callback gets invoked
before we remove it from the global device list, then we risk that
someone will look it up using gpio_device_find() between where we
dropped the last reference and before .release() is done taking a
reference again to an object that's being released.

The device must be removed when it's being unregistered - just like how
we remove it from the GPIO bus.

Fixes: ff2b13592299 ("gpio: make the gpiochip a real device")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
2024-01-04 10:29:16 +01:00
Bartosz Golaszewski
0338f6a6fb gpiolib: drop tabs from local variable declarations
Older code has an annoying habit of putting tabs between the type and the
name of the variable. This doesn't really add to readability and newer
code doesn't do it so make the entire file consistent.

While at it: convert 'unsigned' to 'unsigned int'.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2023-12-27 16:00:17 +01:00
Bartosz Golaszewski
5d5dfc50e5 gpiolib: remove extra_checks
extra_checks is only used in a few places. It also depends on
a non-standard DEBUG define one needs to add to the source file. The
overhead of removing it should be minimal (we already use pure
might_sleep() in the code anyway) so drop it.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
2023-12-27 15:58:39 +01:00
Kent Gibson
d8543cbaf9 gpiolib: remove debounce_period_us from struct gpio_desc
cdev is the only user of the debounce_period_us field in
struct gpio_desc, and it no longer uses it, so remove it.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2023-12-19 09:45:45 +01:00
Bartosz Golaszewski
65a828bab1 gpiolib: use a mutex to protect the list of GPIO devices
The global list of GPIO devices is never modified or accessed from
atomic context so it's fine to protect it using a mutex. Add a new
global lock dedicated to the gpio_devices list and use it whenever
accessing or modifying it.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2023-12-18 10:00:43 +01:00
Bartosz Golaszewski
f95fd4ac15 gpiolib: rename static functions that are called with the lock taken
Rename two functions that read or modify the global GPIO device list but
don't take the lock themselves (and need to be called with it already
acquired). Use the _unlocked() suffix which seems to be used quite
consistently across the kernel despite there also existing the _locked()
suffix for the same purpose.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2023-12-18 09:59:20 +01:00
Bartosz Golaszewski
0a10d10781 gpiolib: allocate memory atomically with a spinlock held
We will eventually switch to protecting the GPIO descriptors with a mutex
but until then, we need to allocate memory for the label copy atomically
while we're holding the global spinlock.

Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-gpio/62588146-eed6-42f7-ba26-160226b109fe@moroto.mountain/T/#u
Fixes: f8d05e276b45 ("gpiolib: remove gpiochip_is_requested()")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
2023-12-15 16:43:24 +01:00
Bartosz Golaszewski
11a94a335a gpio: remove gpiochip_is_requested()
- provide a safer alternative to gpiochip_is_requested()
 - convert all existing users
 - remove gpiochip_is_requested()
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Merge tag 'gpio-remove-gpiochip_is_requested-for-v6.8-rc1' into gpio/for-next

gpio: remove gpiochip_is_requested()

- provide a safer alternative to gpiochip_is_requested()
- convert all existing users
- remove gpiochip_is_requested()
2023-12-08 09:37:12 +01:00
Bartosz Golaszewski
f8d05e276b gpiolib: remove gpiochip_is_requested()
We have no external users of gpiochip_is_requested(). Let's remove it
and replace its internal calls with direct testing of the REQUESTED flag.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
2023-12-08 09:26:43 +01:00