1
Commit Graph

137 Commits

Author SHA1 Message Date
Andy Shevchenko
4b91188dce gpiolib: Replace gpio_suffix_count with NULL-terminated array
There is no need to have and export the count variable for the array
in question. Instead, make it NULL-terminated.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240819142945.327808-6-andriy.shevchenko@linux.intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-08-20 10:22:38 +02:00
Andy Shevchenko
ef3d4b94d2 gpiolib: Introduce for_each_gpio_property_name() helper
Introduce a helper macro for_each_gpio_property_name().
With that in place, update users. This, in particular,
will help making the following simplifications easier.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240819142945.327808-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-08-20 10:22:38 +02:00
Bartosz Golaszewski
6f2a875024 gpiolib: unexport gpiochip_get_desc()
This function has been deprecated for some time and is now only used
within the GPIOLIB core. Remove it from the public header and unexport
it as all current users are linked against the compilation unit where
it is defined.

Link: https://lore.kernel.org/r/20240625073815.12376-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-07-02 11:40:37 +02:00
Bartosz Golaszewski
7e92061f1e gpiolib: put gpio_suffixes in a single compilation unit
The gpio_suffixes array is defined in the gpiolib.h header. This means
the array is stored in .rodata of every compilation unit that includes
it. Put the definition for the array in gpiolib.c and export just the
symbol in the header. We need the size of the array so expose it too.

Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Link: https://lore.kernel.org/r/20240612184821.58053-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-06-14 09:14:58 +02:00
Linus Torvalds
ce952d8f0e gpio updates for v6.10-rc1
GPIO core:
 - remove more unused legacy interfaces (after converting the last remaining
   users to better alternatives)
 - update kerneldocs
 - improve error handling and log messages in GPIO ACPI code
 - remove dead code (always true checks) from GPIOLIB
 
 New drivers:
 - add a driver for Intel Granite Rapids-D vGPIO
 
 Driver improvements:
 - use -ENOTSUPP consistently in gpio-regmap and gpio-pcie-idio-24
 - provide an ID table for gpio-cros-ec to avoid a driver name fallback check
 - add support for gpio-ranges for GPIO drivers supporting multiple GPIO banks
 - switch to using dynamic GPIO base in gpio-brcmstb
 - fix irq handling in gpio-npcm-sgpio
 - switch to memory mapped IO accessors in gpio-sch
 
 DT bindings:
 - add support for gpio-ranges to gpio-brcmstb
 - add support for a new model and the gpio-line-names property to gpio-mpfs
 
 Documentation:
 - replace leading tabs with spaces in code blocks
 - fix typos
 -----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCgAdFiEEFp3rbAvDxGAT0sefEacuoBRx13IFAmZDFa4ACgkQEacuoBRx
 13IJuA//cdR+Y1xaiORhVg9gMjmeQtgP7ve6QK4p/vuwAuZJMxboc4ATPY4cBlvp
 VoMFQD8FgjbxcKRLjugS0wB/5isELzo5C+q699YKY/0R07WMBiTIt6FgS4JJ1j57
 RoAlLrZ7gxmJQyUWuk2dvvQ55MnCL4fzVCzCrQB+foWsZluyeQMnndFU7z+P96bK
 ckvNrfFlZjaTwRBVf9MVpcNUxuk+pFKMKfXCgNCvmhToOaOM3sKkFwMMZCOVRLpJ
 oCcAz6rbj+fn2x3Id2FS2R5f5GoZx31dalLnbJCY4OLgDNhjx1A7sONq+hplfO24
 LXxQgCP26myaxmCFsiKqYgYzh/1bnAeCaRjy+41+RWXy7LUil6c0yP1Z3pOlOK+h
 j32+/LS9aflneoxjXyAAQLAvMulDbIvKeWHUakPXk6bS/AR6zyL16rwfF9U3K795
 ZGAz37xuOCpAevGnRTpPz9eCWwnNFq5v8UMjvVmoMgtbJbIwP4J3cRzj6RCiBvrq
 AvveulP+oXde3vFydAf1NbjaRxf53b8vZp6DLFDqcU+76QCQwG55QqlhT4Nqm/Y4
 KASQYM4vlH+96vnCMW+p2DmN92dkoadwk5pBvEaY7q7eEC2EdAMfujUZ1VdB9OZ+
 FPZ6zAp6T2khVt4jzKFxbobV8xt3FznntEhbm4bo3Ugb2HRwD8g=
 =mBWd
 -----END PGP SIGNATURE-----

Merge tag 'gpio-updates-for-v6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux

Pull gpio updates from Bartosz Golaszewski
 "This was a quiet release cycle for the GPIO tree and so this
  pull-request is relatively small.

  We have one new driver, some minor improvements to the GPIO core code
  and across several drivers, some DT and documentation updates but in
  general nothing stands out or is controversial. All changes have spent
  time in next with no reported issues (or ones that were quickly
  fixed).

  GPIO core:
   - remove more unused legacy interfaces (after converting the last
     remaining users to better alternatives)
   - update kerneldocs
   - improve error handling and log messages in GPIO ACPI code
   - remove dead code (always true checks) from GPIOLIB

  New drivers:
   - add a driver for Intel Granite Rapids-D vGPIO

  Driver improvements:
   - use -ENOTSUPP consistently in gpio-regmap and gpio-pcie-idio-24
   - provide an ID table for gpio-cros-ec to avoid a driver name
     fallback check
   - add support for gpio-ranges for GPIO drivers supporting multiple
     GPIO banks
   - switch to using dynamic GPIO base in gpio-brcmstb
   - fix irq handling in gpio-npcm-sgpio
   - switch to memory mapped IO accessors in gpio-sch

  DT bindings:
   - add support for gpio-ranges to gpio-brcmstb
   - add support for a new model and the gpio-line-names property to
     gpio-mpfs

  Documentation:
   - replace leading tabs with spaces in code blocks
   - fix typos"

* tag 'gpio-updates-for-v6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux: (30 commits)
  gpio: nuvoton: Fix sgpio irq handle error
  gpiolib: Discourage to use formatting strings in line names
  gpio: brcmstb: add support for gpio-ranges
  gpio: of: support gpio-ranges for multiple gpiochip devices
  dt-bindings: gpio: brcmstb: add gpio-ranges
  gpio: Add Intel Granite Rapids-D vGPIO driver
  gpio: brcmstb: Use dynamic GPIO base numbers
  gpiolib: acpi: Set label for IRQ only lines
  gpiolib: acpi: Add fwnode name to the GPIO interrupt label
  gpiolib: Get rid of never false gpio_is_valid() calls
  gpiolib: acpi: Pass con_id instead of property into acpi_dev_gpio_irq_get_by()
  gpiolib: acpi: Move acpi_can_fallback_to_crs() out of __acpi_find_gpio()
  gpiolib: acpi: Simplify error handling in __acpi_find_gpio()
  gpiolib: acpi: Extract __acpi_find_gpio() helper
  gpio: sch: Utilise temporary variable for struct device
  gpio: sch: Switch to memory mapped IO accessors
  gpio: regmap: Use -ENOTSUPP consistently
  gpio: pcie-idio-24: Use -ENOTSUPP consistently
  Documentation: gpio: Replace leading TABs by spaces in code blocks
  gpiolib: acpi: Check for errors first in acpi_find_gpio()
  ...
2024-05-14 15:07:07 -07:00
Bartosz Golaszewski
7765ffed53 gpiolib: use a single SRCU struct for all GPIO descriptors
We used a per-descriptor SRCU struct in order to not impose a wait with
synchronize_srcu() for descriptor X on read-only operations of
descriptor Y. Now that we no longer call synchronize_srcu() on
descriptor label change but only when releasing descriptor resources, we
can use a single SRCU structure for all GPIO descriptors in a given chip.

Suggested-by: "Paul E. McKenney" <paulmck@kernel.org>
Acked-by: "Paul E. McKenney" <paulmck@kernel.org>
Link: https://lore.kernel.org/r/20240507172414.28513-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-05-09 15:06:36 +02:00
Bartosz Golaszewski
a86d276930 gpiolib: fix the speed of descriptor label setting with SRCU
Commit 1f2bcb8c8c ("gpio: protect the descriptor label with SRCU")
caused a massive drop in performance of requesting GPIO lines due to the
call to synchronize_srcu() on each label change. Rework the code to not
wait until all read-only users are done with reading the label but
instead atomically replace the label pointer and schedule its release
after all read-only critical sections are done.

To that end wrap the descriptor label in a struct that also contains the
rcu_head struct required for deferring tasks using call_srcu() and stop
using kstrdup_const() as we're required to allocate memory anyway. Just
allocate enough for the label string and rcu_head in one go.

Reported-by: Neil Armstrong <neil.armstrong@linaro.org>
Closes: https://lore.kernel.org/linux-gpio/CAMRc=Mfig2oooDQYTqo23W3PXSdzhVO4p=G4+P8y1ppBOrkrJQ@mail.gmail.com/
Fixes: 1f2bcb8c8c ("gpio: protect the descriptor label with SRCU")
Suggested-by: "Paul E. McKenney" <paulmck@kernel.org>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-QRD
Acked-by: "Paul E. McKenney" <paulmck@kernel.org>
Link: https://lore.kernel.org/r/20240507121346.16969-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-05-07 18:04:23 +02:00
Andy Shevchenko
8a7a610325 gpiolib: Get rid of never false gpio_is_valid() calls
In the cases when gpio_is_valid() is called with unsigned parameter
the result is always true in the GPIO library code, hence the check
for false won't ever be true. Get rid of such calls.

While at it, move GPIO device base to be unsigned to clearly show
it won't ever be negative. This requires a new definition for the
maximum GPIO number in the system.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2024-04-17 22:46:44 +02:00
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: 8eb1f71e7a ("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
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: d83cee3d2b ("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
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
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
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
0857c39bfd gpio: remove unused logging helpers
The general rule of the kernel is to not provide symbols that have no
users upstream. Let's remove logging helpers that are not used anywhere.

This will save us work later when we'll be modifying them to use the
upcoming SRCU infrastructure.

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 10:50:27 +01:00
Bartosz Golaszewski
efb8235bfd gpiolib: revert the attempt to protect the GPIO device list with an rwsem
This reverts commits 1979a28075 ("gpiolib: replace the GPIO device
mutex with a read-write semaphore") and 65a828bab1 ("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: 1979a28075 ("gpiolib: replace the GPIO device mutex with a read-write semaphore")
Fixes: 65a828bab1 ("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
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
36aa129f22 gpiolib: make gpio_device_get() and gpio_device_put() public
In order to start migrating away from accessing struct gpio_chip by
users other than their owners, let's first make the reference management
functions for the opaque struct gpio_device public in the driver.h
header.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2023-10-04 13:28:58 +02:00
Bartosz Golaszewski
fe4fa2e4f7 gpiolib: make gpiochip_get_desc() public
It makes sense for a GPIO driver to want to get its own descriptor
without requesting it. After all, the driver knows that it'll still be
valid. Let's move this helper to linux/gpio/driver.h.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
2023-09-12 10:05:58 +02:00
Bartosz Golaszewski
f42dafe3da gpiolib: unexport gpiod_set_transitory()
There are no and never have been any users of gpiod_set_transitory()
outside the core GPIOLIB code. Make it private.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
2023-09-11 11:17:05 +02:00
Bartosz Golaszewski
9ce4ed5b4d gpiolib: provide and use gpiod_line_state_notify()
Wrap the calls to blocking_notifier_call_chain() for the line state
notifier with a helper that allows us to use fewer lines of code and
simpler syntax.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2023-08-22 09:37:46 +02:00
Bartosz Golaszewski
a067419ba7 gpiolib: add a second blocking notifier to struct gpio_device
Add a new blocking notifier to struct gpio_device and use it to notify
subscribers about the GPIO device being unregistered from the device
model.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Kent Gibson <warthog618@gmail.com>
2023-08-21 15:57:05 +02:00
Bartosz Golaszewski
17a7ca3589 gpiolib: rename the gpio_device notifier
Change the generic "notifier" name to "line_state_notifier" in order to
reflect its purpose in preparation for adding a second notifier which
will be used to notify wait queues about device unregistering.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Kent Gibson <warthog618@gmail.com>
2023-08-21 15:57:05 +02:00
Asmaa Mnebhi
55b2395e4e gpio: mmio: handle "ngpios" properly in bgpio_init()
bgpio_init() uses "sz" argument to populate ngpio, which is not
accurate. Instead, read the "ngpios" property from the DT and if it
doesn't exist, use the "sz" argument. With this change, drivers no
longer need to overwrite the ngpio variable after calling bgpio_init().

If the "ngpios" property is specified, bgpio_bits is calculated
as the round up value of ngpio. At the moment, the only requirement
specified is that the round up value must be a multiple of 8 but
it should also be a power of 2 because we provide accessors based
on the bank size in bgpio_setup_accessors().

Signed-off-by: Asmaa Mnebhi <asmaa@nvidia.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2023-07-18 20:59:25 +02:00
Bartosz Golaszewski
0f93a345aa gpiolib: order includes alphabetically in gpiolib.h
After adding the missing notifier.h header, let's order all includes
alphabetically.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2023-07-13 09:17:24 +02:00
Bartosz Golaszewski
e2051394a5 gpiolib: add missing include
gpiolib.h uses notifiers but doesn't include <linux/notifier.h>.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Kent Gibson <warthog618@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
2023-07-10 09:54:07 +02:00
Andy Shevchenko
dc0989e3aa gpiolib: Introduce gpio_device_get() and gpio_device_put()
Introduce gpio_device_get() and gpio_device_put() helpers
and convert existing users.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2023-01-30 15:55:29 +01:00
Bartosz Golaszewski
bdbbae241a gpiolib: protect the GPIO device against being dropped while in use by user-space
While any of the GPIO cdev syscalls is in progress, the kernel can call
gpiochip_remove() (for instance, when a USB GPIO expander is disconnected)
which will set gdev->chip to NULL after which any subsequent access will
cause a crash.

To avoid that: use an RW-semaphore in which the syscalls take it for
reading (so that we don't needlessly prohibit the user-space from calling
syscalls simultaneously) while gpiochip_remove() takes it for writing so
that it can only happen once all syscalls return.

Fixes: d7c51b47ac ("gpio: userspace ABI for reading/writing GPIO lines")
Fixes: 3c0d9c635a ("gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL")
Fixes: aad955842d ("gpiolib: cdev: support GPIO_V2_GET_LINEINFO_IOCTL and GPIO_V2_GET_LINEINFO_WATCH_IOCTL")
Fixes: a54756cb24 ("gpiolib: cdev: support GPIO_V2_LINE_SET_CONFIG_IOCTL")
Fixes: 7b8e00d981 ("gpiolib: cdev: support GPIO_V2_LINE_SET_VALUES_IOCTL")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
[Nick: fixed a build failure with CDEV_V1 disabled]
Co-authored-by: Nick Hainke <vincent@systemli.org>
Reviewed-by: Kent Gibson <warthog618@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
2022-12-07 09:35:59 +01:00
Andy Shevchenko
3b7c7478ed gpiolib: Provide to_gpio_device() helper
Provide to_gpio_device() helper which can be utilized in the existing
and future code.

While at it, make sure it becomes no-op at compilation time.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
2022-11-29 14:52:20 +01:00
Linus Torvalds
2981436374 hte: New subsystem for v5.19-rc1
This contains the new HTE subsystem that has been in the works for a
 couple of months now. The infrastructure provided allows for drivers to
 register as hardware timestamp providers, while consumers will be able
 to request events that they are interested in (such as GPIOs and IRQs)
 to be timestamped by the hardware providers.
 
 Note that this currently supports only one provider, but there seems to
 be enough interest in this functionality and we expect to see more
 drivers added once this is merged.
 -----BEGIN PGP SIGNATURE-----
 
 iQJHBAABCAAxFiEEiOrDCAFJzPfAjcif3SOs138+s6EFAmKZ77ATHHRyZWRpbmdA
 bnZpZGlhLmNvbQAKCRDdI6zXfz6zoTgVD/4tdJptbwblr8CCP5jklb81quuKBFu4
 2VaUpyGo4TDD4g0jchmAkmB0JsjO7mauURZ/vwWUfDx+uvsOJyf79smY/4OvL0v6
 MdYFeXb1rqDX8SiZSnpa+PKNI96l9/l1sbkbj1PPIod8hJSgXsASRP4lF21U97ZY
 QTI7u3kMJsUEvZhbEs9E2TXPAUO4+M8HfogJuEoaVRyHdwVHY1+Z+jlUsVXRd1qU
 XpIaKKMWF07FWrs2QUAbdqIUc8cITlcP+ExCc35PMwZnemWHnVwvk0mVyC0XD39P
 PHGlQOR2zTwJmijCwFkKTwuhGufE6bbvKvdns6gyTUlbzpQ4vcjPfVubt9ehX3dp
 acEJp5WdJFUhFU4dhjsLGVVzwE/L7vsZ3RPPh1j/Hjt0wYPg/EYPLr/wz+0wbIxt
 z4AtQZBLwrXSxXUuGkzl139kx0lTEtQZvfiziwi8BWrl6aqeBcGSNYHFLs2rDUTh
 sap+aEYRQ4cGWYfLMhv3yRLkkTlGxDMmEPM9VWGJb96osBcfidvgT+SE5qwoz6yg
 yJyMWwCrjYvYl+ZHwfKE3pEE4z9mrs7VLgcW9yWOF4UwFLuH0DyIEtCx/I4Uk+QG
 7F1HuV3mYZNlOwgJMZooSJ5Z9uzrn+eGzivhw4klJibFZBXqICCQjL5KvQ8wyuY7
 60Ns9+912HV/tQ==
 =sOJn
 -----END PGP SIGNATURE-----

Merge tag 'hte/for-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux

Pull hardware timestamping subsystem from Thierry Reding:
 "This contains the new HTE (hardware timestamping engine) subsystem
  that has been in the works for a couple of months now.

  The infrastructure provided allows for drivers to register as hardware
  timestamp providers, while consumers will be able to request events
  that they are interested in (such as GPIOs and IRQs) to be timestamped
  by the hardware providers.

  Note that this currently supports only one provider, but there seems
  to be enough interest in this functionality and we expect to see more
  drivers added once this is merged"

[ Linus Walleij mentions the Intel PMC in the Elkhart and Tiger Lake
  platforms as another future timestamp provider ]

* tag 'hte/for-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tegra/linux:
  dt-bindings: timestamp: Correct id path
  dt-bindings: Renamed hte directory to timestamp
  hte: Uninitialized variable in hte_ts_get()
  hte: Fix off by one in hte_push_ts_ns()
  hte: Fix possible use-after-free in tegra_hte_test_remove()
  hte: Remove unused including <linux/version.h>
  MAINTAINERS: Add HTE Subsystem
  hte: Add Tegra HTE test driver
  tools: gpio: Add new hardware clock type
  gpiolib: cdev: Add hardware timestamp clock type
  gpio: tegra186: Add HTE support
  gpiolib: Add HTE support
  dt-bindings: Add HTE bindings
  hte: Add Tegra194 HTE kernel provider
  drivers: Add hardware timestamp engine (HTE) subsystem
  Documentation: Add HTE subsystem guide
2022-06-05 09:12:28 -07:00
Dipen Patel
42112dd77b gpiolib: Add HTE support
Some GPIO chip can provide hardware timestamp support on its GPIO lines
, in order to support that, additional API needs to be added which
can talk to both GPIO chip and HTE (hardware timestamping engine)
providers if there is any dependencies. This patch introduces optional
hooks to enable and disable hardware timestamping related features
in the GPIO controller chip.

Signed-off-by: Dipen Patel <dipenp@nvidia.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
2022-05-04 11:06:13 +02:00
Andy Shevchenko
66f46e370a gpiolib: Split out for_each_gpio_desc() macro
In some cases we want to traverse all GPIO descriptors for given
chip, let's split out for_each_gpio_desc() macro for such cases.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2022-04-09 22:38:17 +02:00
Andy Shevchenko
57017edd46 gpiolib: Embed iterator variable into for_each_gpio_desc_with_flag()
The iterator loop is used exclusively to get a descriptor, which in its
turn is what is being used by the caller. Embed the iterator variable
into the loop in the for_each_gpio_desc_with_flag() macro helper.

Suggested-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2022-04-09 22:37:48 +02:00
Linus Torvalds
ebcb577aee gpio updates for v5.18-rc1
- new driver: gpio-en7523
 - dt-bindings: convertion of faraday,ftgpio010 to YAML, new compatible string
   in gpio-vf610 and a bugfix in an example
 - gpiolib core: several improvements and some code shrink
 - documentation: convert all public docs into kerneldoc format
 - set IRQ bus token in gpio-crystalcove (addresses a debugfs issue)
 - add a missing return value check for kstrdup() in gpio-merrifield
 - allow gpio-tps68470 to be built as module
 - more work on limiting usage of of_node in GPIO drivers
 - several sysfs interface improvements
 - use SDPX in gpio-ts4900
 -----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCAAdFiEEFp3rbAvDxGAT0sefEacuoBRx13IFAmI7SAwACgkQEacuoBRx
 13JJEA/+MdTAmPHyCp55POmKmxMIafejc2EXaZKYK82WhuqOBWyc4UHMzGGD/7YF
 TXKidJ8Bnzki2XiAJlHuyRLrBR67qUs79UkCKQPoEsaBJ4AeQj48bR8YHb+1x+gS
 2LS7IqW4sFB5O61ZCB1Bg8k8Ots9E5OI4Q9+gGxyLVbCK0L8mN8U63a/Fhv4sIJU
 z5WBXVTOsIMrprN2N9/VxNnSUkRqaUcl78ko0yV9B6vi957pojkFApg3rdJmWqV6
 RLGdrQIklY95SdlnTHuG8+7Jy0Ut/ohwdUFDpyd/Hv/qvzE/vRWdvsccSS8KHwtL
 dK+8sGN67QWfLmUhjqd0Y+Q/f/IIZyGHTkHWUojPE9cW6HJudgXQlCkcbjdV+tdB
 2DO67wal6UKIw6efScLeBB7N/x9p8UioxVwHQiy05GBZJYTI184NWoel5hKqUbnh
 GZVBf30fVQxmsJoHJa7e+xPLcHOrrTU+80CR9NhZBBm6xNLbkl1MidbJWfuEgNC1
 6+o6jhy5K+SS09NKQteJFNQtc7f2Mt3Rc1NQzxJc2AaQXFvqbQLC36qkk5oqeDKH
 Ndw4AYuxXWBU62sHZCJkWtG2CIAykvBNRoje3rXukbcv583jx18WScWJx/FKS9hh
 k//1hdlesCV1ouo4qDvCiEC5hby0+FQ/HWgkXGIlNC/gZ6fcrZs=
 =0SYv
 -----END PGP SIGNATURE-----

Merge tag 'gpio-updates-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux

Pull gpio updates from Bartosz Golaszewski:
 "Relatively few updates for this release cycle. We have a single new
  driver and some minor changes in drivers, more work on limiting the
  usage of of_node in drivers and DT updates:

   - new driver: gpio-en7523

   - dt-bindings: convertion of faraday,ftgpio010 to YAML, new
     compatible string in gpio-vf610 and a bugfix in an example

   - gpiolib core: several improvements and some code shrink

   - documentation: convert all public docs into kerneldoc format

   - set IRQ bus token in gpio-crystalcove (addresses a debugfs issue)

   - add a missing return value check for kstrdup() in gpio-merrifield

   - allow gpio-tps68470 to be built as module

   - more work on limiting usage of of_node in GPIO drivers

   - several sysfs interface improvements

   - use SDPX in gpio-ts4900"

* tag 'gpio-updates-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux:
  gpio: ts4900: Use SPDX header
  gpiolib: Use list_first_entry()/list_last_entry()
  gpiolib: sysfs: Simplify edge handling in the code
  gpiolib: sysfs: Move kstrtox() calls outside of the mutex lock
  gpiolib: sysfs: Move sysfs_emit() calls outside of the mutex lock
  gpiolib: make struct comments into real kernel docs
  dt-bindings: gpio: convert faraday,ftgpio01 to yaml
  dt-bindings: gpio: gpio-vf610: Add imx93 compatible string
  gpiolib: Simplify error path in gpiod_get_index() when requesting GPIO
  gpiolib: Use short form of ternary operator in gpiod_get_index()
  gpiolib: Introduce for_each_gpio_desc_with_flag() macro
  gpio: Add support for Airoha EN7523 GPIO controller
  dt-bindings: arm: airoha: Add binding for Airoha GPIO controller
  dt-bindings: gpio: fix gpio-hog example
  gpio: tps68470: Allow building as module
  gpio: tegra: Get rid of duplicate of_node assignment
  gpio: altera-a10sr: Switch to use fwnode instead of of_node
  gpio: merrifield: check the return value of devm_kstrdup()
  gpio: crystalcove: Set IRQ domain bus token to DOMAIN_BUS_WIRED
2022-03-25 12:28:23 -07:00
Bartosz Golaszewski
4398693a9e gpiolib: make struct comments into real kernel docs
We have several comments that start with '/**' but don't conform to the
kernel doc standard. Add proper detailed descriptions for the affected
definitions and move the docs from the forward declarations to the
struct definitions where applicable.

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
2022-02-09 10:07:10 +01:00
Andy Shevchenko
80c78fbeef gpiolib: Introduce for_each_gpio_desc_with_flag() macro
In a few places we are using a loop against all GPIO descriptors
with a given flag for a given device. Replace it with a consolidated
for_each type of macro.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2022-02-08 10:35:49 +01:00
Andy Shevchenko
95a4eed7dd gpiolib: Never return internal error codes to user space
Currently it's possible that character device interface may return
the error codes which are not supposed to be seen by user space.
In this case it's EPROBE_DEFER.

Wrap it to return -ENODEV instead as sysfs does.

Fixes: d7c51b47ac ("gpio: userspace ABI for reading/writing GPIO lines")
Fixes: 61f922db72 ("gpio: userspace ABI for reading GPIO line events")
Fixes: 3c0d9c635a ("gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL")
Reported-by: Suresh Balakrishnan <suresh.balakrishnan@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
2022-02-08 10:34:15 +01:00
Linus Walleij
40b37008eb gpio updates for v5.11-rc1
- several refactoring patches of the core gpiolib code
 - add support for NXP PCAL9554B/C to gpio-pca953x
 - allow probing mockup devices from device tree
 - refactoring and improvements to gpio-rcar
 - improvements to locking in gpio-tegra
 - code shrink in gpiolib devres
 - get the irq offset from device tree in gpio-sifive
 - major refactoring of gpio-exar
 - convert gpio-mvebu pwm access to regmap
 - create a new submenu for virtual GPIO drivers
 - fix clang fall-through warnings treewide
 - minor driver refactoring and tweaks sprinkled all over
 -----BEGIN PGP SIGNATURE-----
 
 iQIzBAABCAAdFiEEFp3rbAvDxGAT0sefEacuoBRx13IFAl/QnM8ACgkQEacuoBRx
 13LkDw/+NKHc32hKgMJmSsLLFHgZ8XB+7Y775G5Ejxj+4Z0hVY9LdqL0zSYwrzCg
 D2dKwrKMtM83T8vf0bVbPdZ/9uuqrljvocGYt2CFmDqQa3sSlJkyDiSak2HAqjK/
 p9cgDQaUIlDrg2xh/1kSqELQoONmp4m82i++bItIwxIqAwPWfjSHVD7EQznDu0QD
 MJ7eYSuVlpeBhMwfyGCYSuUFhd4wN+nTkLTYw3nNlU4PHCKpdgYd7SBCJjSsLAhM
 8FOQ+PBspS6t8lPIEa4Mt+TOWUbbboGUBy40GPNU8QcUjbzj3TwPIBJu/0SIdSOy
 fBrk+GRjWtJ9shSlz0WQ19mG+qMjIiw4xLY1Jh3Tr4b75bQ3a4pk50aPWNE6bbHV
 NP1wZer/s06f1TQFKjfuDVFsOoRLyrTuOzlW0COAHoqFOdgimZi36xtjaS3AL3lE
 POBiBxFo9VaQ0enD99QMBt3940IP3ekRmlqRxeR1t8C0gE5np8IMZ5Dti8Fh4eCN
 hUQTDDuWQadluOdhMdLCBh5cA3VfZY8xksAMBzAYnSUHzM2D8TcKVjfJeegCEuZd
 kapAV3nLUv1/ZU36okFpMaHaKBL+xGDv8gtV2ro7rptkm6khNPQ3hxKvRbCRCG+S
 fO6IKThwozZEL/uVvsZLRKvN47g89oAGYYfasqq49932WChVKf8=
 =RmnM
 -----END PGP SIGNATURE-----

Merge tag 'gpio-updates-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux into devel

gpio updates for v5.11-rc1

- several refactoring patches of the core gpiolib code
- add support for NXP PCAL9554B/C to gpio-pca953x
- allow probing mockup devices from device tree
- refactoring and improvements to gpio-rcar
- improvements to locking in gpio-tegra
- code shrink in gpiolib devres
- get the irq offset from device tree in gpio-sifive
- major refactoring of gpio-exar
- convert gpio-mvebu pwm access to regmap
- create a new submenu for virtual GPIO drivers
- fix clang fall-through warnings treewide
- minor driver refactoring and tweaks sprinkled all over
2020-12-09 15:17:24 +01:00
Kent Gibson
26d060e47e gpiolib: cdev: allow edge event timestamps to be configured as REALTIME
Using CLOCK_REALTIME as the source for event timestamps is crucial for
some specific applications, particularly those requiring timetamps
relative to a PTP clock, so provide an option to switch the event
timestamp source from the default CLOCK_MONOTONIC to CLOCK_REALTIME.

Note that CLOCK_REALTIME was the default source clock for GPIO until
Linux 5.7 when it was changed to CLOCK_MONOTONIC due to issues with the
shifting of the realtime clock.
Providing this option maintains the CLOCK_MONOTONIC as the default,
while also providing a path forward for those dependent on the pre-5.7
behaviour.

Suggested-by: Jack Winch <sunt.un.morcov@gmail.com>
Signed-off-by: Kent Gibson <warthog618@gmail.com>
Link: https://lore.kernel.org/r/20201014231158.34117-2-warthog618@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2020-12-05 23:22:47 +01:00
Andy Shevchenko
f725edd86b gpiolib: Introduce gpio_set_debounce_timeout() for internal use
In some cases we would like to have debounce setter which doesn't fail
when a feature is not supported by a controller.

Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
2020-11-16 14:14:34 +02:00
Andy Shevchenko
7b58696d9a gpiolib: Extract gpiod_not_found() helper
Several places in the code are using same idiom, i.e.
	IS_ERR(desc) && PTR_ERR(desc) == -ENOENT
which meaning is GPIO description is not found.

For better readability extract gpiod_not_found() helper and use it.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
2020-10-26 15:23:33 +01:00
Kent Gibson
65cff70464 gpiolib: cdev: support setting debounce
Add support for setting debounce on a line via the GPIO uAPI.
Where debounce is not supported by hardware, a software debounce is
provided.

The implementation of the software debouncer waits for the line to be
stable for the debounce period before determining if a level change,
and a corresponding edge event, has occurred.  This provides maximum
protection against glitches, but also introduces a debounce_period
latency to edge events.

The software debouncer is integrated with the edge detection as it
utilises the line interrupt, and integration is simpler than getting
the two to interwork.  Where software debounce AND edge detection is
required, the debouncer provides both.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
2020-09-30 10:57:04 +02:00
Kent Gibson
73e0341992 gpiolib: cdev: support edge detection for uAPI v2
Add support for edge detection to lines requested using
GPIO_V2_GET_LINE_IOCTL.

The edge_detector implementation is based on the v1 lineevent
implementation.  Unlike the v1 implementation, an overflow of the event
buffer results in discarding older events, rather than the most
recent, so the final event in a burst will correspond to the current
state of the line.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
2020-09-30 10:56:56 +02:00