linux.git/drivers/gpio/gpiolib-cdev.c, branch for-next

gpiolib: cdev: use !mem_is_zero() instead of memchr_inv(s, 0, n)

2024-11-12T08:46:17+00:00

Use the mem_is_zero() helper where possible.

Signed-off-by: Andy Shevchenko 
Link: https://lore.kernel.org/r/20241110201706.16614-1-andy.shevchenko@gmail.com
Signed-off-by: Bartosz Golaszewski

gpio: cdev: don't report GPIOs requested as interrupts as used

2024-11-04T08:08:11+00:00

GPIOs used as shared irqs can still be requested by user-space (or
kernel drivers for that matter) yet we report them as used over the
chardev ABI. Drop the test for FLAG_USED_AS_IRQ from
gpio_desc_to_lineinfo().

Reviewed-by: Kent Gibson 
Reviewed-by: Linus Walleij 
Link: https://lore.kernel.org/r/20241031200842.22712-1-brgl@bgdev.pl
Signed-off-by: Bartosz Golaszewski

gpiolib: avoid format string weakness in workqueue interface

2024-10-31T12:43:09+00:00

Using a string literal as a format string is a possible bug when the
string contains '%' characters:

drivers/gpio/gpiolib-cdev.c:2813:48: error: format string is not a string literal (potentially insecure) [-Werror,-Wformat-security]
 2813 |         gdev->line_state_wq = alloc_ordered_workqueue(dev_name(&gdev->dev),
      |                                                       ^~~~~~~~~~~~~~~~~~~~
drivers/gpio/gpiolib-cdev.c:2813:48: note: treat the string as an argument to avoid this
 2813 |         gdev->line_state_wq = alloc_ordered_workqueue(dev_name(&gdev->dev),
      |                                                       ^
      |                                                       "%s",

Do as clang suggests and use a trivial "%s" format string.

Fixes: 7b9b77a8bba9 ("gpiolib: add a per-gpio_device line state notification workqueue")
Signed-off-by: Arnd Bergmann 
Link: https://lore.kernel.org/r/20241028142152.750650-1-arnd@kernel.org
Signed-off-by: Bartosz Golaszewski

gpiolib: cdev: remove redundant store of debounce_period_us

2024-10-22T07:15:30+00:00

debounce_setup() stores the debounce_period_us if the driver supports
debounce, but the debounce_period_us is also stored where debounce_setup()
is called, independent of whether the debounce is being perfomed by
hardware or software.

Remove the redundant storing of the debounce_period_us in
debounce_setup().

Signed-off-by: Kent Gibson 
Link: https://lore.kernel.org/r/20241020115238.170994-1-warthog618@gmail.com
Signed-off-by: Bartosz Golaszewski

gpiolib: notify user-space about in-kernel line state changes

2024-10-22T06:59:09+00:00

We currently only notify user-space about line config changes that are
made from user-space. Any kernel config changes are not signalled.

Let's improve the situation by emitting the events closer to the source.
To that end let's call the relevant notifier chain from the functions
setting direction, gpiod_set_config(), gpiod_set_consumer_name() and
gpiod_toggle_active_low(). This covers all the options that we can
inform the user-space about. We ignore events which don't have
corresponding flags exported to user-space on purpose - otherwise the
user would see a config-changed event but the associated line-info would
remain unchanged.

gpiod_direction_output/input() can be called from any context.
Fortunately, we now emit line state events using an atomic notifier
chain, so it's no longer an issue.

Let's also add non-notifying wrappers around the direction setters in
order to not emit superfluous reconfigure events when requesting the
lines as the initial config should be part of the request notification.

Use gpio_do_set_config() instead of gpiod_set_debounce() for configuring
debouncing via hardware from the character device code to avoid multiple
reconfigure events.

Reviewed-by: Kent Gibson 
Link: https://lore.kernel.org/r/20241018-gpio-notify-in-kernel-events-v5-8-c79135e58a1c@linaro.org
Signed-off-by: Bartosz Golaszewski

gpiolib: switch the line state notifier to atomic

2024-10-22T06:59:09+00:00

With everything else ready, we can now switch to using the atomic
notifier for line state events which will allow us to notify user-space
about direction changes from atomic context.

Reviewed-by: Kent Gibson 
Link: https://lore.kernel.org/r/20241018-gpio-notify-in-kernel-events-v5-7-c79135e58a1c@linaro.org
Signed-off-by: Bartosz Golaszewski

gpio: cdev: put emitting the line state events on a workqueue

2024-10-22T06:59:09+00:00

In order to allow line state notifications to be emitted from atomic
context (for instance: from gpiod_direction_input/output()), we must
stop calling any sleeping functions in lineinfo_changed_notify(). To
that end let's use the new workqueue.

Let's atomically allocate small structures containing the required data
and fill it with information immediately upon being notified about the
change except for the pinctrl state which will be retrieved later from
process context. We can pretty reliably do this as pin functions are
typically set once per boot.

Let's make sure to bump the reference count of GPIO device and the GPIO
character device file descriptor to keep both alive until the event was
queued.

Reviewed-by: Kent Gibson 
Link: https://lore.kernel.org/r/20241018-gpio-notify-in-kernel-events-v5-6-c79135e58a1c@linaro.org
Signed-off-by: Bartosz Golaszewski

gpiolib: add a per-gpio_device line state notification workqueue

2024-10-22T06:59:08+00:00

In order to prepare the line state notification mechanism for working in
atomic context as well, add a dedicated, high-priority, ordered
workqueue to GPIO device which will be used to queue the events fron any
context for them to be emitted always in process context.

Reviewed-by: Kent Gibson 
Link: https://lore.kernel.org/r/20241018-gpio-notify-in-kernel-events-v5-5-c79135e58a1c@linaro.org
Signed-off-by: Bartosz Golaszewski

gpio: cdev: prepare gpio_desc_to_lineinfo() for being called from atomic

2024-10-22T06:59:08+00:00

In order to prepare gpio_desc_to_lineinfo() to being called from atomic
context, add a new argument - bool atomic - which, if set, indicates
that no sleeping functions must be called (currently: only
pinctrl_gpio_can_use_line()).

Reviewed-by: Kent Gibson 
Link: https://lore.kernel.org/r/20241018-gpio-notify-in-kernel-events-v5-4-c79135e58a1c@linaro.org
Signed-off-by: Bartosz Golaszewski

gpio: cdev: go back to storing debounce period in the GPIO descriptor

2024-10-22T06:59:08+00:00

This effectively reverts commits 9344e34e7992 ("gpiolib: cdev: relocate
debounce_period_us from struct gpio_desc") and d8543cbaf979 ("gpiolib:
remove debounce_period_us from struct gpio_desc") and goes back to
storing the debounce period in microseconds in the GPIO descriptor

We're doing it in preparation for notifying the user-space about
in-kernel line config changes.

Reviewed-by: Kent Gibson 
Link: https://lore.kernel.org/r/20241018-gpio-notify-in-kernel-events-v5-3-c79135e58a1c@linaro.org
Signed-off-by: Bartosz Golaszewski