Commit 6933ba52 authored by Bartosz Golaszewski's avatar Bartosz Golaszewski
Browse files

gpio: improve the API contract for setting direction 



If a GPIO driver returns a positive integer from one of the direction
setter callbacks, we'll end up propagating it to user-space. Whether we
should sanitize the values returned by callbacks is a different question
but let's first improve the documentation and fortify the contract with
GPIO providers.

Reported-by: default avatarJosé Guilherme de Castro Rodrigues <joseguilhermebh@hotmail.com>
Signed-off-by: default avatarBartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: default avatarKent Gibson <warthog618@gmail.com>
parent 88b70496

include/linux/gpio/driver.h

+6 −4
Original line number Diff line number Diff line
@@ -335,10 +335,12 @@ struct gpio_irq_chip { 
 *	(same as GPIO_LINE_DIRECTION_OUT / GPIO_LINE_DIRECTION_IN),

 *	or negative error. It is recommended to always implement this

 *	function, even on input-only or output-only gpio chips.

 * @direction_input: configures signal "offset" as input, or returns error

 *	This can be omitted on input-only or output-only gpio chips.

 * @direction_output: configures signal "offset" as output, or returns error

 *	This can be omitted on input-only or output-only gpio chips.

 * @direction_input: configures signal "offset" as input, returns 0 on success

 *	or a negative error number. This can be omitted on input-only or

 *	output-only gpio chips.

 * @direction_output: configures signal "offset" as output, returns 0 on

 *	success or a negative error number. This can be omitted on input-only

 *	or output-only gpio chips.

 * @get: returns value for signal "offset", 0=low, 1=high, or negative error

 * @get_multiple: reads values for multiple signals defined by "mask" and

 *	stores them in "bits", returns 0 on success or negative error