gpio: improve the API contract for setting direction
PATCH 1/1 gpio: improve the API contract for setting direction
From: Bartosz Golaszewski <[email protected]>
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.
--- include/linux/gpio/driver.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
include/linux/gpio/driver.h +6 -4
@@ -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, or returns a negative +* error number. This can be omitted on input-only or output-only gpio +* chips. +* @direction_output: configures signal "offset" as output, or returns +* 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
Signature · 1 line
2.40.1
Quoted 25 lines · Bartosz Golaszewski
From: Bartosz Golaszewski <[email protected]>
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.
Signed-off-by Bartosz Golaszewski <[email protected]>--- include/linux/gpio/driver.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)include/linux/gpio/driver.h +0
-3@@ -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
include/linux/gpio/driver.h struct gpio_irq_chip { · line 346
Quoted 10 lines
include/linux/gpio/driver.h +6
-1-* This can be omitted on input-only or output-only gpio chips. +* @direction_input: configures signal "offset" as input, or returns a negative +* error number. This can be omitted on input-only or output-only gpio +* chips. +* @direction_output: configures signal "offset" as output, or returns +* 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
Also specify 0 on success, as per @get_multiple?
It would be good to revise the documentation for all the ops, but this is a start.
Cheers,
Kent.