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Commit 87e77e46 authored by Dirk Behme's avatar Dirk Behme Committed by Linus Walleij
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Documentation: gpio: board: describe the con_id parameter 



The con_id parameter has to match the GPIO description and is automatically
extended by the GPIO suffix if not NULL. I had to look into the code to
understand this and properly find the GPIO I've been looking for, so document
this.

Signed-off-by: default avatarDirk Behme <dirk.behme@gmail.com>
Acked-by: default avatarAlexandre Courbot <acourbot@nvidia.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent 69de52ba

Documentation/gpio/board.txt

+9 −0
Original line number Diff line number Diff line
@@ -48,6 +48,15 @@ This property will make GPIOs 15, 16 and 17 available to the driver under the 
The led GPIOs will be active-high, while the power GPIO will be active-low (i.e.

gpiod_is_active_low(power) will be true).



The second parameter of the gpiod_get() functions, the con_id string, has to be

the <function>-prefix of the GPIO suffixes ("gpios" or "gpio", automatically

looked up by the gpiod functions internally) used in the device tree. With above

"led-gpios" example, use the prefix without the "-" as con_id parameter: "led".



Internally, the GPIO subsystem prefixes the GPIO suffix ("gpios" or "gpio")

with the string passed in con_id to get the resulting string

(snprintf(... "%s-%s", con_id, gpio_suffixes[]).



ACPI

----

ACPI also supports function names for GPIOs in a similar fashion to DT.

Documentation/gpio/consumer.txt

+3 −0
Original line number Diff line number Diff line
@@ -39,6 +39,9 @@ device that displays digits), an additional index argument can be specified: 
					  const char *con_id, unsigned int idx,

					  enum gpiod_flags flags)



For a more detailed description of the con_id parameter in the DeviceTree case

see Documentation/gpio/board.txt



The flags parameter is used to optionally specify a direction and initial value

for the GPIO. Values can be: