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| author | Dirk Behme <dirk.behme@gmail.com> | 2015-09-02 20:07:10 +0200 |
|---|---|---|
| committer | Linus Walleij <linus.walleij@linaro.org> | 2015-09-14 09:12:03 +0200 |
| commit | 87e77e46c61a9333227ab41cdefb1875758a4f13 (patch) | |
| tree | aff0adbf941230d730c489b6532a1fdec1f13986 /Documentation/gpio | |
| parent | 69de52ba321dda8dd7f632d1e480983494325ba0 (diff) | |
| download | lwn-87e77e46c61a9333227ab41cdefb1875758a4f13.tar.gz lwn-87e77e46c61a9333227ab41cdefb1875758a4f13.zip | |
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: Dirk Behme <dirk.behme@gmail.com>
Acked-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'Documentation/gpio')
| -rw-r--r-- | Documentation/gpio/board.txt | 9 | ||||
| -rw-r--r-- | Documentation/gpio/consumer.txt | 3 |
2 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/gpio/board.txt b/Documentation/gpio/board.txt index 9edd5af31b3a..5fa069a80171 100644 --- a/Documentation/gpio/board.txt +++ b/Documentation/gpio/board.txt @@ -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. diff --git a/Documentation/gpio/consumer.txt b/Documentation/gpio/consumer.txt index a206639454ab..e000502fde20 100644 --- a/Documentation/gpio/consumer.txt +++ b/Documentation/gpio/consumer.txt @@ -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: |