@@ -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.
@@ -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:
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> --- Changes in v2: Using the "gpios" property without prefix is considered deprecated, therefore don't describe it. Documentation/gpio/board.txt | 9 +++++++++ Documentation/gpio/consumer.txt | 3 +++ 2 files changed, 12 insertions(+)