diff options
Diffstat (limited to 'Documentation/gpio/board.txt')
-rw-r--r-- | Documentation/gpio/board.txt | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/Documentation/gpio/board.txt b/Documentation/gpio/board.txt index 86d3fa95fd12..a0f61898d493 100644 --- a/Documentation/gpio/board.txt +++ b/Documentation/gpio/board.txt @@ -6,11 +6,11 @@ Note that it only applies to the new descriptor-based interface. For a description of the deprecated integer-based GPIO interface please refer to gpio-legacy.txt (actually, there is no real mapping possible with the old interface; you just fetch an integer from somewhere and request the -corresponding GPIO. +corresponding GPIO). -Platforms that make use of GPIOs must select ARCH_REQUIRE_GPIOLIB (if GPIO usage -is mandatory) or ARCH_WANT_OPTIONAL_GPIOLIB (if GPIO support can be omitted) in -their Kconfig. Then, how GPIOs are mapped depends on what the platform uses to +All platforms can enable the GPIO library, but if the platform strictly +requires GPIO functionality to be present, it needs to select GPIOLIB from its +Kconfig. Then, how GPIOs are mapped depends on what the platform uses to describe its hardware layout. Currently, mappings can be defined through device tree, ACPI, and platform data. @@ -162,6 +162,9 @@ The driver controlling "foo.0" will then be able to obtain its GPIOs as follows: Since the "led" GPIOs are mapped as active-high, this example will switch their signals to 1, i.e. enabling the LEDs. And for the "power" GPIO, which is mapped -as active-low, its actual signal will be 0 after this code. Contrary to the legacy -integer GPIO interface, the active-low property is handled during mapping and is -thus transparent to GPIO consumers. +as active-low, its actual signal will be 0 after this code. Contrary to the +legacy integer GPIO interface, the active-low property is handled during +mapping and is thus transparent to GPIO consumers. + +A set of functions such as gpiod_set_value() is available to work with +the new descriptor-oriented interface. |