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| author | Linus Walleij <linus.walleij@linaro.org> | 2018-01-18 12:43:43 +0300 |
|---|---|---|
| committer | Linus Walleij <linus.walleij@linaro.org> | 2018-01-18 12:43:43 +0300 |
| commit | adbf02998b2e21e3f055f72fe2daa86260f03637 (patch) | |
| tree | e9a6b8bd543acf3ab7ad68eecb488f2ed6bd424e /Documentation/gpio/board.txt | |
| parent | 40a3c9db08ad59062c6ca525fca32ca97edcf99e (diff) | |
| download | linux-adbf02998b2e21e3f055f72fe2daa86260f03637.tar.xz | |
gpio: Documentation update
Update a slew of documentation files with the latest changes in the
API/ABI. Again stress that sysfs is deprecated. Add all new flags and
clean up and move some text.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'Documentation/gpio/board.txt')
| -rw-r--r-- | Documentation/gpio/board.txt | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/Documentation/gpio/board.txt b/Documentation/gpio/board.txt index a0f61898d493..b1d106167baa 100644 --- a/Documentation/gpio/board.txt +++ b/Documentation/gpio/board.txt @@ -2,6 +2,7 @@ GPIO Mappings ============= This document explains how GPIOs can be assigned to given devices and functions. + 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 @@ -49,7 +50,7 @@ This property will make GPIOs 15, 16 and 17 available to the driver under the power = gpiod_get(dev, "power", GPIOD_OUT_HIGH); -The led GPIOs will be active-high, while the power GPIO will be active-low (i.e. +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 @@ -122,9 +123,14 @@ where can be NULL, in which case it will match any function. - idx is the index of the GPIO within the function. - flags is defined to specify the following properties: - * GPIOF_ACTIVE_LOW - to configure the GPIO as active-low - * GPIOF_OPEN_DRAIN - GPIO pin is open drain type. - * GPIOF_OPEN_SOURCE - GPIO pin is open source type. + * GPIO_ACTIVE_HIGH - GPIO line is active high + * GPIO_ACTIVE_LOW - GPIO line is active low + * GPIO_OPEN_DRAIN - GPIO line ise set up as open drain + * GPIO_OPEN_SOURCE - GPIO line is set up as open source + * GPIO_PERSISTENT - GPIO line is persistent during + suspend/resume and maintains its value + * GPIO_TRANSITORY - GPIO line is transitory and may loose its + electrical state during suspend/resume In the future, these flags might be extended to support more properties. |