diff options
| author | Lukas Wunner <lukas@wunner.de> | 2017-10-12 12:40:10 +0200 |
|---|---|---|
| committer | Linus Walleij <linus.walleij@linaro.org> | 2017-10-19 22:32:39 +0200 |
| commit | eec1d566cdf94b57e8f5ba9fe60eea214929bcfc (patch) | |
| tree | f10fab2d393d231f711123fcf66c1b01fc893370 /include/linux/gpio/driver.h | |
| parent | 5307e2ad69ab3b0e0622fdf8b254c1d4565eb924 (diff) | |
gpio: Introduce ->get_multiple callback
SPI-attached GPIO controllers typically read out all inputs in one go.
If callers desire the values of multipe inputs, ideally a single readout
should take place to return the desired values. However the current
driver API only offers a ->get callback but no ->get_multiple (unlike
->set_multiple, which is present). Thus, to read multiple inputs, a
full readout needs to be performed for every single value (barring
driver-internal caching), which is inefficient.
In fact, the lack of a ->get_multiple callback has been bemoaned
repeatedly by the gpio subsystem maintainer:
http://www.spinics.net/lists/linux-gpio/msg10571.html
http://www.spinics.net/lists/devicetree/msg121734.html
Introduce the missing callback. Add corresponding consumer functions
such as gpiod_get_array_value(). Amend linehandle_ioctl() to take
advantage of the newly added infrastructure. Update the documentation.
Cc: Rojhalat Ibrahim <imr@rtschenk.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Diffstat (limited to 'include/linux/gpio/driver.h')
| -rw-r--r-- | include/linux/gpio/driver.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h index 6bbda879fb8b..bda95a9b7b8c 100644 --- a/include/linux/gpio/driver.h +++ b/include/linux/gpio/driver.h @@ -35,6 +35,8 @@ struct module; * @direction_input: configures signal "offset" as input, or returns error * @direction_output: configures signal "offset" as output, or returns error * @get: returns value for signal "offset", 0=low, 1=high, or negative error + * @get_multiple: reads values for multiple signals defined by "mask" and + * stores them in "bits", returns 0 on success or negative error * @set: assigns output value for signal "offset" * @set_multiple: assigns output values for multiple signals defined by "mask" * @set_config: optional hook for all kinds of settings. Uses the same @@ -125,6 +127,9 @@ struct gpio_chip { unsigned offset, int value); int (*get)(struct gpio_chip *chip, unsigned offset); + int (*get_multiple)(struct gpio_chip *chip, + unsigned long *mask, + unsigned long *bits); void (*set)(struct gpio_chip *chip, unsigned offset, int value); void (*set_multiple)(struct gpio_chip *chip, |