From 60befd2ea1c2061775838ea7bac5cc2b1353afd0 Mon Sep 17 00:00:00 2001 From: Vladimir Zapolskiy Date: Tue, 22 Dec 2015 16:37:28 +0200 Subject: [PATCH] gpio: update gpiochip .get() callback description Since gpiochip .get() callback may return a negative error value, it strictly limits the range of possible non-error returned values to a subset of [30:0] bitmask, however on practice on success all gpiochip drivers return either 0 for low signal or 1 for high signal, this is assured by "gpio: *: Be sure to clamp return value" series of changes. To avoid any confusion, misinterpretation and potential errors while developing gpiochip drivers in future convert this implicit assumption to a mandatory rule. For output signals with unknown output signal state gpiochip drivers should return a negative error instead of 0. Signed-off-by: Vladimir Zapolskiy Signed-off-by: Linus Walleij --- include/linux/gpio/driver.h | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h index b02c43be7859..990797589408 100644 --- a/include/linux/gpio/driver.h +++ b/include/linux/gpio/driver.h @@ -32,8 +32,7 @@ struct seq_file; * (same as GPIOF_DIR_XXX), or negative error * @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"; for output signals this - * returns either the value actually sensed, or zero + * @get: returns value for signal "offset", 0=low, 1=high, or negative error * @set: assigns output value for signal "offset" * @set_multiple: assigns output values for multiple signals defined by "mask" * @set_debounce: optional hook for setting debounce time for specified gpio in -- 2.11.0