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authorGuenter Roeck <linux@roeck-us.net>2014-07-21 11:12:16 -0700
committerLinus Walleij <linus.walleij@linaro.org>2014-07-23 17:31:57 +0200
commit2be001739242fac1083f3b21898158492844699d (patch)
treef9f3564e20cd82eea5c0b27b0155dff51f24b365
parent190dc2e6844ad8a47838207cbe739c94d88d94cd (diff)
gpio: Add support for GPIOF_ACTIVE_LOW to gpio_request_one functions
The gpio include file and the gpio documentation declare and document GPIOF_ACTIVE_LOW as one of the flags to be passed to gpio_request_one and related functions. However, the flag is not evaluated or used. This can cause problems in at least two areas: First, the same API can be used to auto-export pins to user space. The missing support for GPIOF_ACTIVE_LOW results in unexpected behavior for such auto-exported pins. Second, the requested gpio pin can be convered for use by gpiod functions with gpio_to_desc(). While gpio API functions do not support GPIOF_ACTIVE_LOW, gpiod functions do, which again results in unexpected behavior. Check the flag in gpio_request_one and set the gpio internal flag FLAG_ACTIVE_LOW if it is set to address those problems. Signed-off-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
-rw-r--r--drivers/gpio/gpiolib-legacy.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/gpio/gpiolib-legacy.c b/drivers/gpio/gpiolib-legacy.c
index eb5a4e2cee85..c684d94cdbb4 100644
--- a/drivers/gpio/gpiolib-legacy.c
+++ b/drivers/gpio/gpiolib-legacy.c
@@ -34,6 +34,9 @@ int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
if (flags & GPIOF_OPEN_SOURCE)
set_bit(FLAG_OPEN_SOURCE, &desc->flags);
+ if (flags & GPIOF_ACTIVE_LOW)
+ set_bit(FLAG_ACTIVE_LOW, &desc->flags);
+
if (flags & GPIOF_DIR_IN)
err = gpiod_direction_input(desc);
else