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| author | Jie Li <lj29312931@gmail.com> | 2026-05-11 14:37:25 +0300 |
|---|---|---|
| committer | Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com> | 2026-05-11 15:25:25 +0300 |
| commit | b5fafa01bdaade5253bd39317f5455d13e6efc7d (patch) | |
| tree | 9d69eb5044f41cf70461740e7c945980f58ca9b0 /include/linux | |
| parent | 254f49634ee16a731174d2ae34bc50bd5f45e731 (diff) | |
| download | linux-b5fafa01bdaade5253bd39317f5455d13e6efc7d.tar.xz | |
gpiolib: add gpiod_is_single_ended() helper
The direction of a single-ended (open-drain or open-source) GPIO line
cannot always be reliably determined by reading hardware registers.
In true open-drain implementations, the "high" state is achieved by
entering a high-impedance mode, which many hardware controllers report
as "input" even if the software intends to use it as an output.
This creates issues for consumer drivers (like I2C) that rely on
gpiod_get_direction() to decide if a line can be driven.
Introduce gpiod_is_single_ended() to allow consumers to check the
software configuration (GPIO_FLAG_OPEN_DRAIN/GPIO_FLAG_OPEN_SOURCE) of
a descriptor. This provides a robust way to identify lines that are
capable of being driven, regardless of their instantaneous hardware state.
Signed-off-by: Jie Li <jie.i.li@nokia.com>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/20260511113726.49041-2-jie.i.li@nokia.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/gpio/consumer.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h index 3efb5cb1e1d1..8fb27f9aa67f 100644 --- a/include/linux/gpio/consumer.h +++ b/include/linux/gpio/consumer.h @@ -111,6 +111,7 @@ void devm_gpiod_unhinge(struct device *dev, struct gpio_desc *desc); void devm_gpiod_put_array(struct device *dev, struct gpio_descs *descs); int gpiod_get_direction(struct gpio_desc *desc); +bool gpiod_is_single_ended(struct gpio_desc *desc); int gpiod_direction_input(struct gpio_desc *desc); int gpiod_direction_output(struct gpio_desc *desc, int value); int gpiod_direction_output_raw(struct gpio_desc *desc, int value); @@ -337,6 +338,10 @@ static inline int gpiod_get_direction(const struct gpio_desc *desc) WARN_ON(desc); return -ENOSYS; } +static inline bool gpiod_is_single_ended(struct gpio_desc *desc) +{ + return false; +} static inline int gpiod_direction_input(struct gpio_desc *desc) { /* GPIO can never have been requested */ |