From: "mario.six@gdsys.cc" mario.six@gdsys.cc
Certain GPIO devices have the capability to switch their GPIOs into open-drain mode, that is, instead of actively driving the output (Push-pull output), the pin is connected to the collector (for a NPN transistor) or the drain (for a MOSFET) of a transistor, respectively. The pin then either forms an open circuit or a connection to ground, depending on the state of the transistor.
This patch adds functions to the GPIO uclass to switch GPIOs to open-drain mode on devices that support it.
Signed-off-by: Mario Six mario.six@gdsys.cc ---
v2: - Added missing commit message - Fixed error return value of dm_gpio_get_open_drain - Fixed return value passing in dm_gpio_set_open_drain and added comment - Added description of open-drain mode
--- drivers/gpio/gpio-uclass.c | 32 ++++++++++++++++++++++++++++++++ include/asm-generic/gpio.h | 34 ++++++++++++++++++++++++++++++++++ 2 files changed, 66 insertions(+)
diff --git a/drivers/gpio/gpio-uclass.c b/drivers/gpio/gpio-uclass.c index b58d4e6..1be9988 100644 --- a/drivers/gpio/gpio-uclass.c +++ b/drivers/gpio/gpio-uclass.c @@ -352,6 +352,38 @@ int dm_gpio_set_value(const struct gpio_desc *desc, int value) return 0; }
+int dm_gpio_get_open_drain(struct gpio_desc *desc) +{ + struct dm_gpio_ops *ops = gpio_get_ops(desc->dev); + int ret; + + ret = check_reserved(desc, "get_open_drain"); + if (ret) + return ret; + + if (ops->set_open_drain) + return ops->get_open_drain(desc->dev, desc->offset); + else + return -ENOSYS; +} + +int dm_gpio_set_open_drain(struct gpio_desc *desc, int value) +{ + struct dm_gpio_ops *ops = gpio_get_ops(desc->dev); + int ret; + + ret = check_reserved(desc, "set_open_drain"); + if (ret) + return ret; + + if (ops->set_open_drain) + ret = ops->set_open_drain(desc->dev, desc->offset, value); + else + return 0; /* feature not supported -> ignore setting */ + + return ret; +} + int dm_gpio_set_dir_flags(struct gpio_desc *desc, ulong flags) { struct udevice *dev = desc->dev; diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h index 68b5f0b..ece7552 100644 --- a/include/asm-generic/gpio.h +++ b/include/asm-generic/gpio.h @@ -241,6 +241,8 @@ struct dm_gpio_ops { int value); int (*get_value)(struct udevice *dev, unsigned offset); int (*set_value)(struct udevice *dev, unsigned offset, int value); + int (*get_open_drain)(struct udevice *dev, unsigned offset); + int (*set_open_drain)(struct udevice *dev, unsigned offset, int value); /** * get_function() Get the GPIO function * @@ -541,6 +543,38 @@ int dm_gpio_get_value(const struct gpio_desc *desc); int dm_gpio_set_value(const struct gpio_desc *desc, int value);
/** + * dm_gpio_get_open_drain() - Check if open-drain-mode of a GPIO is active + * + * This checks if open-drain-mode for a GPIO is enabled or not. This method is + * optional. + * + * @desc: GPIO description containing device, offset and flags, + * previously returned by gpio_request_by_name() + * @return Value of open drain mode for GPIO (0 for inactive, 1 for active) or + * -ve on error + */ +int dm_gpio_get_open_drain(struct gpio_desc *desc); + +/** + * dm_gpio_set_open_drain() - Switch open-drain-mode of a GPIO on or off + * + * This enables or disables open-drain mode for a GPIO. This method is + * optional; if the driver does not support it, nothing happens when the method + * is called. + * + * In open-drain mode, instead of actively driving the output (Push-pull + * output), the GPIO's pin is connected to the collector (for a NPN transistor) + * or the drain (for a MOSFET) of a transistor, respectively. The pin then + * either forms an open circuit or a connection to ground, depending on the + * state of the transistor. + * + * @desc: GPIO description containing device, offset and flags, + * previously returned by gpio_request_by_name() + * @return 0 if OK, -ve on error + */ +int dm_gpio_set_open_drain(struct gpio_desc *desc, int value); + +/** * dm_gpio_set_dir() - Set the direction for a GPIO * * This sets up the direction according tot the provided flags. It will do -- 2.7.0.GIT