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authormario.six@gdsys.cc <mario.six@gdsys.cc>2016-05-25 15:15:21 +0200
committerYork Sun <york.sun@nxp.com>2016-06-03 22:13:52 -0700
commit53ecdfb92034ce836ec94ba33ba0d8d27ea3c16c (patch)
tree22547ebd91bd1284d0a966d62743d08f307e87d8
parent07d31f8f98fb350776c78a681ef27fd8ee288acd (diff)
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dm: gpio: Add methods for open drain setting
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> Reviewed-by: Simon Glass <sjg@chromium.org> Reviewed-by: York Sun <york.sun@nxp.com>
-rw-r--r--drivers/gpio/gpio-uclass.c32
-rw-r--r--include/asm-generic/gpio.h34
2 files changed, 66 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-uclass.c b/drivers/gpio/gpio-uclass.c
index 732b6c2..4559739 100644
--- a/drivers/gpio/gpio-uclass.c
+++ b/drivers/gpio/gpio-uclass.c
@@ -367,6 +367,38 @@ 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 2500c10..4aa0004 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -251,6 +251,8 @@ 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
*
@@ -550,6 +552,38 @@ 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