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dm: gpio: Add methods for open drain setting

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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>
This commit is contained in:
mario.six@gdsys.cc 2016-05-25 15:15:21 +02:00 • committed by York Sun
parent 07d31f8f98
commit 53ecdfb920
2 changed files with 66 additions and 0 deletions
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32
drivers/gpio/gpio-uclass.c
View file

@ -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;

34
include/asm-generic/gpio.h
View file

@ -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
*
@ -549,6 +551,38 @@ 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
*