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pinctrl: GPIO direction support for muxing

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When requesting a single GPIO pin to be muxed in, some controllers
will need to poke a different value into the control register
depending on whether the pin will be used for GPIO output or GPIO
input. So create pinmux counterparts to gpio_direction_[input|output]
in the pinctrl framework.

ChangeLog v1->v2:
- This also amends the documentation to make it clear the this
  function and associated machinery is *ONLY* intended as a backend
  to gpiolib machinery, not for everyone and his dog to start playing
  around with pins.
ChangeLog v2->v3:
- Don't pass an argument to the common request function, instead
  provide pinmux_* counterparts to the gpio_direction_[input|output]
  calls, simpler and anyone can understand it.
ChangeLog v3->v4:
- Fix numerous spelling mistakes and dangling text in documentation.
  Add Ack and Rewewed-by.

Cc: Igor Grinberg <grinberg@compulab.co.il>
Acked-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Thomas Abraham <thomas.abraham@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Linus Walleij
2011-11-14 10:06:22 +01:00
parent 75d6642a3e
commit 542e704f3f
3 changed files with 108 additions and 9 deletions
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24
include/linux/pinctrl/pinmux.h
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@@ -54,7 +54,13 @@ struct pinctrl_dev;
* Implement this only if you can mux every pin individually as GPIO. The
* affected GPIO range is passed along with an offset(pin number) into that
* specific GPIO range - function selectors and pin groups are orthogonal
* to this, the core will however make sure the pins do not collide
* to this, the core will however make sure the pins do not collide.
* @gpio_disable_free: free up GPIO muxing on a certain pin, the reverse of
* @gpio_request_enable
* @gpio_set_direction: Since controllers may need different configurations
* depending on whether the GPIO is configured as input or output,
* a direction selector function may be implemented as a backing
* to the GPIO controllers that need pin muxing.
*/
struct pinmux_ops {
int (*request) (struct pinctrl_dev *pctldev, unsigned offset);
@@ -76,11 +82,17 @@ struct pinmux_ops {
void (*gpio_disable_free) (struct pinctrl_dev *pctldev,
struct pinctrl_gpio_range *range,
unsigned offset);
int (*gpio_set_direction) (struct pinctrl_dev *pctldev,
struct pinctrl_gpio_range *range,
unsigned offset,
bool input);
};
/* External interface to pinmux */
extern int pinmux_request_gpio(unsigned gpio);
extern void pinmux_free_gpio(unsigned gpio);
extern int pinmux_gpio_direction_input(unsigned gpio);
extern int pinmux_gpio_direction_output(unsigned gpio);
extern struct pinmux * __must_check pinmux_get(struct device *dev, const char *name);
extern void pinmux_put(struct pinmux *pmx);
extern int pinmux_enable(struct pinmux *pmx);
@@ -97,6 +109,16 @@ static inline void pinmux_free_gpio(unsigned gpio)
{
}
static inline int pinmux_gpio_direction_input(unsigned gpio)
{
return 0;
}
static inline int pinmux_gpio_direction_output(unsigned gpio)
{
return 0;
}
static inline struct pinmux * __must_check pinmux_get(struct device *dev, const char *name)
{
return NULL;