Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 3e45f1d1 authored by Eric Miao's avatar Eric Miao Committed by Linus Torvalds
Browse files

gpio: introduce gpio_request_one() and friends 



gpio_request() without initial configuration of the GPIO is normally
useless, introduce gpio_request_one() together with GPIOF_ flags for
input/output direction and initial output level.

gpio_{request,free}_array() for multiple GPIOs.

Signed-off-by: default avatarEric Miao <eric.y.miao@gmail.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Ben Nizette <bn@niasdigital.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 62fecb70

Documentation/gpio.txt

+64 −0
Original line number Diff line number Diff line
@@ -253,6 +253,70 @@ pin setup (e.g. controlling which pin the GPIO uses, pullup/pulldown). 
Also note that it's your responsibility to have stopped using a GPIO

before you free it.



Considering in most cases GPIOs are actually configured right after they

are claimed, three additional calls are defined:



	/* request a single GPIO, with initial configuration specified by

	 * 'flags', identical to gpio_request() wrt other arguments and

	 * return value

	 */

	int gpio_request_one(unsigned gpio, unsigned long flags, const char *label);



	/* request multiple GPIOs in a single call

	 */

	int gpio_request_array(struct gpio *array, size_t num);



	/* release multiple GPIOs in a single call

	 */

	void gpio_free_array(struct gpio *array, size_t num);



where 'flags' is currently defined to specify the following properties:



	* GPIOF_DIR_IN		- to configure direction as input

	* GPIOF_DIR_OUT		- to configure direction as output



	* GPIOF_INIT_LOW	- as output, set initial level to LOW

	* GPIOF_INIT_HIGH	- as output, set initial level to HIGH



since GPIOF_INIT_* are only valid when configured as output, so group valid

combinations as:



	* GPIOF_IN		- configure as input

	* GPIOF_OUT_INIT_LOW	- configured as output, initial level LOW

	* GPIOF_OUT_INIT_HIGH	- configured as output, initial level HIGH



In the future, these flags can be extended to support more properties such

as open-drain status.



Further more, to ease the claim/release of multiple GPIOs, 'struct gpio' is

introduced to encapsulate all three fields as:



	struct gpio {

		unsigned	gpio;

		unsigned long	flags;

		const char	*label;

	};



A typical example of usage:



	static struct gpio leds_gpios[] = {

		{ 32, GPIOF_OUT_INIT_HIGH, "Power LED" }, /* default to ON */

		{ 33, GPIOF_OUT_INIT_LOW,  "Green LED" }, /* default to OFF */

		{ 34, GPIOF_OUT_INIT_LOW,  "Red LED"   }, /* default to OFF */

		{ 35, GPIOF_OUT_INIT_LOW,  "Blue LED"  }, /* default to OFF */

		{ ... },

	};



	err = gpio_request_one(31, GPIOF_IN, "Reset Button");

	if (err)

		...



	err = gpio_request_array(leds_gpios, ARRAY_SIZE(leds_gpios));

	if (err)

		...



	gpio_free_array(leds_gpios, ARRAY_SIZE(leds_gpios));





GPIOs mapped to IRQs

--------------------

drivers/gpio/gpiolib.c

+58 −0
Original line number Diff line number Diff line
@@ -1237,6 +1237,64 @@ void gpio_free(unsigned gpio) 
}

EXPORT_SYMBOL_GPL(gpio_free);



/**

 * gpio_request_one - request a single GPIO with initial configuration

 * @gpio:	the GPIO number

 * @flags:	GPIO configuration as specified by GPIOF_*

 * @label:	a literal description string of this GPIO

 */

int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)

{

	int err;



	err = gpio_request(gpio, label);

	if (err)

		return err;



	if (flags & GPIOF_DIR_IN)

		err = gpio_direction_input(gpio);

	else

		err = gpio_direction_output(gpio,

				(flags & GPIOF_INIT_HIGH) ? 1 : 0);



	return err;

}

EXPORT_SYMBOL_GPL(gpio_request_one);



/**

 * gpio_request_array - request multiple GPIOs in a single call

 * @array:	array of the 'struct gpio'

 * @num:	how many GPIOs in the array

 */

int gpio_request_array(struct gpio *array, size_t num)

{

	int i, err;



	for (i = 0; i < num; i++, array++) {

		err = gpio_request_one(array->gpio, array->flags, array->label);

		if (err)

			goto err_free;

	}

	return 0;



err_free:

	while (i--)

		gpio_free((--array)->gpio);

	return err;

}

EXPORT_SYMBOL_GPL(gpio_request_array);



/**

 * gpio_free_array - release multiple GPIOs in a single call

 * @array:	array of the 'struct gpio'

 * @num:	how many GPIOs in the array

 */

void gpio_free_array(struct gpio *array, size_t num)

{

	while (num--)

		gpio_free((array++)->gpio);

}

EXPORT_SYMBOL_GPL(gpio_free_array);



/**

 * gpiochip_is_requested - return string iff signal was requested

include/asm-generic/gpio.h

+26 −0
Original line number Diff line number Diff line
@@ -136,6 +136,32 @@ extern int __gpio_cansleep(unsigned gpio); 


extern int __gpio_to_irq(unsigned gpio);



#define GPIOF_DIR_OUT	(0 << 0)

#define GPIOF_DIR_IN	(1 << 0)



#define GPIOF_INIT_LOW	(0 << 1)

#define GPIOF_INIT_HIGH	(1 << 1)



#define GPIOF_IN		(GPIOF_DIR_IN)

#define GPIOF_OUT_INIT_LOW	(GPIOF_DIR_OUT | GPIOF_INIT_LOW)

#define GPIOF_OUT_INIT_HIGH	(GPIOF_DIR_OUT | GPIOF_INIT_HIGH)



/**

 * struct gpio - a structure describing a GPIO with configuration

 * @gpio:	the GPIO number

 * @flags:	GPIO configuration as specified by GPIOF_*

 * @label:	a literal description string of this GPIO

 */

struct gpio {

	unsigned	gpio;

	unsigned long	flags;

	const char	*label;

};



extern int gpio_request_one(unsigned gpio, unsigned long flags, const char *label);

extern int gpio_request_array(struct gpio *array, size_t num);

extern void gpio_free_array(struct gpio *array, size_t num);



#ifdef CONFIG_GPIO_SYSFS



/*