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gpio: introduce gpio_request_one() and friends

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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: Eric Miao <eric.y.miao@gmail.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Ben Nizette <bn@niasdigital.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Eric Miao 2010-03-05 13:44:35 -08:00 committed by Linus Torvalds
parent 62fecb70cf
commit 3e45f1d115
3 changed files with 148 additions and 0 deletions
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64
Documentation/gpio.txt
View file

@ -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
--------------------

58
drivers/gpio/gpiolib.c
View file

@ -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

26
include/asm-generic/gpio.h
View file

@ -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
/*