diff options
| -rw-r--r-- | Documentation/gpio.txt | 64 | ||||
| -rw-r--r-- | drivers/gpio/gpiolib.c | 58 | ||||
| -rw-r--r-- | include/asm-generic/gpio.h | 26 |
3 files changed, 148 insertions, 0 deletions
diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt index 1866c27eec6..c2c6e9b39bb 100644 --- a/Documentation/gpio.txt +++ b/Documentation/gpio.txt @@ -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 -------------------- diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 350842ad363..9006fdb26fe 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -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 diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h index 485eeb6c4ef..979c6a57f2f 100644 --- a/include/asm-generic/gpio.h +++ b/include/asm-generic/gpio.h @@ -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 /* |