From aca5ce14eb773a75e5d935968b2e390dc5bd29c3 Mon Sep 17 00:00:00 2001 From: Laxman Dewangan Date: Fri, 17 Feb 2012 20:26:21 +0530 Subject: gpio: gpiolib: Support for open drain/collector gpios Adding support for the open drain gpio on which client can specify the open drain property through GPIO flag GPIOF_OPEN_DRAIN at the time of gpio request. The open drain pins are normally pulled high and it cannot be driven to output with value of 1 and so when client request for setting the pin to HIGH, the gpio will be set to input direction to make pin in tristate and hence PULL-UP on pins will make the state to HIGH. The open drain pin can be driven to LOW by setting output with value of 0. Signed-off-by: Laxman Dewangan Reviwed-by: Mark Brown Acked-by: Linus Walleij Signed-off-by: Grant Likely --- include/linux/gpio.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/gpio.h') diff --git a/include/linux/gpio.h b/include/linux/gpio.h index 38ac48b7d3a8..66a5b2e9d35a 100644 --- a/include/linux/gpio.h +++ b/include/linux/gpio.h @@ -14,6 +14,9 @@ #define GPIOF_OUT_INIT_LOW (GPIOF_DIR_OUT | GPIOF_INIT_LOW) #define GPIOF_OUT_INIT_HIGH (GPIOF_DIR_OUT | GPIOF_INIT_HIGH) +/* Gpio pin is open drain */ +#define GPIOF_OPEN_DRAIN (1 << 2) + /** * struct gpio - a structure describing a GPIO with configuration * @gpio: the GPIO number -- cgit v1.2.3-59-g8ed1b From 25553ff0756c59b617af6bdd280c94e943164184 Mon Sep 17 00:00:00 2001 From: Laxman Dewangan Date: Fri, 17 Feb 2012 20:26:22 +0530 Subject: gpio: gpiolib: Support for open source/emitter gpios Adding support for the open source gpio on which client can specify the open source property through GPIO flag GPIOF_OPEN_SOURCE at the time of gpio request. The open source pins are normally pulled low and it cannot be driven to output with value of 0 and so when client request for setting the pin to LOW, the gpio will be set to input direction to make pin in tristate and hence PULL-DOWN on pins will make the state to LOW. The open source pin can be driven to HIGH by setting output with value of 1. Signed-off-by: Laxman Dewangan Reviwed-by: Mark Brown Acked-by: Linus Walleij Signed-off-by: Grant Likely --- drivers/gpio/gpiolib.c | 39 +++++++++++++++++++++++++++++++++++++++ include/linux/gpio.h | 3 +++ 2 files changed, 42 insertions(+) (limited to 'include/linux/gpio.h') diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 5d25a33d5359..58f40dfc5265 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -59,6 +59,7 @@ struct gpio_desc { #define FLAG_TRIG_RISE 6 /* trigger on rising edge */ #define FLAG_ACTIVE_LOW 7 /* sysfs value has active low */ #define FLAG_OPEN_DRAIN 8 /* Gpio is open drain type */ +#define FLAG_OPEN_SOURCE 9 /* Gpio is open source type */ #define ID_SHIFT 16 /* add new flags before this one */ @@ -1266,6 +1267,7 @@ void gpio_free(unsigned gpio) clear_bit(FLAG_ACTIVE_LOW, &desc->flags); clear_bit(FLAG_REQUESTED, &desc->flags); clear_bit(FLAG_OPEN_DRAIN, &desc->flags); + clear_bit(FLAG_OPEN_SOURCE, &desc->flags); } else WARN_ON(extra_checks); @@ -1290,6 +1292,9 @@ int gpio_request_one(unsigned gpio, unsigned long flags, const char *label) if (flags & GPIOF_OPEN_DRAIN) set_bit(FLAG_OPEN_DRAIN, &gpio_desc[gpio].flags); + if (flags & GPIOF_OPEN_SOURCE) + set_bit(FLAG_OPEN_SOURCE, &gpio_desc[gpio].flags); + if (flags & GPIOF_DIR_IN) err = gpio_direction_input(gpio); else @@ -1443,6 +1448,10 @@ int gpio_direction_output(unsigned gpio, int value) if (value && test_bit(FLAG_OPEN_DRAIN, &desc->flags)) return gpio_direction_input(gpio); + /* Open source pin should not be driven to 0 */ + if (!value && test_bit(FLAG_OPEN_SOURCE, &desc->flags)) + return gpio_direction_input(gpio); + spin_lock_irqsave(&gpio_lock, flags); if (!gpio_is_valid(gpio)) @@ -1604,6 +1613,32 @@ static void _gpio_set_open_drain_value(unsigned gpio, __func__, gpio, err); } +/* + * _gpio_set_open_source() - Set the open source gpio's value. + * @gpio: Gpio whose state need to be set. + * @chip: Gpio chip. + * @value: Non-zero for setting it HIGH otherise it will set to LOW. + */ +static void _gpio_set_open_source_value(unsigned gpio, + struct gpio_chip *chip, int value) +{ + int err = 0; + if (value) { + err = chip->direction_output(chip, gpio - chip->base, 1); + if (!err) + set_bit(FLAG_IS_OUT, &gpio_desc[gpio].flags); + } else { + err = chip->direction_input(chip, gpio - chip->base); + if (!err) + clear_bit(FLAG_IS_OUT, &gpio_desc[gpio].flags); + } + trace_gpio_direction(gpio, !value, err); + if (err < 0) + pr_err("%s: Error in set_value for open source gpio%d err %d\n", + __func__, gpio, err); +} + + /** * __gpio_set_value() - assign a gpio's value * @gpio: gpio whose value will be assigned @@ -1622,6 +1657,8 @@ void __gpio_set_value(unsigned gpio, int value) trace_gpio_value(gpio, 0, value); if (test_bit(FLAG_OPEN_DRAIN, &gpio_desc[gpio].flags)) _gpio_set_open_drain_value(gpio, chip, value); + else if (test_bit(FLAG_OPEN_SOURCE, &gpio_desc[gpio].flags)) + _gpio_set_open_source_value(gpio, chip, value); else chip->set(chip, gpio - chip->base, value); } @@ -1692,6 +1729,8 @@ void gpio_set_value_cansleep(unsigned gpio, int value) trace_gpio_value(gpio, 0, value); if (test_bit(FLAG_OPEN_DRAIN, &gpio_desc[gpio].flags)) _gpio_set_open_drain_value(gpio, chip, value); + else if (test_bit(FLAG_OPEN_SOURCE, &gpio_desc[gpio].flags)) + _gpio_set_open_source_value(gpio, chip, value); else chip->set(chip, gpio - chip->base, value); } diff --git a/include/linux/gpio.h b/include/linux/gpio.h index 66a5b2e9d35a..67851bbd3a42 100644 --- a/include/linux/gpio.h +++ b/include/linux/gpio.h @@ -17,6 +17,9 @@ /* Gpio pin is open drain */ #define GPIOF_OPEN_DRAIN (1 << 2) +/* Gpio pin is open source */ +#define GPIOF_OPEN_SOURCE (1 << 3) + /** * struct gpio - a structure describing a GPIO with configuration * @gpio: the GPIO number -- cgit v1.2.3-59-g8ed1b