Add gpio_get_direction() for checking the current direction of a gpio. Returns 1 for input, 0 for output, or negative error. Gpio drivers need to set the gpio_chip .get_direction callback for this functionality, otherwise gpio_get_direction() returns error.
If the .get_direction callback is set, then gpiolib will use it for showing correct gpio direction in sysfs and debug. If not set then it will work the old way; e.g. guessing everything is input until direction is set. Signed-off-by: Mathias Nyman <[email protected]> --- drivers/gpio/gpiolib.c | 64 ++++++++++++++++++++++++++++++++++++++++++- include/asm-generic/gpio.h | 6 +++- include/linux/gpio.h | 5 +++ 3 files changed, 72 insertions(+), 3 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index de0213c..28deb86 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -223,6 +223,7 @@ static ssize_t gpio_direction_show(struct device *dev, struct device_attribute *attr, char *buf) { const struct gpio_desc *desc = dev_get_drvdata(dev); + unsigned gpio = desc - gpio_desc; ssize_t status; mutex_lock(&sysfs_lock); @@ -230,6 +231,7 @@ static ssize_t gpio_direction_show(struct device *dev, if (!test_bit(FLAG_EXPORT, &desc->flags)) status = -EIO; else + gpio_get_direction(gpio); status = sprintf(buf, "%s\n", test_bit(FLAG_IS_OUT, &desc->flags) ? "out" : "in"); @@ -1073,6 +1075,7 @@ int gpiochip_add(struct gpio_chip *chip) * inputs (often with pullups enabled) so power * usage is minimized. Linux code should set the * gpio direction first thing; but until it does, + * and in case chip->get_direction is not set, * we may expose the wrong direction in sysfs. */ gpio_desc[id].flags = !chip->direction_input @@ -1392,6 +1395,62 @@ EXPORT_SYMBOL_GPL(gpiochip_is_requested); * rely on gpio_request() having been called beforehand. */ +int gpio_get_direction(unsigned gpio) +{ + unsigned long flags; + struct gpio_chip *chip; + struct gpio_desc *desc = &gpio_desc[gpio]; + int status = -EINVAL; + + spin_lock_irqsave(&gpio_lock, flags); + + if (!gpio_is_valid(gpio)) + goto fail; + chip = desc->chip; + if (!chip || !chip->get_direction) + goto fail; + gpio -= chip->base; + if (gpio >= chip->ngpio) + goto fail; + status = gpio_ensure_requested(desc, gpio); + if (status < 0) + goto fail; + + /* now we know the gpio is valid and chip won't vanish */ + + spin_unlock_irqrestore(&gpio_lock, flags); + + might_sleep_if(chip->can_sleep); + + if (status) { + status = chip->request(chip, gpio); + if (status < 0) { + pr_debug("GPIO-%d: chip request fail, %d\n", + chip->base + gpio, status); + /* and it's not available to anyone else ... + * gpio_request() is the fully clean solution. + */ + return status; + } + } + + status = chip->get_direction(chip, gpio); + if (status > 0) { + /* GPIOF_DIR_IN, or other positive */ + status = 1; + clear_bit(FLAG_IS_OUT, &desc->flags); + } + if (status == 0) { + /* GPIOF_DIR_OUT */ + set_bit(FLAG_IS_OUT, &desc->flags); + } + return status; +fail: + spin_unlock_irqrestore(&gpio_lock, flags); + return status; +} +EXPORT_SYMBOL_GPL(gpio_get_direction); + int gpio_direction_input(unsigned gpio) { unsigned long flags; @@ -1761,8 +1820,9 @@ static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip) for (i = 0; i < chip->ngpio; i++, gpio++, gdesc++) { if (!test_bit(FLAG_REQUESTED, &gdesc->flags)) continue; - - is_out = test_bit(FLAG_IS_OUT, &gdesc->flags); + chip->get_direction + ? (is_out = !chip->get_direction(chip, i)) + : (is_out = test_bit(FLAG_IS_OUT, &gdesc->flags)); seq_printf(s, " gpio-%-3d (%-20.20s) %s %s", gpio, gdesc->label, is_out ? "out" : "in ", diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h index 365ea09..4e58743 100644 --- a/include/asm-generic/gpio.h +++ b/include/asm-generic/gpio.h @@ -56,6 +56,8 @@ struct device_node; * enabling module power and clock; may sleep * @free: optional hook for chip-specific deactivation, such as * disabling module power and clock; may sleep + * @get_direction: returns direction for signal "offset", 0=out, 1=in, + * (same as GPIOF_DIR_XXX), or negative error * @direction_input: configures signal "offset" as input, or returns error * @get: returns value for signal "offset"; for output signals this * returns either the value actually sensed, or zero @@ -98,7 +100,8 @@ struct gpio_chip { unsigned offset); void (*free)(struct gpio_chip *chip, unsigned offset); - + int (*get_direction)(struct gpio_chip *chip, + unsigned offset); int (*direction_input)(struct gpio_chip *chip, unsigned offset); int (*get)(struct gpio_chip *chip, @@ -153,6 +156,7 @@ extern struct gpio_chip *gpiochip_find(void *data, extern int gpio_request(unsigned gpio, const char *label); extern void gpio_free(unsigned gpio); +extern int gpio_get_direction(unsigned gpio); extern int gpio_direction_input(unsigned gpio); extern int gpio_direction_output(unsigned gpio, int value); diff --git a/include/linux/gpio.h b/include/linux/gpio.h index 2e31e8b..9bfc008 100644 --- a/include/linux/gpio.h +++ b/include/linux/gpio.h @@ -141,6 +141,11 @@ static inline void gpio_free_array(const struct gpio *array, size_t num) WARN_ON(1); } +static inline int gpio_get_direction(unsigned gpio) +{ + return -ENOSYS; +} + static inline int gpio_direction_input(unsigned gpio) { return -ENOSYS; -- 1.7.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
