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Commit 80b0a602 authored by Mathias Nyman's avatar Mathias Nyman Committed by Linus Walleij
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gpiolib: add gpio get direction callback support 



Add .get_direction callback to gpio_chip. This allows gpiolib
to check the current direction of a gpio.
Used to show the correct gpio direction in sysfs and debug entries.

If callback is not set then gpiolib will work as previously;
e.g. guessing everything is input until a direction is set.

Signed-off-by: default avatarMathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent d6a2fa04

drivers/gpio/gpiolib.c

+37 −1
Original line number Original line Diff line number Diff line
@@ -191,6 +191,32 @@ int __init gpiochip_reserve(int start, int ngpio) 
	return ret;

	return ret;

}

}





/* caller ensures gpio is valid and requested, chip->get_direction may sleep  */

static int gpio_get_direction(unsigned gpio)

{

	struct gpio_chip	*chip;

	struct gpio_desc	*desc = &gpio_desc[gpio];

	int			status = -EINVAL;



	chip = gpio_to_chip(gpio);

	gpio -= chip->base;



	if (!chip->get_direction)

		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;

}



#ifdef CONFIG_GPIO_SYSFS

#ifdef CONFIG_GPIO_SYSFS





/* lock protects against unexport_gpio() being called while

/* lock protects against unexport_gpio() being called while
@@ -223,6 +249,7 @@ static ssize_t gpio_direction_show(struct device *dev, 
		struct device_attribute *attr, char *buf)

		struct device_attribute *attr, char *buf)

{

{

	const struct gpio_desc	*desc = dev_get_drvdata(dev);

	const struct gpio_desc	*desc = dev_get_drvdata(dev);

	unsigned		gpio = desc - gpio_desc;

	ssize_t			status;

	ssize_t			status;





	mutex_lock(&sysfs_lock);

	mutex_lock(&sysfs_lock);
@@ -230,6 +257,7 @@ static ssize_t gpio_direction_show(struct device *dev, 
	if (!test_bit(FLAG_EXPORT, &desc->flags))

	if (!test_bit(FLAG_EXPORT, &desc->flags))

		status = -EIO;

		status = -EIO;

	else

	else

		gpio_get_direction(gpio);

		status = sprintf(buf, "%s\n",

		status = sprintf(buf, "%s\n",

			test_bit(FLAG_IS_OUT, &desc->flags)

			test_bit(FLAG_IS_OUT, &desc->flags)

				? "out" : "in");

				? "out" : "in");
@@ -1080,6 +1108,7 @@ int gpiochip_add(struct gpio_chip *chip) 
			 * inputs (often with pullups enabled) so power

			 * inputs (often with pullups enabled) so power

			 * usage is minimized.  Linux code should set the

			 * usage is minimized.  Linux code should set the

			 * gpio direction first thing; but until it does,

			 * 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.

			 * we may expose the wrong direction in sysfs.

			 */

			 */

			gpio_desc[id].flags = !chip->direction_input

			gpio_desc[id].flags = !chip->direction_input
@@ -1231,9 +1260,15 @@ int gpio_request(unsigned gpio, const char *label) 
			desc_set_label(desc, NULL);

			desc_set_label(desc, NULL);

			module_put(chip->owner);

			module_put(chip->owner);

			clear_bit(FLAG_REQUESTED, &desc->flags);

			clear_bit(FLAG_REQUESTED, &desc->flags);

			goto done;

		}

		}

	}

	}



	if (chip->get_direction) {

		/* chip->get_direction may sleep */

		spin_unlock_irqrestore(&gpio_lock, flags);

		gpio_get_direction(gpio);

		spin_lock_irqsave(&gpio_lock, flags);

	}

done:

done:

	if (status)

	if (status)

		pr_debug("gpio_request: gpio-%d (%s) status %d\n",

		pr_debug("gpio_request: gpio-%d (%s) status %d\n",
@@ -1769,6 +1804,7 @@ static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip) 
		if (!test_bit(FLAG_REQUESTED, &gdesc->flags))

		if (!test_bit(FLAG_REQUESTED, &gdesc->flags))

			continue;

			continue;





		gpio_get_direction(gpio);

		is_out = test_bit(FLAG_IS_OUT, &gdesc->flags);

		is_out = test_bit(FLAG_IS_OUT, &gdesc->flags);

		seq_printf(s, " gpio-%-3d (%-20.20s) %s %s",

		seq_printf(s, " gpio-%-3d (%-20.20s) %s %s",

			gpio, gdesc->label,

			gpio, gdesc->label,

include/asm-generic/gpio.h

+4 −1
Original line number Original line Diff line number Diff line
@@ -56,6 +56,8 @@ struct device_node; 
 *	enabling module power and clock; may sleep

 *	enabling module power and clock; may sleep

 * @free: optional hook for chip-specific deactivation, such as

 * @free: optional hook for chip-specific deactivation, such as

 *	disabling module power and clock; may sleep

 *	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

 * @direction_input: configures signal "offset" as input, or returns error

 * @get: returns value for signal "offset"; for output signals this

 * @get: returns value for signal "offset"; for output signals this

 *	returns either the value actually sensed, or zero

 *	returns either the value actually sensed, or zero
@@ -100,7 +102,8 @@ struct gpio_chip { 
						unsigned offset);

						unsigned offset);

	void			(*free)(struct gpio_chip *chip,

	void			(*free)(struct gpio_chip *chip,

						unsigned offset);

						unsigned offset);



	int			(*get_direction)(struct gpio_chip *chip,

						unsigned offset);

	int			(*direction_input)(struct gpio_chip *chip,

	int			(*direction_input)(struct gpio_chip *chip,

						unsigned offset);

						unsigned offset);

	int			(*get)(struct gpio_chip *chip,

	int			(*get)(struct gpio_chip *chip,