Commit 9225d516 authored by Drew Fustini's avatar Drew Fustini Committed by Bartosz Golaszewski
Browse files

gpio: expose pull-up/pull-down line flags to userspace 

Add pull-up/pull-down flags to the gpio line get and
set ioctl() calls.  Use cases include a push button
that does not have an external resistor.

Addition use cases described by Limor Fried (ladyada) of
Adafruit in this PR for Adafruit_Blinka Python lib:
https://github.com/adafruit/Adafruit_Blinka/pull/59



Signed-off-by: default avatarDrew Fustini <drew@pdp7.com>
[Kent: added BIAS to GPIO flag names and restrict application to input
lines]
Signed-off-by: default avatarKent Gibson <warthog618@gmail.com>
Signed-off-by: default avatarBartosz Golaszewski <bgolaszewski@baylibre.com>
parent f932a686

drivers/gpio/gpiolib.c

+18 −0
Original line number Diff line number Diff line
@@ -422,6 +422,8 @@ struct linehandle_state { 
	(GPIOHANDLE_REQUEST_INPUT | \

	GPIOHANDLE_REQUEST_OUTPUT | \

	GPIOHANDLE_REQUEST_ACTIVE_LOW | \

	GPIOHANDLE_REQUEST_BIAS_PULL_UP | \

	GPIOHANDLE_REQUEST_BIAS_PULL_DOWN | \

	GPIOHANDLE_REQUEST_OPEN_DRAIN | \

	GPIOHANDLE_REQUEST_OPEN_SOURCE)
@@ -553,6 +555,12 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip) 
	     (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE)))

		return -EINVAL;



	/* PULL_UP and PULL_DOWN flags only make sense for input mode. */

	if (!(lflags & GPIOHANDLE_REQUEST_INPUT) &&

	    ((lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP) ||

	     (lflags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN)))

		return -EINVAL;



	lh = kzalloc(sizeof(*lh), GFP_KERNEL);

	if (!lh)

		return -ENOMEM;
@@ -593,6 +601,10 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip) 
			set_bit(FLAG_OPEN_DRAIN, &desc->flags);

		if (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE)

			set_bit(FLAG_OPEN_SOURCE, &desc->flags);

		if (lflags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN)

			set_bit(FLAG_PULL_DOWN, &desc->flags);

		if (lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP)

			set_bit(FLAG_PULL_UP, &desc->flags);



		ret = gpiod_set_transitory(desc, false);

		if (ret < 0)
@@ -1092,6 +1104,10 @@ static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 
		if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))

			lineinfo.flags |= (GPIOLINE_FLAG_OPEN_SOURCE |

					   GPIOLINE_FLAG_IS_OUT);

		if (test_bit(FLAG_PULL_DOWN, &desc->flags))

			lineinfo.flags |= GPIOLINE_FLAG_BIAS_PULL_DOWN;

		if (test_bit(FLAG_PULL_UP, &desc->flags))

			lineinfo.flags |= GPIOLINE_FLAG_BIAS_PULL_UP;



		if (copy_to_user(ip, &lineinfo, sizeof(lineinfo)))

			return -EFAULT;
@@ -2785,6 +2801,8 @@ static bool gpiod_free_commit(struct gpio_desc *desc) 
		clear_bit(FLAG_REQUESTED, &desc->flags);

		clear_bit(FLAG_OPEN_DRAIN, &desc->flags);

		clear_bit(FLAG_OPEN_SOURCE, &desc->flags);

		clear_bit(FLAG_PULL_UP, &desc->flags);

		clear_bit(FLAG_PULL_DOWN, &desc->flags);

		clear_bit(FLAG_IS_HOGGED, &desc->flags);

		ret = true;

	}

include/uapi/linux/gpio.h

+4 −0
Original line number Diff line number Diff line
@@ -33,6 +33,8 @@ struct gpiochip_info { 
#define GPIOLINE_FLAG_ACTIVE_LOW	(1UL << 2)

#define GPIOLINE_FLAG_OPEN_DRAIN	(1UL << 3)

#define GPIOLINE_FLAG_OPEN_SOURCE	(1UL << 4)

#define GPIOLINE_FLAG_BIAS_PULL_UP	(1UL << 5)

#define GPIOLINE_FLAG_BIAS_PULL_DOWN	(1UL << 6)



/**

 * struct gpioline_info - Information about a certain GPIO line
@@ -62,6 +64,8 @@ struct gpioline_info { 
#define GPIOHANDLE_REQUEST_ACTIVE_LOW	(1UL << 2)

#define GPIOHANDLE_REQUEST_OPEN_DRAIN	(1UL << 3)

#define GPIOHANDLE_REQUEST_OPEN_SOURCE	(1UL << 4)

#define GPIOHANDLE_REQUEST_BIAS_PULL_UP	(1UL << 5)

#define GPIOHANDLE_REQUEST_BIAS_PULL_DOWN	(1UL << 6)



/**

 * struct gpiohandle_request - Information about a GPIO handle request

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