Commit 3c0d9c63 authored by Kent Gibson's avatar Kent Gibson Committed by Bartosz Golaszewski
Browse files

gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL 



Add support for requesting lines using the GPIO_V2_GET_LINE_IOCTL, and
returning their current values using GPIO_V2_LINE_GET_VALUES_IOCTL.

The struct linereq implementation is based on the v1 struct linehandle
implementation.

Signed-off-by: default avatarKent Gibson <warthog618@gmail.com>
Signed-off-by: default avatarBartosz Golaszewski <bgolaszewski@baylibre.com>
parent 957ebb61

drivers/gpio/gpiolib-cdev.c

+424 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0



#include <linux/anon_inodes.h>

#include <linux/atomic.h>

#include <linux/bitmap.h>

#include <linux/build_bug.h>

#include <linux/cdev.h>

#include <linux/compat.h>

#include <linux/device.h>
@@ -24,6 +26,25 @@ 
#include "gpiolib.h"

#include "gpiolib-cdev.h"



/*

 * Array sizes must ensure 64-bit alignment and not create holes in the

 * struct packing.

 */

static_assert(IS_ALIGNED(GPIO_V2_LINES_MAX, 2));

static_assert(IS_ALIGNED(GPIO_MAX_NAME_SIZE, 8));



/*

 * Check that uAPI structs are 64-bit aligned for 32/64-bit compatibility

 */

static_assert(IS_ALIGNED(sizeof(struct gpio_v2_line_attribute), 8));

static_assert(IS_ALIGNED(sizeof(struct gpio_v2_line_config_attribute), 8));

static_assert(IS_ALIGNED(sizeof(struct gpio_v2_line_config), 8));

static_assert(IS_ALIGNED(sizeof(struct gpio_v2_line_request), 8));

static_assert(IS_ALIGNED(sizeof(struct gpio_v2_line_info), 8));

static_assert(IS_ALIGNED(sizeof(struct gpio_v2_line_info_changed), 8));

static_assert(IS_ALIGNED(sizeof(struct gpio_v2_line_event), 8));

static_assert(IS_ALIGNED(sizeof(struct gpio_v2_line_values), 8));



/* Character device interface to GPIO.

 *

 * The GPIO character device, /dev/gpiochipN, provides userspace an
@@ -34,6 +55,7 @@ 
 * GPIO line handle management

 */



#ifdef CONFIG_GPIO_CDEV_V1

/**

 * struct linehandle_state - contains the state of a userspace handle

 * @gdev: the GPIO device the handle pertains to
@@ -376,6 +398,402 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip) 
	linehandle_free(lh);

	return ret;

}

#endif /* CONFIG_GPIO_CDEV_V1 */



/**

 * struct line - contains the state of a requested line

 * @desc: the GPIO descriptor for this line.

 */

struct line {

	struct gpio_desc *desc;

};



/**

 * struct linereq - contains the state of a userspace line request

 * @gdev: the GPIO device the line request pertains to

 * @label: consumer label used to tag GPIO descriptors

 * @num_lines: the number of lines in the lines array

 * @lines: the lines held by this line request, with @num_lines elements.

 */

struct linereq {

	struct gpio_device *gdev;

	const char *label;

	u32 num_lines;

	struct line lines[];

};



#define GPIO_V2_LINE_BIAS_FLAGS \

	(GPIO_V2_LINE_FLAG_BIAS_PULL_UP | \

	 GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN | \

	 GPIO_V2_LINE_FLAG_BIAS_DISABLED)



#define GPIO_V2_LINE_DIRECTION_FLAGS \

	(GPIO_V2_LINE_FLAG_INPUT | \

	 GPIO_V2_LINE_FLAG_OUTPUT)



#define GPIO_V2_LINE_DRIVE_FLAGS \

	(GPIO_V2_LINE_FLAG_OPEN_DRAIN | \

	 GPIO_V2_LINE_FLAG_OPEN_SOURCE)



#define GPIO_V2_LINE_VALID_FLAGS \

	(GPIO_V2_LINE_FLAG_ACTIVE_LOW | \

	 GPIO_V2_LINE_DIRECTION_FLAGS | \

	 GPIO_V2_LINE_DRIVE_FLAGS | \

	 GPIO_V2_LINE_BIAS_FLAGS)



static u64 gpio_v2_line_config_flags(struct gpio_v2_line_config *lc,

				     unsigned int line_idx)

{

	unsigned int i;

	u64 mask = BIT_ULL(line_idx);



	for (i = 0; i < lc->num_attrs; i++) {

		if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_FLAGS) &&

		    (lc->attrs[i].mask & mask))

			return lc->attrs[i].attr.flags;

	}

	return lc->flags;

}



static int gpio_v2_line_config_output_value(struct gpio_v2_line_config *lc,

					    unsigned int line_idx)

{

	unsigned int i;

	u64 mask = BIT_ULL(line_idx);



	for (i = 0; i < lc->num_attrs; i++) {

		if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_OUTPUT_VALUES) &&

		    (lc->attrs[i].mask & mask))

			return !!(lc->attrs[i].attr.values & mask);

	}

	return 0;

}



static int gpio_v2_line_flags_validate(u64 flags)

{

	/* Return an error if an unknown flag is set */

	if (flags & ~GPIO_V2_LINE_VALID_FLAGS)

		return -EINVAL;



	/*

	 * Do not allow both INPUT and OUTPUT flags to be set as they are

	 * contradictory.

	 */

	if ((flags & GPIO_V2_LINE_FLAG_INPUT) &&

	    (flags & GPIO_V2_LINE_FLAG_OUTPUT))

		return -EINVAL;



	/*

	 * Do not allow OPEN_SOURCE and OPEN_DRAIN flags in a single

	 * request. If the hardware actually supports enabling both at the

	 * same time the electrical result would be disastrous.

	 */

	if ((flags & GPIO_V2_LINE_FLAG_OPEN_DRAIN) &&

	    (flags & GPIO_V2_LINE_FLAG_OPEN_SOURCE))

		return -EINVAL;



	/* Drive requires explicit output direction. */

	if ((flags & GPIO_V2_LINE_DRIVE_FLAGS) &&

	    !(flags & GPIO_V2_LINE_FLAG_OUTPUT))

		return -EINVAL;



	/* Bias requires explicit direction. */

	if ((flags & GPIO_V2_LINE_BIAS_FLAGS) &&

	    !(flags & GPIO_V2_LINE_DIRECTION_FLAGS))

		return -EINVAL;



	/* Only one bias flag can be set. */

	if (((flags & GPIO_V2_LINE_FLAG_BIAS_DISABLED) &&

	     (flags & (GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN |

		       GPIO_V2_LINE_FLAG_BIAS_PULL_UP))) ||

	    ((flags & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN) &&

	     (flags & GPIO_V2_LINE_FLAG_BIAS_PULL_UP)))

		return -EINVAL;



	return 0;

}



static int gpio_v2_line_config_validate(struct gpio_v2_line_config *lc,

					unsigned int num_lines)

{

	unsigned int i;

	u64 flags;

	int ret;



	if (lc->num_attrs > GPIO_V2_LINE_NUM_ATTRS_MAX)

		return -EINVAL;



	if (memchr_inv(lc->padding, 0, sizeof(lc->padding)))

		return -EINVAL;



	for (i = 0; i < num_lines; i++) {

		flags = gpio_v2_line_config_flags(lc, i);

		ret = gpio_v2_line_flags_validate(flags);

		if (ret)

			return ret;

	}

	return 0;

}



static void gpio_v2_line_config_flags_to_desc_flags(u64 flags,

						    unsigned long *flagsp)

{

	assign_bit(FLAG_ACTIVE_LOW, flagsp,

		   flags & GPIO_V2_LINE_FLAG_ACTIVE_LOW);



	if (flags & GPIO_V2_LINE_FLAG_OUTPUT)

		set_bit(FLAG_IS_OUT, flagsp);

	else if (flags & GPIO_V2_LINE_FLAG_INPUT)

		clear_bit(FLAG_IS_OUT, flagsp);



	assign_bit(FLAG_OPEN_DRAIN, flagsp,

		   flags & GPIO_V2_LINE_FLAG_OPEN_DRAIN);

	assign_bit(FLAG_OPEN_SOURCE, flagsp,

		   flags & GPIO_V2_LINE_FLAG_OPEN_SOURCE);



	assign_bit(FLAG_PULL_UP, flagsp,

		   flags & GPIO_V2_LINE_FLAG_BIAS_PULL_UP);

	assign_bit(FLAG_PULL_DOWN, flagsp,

		   flags & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN);

	assign_bit(FLAG_BIAS_DISABLE, flagsp,

		   flags & GPIO_V2_LINE_FLAG_BIAS_DISABLED);

}



static long linereq_get_values(struct linereq *lr, void __user *ip)

{

	struct gpio_v2_line_values lv;

	DECLARE_BITMAP(vals, GPIO_V2_LINES_MAX);

	struct gpio_desc **descs;

	unsigned int i, didx, num_get;

	int ret;



	/* NOTE: It's ok to read values of output lines. */

	if (copy_from_user(&lv, ip, sizeof(lv)))

		return -EFAULT;



	for (num_get = 0, i = 0; i < lr->num_lines; i++) {

		if (lv.mask & BIT_ULL(i)) {

			num_get++;

			descs = &lr->lines[i].desc;

		}

	}



	if (num_get == 0)

		return -EINVAL;



	if (num_get != 1) {

		descs = kmalloc_array(num_get, sizeof(*descs), GFP_KERNEL);

		if (!descs)

			return -ENOMEM;

		for (didx = 0, i = 0; i < lr->num_lines; i++) {

			if (lv.mask & BIT_ULL(i)) {

				descs[didx] = lr->lines[i].desc;

				didx++;

			}

		}

	}

	ret = gpiod_get_array_value_complex(false, true, num_get,

					    descs, NULL, vals);



	if (num_get != 1)

		kfree(descs);

	if (ret)

		return ret;



	lv.bits = 0;

	for (didx = 0, i = 0; i < lr->num_lines; i++) {

		if (lv.mask & BIT_ULL(i)) {

			if (test_bit(didx, vals))

				lv.bits |= BIT_ULL(i);

			didx++;

		}

	}



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

		return -EFAULT;



	return 0;

}



static long linereq_ioctl(struct file *file, unsigned int cmd,

			  unsigned long arg)

{

	struct linereq *lr = file->private_data;

	void __user *ip = (void __user *)arg;



	if (cmd == GPIO_V2_LINE_GET_VALUES_IOCTL)

		return linereq_get_values(lr, ip);



	return -EINVAL;

}



#ifdef CONFIG_COMPAT

static long linereq_ioctl_compat(struct file *file, unsigned int cmd,

				 unsigned long arg)

{

	return linereq_ioctl(file, cmd, (unsigned long)compat_ptr(arg));

}

#endif



static void linereq_free(struct linereq *lr)

{

	unsigned int i;



	for (i = 0; i < lr->num_lines; i++) {

		if (lr->lines[i].desc)

			gpiod_free(lr->lines[i].desc);

	}

	kfree(lr->label);

	put_device(&lr->gdev->dev);

	kfree(lr);

}



static int linereq_release(struct inode *inode, struct file *file)

{

	struct linereq *lr = file->private_data;



	linereq_free(lr);

	return 0;

}



static const struct file_operations line_fileops = {

	.release = linereq_release,

	.owner = THIS_MODULE,

	.llseek = noop_llseek,

	.unlocked_ioctl = linereq_ioctl,

#ifdef CONFIG_COMPAT

	.compat_ioctl = linereq_ioctl_compat,

#endif

};



static int linereq_create(struct gpio_device *gdev, void __user *ip)

{

	struct gpio_v2_line_request ulr;

	struct gpio_v2_line_config *lc;

	struct linereq *lr;

	struct file *file;

	u64 flags;

	unsigned int i;

	int fd, ret;



	if (copy_from_user(&ulr, ip, sizeof(ulr)))

		return -EFAULT;



	if ((ulr.num_lines == 0) || (ulr.num_lines > GPIO_V2_LINES_MAX))

		return -EINVAL;



	if (memchr_inv(ulr.padding, 0, sizeof(ulr.padding)))

		return -EINVAL;



	lc = &ulr.config;

	ret = gpio_v2_line_config_validate(lc, ulr.num_lines);

	if (ret)

		return ret;



	lr = kzalloc(struct_size(lr, lines, ulr.num_lines), GFP_KERNEL);

	if (!lr)

		return -ENOMEM;



	lr->gdev = gdev;

	get_device(&gdev->dev);



	/* Make sure this is terminated */

	ulr.consumer[sizeof(ulr.consumer)-1] = '\0';

	if (strlen(ulr.consumer)) {

		/* label is only initialized if consumer is set */

		lr->label = kstrdup(ulr.consumer, GFP_KERNEL);

		if (!lr->label) {

			ret = -ENOMEM;

			goto out_free_linereq;

		}

	}



	lr->num_lines = ulr.num_lines;



	/* Request each GPIO */

	for (i = 0; i < ulr.num_lines; i++) {

		u32 offset = ulr.offsets[i];

		struct gpio_desc *desc = gpiochip_get_desc(gdev->chip, offset);



		if (IS_ERR(desc)) {

			ret = PTR_ERR(desc);

			goto out_free_linereq;

		}



		ret = gpiod_request(desc, lr->label);

		if (ret)

			goto out_free_linereq;



		lr->lines[i].desc = desc;

		flags = gpio_v2_line_config_flags(lc, i);

		gpio_v2_line_config_flags_to_desc_flags(flags, &desc->flags);



		ret = gpiod_set_transitory(desc, false);

		if (ret < 0)

			goto out_free_linereq;



		/*

		 * Lines have to be requested explicitly for input

		 * or output, else the line will be treated "as is".

		 */

		if (flags & GPIO_V2_LINE_FLAG_OUTPUT) {

			int val = gpio_v2_line_config_output_value(lc, i);



			ret = gpiod_direction_output(desc, val);

			if (ret)

				goto out_free_linereq;

		} else if (flags & GPIO_V2_LINE_FLAG_INPUT) {

			ret = gpiod_direction_input(desc);

			if (ret)

				goto out_free_linereq;

		}



		blocking_notifier_call_chain(&desc->gdev->notifier,

					     GPIOLINE_CHANGED_REQUESTED, desc);



		dev_dbg(&gdev->dev, "registered chardev handle for line %d\n",

			offset);

	}



	fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);

	if (fd < 0) {

		ret = fd;

		goto out_free_linereq;

	}



	file = anon_inode_getfile("gpio-line", &line_fileops, lr,

				  O_RDONLY | O_CLOEXEC);

	if (IS_ERR(file)) {

		ret = PTR_ERR(file);

		goto out_put_unused_fd;

	}



	ulr.fd = fd;

	if (copy_to_user(ip, &ulr, sizeof(ulr))) {

		/*

		 * fput() will trigger the release() callback, so do not go onto

		 * the regular error cleanup path here.

		 */

		fput(file);

		put_unused_fd(fd);

		return -EFAULT;

	}



	fd_install(fd, file);



	dev_dbg(&gdev->dev, "registered chardev handle for %d lines\n",

		lr->num_lines);



	return 0;



out_put_unused_fd:

	put_unused_fd(fd);

out_free_linereq:

	linereq_free(lr);

	return ret;

}



#ifdef CONFIG_GPIO_CDEV_V1



/*

 * GPIO line event management
@@ -745,6 +1163,8 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip) 
	return ret;

}



#endif /* CONFIG_GPIO_CDEV_V1 */



static void gpio_desc_to_lineinfo(struct gpio_desc *desc,

				  struct gpioline_info *info)

{
@@ -843,6 +1263,7 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 
		if (copy_to_user(ip, &chipinfo, sizeof(chipinfo)))

			return -EFAULT;

		return 0;

#ifdef CONFIG_GPIO_CDEV_V1

	} else if (cmd == GPIO_GET_LINEINFO_IOCTL) {

		struct gpioline_info lineinfo;
@@ -885,6 +1306,9 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 
		}



		return 0;

#endif /* CONFIG_GPIO_CDEV_V1 */

	} else if (cmd == GPIO_V2_GET_LINE_IOCTL) {

		return linereq_create(gdev, ip);

	} else if (cmd == GPIO_GET_LINEINFO_UNWATCH_IOCTL) {

		if (copy_from_user(&offset, ip, sizeof(offset)))

			return -EFAULT;