gpiolib.c 98.4 KB
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#include <linux/kernel.h>
#include <linux/module.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
#include <linux/spinlock.h>
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#include <linux/list.h>
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#include <linux/device.h>
#include <linux/err.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/gpio.h>
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#include <linux/of_gpio.h>
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#include <linux/idr.h>
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#include <linux/slab.h>
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#include <linux/acpi.h>
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#include <linux/gpio/driver.h>
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#include <linux/gpio/machine.h>
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#include <linux/pinctrl/consumer.h>
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#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
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#include <linux/compat.h>
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#include <linux/anon_inodes.h>
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#include <linux/file.h>
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#include <linux/kfifo.h>
#include <linux/poll.h>
#include <linux/timekeeping.h>
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#include <uapi/linux/gpio.h>
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#include "gpiolib.h"

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#define CREATE_TRACE_POINTS
#include <trace/events/gpio.h>
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/* Implementation infrastructure for GPIO interfaces.
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 *
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 * The GPIO programming interface allows for inlining speed-critical
 * get/set operations for common cases, so that access to SOC-integrated
 * GPIOs can sometimes cost only an instruction or two per bit.
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 */


/* When debugging, extend minimal trust to callers and platform code.
 * Also emit diagnostic messages that may help initial bringup, when
 * board setup or driver bugs are most common.
 *
 * Otherwise, minimize overhead in what may be bitbanging codepaths.
 */
#ifdef	DEBUG
#define	extra_checks	1
#else
#define	extra_checks	0
#endif

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/* Device and char device-related information */
static DEFINE_IDA(gpio_ida);
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static dev_t gpio_devt;
#define GPIO_DEV_MAX 256 /* 256 GPIO chip devices supported */
static struct bus_type gpio_bus_type = {
	.name = "gpio",
};
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/* gpio_lock prevents conflicts during gpio_desc[] table updates.
 * While any GPIO is requested, its gpio_chip is not removable;
 * each GPIO's "requested" flag serves as a lock and refcount.
 */
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DEFINE_SPINLOCK(gpio_lock);
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static DEFINE_MUTEX(gpio_lookup_lock);
static LIST_HEAD(gpio_lookup_list);
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LIST_HEAD(gpio_devices);
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static void gpiochip_free_hogs(struct gpio_chip *chip);
static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip);
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static int gpiochip_irqchip_init_valid_mask(struct gpio_chip *gpiochip);
static void gpiochip_irqchip_free_valid_mask(struct gpio_chip *gpiochip);
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static bool gpiolib_initialized;
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static inline void desc_set_label(struct gpio_desc *d, const char *label)
{
	d->label = label;
}

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/**
 * Convert a GPIO number to its descriptor
 */
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struct gpio_desc *gpio_to_desc(unsigned gpio)
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{
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	struct gpio_device *gdev;
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	unsigned long flags;

	spin_lock_irqsave(&gpio_lock, flags);

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	list_for_each_entry(gdev, &gpio_devices, list) {
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		if (gdev->base <= gpio &&
		    gdev->base + gdev->ngpio > gpio) {
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			spin_unlock_irqrestore(&gpio_lock, flags);
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			return &gdev->descs[gpio - gdev->base];
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		}
	}

	spin_unlock_irqrestore(&gpio_lock, flags);

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	if (!gpio_is_valid(gpio))
		WARN(1, "invalid GPIO %d\n", gpio);

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	return NULL;
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}
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EXPORT_SYMBOL_GPL(gpio_to_desc);
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/**
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 * Get the GPIO descriptor corresponding to the given hw number for this chip.
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 */
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struct gpio_desc *gpiochip_get_desc(struct gpio_chip *chip,
				    u16 hwnum)
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{
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	struct gpio_device *gdev = chip->gpiodev;

	if (hwnum >= gdev->ngpio)
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		return ERR_PTR(-EINVAL);
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	return &gdev->descs[hwnum];
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}
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/**
 * Convert a GPIO descriptor to the integer namespace.
 * This should disappear in the future but is needed since we still
 * use GPIO numbers for error messages and sysfs nodes
 */
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int desc_to_gpio(const struct gpio_desc *desc)
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{
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	return desc->gdev->base + (desc - &desc->gdev->descs[0]);
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}
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EXPORT_SYMBOL_GPL(desc_to_gpio);
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/**
 * gpiod_to_chip - Return the GPIO chip to which a GPIO descriptor belongs
 * @desc:	descriptor to return the chip of
 */
struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
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{
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	if (!desc || !desc->gdev || !desc->gdev->chip)
		return NULL;
	return desc->gdev->chip;
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}
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EXPORT_SYMBOL_GPL(gpiod_to_chip);
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/* dynamic allocation of GPIOs, e.g. on a hotplugged device */
static int gpiochip_find_base(int ngpio)
{
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	struct gpio_device *gdev;
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	int base = ARCH_NR_GPIOS - ngpio;
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	list_for_each_entry_reverse(gdev, &gpio_devices, list) {
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		/* found a free space? */
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		if (gdev->base + gdev->ngpio <= base)
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			break;
		else
			/* nope, check the space right before the chip */
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			base = gdev->base - ngpio;
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	}

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	if (gpio_is_valid(base)) {
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		pr_debug("%s: found new base at %d\n", __func__, base);
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		return base;
	} else {
		pr_err("%s: cannot find free range\n", __func__);
		return -ENOSPC;
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	}
}

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/**
 * gpiod_get_direction - return the current direction of a GPIO
 * @desc:	GPIO to get the direction of
 *
 * Return GPIOF_DIR_IN or GPIOF_DIR_OUT, or an error code in case of error.
 *
 * This function may sleep if gpiod_cansleep() is true.
 */
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int gpiod_get_direction(struct gpio_desc *desc)
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{
	struct gpio_chip	*chip;
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	unsigned		offset;
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	int			status = -EINVAL;

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	chip = gpiod_to_chip(desc);
	offset = gpio_chip_hwgpio(desc);
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	if (!chip->get_direction)
		return status;

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	status = chip->get_direction(chip, offset);
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	if (status > 0) {
		/* GPIOF_DIR_IN, or other positive */
		status = 1;
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		clear_bit(FLAG_IS_OUT, &desc->flags);
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	}
	if (status == 0) {
		/* GPIOF_DIR_OUT */
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		set_bit(FLAG_IS_OUT, &desc->flags);
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	}
	return status;
}
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EXPORT_SYMBOL_GPL(gpiod_get_direction);
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/*
 * Add a new chip to the global chips list, keeping the list of chips sorted
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 * by range(means [base, base + ngpio - 1]) order.
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 *
 * Return -EBUSY if the new chip overlaps with some other chip's integer
 * space.
 */
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static int gpiodev_add_to_list(struct gpio_device *gdev)
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{
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	struct gpio_device *prev, *next;
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	if (list_empty(&gpio_devices)) {
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		/* initial entry in list */
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		list_add_tail(&gdev->list, &gpio_devices);
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		return 0;
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	}

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	next = list_entry(gpio_devices.next, struct gpio_device, list);
	if (gdev->base + gdev->ngpio <= next->base) {
		/* add before first entry */
		list_add(&gdev->list, &gpio_devices);
		return 0;
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	}

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	prev = list_entry(gpio_devices.prev, struct gpio_device, list);
	if (prev->base + prev->ngpio <= gdev->base) {
		/* add behind last entry */
		list_add_tail(&gdev->list, &gpio_devices);
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		return 0;
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	}

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	list_for_each_entry_safe(prev, next, &gpio_devices, list) {
		/* at the end of the list */
		if (&next->list == &gpio_devices)
			break;
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		/* add between prev and next */
		if (prev->base + prev->ngpio <= gdev->base
				&& gdev->base + gdev->ngpio <= next->base) {
			list_add(&gdev->list, &prev->list);
			return 0;
		}
	}

	dev_err(&gdev->dev, "GPIO integer space overlap, cannot add chip\n");
	return -EBUSY;
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}

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/**
 * Convert a GPIO name to its descriptor
 */
static struct gpio_desc *gpio_name_to_desc(const char * const name)
{
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	struct gpio_device *gdev;
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	unsigned long flags;

	spin_lock_irqsave(&gpio_lock, flags);

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	list_for_each_entry(gdev, &gpio_devices, list) {
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		int i;

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		for (i = 0; i != gdev->ngpio; ++i) {
			struct gpio_desc *desc = &gdev->descs[i];
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			if (!desc->name || !name)
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				continue;

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			if (!strcmp(desc->name, name)) {
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				spin_unlock_irqrestore(&gpio_lock, flags);
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				return desc;
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			}
		}
	}

	spin_unlock_irqrestore(&gpio_lock, flags);

	return NULL;
}

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/*
 * Takes the names from gc->names and checks if they are all unique. If they
 * are, they are assigned to their gpio descriptors.
 *
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 * Warning if one of the names is already used for a different GPIO.
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 */
static int gpiochip_set_desc_names(struct gpio_chip *gc)
{
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	struct gpio_device *gdev = gc->gpiodev;
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	int i;

	if (!gc->names)
		return 0;

	/* First check all names if they are unique */
	for (i = 0; i != gc->ngpio; ++i) {
		struct gpio_desc *gpio;

		gpio = gpio_name_to_desc(gc->names[i]);
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		if (gpio)
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			dev_warn(&gdev->dev,
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				 "Detected name collision for GPIO name '%s'\n",
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				 gc->names[i]);
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	}

	/* Then add all names to the GPIO descriptors */
	for (i = 0; i != gc->ngpio; ++i)
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		gdev->descs[i].name = gc->names[i];
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	return 0;
}

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/*
 * GPIO line handle management
 */

/**
 * struct linehandle_state - contains the state of a userspace handle
 * @gdev: the GPIO device the handle pertains to
 * @label: consumer label used to tag descriptors
 * @descs: the GPIO descriptors held by this handle
 * @numdescs: the number of descriptors held in the descs array
 */
struct linehandle_state {
	struct gpio_device *gdev;
	const char *label;
	struct gpio_desc *descs[GPIOHANDLES_MAX];
	u32 numdescs;
};

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#define GPIOHANDLE_REQUEST_VALID_FLAGS \
	(GPIOHANDLE_REQUEST_INPUT | \
	GPIOHANDLE_REQUEST_OUTPUT | \
	GPIOHANDLE_REQUEST_ACTIVE_LOW | \
	GPIOHANDLE_REQUEST_OPEN_DRAIN | \
	GPIOHANDLE_REQUEST_OPEN_SOURCE)

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static long linehandle_ioctl(struct file *filep, unsigned int cmd,
			     unsigned long arg)
{
	struct linehandle_state *lh = filep->private_data;
	void __user *ip = (void __user *)arg;
	struct gpiohandle_data ghd;
	int i;

	if (cmd == GPIOHANDLE_GET_LINE_VALUES_IOCTL) {
		int val;

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		memset(&ghd, 0, sizeof(ghd));

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		/* TODO: check if descriptors are really input */
		for (i = 0; i < lh->numdescs; i++) {
			val = gpiod_get_value_cansleep(lh->descs[i]);
			if (val < 0)
				return val;
			ghd.values[i] = val;
		}

		if (copy_to_user(ip, &ghd, sizeof(ghd)))
			return -EFAULT;

		return 0;
	} else if (cmd == GPIOHANDLE_SET_LINE_VALUES_IOCTL) {
		int vals[GPIOHANDLES_MAX];

		/* TODO: check if descriptors are really output */
		if (copy_from_user(&ghd, ip, sizeof(ghd)))
			return -EFAULT;

		/* Clamp all values to [0,1] */
		for (i = 0; i < lh->numdescs; i++)
			vals[i] = !!ghd.values[i];

		/* Reuse the array setting function */
		gpiod_set_array_value_complex(false,
					      true,
					      lh->numdescs,
					      lh->descs,
					      vals);
		return 0;
	}
	return -EINVAL;
}

#ifdef CONFIG_COMPAT
static long linehandle_ioctl_compat(struct file *filep, unsigned int cmd,
			     unsigned long arg)
{
	return linehandle_ioctl(filep, cmd, (unsigned long)compat_ptr(arg));
}
#endif

static int linehandle_release(struct inode *inode, struct file *filep)
{
	struct linehandle_state *lh = filep->private_data;
	struct gpio_device *gdev = lh->gdev;
	int i;

	for (i = 0; i < lh->numdescs; i++)
		gpiod_free(lh->descs[i]);
	kfree(lh->label);
	kfree(lh);
	put_device(&gdev->dev);
	return 0;
}

static const struct file_operations linehandle_fileops = {
	.release = linehandle_release,
	.owner = THIS_MODULE,
	.llseek = noop_llseek,
	.unlocked_ioctl = linehandle_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl = linehandle_ioctl_compat,
#endif
};

static int linehandle_create(struct gpio_device *gdev, void __user *ip)
{
	struct gpiohandle_request handlereq;
	struct linehandle_state *lh;
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	struct file *file;
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	int fd, i, ret;

	if (copy_from_user(&handlereq, ip, sizeof(handlereq)))
		return -EFAULT;
	if ((handlereq.lines == 0) || (handlereq.lines > GPIOHANDLES_MAX))
		return -EINVAL;

	lh = kzalloc(sizeof(*lh), GFP_KERNEL);
	if (!lh)
		return -ENOMEM;
	lh->gdev = gdev;
	get_device(&gdev->dev);

	/* Make sure this is terminated */
	handlereq.consumer_label[sizeof(handlereq.consumer_label)-1] = '\0';
	if (strlen(handlereq.consumer_label)) {
		lh->label = kstrdup(handlereq.consumer_label,
				    GFP_KERNEL);
		if (!lh->label) {
			ret = -ENOMEM;
			goto out_free_lh;
		}
	}

	/* Request each GPIO */
	for (i = 0; i < handlereq.lines; i++) {
		u32 offset = handlereq.lineoffsets[i];
		u32 lflags = handlereq.flags;
		struct gpio_desc *desc;

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		if (offset >= gdev->ngpio) {
			ret = -EINVAL;
			goto out_free_descs;
		}

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		/* Return an error if a unknown flag is set */
		if (lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) {
			ret = -EINVAL;
			goto out_free_descs;
		}

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		desc = &gdev->descs[offset];
		ret = gpiod_request(desc, lh->label);
		if (ret)
			goto out_free_descs;
		lh->descs[i] = desc;

		if (lflags & GPIOHANDLE_REQUEST_ACTIVE_LOW)
			set_bit(FLAG_ACTIVE_LOW, &desc->flags);
		if (lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN)
			set_bit(FLAG_OPEN_DRAIN, &desc->flags);
		if (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE)
			set_bit(FLAG_OPEN_SOURCE, &desc->flags);

		/*
		 * Lines have to be requested explicitly for input
		 * or output, else the line will be treated "as is".
		 */
		if (lflags & GPIOHANDLE_REQUEST_OUTPUT) {
			int val = !!handlereq.default_values[i];

			ret = gpiod_direction_output(desc, val);
			if (ret)
				goto out_free_descs;
		} else if (lflags & GPIOHANDLE_REQUEST_INPUT) {
			ret = gpiod_direction_input(desc);
			if (ret)
				goto out_free_descs;
		}
		dev_dbg(&gdev->dev, "registered chardev handle for line %d\n",
			offset);
	}
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	/* Let i point at the last handle */
	i--;
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	lh->numdescs = handlereq.lines;

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	fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
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	if (fd < 0) {
		ret = fd;
		goto out_free_descs;
	}

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	file = anon_inode_getfile("gpio-linehandle",
				  &linehandle_fileops,
				  lh,
				  O_RDONLY | O_CLOEXEC);
	if (IS_ERR(file)) {
		ret = PTR_ERR(file);
		goto out_put_unused_fd;
	}

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	handlereq.fd = fd;
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	if (copy_to_user(ip, &handlereq, sizeof(handlereq))) {
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		/*
		 * 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;
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	}
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	fd_install(fd, file);

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

	return 0;

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out_put_unused_fd:
	put_unused_fd(fd);
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out_free_descs:
	for (; i >= 0; i--)
		gpiod_free(lh->descs[i]);
	kfree(lh->label);
out_free_lh:
	kfree(lh);
	put_device(&gdev->dev);
	return ret;
}

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/*
 * GPIO line event management
 */

/**
 * struct lineevent_state - contains the state of a userspace event
 * @gdev: the GPIO device the event pertains to
 * @label: consumer label used to tag descriptors
 * @desc: the GPIO descriptor held by this event
 * @eflags: the event flags this line was requested with
 * @irq: the interrupt that trigger in response to events on this GPIO
 * @wait: wait queue that handles blocking reads of events
 * @events: KFIFO for the GPIO events
 * @read_lock: mutex lock to protect reads from colliding with adding
 * new events to the FIFO
 */
struct lineevent_state {
	struct gpio_device *gdev;
	const char *label;
	struct gpio_desc *desc;
	u32 eflags;
	int irq;
	wait_queue_head_t wait;
	DECLARE_KFIFO(events, struct gpioevent_data, 16);
	struct mutex read_lock;
};

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#define GPIOEVENT_REQUEST_VALID_FLAGS \
	(GPIOEVENT_REQUEST_RISING_EDGE | \
	GPIOEVENT_REQUEST_FALLING_EDGE)

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static unsigned int lineevent_poll(struct file *filep,
				   struct poll_table_struct *wait)
{
	struct lineevent_state *le = filep->private_data;
	unsigned int events = 0;

	poll_wait(filep, &le->wait, wait);

	if (!kfifo_is_empty(&le->events))
		events = POLLIN | POLLRDNORM;

	return events;
}


static ssize_t lineevent_read(struct file *filep,
			      char __user *buf,
			      size_t count,
			      loff_t *f_ps)
{
	struct lineevent_state *le = filep->private_data;
	unsigned int copied;
	int ret;

	if (count < sizeof(struct gpioevent_data))
		return -EINVAL;

	do {
		if (kfifo_is_empty(&le->events)) {
			if (filep->f_flags & O_NONBLOCK)
				return -EAGAIN;

			ret = wait_event_interruptible(le->wait,
					!kfifo_is_empty(&le->events));
			if (ret)
				return ret;
		}

		if (mutex_lock_interruptible(&le->read_lock))
			return -ERESTARTSYS;
		ret = kfifo_to_user(&le->events, buf, count, &copied);
		mutex_unlock(&le->read_lock);

		if (ret)
			return ret;

		/*
		 * If we couldn't read anything from the fifo (a different
		 * thread might have been faster) we either return -EAGAIN if
		 * the file descriptor is non-blocking, otherwise we go back to
		 * sleep and wait for more data to arrive.
		 */
		if (copied == 0 && (filep->f_flags & O_NONBLOCK))
			return -EAGAIN;

	} while (copied == 0);

	return copied;
}

static int lineevent_release(struct inode *inode, struct file *filep)
{
	struct lineevent_state *le = filep->private_data;
	struct gpio_device *gdev = le->gdev;

	free_irq(le->irq, le);
	gpiod_free(le->desc);
	kfree(le->label);
	kfree(le);
	put_device(&gdev->dev);
	return 0;
}

static long lineevent_ioctl(struct file *filep, unsigned int cmd,
			    unsigned long arg)
{
	struct lineevent_state *le = filep->private_data;
	void __user *ip = (void __user *)arg;
	struct gpiohandle_data ghd;

	/*
	 * We can get the value for an event line but not set it,
	 * because it is input by definition.
	 */
	if (cmd == GPIOHANDLE_GET_LINE_VALUES_IOCTL) {
		int val;

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		memset(&ghd, 0, sizeof(ghd));

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		val = gpiod_get_value_cansleep(le->desc);
		if (val < 0)
			return val;
		ghd.values[0] = val;

		if (copy_to_user(ip, &ghd, sizeof(ghd)))
			return -EFAULT;

		return 0;
	}
	return -EINVAL;
}

#ifdef CONFIG_COMPAT
static long lineevent_ioctl_compat(struct file *filep, unsigned int cmd,
				   unsigned long arg)
{
	return lineevent_ioctl(filep, cmd, (unsigned long)compat_ptr(arg));
}
#endif

static const struct file_operations lineevent_fileops = {
	.release = lineevent_release,
	.read = lineevent_read,
	.poll = lineevent_poll,
	.owner = THIS_MODULE,
	.llseek = noop_llseek,
	.unlocked_ioctl = lineevent_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl = lineevent_ioctl_compat,
#endif
};

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static irqreturn_t lineevent_irq_thread(int irq, void *p)
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{
	struct lineevent_state *le = p;
	struct gpioevent_data ge;
	int ret;

	ge.timestamp = ktime_get_real_ns();

	if (le->eflags & GPIOEVENT_REQUEST_BOTH_EDGES) {
		int level = gpiod_get_value_cansleep(le->desc);

		if (level)
			/* Emit low-to-high event */
			ge.id = GPIOEVENT_EVENT_RISING_EDGE;
		else
			/* Emit high-to-low event */
			ge.id = GPIOEVENT_EVENT_FALLING_EDGE;
	} else if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE) {
		/* Emit low-to-high event */
		ge.id = GPIOEVENT_EVENT_RISING_EDGE;
	} else if (le->eflags & GPIOEVENT_REQUEST_FALLING_EDGE) {
		/* Emit high-to-low event */
		ge.id = GPIOEVENT_EVENT_FALLING_EDGE;
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	} else {
		return IRQ_NONE;
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	}

	ret = kfifo_put(&le->events, ge);
	if (ret != 0)
		wake_up_poll(&le->wait, POLLIN);

	return IRQ_HANDLED;
}

static int lineevent_create(struct gpio_device *gdev, void __user *ip)
{
	struct gpioevent_request eventreq;
	struct lineevent_state *le;
	struct gpio_desc *desc;
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	struct file *file;
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	u32 offset;
	u32 lflags;
	u32 eflags;
	int fd;
	int ret;
	int irqflags = 0;

	if (copy_from_user(&eventreq, ip, sizeof(eventreq)))
		return -EFAULT;

	le = kzalloc(sizeof(*le), GFP_KERNEL);
	if (!le)
		return -ENOMEM;
	le->gdev = gdev;
	get_device(&gdev->dev);

	/* Make sure this is terminated */
	eventreq.consumer_label[sizeof(eventreq.consumer_label)-1] = '\0';
	if (strlen(eventreq.consumer_label)) {
		le->label = kstrdup(eventreq.consumer_label,
				    GFP_KERNEL);
		if (!le->label) {
			ret = -ENOMEM;
			goto out_free_le;
		}
	}

	offset = eventreq.lineoffset;
	lflags = eventreq.handleflags;
	eflags = eventreq.eventflags;

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	if (offset >= gdev->ngpio) {
		ret = -EINVAL;
		goto out_free_label;
	}

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	/* Return an error if a unknown flag is set */
	if ((lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) ||
	    (eflags & ~GPIOEVENT_REQUEST_VALID_FLAGS)) {
		ret = -EINVAL;
		goto out_free_label;
	}

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	/* This is just wrong: we don't look for events on output lines */
	if (lflags & GPIOHANDLE_REQUEST_OUTPUT) {
		ret = -EINVAL;
		goto out_free_label;
	}

	desc = &gdev->descs[offset];
	ret = gpiod_request(desc, le->label);
	if (ret)
		goto out_free_desc;
	le->desc = desc;
	le->eflags = eflags;

	if (lflags & GPIOHANDLE_REQUEST_ACTIVE_LOW)
		set_bit(FLAG_ACTIVE_LOW, &desc->flags);
	if (lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN)
		set_bit(FLAG_OPEN_DRAIN, &desc->flags);
	if (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE)
		set_bit(FLAG_OPEN_SOURCE, &desc->flags);

	ret = gpiod_direction_input(desc);
	if (ret)
		goto out_free_desc;

	le->irq = gpiod_to_irq(desc);
	if (le->irq <= 0) {
		ret = -ENODEV;
		goto out_free_desc;
	}

	if (eflags & GPIOEVENT_REQUEST_RISING_EDGE)
		irqflags |= IRQF_TRIGGER_RISING;
	if (eflags & GPIOEVENT_REQUEST_FALLING_EDGE)
		irqflags |= IRQF_TRIGGER_FALLING;
	irqflags |= IRQF_ONESHOT;
	irqflags |= IRQF_SHARED;

	INIT_KFIFO(le->events);
	init_waitqueue_head(&le->wait);
	mutex_init(&le->read_lock);

	/* Request a thread to read the events */
	ret = request_threaded_irq(le->irq,
			NULL,
			lineevent_irq_thread,
			irqflags,
			le->label,
			le);
	if (ret)
		goto out_free_desc;

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	fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
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	if (fd < 0) {
		ret = fd;
		goto out_free_irq;
	}

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	file = anon_inode_getfile("gpio-event",
				  &lineevent_fileops,
				  le,
				  O_RDONLY | O_CLOEXEC);
	if (IS_ERR(file)) {
		ret = PTR_ERR(file);
		goto out_put_unused_fd;
	}

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	eventreq.fd = fd;
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	if (copy_to_user(ip, &eventreq, sizeof(eventreq))) {
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		/*
		 * 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;
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	}
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	fd_install(fd, file);

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	return 0;

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out_put_unused_fd:
	put_unused_fd(fd);
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out_free_irq:
	free_irq(le->irq, le);
out_free_desc:
	gpiod_free(le->desc);
out_free_label:
	kfree(le->label);
out_free_le:
	kfree(le);
	put_device(&gdev->dev);
	return ret;
}

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/**
 * gpio_ioctl() - ioctl handler for the GPIO chardev
 */
static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
	struct gpio_device *gdev = filp->private_data;
	struct gpio_chip *chip = gdev->chip;
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	void __user *ip = (void __user *)arg;
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	/* We fail any subsequent ioctl():s when the chip is gone */
	if (!chip)
		return -ENODEV;

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	/* Fill in the struct and pass to userspace */
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	if (cmd == GPIO_GET_CHIPINFO_IOCTL) {
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		struct gpiochip_info chipinfo;

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		memset(&chipinfo, 0, sizeof(chipinfo));

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		strncpy(chipinfo.name, dev_name(&gdev->dev),
			sizeof(chipinfo.name));
		chipinfo.name[sizeof(chipinfo.name)-1] = '\0';
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		strncpy(chipinfo.label, gdev->label,
			sizeof(chipinfo.label));
		chipinfo.label[sizeof(chipinfo.label)-1] = '\0';
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		chipinfo.lines = gdev->ngpio;
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		if (copy_to_user(ip, &chipinfo, sizeof(chipinfo)))
			return -EFAULT;
		return 0;
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	} else if (cmd == GPIO_GET_LINEINFO_IOCTL) {
		struct gpioline_info lineinfo;
		struct gpio_desc *desc;

		if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
			return -EFAULT;
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		if (lineinfo.line_offset >= gdev->ngpio)
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			return -EINVAL;

		desc = &gdev->descs[lineinfo.line_offset];
		if (desc->name) {
			strncpy(lineinfo.name, desc->name,
				sizeof(lineinfo.name));
			lineinfo.name[sizeof(lineinfo.name)-1] = '\0';
		} else {
			lineinfo.name[0] = '\0';
		}
		if (desc->label) {
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			strncpy(lineinfo.consumer, desc->label,
				sizeof(lineinfo.consumer));
			lineinfo.consumer[sizeof(lineinfo.consumer)-1] = '\0';
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		} else {
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			lineinfo.consumer[0] = '\0';
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		}

		/*
		 * Userspace only need to know that the kernel is using
		 * this GPIO so it can't use it.
		 */
		lineinfo.flags = 0;
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		if (test_bit(FLAG_REQUESTED, &desc->flags) ||
		    test_bit(FLAG_IS_HOGGED, &desc->flags) ||
		    test_bit(FLAG_USED_AS_IRQ, &desc->flags) ||
		    test_bit(FLAG_EXPORT, &desc->flags) ||
		    test_bit(FLAG_SYSFS, &desc->flags))
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			lineinfo.flags |= GPIOLINE_FLAG_KERNEL;
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		if (test_bit(FLAG_IS_OUT, &desc->flags))
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			lineinfo.flags |= GPIOLINE_FLAG_IS_OUT;
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		if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
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			lineinfo.flags |= GPIOLINE_FLAG_ACTIVE_LOW;
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		if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
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			lineinfo.flags |= GPIOLINE_FLAG_OPEN_DRAIN;
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		if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
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			lineinfo.flags |= GPIOLINE_FLAG_OPEN_SOURCE;

		if (copy_to_user(ip, &lineinfo, sizeof(lineinfo)))
			return -EFAULT;
		return 0;
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	} else if (cmd == GPIO_GET_LINEHANDLE_IOCTL) {
		return linehandle_create(gdev, ip);
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	} else if (cmd == GPIO_GET_LINEEVENT_IOCTL) {
		return lineevent_create(gdev, ip);
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	}
	return -EINVAL;
}

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#ifdef CONFIG_COMPAT
static long gpio_ioctl_compat(struct file *filp, unsigned int cmd,
			      unsigned long arg)
{
	return gpio_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
}
#endif

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/**
 * gpio_chrdev_open() - open the chardev for ioctl operations
 * @inode: inode for this chardev
 * @filp: file struct for storing private data
 * Returns 0 on success
 */
static int gpio_chrdev_open(struct inode *inode, struct file *filp)
{
	struct gpio_device *gdev = container_of(inode->i_cdev,
					      struct gpio_device, chrdev);

	/* Fail on open if the backing gpiochip is gone */
	if (!gdev || !gdev->chip)
		return -ENODEV;
	get_device(&gdev->dev);
	filp->private_data = gdev;
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	return nonseekable_open(inode, filp);
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}

/**
 * gpio_chrdev_release() - close chardev after ioctl operations
 * @inode: inode for this chardev
 * @filp: file struct for storing private data
 * Returns 0 on success
 */
static int gpio_chrdev_release(struct inode *inode, struct file *filp)
{
	struct gpio_device *gdev = container_of(inode->i_cdev,
					      struct gpio_device, chrdev);

	if (!gdev)
		return -ENODEV;
	put_device(&gdev->dev);
	return 0;
}


static const struct file_operations gpio_fileops = {
	.release = gpio_chrdev_release,
	.open = gpio_chrdev_open,
	.owner = THIS_MODULE,
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	.llseek = no_llseek,
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	.unlocked_ioctl = gpio_ioctl,
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#ifdef CONFIG_COMPAT
	.compat_ioctl = gpio_ioctl_compat,
#endif
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};

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static void gpiodevice_release(struct device *dev)
{
	struct gpio_device *gdev = dev_get_drvdata(dev);

	list_del(&gdev->list);
	ida_simple_remove(&gpio_ida, gdev->id);
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	kfree(gdev->label);
	kfree(gdev->descs);
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	kfree(gdev);
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}

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static int gpiochip_setup_dev(struct gpio_device *gdev)
{
	int status;

	cdev_init(&gdev->chrdev, &gpio_fileops);
	gdev->chrdev.owner = THIS_MODULE;
	gdev->chrdev.kobj.parent = &gdev->dev.kobj;
	gdev->dev.devt = MKDEV(MAJOR(gpio_devt), gdev->id);
	status = cdev_add(&gdev->chrdev, gdev->dev.devt, 1);
	if (status < 0)
		chip_warn(gdev->chip, "failed to add char device %d:%d\n",
			  MAJOR(gpio_devt), gdev->id);
	else
		chip_dbg(gdev->chip, "added GPIO chardev (%d:%d)\n",
			 MAJOR(gpio_devt), gdev->id);
	status = device_add(&gdev->dev);
	if (status)
		goto err_remove_chardev;

	status = gpiochip_sysfs_register(gdev);
	if (status)
		goto err_remove_device;

	/* From this point, the .release() function cleans up gpio_device */
	gdev->dev.release = gpiodevice_release;
	pr_debug("%s: registered GPIOs %d to %d on device: %s (%s)\n",
		 __func__, gdev->base, gdev->base + gdev->ngpio - 1,
		 dev_name(&gdev->dev), gdev->chip->label ? : "generic");

	return 0;

err_remove_device:
	device_del(&gdev->dev);
err_remove_chardev:
	cdev_del(&gdev->chrdev);
	return status;
}

static void gpiochip_setup_devs(void)
{
	struct gpio_device *gdev;
	int err;

	list_for_each_entry(gdev, &gpio_devices, list) {
		err = gpiochip_setup_dev(gdev);
		if (err)
			pr_err("%s: Failed to initialize gpio device (%d)\n",
			       dev_name(&gdev->dev), err);
	}
}

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/**
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 * gpiochip_add_data() - register a gpio_chip
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 * @chip: the chip to register, with chip->base initialized
1087
 * Context: potentially before irqs will work
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 *
 * Returns a negative errno if the chip can't be registered, such as
 * because the chip->base is invalid or already associated with a
 * different chip.  Otherwise it returns zero as a success code.
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 *
1093
 * When gpiochip_add_data() is called very early during boot, so that GPIOs
1094
 * can be freely used, the chip->parent device must be registered before
David Brownell's avatar
David Brownell committed
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 * the gpio framework's arch_initcall().  Otherwise sysfs initialization
 * for GPIOs will fail rudely.
 *
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 * gpiochip_add_data() must only be called after gpiolib initialization,
 * ie after core_initcall().
 *
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 * If chip->base is negative, this requests dynamic assignment of
 * a range of valid GPIOs.
1103
 */
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int gpiochip_add_data(struct gpio_chip *chip, void *data)
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{
	unsigned long	flags;
	int		status = 0;
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	unsigned	i;
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	int		base = chip->base;
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	struct gpio_device *gdev;
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	/*
	 * First: allocate and populate the internal stat container, and
	 * set up the struct device.
	 */
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	gdev = kzalloc(sizeof(*gdev), GFP_KERNEL);
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	if (!gdev)
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		return -ENOMEM;
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	gdev->dev.bus = &gpio_bus_type;
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	gdev->chip = chip;
	chip->gpiodev = gdev;
	if (chip->parent) {
		gdev->dev.parent = chip->parent;
		gdev->dev.of_node = chip->parent->of_node;
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	}

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#ifdef CONFIG_OF_GPIO
	/* If the gpiochip has an assigned OF node this takes precedence */
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	if (chip->of_node)
		gdev->dev.of_node = chip->of_node;
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#endif
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	gdev->id = ida_simple_get(&gpio_ida, 0, 0, GFP_KERNEL);
	if (gdev->id < 0) {
		status = gdev->id;
		goto err_free_gdev;
	}
	dev_set_name(&gdev->dev, "gpiochip%d", gdev->id);
	device_initialize(&gdev->dev);
	dev_set_drvdata(&gdev->dev, gdev);
	if (chip->parent && chip->parent->driver)
		gdev->owner = chip->parent->driver->owner;
	else if (chip->owner)
		/* TODO: remove chip->owner */
		gdev->owner = chip->owner;
	else
		gdev->owner = THIS_MODULE;
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1149
	gdev->descs = kcalloc(chip->ngpio, sizeof(gdev->descs[0]), GFP_KERNEL);
1150
	if (!gdev->descs) {
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		status = -ENOMEM;
		goto err_free_gdev;
	}

1155 1156
	if (chip->ngpio == 0) {
		chip_err(chip, "tried to insert a GPIO chip with zero lines\n");
1157
		status = -EINVAL;
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		goto err_free_descs;
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	}
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	if (chip->label)
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		gdev->label = kstrdup(chip->label, GFP_KERNEL);
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	else
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		gdev->label = kstrdup("unknown", GFP_KERNEL);
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	if (!gdev->label) {
		status = -ENOMEM;
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		goto err_free_descs;
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	}

1170
	gdev->ngpio = chip->ngpio;
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	gdev->data = data;
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1173 1174
	spin_lock_irqsave(&gpio_lock, flags);

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	/*
	 * TODO: this allocates a Linux GPIO number base in the global
	 * GPIO numberspace for this chip. In the long run we want to
	 * get *rid* of this numberspace and use only descriptors, but
	 * it may be a pipe dream. It will not happen before we get rid
	 * of the sysfs interface anyways.
	 */
1182 1183 1184 1185
	if (base < 0) {
		base = gpiochip_find_base(chip->ngpio);
		if (base < 0) {
			status = base;
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			spin_unlock_irqrestore(&gpio_lock, flags);
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			goto err_free_label;
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		}
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		/*
		 * TODO: it should not be necessary to reflect the assigned
		 * base outside of the GPIO subsystem. Go over drivers and
		 * see if anyone makes use of this, else drop this and assign
		 * a poison instead.
		 */
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		chip->base = base;
	}
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	gdev->base = base;
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	status = gpiodev_add_to_list(gdev);
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	if (status) {
		spin_unlock_irqrestore(&gpio_lock, flags);
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		goto err_free_label;
1203
	}
1204

1205 1206
	spin_unlock_irqrestore(&gpio_lock, flags);

1207
	for (i = 0; i < chip->ngpio; i++) {
1208
		struct gpio_desc *desc = &gdev->descs[i];
1209

1210
		desc->gdev = gdev;
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		/*
		 * REVISIT: most hardware initializes GPIOs as 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.
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		 */
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		if (chip->get_direction) {
			/*
			 * If we have .get_direction, set up the initial
			 * direction flag from the hardware.
			 */
			int dir = chip->get_direction(chip, i);

			if (!dir)
				set_bit(FLAG_IS_OUT, &desc->flags);
		} else if (!chip->direction_input) {
			/*
			 * If the chip lacks the .direction_input callback
			 * we logically assume all lines are outputs.
			 */
			set_bit(FLAG_IS_OUT, &desc->flags);
		}
1236
	}
1237

1238
#ifdef CONFIG_PINCTRL
1239
	INIT_LIST_HEAD(&gdev->pin_ranges);
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#endif

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	status = gpiochip_set_desc_names(chip);
	if (status)
		goto err_remove_from_list;

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	status = gpiochip_irqchip_init_valid_mask(chip);
	if (status)
		goto err_remove_from_list;

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	status = of_gpiochip_add(chip);
	if (status)
		goto err_remove_chip;

1254
	acpi_gpiochip_add(chip);
1255

1256 1257 1258 1259 1260
	/*
	 * By first adding the chardev, and then adding the device,
	 * we get a device node entry in sysfs under
	 * /sys/bus/gpio/devices/gpiochipN/dev that can be used for
	 * coldplug of device nodes and other udev business.
1261 1262
	 * We can do this only if gpiolib has been initialized.
	 * Otherwise, defer until later.
1263
	 */
1264 1265 1266 1267 1268
	if (gpiolib_initialized) {
		status = gpiochip_setup_dev(gdev);
		if (status)
			goto err_remove_chip;
	}