text: // SPDX-License-Identifier: GPL-2.0
  #include <linux/bitmap.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/interrupt.h>
  #include <linux/irq.h>
  #include <linux/spinlock.h>
  #include <linux/list.h>
  #include <linux/device.h>
  #include <linux/err.h>
  #include <linux/debugfs.h>
  #include <linux/seq_file.h>
  #include <linux/gpio.h>
  #include <linux/of_gpio.h>
  #include <linux/idr.h>
  #include <linux/slab.h>
  #include <linux/acpi.h>
  #include <linux/gpio/driver.h>
  #include <linux/gpio/machine.h>
  #include <linux/pinctrl/consumer.h>
  #include <linux/cdev.h>
  #include <linux/fs.h>
  #include <linux/uaccess.h>
  #include <linux/compat.h>
  #include <linux/anon_inodes.h>
  #include <linux/file.h>
  #include <linux/kfifo.h>
  #include <linux/poll.h>
  #include <linux/timekeeping.h>
  #include <uapi/linux/gpio.h>
  
  #include "gpiolib.h"
  
  #define CREATE_TRACE_POINTS
  #include <trace/events/gpio.h>
  
  /* Implementation infrastructure for GPIO interfaces.
   *
   * 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.
   */
  
  
  /* 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
  
  /* Device and char device-related information */
  static DEFINE_IDA(gpio_ida);
  static dev_t gpio_devt;
  #define GPIO_DEV_MAX 256 /* 256 GPIO chip devices supported */
  static struct bus_type gpio_bus_type = {
  	.name = "gpio",
  };
  
  /*
   * Number of GPIOs to use for the fast path in set array
   */
  #define FASTPATH_NGPIO CONFIG_GPIOLIB_FASTPATH_LIMIT
  
  /* 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.
   */
  DEFINE_SPINLOCK(gpio_lock);
  
  static DEFINE_MUTEX(gpio_lookup_lock);
  static LIST_HEAD(gpio_lookup_list);
  LIST_HEAD(gpio_devices);
  
  static DEFINE_MUTEX(gpio_machine_hogs_mutex);
  static LIST_HEAD(gpio_machine_hogs);
  
  static void gpiochip_free_hogs(struct gpio_chip *chip);
  static int gpiochip_add_irqchip(struct gpio_chip *gpiochip,
  				struct lock_class_key *lock_key,
  				struct lock_class_key *request_key);
  static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip);
  static int gpiochip_irqchip_init_valid_mask(struct gpio_chip *gpiochip);
  static void gpiochip_irqchip_free_valid_mask(struct gpio_chip *gpiochip);
  
  static bool gpiolib_initialized;
  
  static inline void desc_set_label(struct gpio_desc *d, const char *label)
  {
  	d->label = label;
  }
  
  /**
   * gpio_to_desc - Convert a GPIO number to its descriptor
   * @gpio: global GPIO number
   *
   * Returns:
   * The GPIO descriptor associated with the given GPIO, or %NULL if no GPIO
   * with the given number exists in the system.
   */
  struct gpio_desc *gpio_to_desc(unsigned gpio)
  {
  	struct gpio_device *gdev;
  	unsigned long flags;
  
  	spin_lock_irqsave(&gpio_lock, flags);
  
  	list_for_each_entry(gdev, &gpio_devices, list) {
  		if (gdev->base <= gpio &&
  		    gdev->base + gdev->ngpio > gpio) {
  			spin_unlock_irqrestore(&gpio_lock, flags);
  			return &gdev->descs[gpio - gdev->base];
  		}
  	}
  
  	spin_unlock_irqrestore(&gpio_lock, flags);
  
  	if (!gpio_is_valid(gpio))
  		WARN(1, "invalid GPIO %d\n", gpio);
  
  	return NULL;
  }
  EXPORT_SYMBOL_GPL(gpio_to_desc);
  
  /**
   * gpiochip_get_desc - get the GPIO descriptor corresponding to the given
   *                     hardware number for this chip
   * @chip: GPIO chip
   * @hwnum: hardware number of the GPIO for this chip
   *
   * Returns:
   * A pointer to the GPIO descriptor or %ERR_PTR(-EINVAL) if no GPIO exists
   * in the given chip for the specified hardware number.
   */
  struct gpio_desc *gpiochip_get_desc(struct gpio_chip *chip,
  				    u16 hwnum)
  {
  	struct gpio_device *gdev = chip->gpiodev;
  
  	if (hwnum >= gdev->ngpio)
  		return ERR_PTR(-EINVAL);
  
  	return &gdev->descs[hwnum];
  }
  
  /**
   * desc_to_gpio - convert a GPIO descriptor to the integer namespace
   * @desc: GPIO descriptor
   *
   * This should disappear in the future but is needed since we still
   * use GPIO numbers for error messages and sysfs nodes.
   *
   * Returns:
   * The global GPIO number for the GPIO specified by its descriptor.
   */
  int desc_to_gpio(const struct gpio_desc *desc)
  {
  	return desc->gdev->base + (desc - &desc->gdev->descs[0]);
  }
  EXPORT_SYMBOL_GPL(desc_to_gpio);
  
  
  /**
   * 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)
  {
  	if (!desc || !desc->gdev)
  		return NULL;
  	return desc->gdev->chip;
  }
  EXPORT_SYMBOL_GPL(gpiod_to_chip);
  
  /* dynamic allocation of GPIOs, e.g. on a hotplugged device */
  static int gpiochip_find_base(int ngpio)
  {
  	struct gpio_device *gdev;
  	int base = ARCH_NR_GPIOS - ngpio;
  
  	list_for_each_entry_reverse(gdev, &gpio_devices, list) {
  		/* found a free space? */
  		if (gdev->base + gdev->ngpio <= base)
  			break;
  		else
  			/* nope, check the space right before the chip */
  			base = gdev->base - ngpio;
  	}
  
  	if (gpio_is_valid(base)) {
  		pr_debug("%s: found new base at %d\n", __func__, base);
  		return base;
  	} else {
  		pr_err("%s: cannot find free range\n", __func__);
  		return -ENOSPC;
  	}
  }
  
  /**
   * gpiod_get_direction - return the current direction of a GPIO
   * @desc:	GPIO to get the direction of
   *
   * Returns 0 for output, 1 for input, or an error code in case of error.
   *
   * This function may sleep if gpiod_cansleep() is true.
   */
  int gpiod_get_direction(struct gpio_desc *desc)
  {
  	struct gpio_chip *chip;
  	unsigned offset;
  	int status;
  
  	chip = gpiod_to_chip(desc);
  	offset = gpio_chip_hwgpio(desc);
  
  	if (!chip->get_direction)
  		return -ENOTSUPP;
  
  	status = chip->get_direction(chip, offset);
  	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;
  }
  EXPORT_SYMBOL_GPL(gpiod_get_direction);
  
  /*
   * Add a new chip to the global chips list, keeping the list of chips sorted
   * by range(means [base, base + ngpio - 1]) order.
   *
   * Return -EBUSY if the new chip overlaps with some other chip's integer
   * space.
   */
  static int gpiodev_add_to_list(struct gpio_device *gdev)
  {
  	struct gpio_device *prev, *next;
  
  	if (list_empty(&gpio_devices)) {
  		/* initial entry in list */
  		list_add_tail(&gdev->list, &gpio_devices);
  		return 0;
  	}
  
  	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;
  	}
  
  	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);
  		return 0;
  	}
  
  	list_for_each_entry_safe(prev, next, &gpio_devices, list) {
  		/* at the end of the list */
  		if (&next->list == &gpio_devices)
  			break;
  
  		/* 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;
  }
  
  /*
   * Convert a GPIO name to its descriptor
   */
  static struct gpio_desc *gpio_name_to_desc(const char * const name)
  {
  	struct gpio_device *gdev;
  	unsigned long flags;
  
  	spin_lock_irqsave(&gpio_lock, flags);
  
  	list_for_each_entry(gdev, &gpio_devices, list) {
  		int i;
  
  		for (i = 0; i != gdev->ngpio; ++i) {
  			struct gpio_desc *desc = &gdev->descs[i];
  
  			if (!desc->name || !name)
  				continue;
  
  			if (!strcmp(desc->name, name)) {
  				spin_unlock_irqrestore(&gpio_lock, flags);
  				return desc;
  			}
  		}
  	}
  
  	spin_unlock_irqrestore(&gpio_lock, flags);
  
  	return NULL;
  }
  
  /*
   * Takes the names from gc->names and checks if they are all unique. If they
   * are, they are assigned to their gpio descriptors.
   *
   * Warning if one of the names is already used for a different GPIO.
   */
  static int gpiochip_set_desc_names(struct gpio_chip *gc)
  {
  	struct gpio_device *gdev = gc->gpiodev;
  	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]);
  		if (gpio)
  			dev_warn(&gdev->dev,
  				 "Detected name collision for GPIO name '%s'\n",
  				 gc->names[i]);
  	}
  
  	/* Then add all names to the GPIO descriptors */
  	for (i = 0; i != gc->ngpio; ++i)
  		gdev->descs[i].name = gc->names[i];
  
  	return 0;
  }
  
  static unsigned long *gpiochip_allocate_mask(struct gpio_chip *chip)
  {
  	unsigned long *p;
  
  	p = kmalloc_array(BITS_TO_LONGS(chip->ngpio), sizeof(*p), GFP_KERNEL);
  	if (!p)
  		return NULL;
  
  	/* Assume by default all GPIOs are valid */
  	bitmap_fill(p, chip->ngpio);
  
  	return p;
  }
  
  static int gpiochip_alloc_valid_mask(struct gpio_chip *gpiochip)
  {
  #ifdef CONFIG_OF_GPIO
  	int size;
  	struct device_node *np = gpiochip->of_node;
  
  	size = of_property_count_u32_elems(np,  "gpio-reserved-ranges");
  	if (size > 0 && size % 2 == 0)
  		gpiochip->need_valid_mask = true;
  #endif
  
  	if (!gpiochip->need_valid_mask)
  		return 0;
  
  	gpiochip->valid_mask = gpiochip_allocate_mask(gpiochip);
  	if (!gpiochip->valid_mask)
  		return -ENOMEM;
  
  	return 0;
  }
  
  static int gpiochip_init_valid_mask(struct gpio_chip *gpiochip)
  {
  	if (gpiochip->init_valid_mask)
  		return gpiochip->init_valid_mask(gpiochip);
  
  	return 0;
  }
  
  static void gpiochip_free_valid_mask(struct gpio_chip *gpiochip)
  {
  	kfree(gpiochip->valid_mask);
  	gpiochip->valid_mask = NULL;
  }
  
  bool gpiochip_line_is_valid(const struct gpio_chip *gpiochip,
  				unsigned int offset)
  {
  	/* No mask means all valid */
  	if (likely(!gpiochip->valid_mask))
  		return true;
  	return test_bit(offset, gpiochip->valid_mask);
  }
  EXPORT_SYMBOL_GPL(gpiochip_line_is_valid);
  
  /*
   * 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;
  };
  
  #define GPIOHANDLE_REQUEST_VALID_FLAGS \
  	(GPIOHANDLE_REQUEST_INPUT | \
  	GPIOHANDLE_REQUEST_OUTPUT | \
  	GPIOHANDLE_REQUEST_ACTIVE_LOW | \
  	GPIOHANDLE_REQUEST_OPEN_DRAIN | \
  	GPIOHANDLE_REQUEST_OPEN_SOURCE)
  
  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;
  	DECLARE_BITMAP(vals, GPIOHANDLES_MAX);
  	int i;
  
  	if (cmd == GPIOHANDLE_GET_LINE_VALUES_IOCTL) {
  		/* NOTE: It's ok to read values of output lines. */
  		int ret = gpiod_get_array_value_complex(false,
  							true,
  							lh->numdescs,
  							lh->descs,
  							NULL,
  							vals);
  		if (ret)
  			return ret;
  
  		memset(&ghd, 0, sizeof(ghd));
  		for (i = 0; i < lh->numdescs; i++)
  			ghd.values[i] = test_bit(i, vals);
  
  		if (copy_to_user(ip, &ghd, sizeof(ghd)))
  			return -EFAULT;
  
  		return 0;
  	} else if (cmd == GPIOHANDLE_SET_LINE_VALUES_IOCTL) {
  		/*
  		 * All line descriptors were created at once with the same
  		 * flags so just check if the first one is really output.
  		 */
  		if (!test_bit(FLAG_IS_OUT, &lh->descs[0]->flags))
  			return -EPERM;
  
  		if (copy_from_user(&ghd, ip, sizeof(ghd)))
  			return -EFAULT;
  
  		/* Clamp all values to [0,1] */
  		for (i = 0; i < lh->numdescs; i++)
  			__assign_bit(i, vals, ghd.values[i]);
  
  		/* Reuse the array setting function */
  		return gpiod_set_array_value_complex(false,
  					      true,
  					      lh->numdescs,
  					      lh->descs,
  					      NULL,
  					      vals);
  	}
  	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;
  	struct file *file;
  	int fd, i, count = 0, ret;
  	u32 lflags;
  
  	if (copy_from_user(&handlereq, ip, sizeof(handlereq)))
  		return -EFAULT;
  	if ((handlereq.lines == 0) || (handlereq.lines > GPIOHANDLES_MAX))
  		return -EINVAL;
  
  	lflags = handlereq.flags;
  
  	/* Return an error if an unknown flag is set */
  	if (lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS)
  		return -EINVAL;
  
  	/*
  	 * Do not allow OPEN_SOURCE & 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 ((lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) &&
  	    (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE))
  		return -EINVAL;
  
  	/* OPEN_DRAIN and OPEN_SOURCE flags only make sense for output mode. */
  	if (!(lflags & GPIOHANDLE_REQUEST_OUTPUT) &&
  	    ((lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) ||
  	     (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE)))
  		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];
  		struct gpio_desc *desc;
  
  		if (offset >= gdev->ngpio) {
  			ret = -EINVAL;
  			goto out_free_descs;
  		}
  
  		desc = &gdev->descs[offset];
  		ret = gpiod_request(desc, lh->label);
  		if (ret)
  			goto out_free_descs;
  		lh->descs[i] = desc;
  		count = i + 1;
  
  		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_set_transitory(desc, false);
  		if (ret < 0)
  			goto out_free_descs;
  
  		/*
  		 * 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);
  	}
  	/* Let i point at the last handle */
  	i--;
  	lh->numdescs = handlereq.lines;
  
  	fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
  	if (fd < 0) {
  		ret = fd;
  		goto out_free_descs;
  	}
  
  	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;
  	}
  
  	handlereq.fd = fd;
  	if (copy_to_user(ip, &handlereq, sizeof(handlereq))) {
  		/*
  		 * 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",
  		lh->numdescs);
  
  	return 0;
  
  out_put_unused_fd:
  	put_unused_fd(fd);
  out_free_descs:
  	for (i = 0; i < count; i++)
  		gpiod_free(lh->descs[i]);
  	kfree(lh->label);
  out_free_lh:
  	kfree(lh);
  	put_device(&gdev->dev);
  	return ret;
  }
  
  /*
   * 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
   * @timestamp: cache for the timestamp storing it between hardirq
   * and IRQ thread, used to bring the timestamp close to the actual
   * event
   */
  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;
  	u64 timestamp;
  };
  
  #define GPIOEVENT_REQUEST_VALID_FLAGS \
  	(GPIOEVENT_REQUEST_RISING_EDGE | \
  	GPIOEVENT_REQUEST_FALLING_EDGE)
  
  static __poll_t lineevent_poll(struct file *filep,
  				   struct poll_table_struct *wait)
  {
  	struct lineevent_state *le = filep->private_data;
  	__poll_t events = 0;
  
  	poll_wait(filep, &le->wait, wait);
  
  	if (!kfifo_is_empty(&le->events))
  		events = EPOLLIN | EPOLLRDNORM;
  
  	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;
  
  		memset(&ghd, 0, sizeof(ghd));
  
  		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
  };
  
  static irqreturn_t lineevent_irq_thread(int irq, void *p)
  {
  	struct lineevent_state *le = p;
  	struct gpioevent_data ge;
  	int ret;
  
  	/* Do not leak kernel stack to userspace */
  	memset(&ge, 0, sizeof(ge));
  
  	/*
  	 * We may be running from a nested threaded interrupt in which case
  	 * we didn't get the timestamp from lineevent_irq_handler().
  	 */
  	if (!le->timestamp)
  		ge.timestamp = ktime_get_real_ns();
  	else
  		ge.timestamp = le->timestamp;
  
  	if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE
  	    && le->eflags & GPIOEVENT_REQUEST_FALLING_EDGE) {
  		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;
  	} else {
  		return IRQ_NONE;
  	}
  
  	ret = kfifo_put(&le->events, ge);
  	if (ret != 0)
  		wake_up_poll(&le->wait, EPOLLIN);
  
  	return IRQ_HANDLED;
  }
  
  static irqreturn_t lineevent_irq_handler(int irq, void *p)
  {
  	struct lineevent_state *le = p;
  
  	/*
  	 * Just store the timestamp in hardirq context so we get it as
  	 * close in time as possible to the actual event.
  	 */
  	le->timestamp = ktime_get_real_ns();
  
  	return IRQ_WAKE_THREAD;
  }
  
  static int lineevent_create(struct gpio_device *gdev, void __user *ip)
  {
  	struct gpioevent_request eventreq;
  	struct lineevent_state *le;
  	struct gpio_desc *desc;
  	struct file *file;
  	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;
  
  	if (offset >= gdev->ngpio) {
  		ret = -EINVAL;
  		goto out_free_label;
  	}
  
  	/* 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;
  	}
  
  	/* 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_label;
  	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;
  
  	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,
  			lineevent_irq_handler,
  			lineevent_irq_thread,
  			irqflags,
  			le->label,
  			le);
  	if (ret)
  		goto out_free_desc;
  
  	fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
  	if (fd < 0) {
  		ret = fd;
  		goto out_free_irq;
  	}
  
  	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;
  	}
  
  	eventreq.fd = fd;
  	if (copy_to_user(ip, &eventreq, sizeof(eventreq))) {
  		/*
  		 * 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);
  
  	return 0;
  
  out_put_unused_fd:
  	put_unused_fd(fd);
  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;
  }
  
  /*
   * 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;
  	void __user *ip = (void __user *)arg;
  
  	/* We fail any subsequent ioctl():s when the chip is gone */
  	if (!chip)
  		return -ENODEV;
  
  	/* Fill in the struct and pass to userspace */
  	if (cmd == GPIO_GET_CHIPINFO_IOCTL) {
  		struct gpiochip_info chipinfo;
  
  		memset(&chipinfo, 0, sizeof(chipinfo));
  
  		strncpy(chipinfo.name, dev_name(&gdev->dev),
  			sizeof(chipinfo.name));
  		chipinfo.name[sizeof(chipinfo.name)-1] = '\0';
  		strncpy(chipinfo.label, gdev->label,
  			sizeof(chipinfo.label));
  		chipinfo.label[sizeof(chipinfo.label)-1] = '\0';
  		chipinfo.lines = gdev->ngpio;
  		if (copy_to_user(ip, &chipinfo, sizeof(chipinfo)))
  			return -EFAULT;
  		return 0;
  	} 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;
  		if (lineinfo.line_offset >= gdev->ngpio)
  			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) {
  			strncpy(lineinfo.consumer, desc->label,
  				sizeof(lineinfo.consumer));
  			lineinfo.consumer[sizeof(lineinfo.consumer)-1] = '\0';
  		} else {
  			lineinfo.consumer[0] = '\0';
  		}
  
  		/*
  		 * Userspace only need to know that the kernel is using
  		 * this GPIO so it can't use it.
  		 */
  		lineinfo.flags = 0;
  		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))
  			lineinfo.flags |= GPIOLINE_FLAG_KERNEL;
  		if (test_bit(FLAG_IS_OUT, &desc->flags))
  			lineinfo.flags |= GPIOLINE_FLAG_IS_OUT;
  		if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
  			lineinfo.flags |= GPIOLINE_FLAG_ACTIVE_LOW;
  		if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
  			lineinfo.flags |= GPIOLINE_FLAG_OPEN_DRAIN;
  		if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
  			lineinfo.flags |= GPIOLINE_FLAG_OPEN_SOURCE;
  
  		if (copy_to_user(ip, &lineinfo, sizeof(lineinfo)))
  			return -EFAULT;
  		return 0;
  	} else if (cmd == GPIO_GET_LINEHANDLE_IOCTL) {
  		return linehandle_create(gdev, ip);
  	} else if (cmd == GPIO_GET_LINEEVENT_IOCTL) {
  		return lineevent_create(gdev, ip);
  	}
  	return -EINVAL;
  }
  
  #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
  
  /**
   * 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->chip)
  		return -ENODEV;
  	get_device(&gdev->dev);
  	filp->private_data = gdev;
  
  	return nonseekable_open(inode, filp);
  }
  
  /**
   * 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);
  
  	put_device(&gdev->dev);
  	return 0;
  }
  
  
  static const struct file_operations gpio_fileops = {
  	.release = gpio_chrdev_release,
  	.open = gpio_chrdev_open,
  	.owner = THIS_MODULE,
  	.llseek = no_llseek,
  	.unlocked_ioctl = gpio_ioctl,
  #ifdef CONFIG_COMPAT
  	.compat_ioctl = gpio_ioctl_compat,
  #endif
  };
  
  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);
  	kfree_const(gdev->label);
  	kfree(gdev->descs);
  	kfree(gdev);
  }
  
  static int gpiochip_setup_dev(struct gpio_device *gdev)
  {
  	int status;
  
  	cdev_init(&gdev->chrdev, &gpio_fileops);
  	gdev->chrdev.owner = THIS_MODULE;
  	gdev->dev.devt = MKDEV(MAJOR(gpio_devt), gdev->id);
  
  	status = cdev_device_add(&gdev->chrdev, &gdev->dev);
  	if (status)
  		return status;
  
  	chip_dbg(gdev->chip, "added GPIO chardev (%d:%d)\n",
  		 MAJOR(gpio_devt), gdev->id);
  
  	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:
  	cdev_device_del(&gdev->chrdev, &gdev->dev);
  	return status;
  }
  
  static void gpiochip_machine_hog(struct gpio_chip *chip, struct gpiod_hog *hog)
  {
  	struct gpio_desc *desc;
  	int rv;
  
  	desc = gpiochip_get_desc(chip, hog->chip_hwnum);
  	if (IS_ERR(desc)) {
  		pr_err("%s: unable to get GPIO desc: %ld\n",
  		       __func__, PTR_ERR(desc));
  		return;
  	}
  
  	if (test_bit(FLAG_IS_HOGGED, &desc->flags))
  		return;
  
  	rv = gpiod_hog(desc, hog->line_name, hog->lflags, hog->dflags);
  	if (rv)
  		pr_err("%s: unable to hog GPIO line (%s:%u): %d\n",
  		       __func__, chip->label, hog->chip_hwnum, rv);
  }
  
  static void machine_gpiochip_add(struct gpio_chip *chip)
  {
  	struct gpiod_hog *hog;
  
  	mutex_lock(&gpio_machine_hogs_mutex);
  
  	list_for_each_entry(hog, &gpio_machine_hogs, list) {
  		if (!strcmp(chip->label, hog->chip_label))
  			gpiochip_machine_hog(chip, hog);
  	}
  
  	mutex_unlock(&gpio_machine_hogs_mutex);
  }
  
  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);
  	}
  }
  
  int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data,
  			       struct lock_class_key *lock_key,
  			       struct lock_class_key *request_key)
  {
  	unsigned long	flags;
  	int		status = 0;
  	unsigned	i;
  	int		base = chip->base;
  	struct gpio_device *gdev;
  
  	/*
  	 * First: allocate and populate the internal stat container, and
  	 * set up the struct device.
  	 */
  	gdev = kzalloc(sizeof(*gdev), GFP_KERNEL);
  	if (!gdev)
  		return -ENOMEM;
  	gdev->dev.bus = &gpio_bus_type;
  	gdev->chip = chip;
  	chip->gpiodev = gdev;
  	if (chip->parent) {
  		gdev->dev.parent = chip->parent;
  		gdev->dev.of_node = chip->parent->of_node;
  	}
  
  #ifdef CONFIG_OF_GPIO
  	/* If the gpiochip has an assigned OF node this takes precedence */
  	if (chip->of_node)
  		gdev->dev.of_node = chip->of_node;
  	else
  		chip->of_node = gdev->dev.of_node;
  #endif
  
  	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;
  
  	gdev->descs = kcalloc(chip->ngpio, sizeof(gdev->descs[0]), GFP_KERNEL);
  	if (!gdev->descs) {
  		status = -ENOMEM;
  		goto err_free_ida;
  	}
  
  	if (chip->ngpio == 0) {
  		chip_err(chip, "tried to insert a GPIO chip with zero lines\n");
  		status = -EINVAL;
  		goto err_free_descs;
  	}
  
  	if (chip->ngpio > FASTPATH_NGPIO)
  		chip_warn(chip, "line cnt %u is greater than fast path cnt %u\n",
  		chip->ngpio, FASTPATH_NGPIO);
  
  	gdev->label = kstrdup_const(chip->label ?: "unknown", GFP_KERNEL);
  	if (!gdev->label) {
  		status = -ENOMEM;
  		goto err_free_descs;
  	}
  
  	gdev->ngpio = chip->ngpio;
  	gdev->data = data;
  
  	spin_lock_irqsave(&gpio_lock, flags);
  
  	/*
  	 * 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.
  	 */
  	if (base < 0) {
  		base = gpiochip_find_base(chip->ngpio);
  		if (base < 0) {
  			status = base;
  			spin_unlock_irqrestore(&gpio_lock, flags);
  			goto err_free_label;
  		}
  		/*
  		 * 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.
  		 */
  		chip->base = base;
  	}
  	gdev->base = base;
  
  	status = gpiodev_add_to_list(gdev);
  	if (status) {
  		spin_unlock_irqrestore(&gpio_lock, flags);
  		goto err_free_label;
  	}
  
  	spin_unlock_irqrestore(&gpio_lock, flags);
  
  	for (i = 0; i < chip->ngpio; i++)
  		gdev->descs[i].gdev = gdev;
  
  #ifdef CONFIG_PINCTRL
  	INIT_LIST_HEAD(&gdev->pin_ranges);
  #endif
  
  	status = gpiochip_set_desc_names(chip);
  	if (status)
  		goto err_remove_from_list;
  
  	status = gpiochip_irqchip_init_valid_mask(chip);
  	if (status)
  		goto err_remove_from_list;
  
  	status = gpiochip_alloc_valid_mask(chip);
  	if (status)
  		goto err_remove_irqchip_mask;
  
  	status = gpiochip_add_irqchip(chip, lock_key, request_key);
  	if (status)
  		goto err_remove_chip;
  
  	status = of_gpiochip_add(chip);
  	if (status)
  		goto err_remove_chip;
  
  	status = gpiochip_init_valid_mask(chip);
  	if (status)
  		goto err_remove_chip;
  
  	for (i = 0; i < chip->ngpio; i++) {
  		struct gpio_desc *desc = &gdev->descs[i];
  
  		if (chip->get_direction && gpiochip_line_is_valid(chip, i))
  			desc->flags = !chip->get_direction(chip, i) ?
  					(1 << FLAG_IS_OUT) : 0;
  		else
  			desc->flags = !chip->direction_input ?
  					(1 << FLAG_IS_OUT) : 0;
  	}
  
  	acpi_gpiochip_add(chip);
  
  	machine_gpiochip_add(chip);
  
  	/*
  	 * 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.
  	 * We can do this only if gpiolib has been initialized.
  	 * Otherwise, defer until later.
  	 */
  	if (gpiolib_initialized) {
  		status = gpiochip_setup_dev(gdev);
  		if (status)
  			goto err_remove_chip;
  	}
  	return 0;
  
  err_remove_chip:
  	acpi_gpiochip_remove(chip);
  	gpiochip_free_hogs(chip);
  	of_gpiochip_remove(chip);
  	gpiochip_free_valid_mask(chip);
  err_remove_irqchip_mask:
  	gpiochip_irqchip_free_valid_mask(chip);
  err_remove_from_list:
  	spin_lock_irqsave(&gpio_lock, flags);
  	list_del(&gdev->list);
  	spin_unlock_irqrestore(&gpio_lock, flags);
  err_free_label:
  	kfree_const(gdev->label);
  err_free_descs:
  	kfree(gdev->descs);
  err_free_ida:
  	ida_simple_remove(&gpio_ida, gdev->id);
  err_free_gdev:
  	/* failures here can mean systems won't boot... */
  	pr_err("%s: GPIOs %d..%d (%s) failed to register, %d\n", __func__,
  	       gdev->base, gdev->base + gdev->ngpio - 1,
  	       chip->label ? : "generic", status);
  	kfree(gdev);
  	return status;
  }
  EXPORT_SYMBOL_GPL(gpiochip_add_data_with_key);
  
  /**
   * gpiochip_get_data() - get per-subdriver data for the chip
   * @chip: GPIO chip
   *
   * Returns:
   * The per-subdriver data for the chip.
   */
  void *gpiochip_get_data(struct gpio_chip *chip)
  {
  	return chip->gpiodev->data;
  }
  EXPORT_SYMBOL_GPL(gpiochip_get_data);
  
  /**
   * gpiochip_remove() - unregister a gpio_chip
   * @chip: the chip to unregister
   *
   * A gpio_chip with any GPIOs still requested may not be removed.
   */
  void gpiochip_remove(struct gpio_chip *chip)
  {
  	struct gpio_device *gdev = chip->gpiodev;
  	struct gpio_desc *desc;
  	unsigned long	flags;
  	unsigned	i;
  	bool		requested = false;
  
  	/* FIXME: should the legacy sysfs handling be moved to gpio_device? */
  	gpiochip_sysfs_unregister(gdev);
  	gpiochip_free_hogs(chip);
  	/* Numb the device, cancelling all outstanding operations */
  	gdev->chip = NULL;
  	gpiochip_irqchip_remove(chip);
  	acpi_gpiochip_remove(chip);
  	gpiochip_remove_pin_ranges(chip);
  	of_gpiochip_remove(chip);
  	gpiochip_free_valid_mask(chip);
  	/*
  	 * We accept no more calls into the driver from this point, so
  	 * NULL the driver data pointer
  	 */
  	gdev->data = NULL;
  
  	spin_lock_irqsave(&gpio_lock, flags);
  	for (i = 0; i < gdev->ngpio; i++) {
  		desc = &gdev->descs[i];
  		if (test_bit(FLAG_REQUESTED, &desc->flags))
  			requested = true;
  	}
  	spin_unlock_irqrestore(&gpio_lock, flags);
  
  	if (requested)
  		dev_crit(&gdev->dev,
  			 "REMOVING GPIOCHIP WITH GPIOS STILL REQUESTED\n");
  
  	/*
  	 * The gpiochip side puts its use of the device to rest here:
  	 * if there are no userspace clients, the chardev and device will
  	 * be removed, else it will be dangling until the last user is
  	 * gone.
  	 */
  	cdev_device_del(&gdev->chrdev, &gdev->dev);
  	put_device(&gdev->dev);
  }
  EXPORT_SYMBOL_GPL(gpiochip_remove);
  
  static void devm_gpio_chip_release(struct device *dev, void *res)
  {
  	struct gpio_chip *chip = *(struct gpio_chip **)res;
  
  	gpiochip_remove(chip);
  }
  
  /**
   * devm_gpiochip_add_data() - Resource manager gpiochip_add_data()
   * @dev: pointer to the device that gpio_chip belongs to.
   * @chip: the chip to register, with chip->base initialized
   * @data: driver-private data associated with this chip
   *
   * Context: potentially before irqs will work
   *
   * The gpio chip automatically be released when the device is unbound.
   *
   * 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.
   */
  int devm_gpiochip_add_data(struct device *dev, struct gpio_chip *chip,
  			   void *data)
  {
  	struct gpio_chip **ptr;
  	int ret;
  
  	ptr = devres_alloc(devm_gpio_chip_release, sizeof(*ptr),
  			     GFP_KERNEL);
  	if (!ptr)
  		return -ENOMEM;
  
  	ret = gpiochip_add_data(chip, data);
  	if (ret < 0) {
  		devres_free(ptr);
  		return ret;
  	}
  
  	*ptr = chip;
  	devres_add(dev, ptr);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(devm_gpiochip_add_data);
  
  /**
   * gpiochip_find() - iterator for locating a specific gpio_chip
   * @data: data to pass to match function
   * @match: Callback function to check gpio_chip
   *
   * Similar to bus_find_device.  It returns a reference to a gpio_chip as
   * determined by a user supplied @match callback.  The callback should return
   * 0 if the device doesn't match and non-zero if it does.  If the callback is
   * non-zero, this function will return to the caller and not iterate over any
   * more gpio_chips.
   */
  struct gpio_chip *gpiochip_find(void *data,
  				int (*match)(struct gpio_chip *chip,
  					     void *data))
  {
  	struct gpio_device *gdev;
  	struct gpio_chip *chip = NULL;
  	unsigned long flags;
  
  	spin_lock_irqsave(&gpio_lock, flags);
  	list_for_each_entry(gdev, &gpio_devices, list)
  		if (gdev->chip && match(gdev->chip, data)) {
  			chip = gdev->chip;
  			break;
  		}
  
  	spin_unlock_irqrestore(&gpio_lock, flags);
  
  	return chip;
  }
  EXPORT_SYMBOL_GPL(gpiochip_find);
  
  static int gpiochip_match_name(struct gpio_chip *chip, void *data)
  {
  	const char *name = data;
  
  	return !strcmp(chip->label, name);
  }
  
  static struct gpio_chip *find_chip_by_name(const char *name)
  {
  	return gpiochip_find((void *)name, gpiochip_match_name);
  }
  
  #ifdef CONFIG_GPIOLIB_IRQCHIP
  
  /*
   * The following is irqchip helper code for gpiochips.
   */
  
  static int gpiochip_irqchip_init_valid_mask(struct gpio_chip *gpiochip)
  {
  	if (!gpiochip->irq.need_valid_mask)
  		return 0;
  
  	gpiochip->irq.valid_mask = gpiochip_allocate_mask(gpiochip);
  	if (!gpiochip->irq.valid_mask)
  		return -ENOMEM;
  
  	return 0;
  }
  
  static void gpiochip_irqchip_free_valid_mask(struct gpio_chip *gpiochip)
  {
  	kfree(gpiochip->irq.valid_mask);
  	gpiochip->irq.valid_mask = NULL;
  }
  
  bool gpiochip_irqchip_irq_valid(const struct gpio_chip *gpiochip,
  				unsigned int offset)
  {
  	if (!gpiochip_line_is_valid(gpiochip, offset))
  		return false;
  	/* No mask means all valid */
  	if (likely(!gpiochip->irq.valid_mask))
  		return true;
  	return test_bit(offset, gpiochip->irq.valid_mask);
  }
  EXPORT_SYMBOL_GPL(gpiochip_irqchip_irq_valid);
  
  /**
   * gpiochip_set_cascaded_irqchip() - connects a cascaded irqchip to a gpiochip
   * @gpiochip: the gpiochip to set the irqchip chain to
   * @parent_irq: the irq number corresponding to the parent IRQ for this
   * chained irqchip
   * @parent_handler: the parent interrupt handler for the accumulated IRQ
   * coming out of the gpiochip. If the interrupt is nested rather than
   * cascaded, pass NULL in this handler argument
   */
  static void gpiochip_set_cascaded_irqchip(struct gpio_chip *gpiochip,
  					  unsigned int parent_irq,
  					  irq_flow_handler_t parent_handler)
  {
  	if (!gpiochip->irq.domain) {
  		chip_err(gpiochip, "called %s before setting up irqchip\n",
  			 __func__);
  		return;
  	}
  
  	if (parent_handler) {
  		if (gpiochip->can_sleep) {
  			chip_err(gpiochip,
  				 "you cannot have chained interrupts on a chip that may sleep\n");
  			return;
  		}
  		/*
  		 * The parent irqchip is already using the chip_data for this
  		 * irqchip, so our callbacks simply use the handler_data.
  		 */
  		irq_set_chained_handler_and_data(parent_irq, parent_handler,
  						 gpiochip);
  
  		gpiochip->irq.parent_irq = parent_irq;
  		gpiochip->irq.parents = &gpiochip->irq.parent_irq;
  		gpiochip->irq.num_parents = 1;
  	}
  }
  
  /**
   * gpiochip_set_chained_irqchip() - connects a chained irqchip to a gpiochip
   * @gpiochip: the gpiochip to set the irqchip chain to
   * @irqchip: the irqchip to chain to the gpiochip
   * @parent_irq: the irq number corresponding to the parent IRQ for this
   * chained irqchip
   * @parent_handler: the parent interrupt handler for the accumulated IRQ
   * coming out of the gpiochip.
   */
  void gpiochip_set_chained_irqchip(struct gpio_chip *gpiochip,
  				  struct irq_chip *irqchip,
  				  unsigned int parent_irq,
  				  irq_flow_handler_t parent_handler)
  {
  	if (gpiochip->irq.threaded) {
  		chip_err(gpiochip, "tried to chain a threaded gpiochip\n");
  		return;
  	}
  
  	gpiochip_set_cascaded_irqchip(gpiochip, parent_irq, parent_handler);
  }
  EXPORT_SYMBOL_GPL(gpiochip_set_chained_irqchip);
  
  /**
   * gpiochip_set_nested_irqchip() - connects a nested irqchip to a gpiochip
   * @gpiochip: the gpiochip to set the irqchip nested handler to
   * @irqchip: the irqchip to nest to the gpiochip
   * @parent_irq: the irq number corresponding to the parent IRQ for this
   * nested irqchip
   */
  void gpiochip_set_nested_irqchip(struct gpio_chip *gpiochip,
  				 struct irq_chip *irqchip,
  				 unsigned int parent_irq)
  {
  	gpiochip_set_cascaded_irqchip(gpiochip, parent_irq, NULL);
  }
  EXPORT_SYMBOL_GPL(gpiochip_set_nested_irqchip);
  
  /**
   * gpiochip_irq_map() - maps an IRQ into a GPIO irqchip
   * @d: the irqdomain used by this irqchip
   * @irq: the global irq number used by this GPIO irqchip irq
   * @hwirq: the local IRQ/GPIO line offset on this gpiochip
   *
   * This function will set up the mapping for a certain IRQ line on a
   * gpiochip by assigning the gpiochip as chip data, and using the irqchip
   * stored inside the gpiochip.
   */
  int gpiochip_irq_map(struct irq_domain *d, unsigned int irq,
  		     irq_hw_number_t hwirq)
  {
  	struct gpio_chip *chip = d->host_data;
  	int err = 0;
  
  	if (!gpiochip_irqchip_irq_valid(chip, hwirq))
  		return -ENXIO;
  
  	irq_set_chip_data(irq, chip);
  	/*
  	 * This lock class tells lockdep that GPIO irqs are in a different
  	 * category than their parents, so it won't report false recursion.
  	 */
  	irq_set_lockdep_class(irq, chip->irq.lock_key, chip->irq.request_key);
  	irq_set_chip_and_handler(irq, chip->irq.chip, chip->irq.handler);
  	/* Chips that use nested thread handlers have them marked */
  	if (chip->irq.threaded)
  		irq_set_nested_thread(irq, 1);
  	irq_set_noprobe(irq);
  
  	if (chip->irq.num_parents == 1)
  		err = irq_set_parent(irq, chip->irq.parents[0]);
  	else if (chip->irq.map)
  		err = irq_set_parent(irq, chip->irq.map[hwirq]);
  
  	if (err < 0)
  		return err;
  
  	/*
  	 * No set-up of the hardware will happen if IRQ_TYPE_NONE
  	 * is passed as default type.
  	 */
  	if (chip->irq.default_type != IRQ_TYPE_NONE)
  		irq_set_irq_type(irq, chip->irq.default_type);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(gpiochip_irq_map);
  
  void gpiochip_irq_unmap(struct irq_domain *d, unsigned int irq)
  {
  	struct gpio_chip *chip = d->host_data;
  
  	if (chip->irq.threaded)
  		irq_set_nested_thread(irq, 0);
  	irq_set_chip_and_handler(irq, NULL, NULL);
  	irq_set_chip_data(irq, NULL);
  }
  EXPORT_SYMBOL_GPL(gpiochip_irq_unmap);
  
  static const struct irq_domain_ops gpiochip_domain_ops = {
  	.map	= gpiochip_irq_map,
  	.unmap	= gpiochip_irq_unmap,
  	/* Virtually all GPIO irqchips are twocell:ed */
  	.xlate	= irq_domain_xlate_twocell,
  };
  
  static int gpiochip_to_irq(struct gpio_chip *chip, unsigned offset)
  {
  	if (!gpiochip_irqchip_irq_valid(chip, offset))
  		return -ENXIO;
  
  	return irq_create_mapping(chip->irq.domain, offset);
  }
  
  static int gpiochip_irq_reqres(struct irq_data *d)
  {
  	struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
  
  	return gpiochip_reqres_irq(chip, d->hwirq);
  }
  
  static void gpiochip_irq_relres(struct irq_data *d)
  {
  	struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
  
  	gpiochip_relres_irq(chip, d->hwirq);
  }
  
  static void gpiochip_irq_enable(struct irq_data *d)
  {
  	struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
  
  	gpiochip_enable_irq(chip, d->hwirq);
  	if (chip->irq.irq_enable)
  		chip->irq.irq_enable(d);
  	else
  		chip->irq.chip->irq_unmask(d);
  }
  
  static void gpiochip_irq_disable(struct irq_data *d)
  {
  	struct gpio_chip *chip = irq_data_get_irq_chip_data(d);
  
  	if (chip->irq.irq_disable)
  		chip->irq.irq_disable(d);
  	else
  		chip->irq.chip->irq_mask(d);
  	gpiochip_disable_irq(chip, d->hwirq);
  }
  
  static void gpiochip_set_irq_hooks(struct gpio_chip *gpiochip)
  {
  	struct irq_chip *irqchip = gpiochip->irq.chip;
  
  	if (!irqchip->irq_request_resources &&
  	    !irqchip->irq_release_resources) {
  		irqchip->irq_request_resources = gpiochip_irq_reqres;
  		irqchip->irq_release_resources = gpiochip_irq_relres;
  	}
  	if (WARN_ON(gpiochip->irq.irq_enable))
  		return;
  	/* Check if the irqchip already has this hook... */
  	if (irqchip->irq_enable == gpiochip_irq_enable) {
  		/*
  		 * ...and if so, give a gentle warning that this is bad
  		 * practice.
  		 */
  		chip_info(gpiochip,
  			  "detected irqchip that is shared with multiple gpiochips: please fix the driver.\n");
  		return;
  	}
  	gpiochip->irq.irq_enable = irqchip->irq_enable;
  	gpiochip->irq.irq_disable = irqchip->irq_disable;
  	irqchip->irq_enable = gpiochip_irq_enable;
  	irqchip->irq_disable = gpiochip_irq_disable;
  }
  
  /**
   * gpiochip_add_irqchip() - adds an IRQ chip to a GPIO chip
   * @gpiochip: the GPIO chip to add the IRQ chip to
   * @lock_key: lockdep class for IRQ lock
   * @request_key: lockdep class for IRQ request
   */
  static int gpiochip_add_irqchip(struct gpio_chip *gpiochip,
  				struct lock_class_key *lock_key,
  				struct lock_class_key *request_key)
  {
  	struct irq_chip *irqchip = gpiochip->irq.chip;
  	const struct irq_domain_ops *ops;
  	struct device_node *np;
  	unsigned int type;
  	unsigned int i;
  
  	if (!irqchip)
  		return 0;
  
  	if (gpiochip->irq.parent_handler && gpiochip->can_sleep) {
  		chip_err(gpiochip, "you cannot have chained interrupts on a chip that may sleep\n");
  		return -EINVAL;
  	}
  
  	np = gpiochip->gpiodev->dev.of_node;
  	type = gpiochip->irq.default_type;
  
  	/*
  	 * Specifying a default trigger is a terrible idea if DT or ACPI is
  	 * used to configure the interrupts, as you may end up with
  	 * conflicting triggers. Tell the user, and reset to NONE.
  	 */
  	if (WARN(np && type != IRQ_TYPE_NONE,
  		 "%s: Ignoring %u default trigger\n", np->full_name, type))
  		type = IRQ_TYPE_NONE;
  
  	if (has_acpi_companion(gpiochip->parent) && type != IRQ_TYPE_NONE) {
  		acpi_handle_warn(ACPI_HANDLE(gpiochip->parent),
  				 "Ignoring %u default trigger\n", type);
  		type = IRQ_TYPE_NONE;
  	}
  
  	gpiochip->to_irq = gpiochip_to_irq;
  	gpiochip->irq.default_type = type;
  	gpiochip->irq.lock_key = lock_key;
  	gpiochip->irq.request_key = request_key;
  
  	if (gpiochip->irq.domain_ops)
  		ops = gpiochip->irq.domain_ops;
  	else
  		ops = &gpiochip_domain_ops;
  
  	gpiochip->irq.domain = irq_domain_add_simple(np, gpiochip->ngpio,
  						     gpiochip->irq.first,
  						     ops, gpiochip);
  	if (!gpiochip->irq.domain)
  		return -EINVAL;
  
  	if (gpiochip->irq.parent_handler) {
  		void *data = gpiochip->irq.parent_handler_data ?: gpiochip;
  
  		for (i = 0; i < gpiochip->irq.num_parents; i++) {
  			/*
  			 * The parent IRQ chip is already using the chip_data
  			 * for this IRQ chip, so our callbacks simply use the
  			 * handler_data.
  			 */
  			irq_set_chained_handler_and_data(gpiochip->irq.parents[i],
  							 gpiochip->irq.parent_handler,
  							 data);
  		}
  	}
  
  	gpiochip_set_irq_hooks(gpiochip);
  
  	acpi_gpiochip_request_interrupts(gpiochip);
  
  	return 0;
  }
  
  /**
   * gpiochip_irqchip_remove() - removes an irqchip added to a gpiochip
   * @gpiochip: the gpiochip to remove the irqchip from
   *
   * This is called only from gpiochip_remove()
   */
  static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip)
  {
  	struct irq_chip *irqchip = gpiochip->irq.chip;
  	unsigned int offset;
  
  	acpi_gpiochip_free_interrupts(gpiochip);
  
  	if (irqchip && gpiochip->irq.parent_handler) {
  		struct gpio_irq_chip *irq = &gpiochip->irq;
  		unsigned int i;
  
  		for (i = 0; i < irq->num_parents; i++)
  			irq_set_chained_handler_and_data(irq->parents[i],
  							 NULL, NULL);
  	}
  
  	/* Remove all IRQ mappings and delete the domain */
  	if (gpiochip->irq.domain) {
  		unsigned int irq;
  
  		for (offset = 0; offset < gpiochip->ngpio; offset++) {
  			if (!gpiochip_irqchip_irq_valid(gpiochip, offset))
  				continue;
  
  			irq = irq_find_mapping(gpiochip->irq.domain, offset);
  			irq_dispose_mapping(irq);
  		}
  
  		irq_domain_remove(gpiochip->irq.domain);
  	}
  
  	if (irqchip) {
  		if (irqchip->irq_request_resources == gpiochip_irq_reqres) {
  			irqchip->irq_request_resources = NULL;
  			irqchip->irq_release_resources = NULL;
  		}
  		if (irqchip->irq_enable == gpiochip_irq_enable) {
  			irqchip->irq_enable = gpiochip->irq.irq_enable;
  			irqchip->irq_disable = gpiochip->irq.irq_disable;
  		}
  	}
  	gpiochip->irq.irq_enable = NULL;
  	gpiochip->irq.irq_disable = NULL;
  	gpiochip->irq.chip = NULL;
  
  	gpiochip_irqchip_free_valid_mask(gpiochip);
  }
  
  /**
   * gpiochip_irqchip_add_key() - adds an irqchip to a gpiochip
   * @gpiochip: the gpiochip to add the irqchip to
   * @irqchip: the irqchip to add to the gpiochip
   * @first_irq: if not dynamically assigned, the base (first) IRQ to
   * allocate gpiochip irqs from
   * @handler: the irq handler to use (often a predefined irq core function)
   * @type: the default type for IRQs on this irqchip, pass IRQ_TYPE_NONE
   * to have the core avoid setting up any default type in the hardware.
   * @threaded: whether this irqchip uses a nested thread handler
   * @lock_key: lockdep class for IRQ lock
   * @request_key: lockdep class for IRQ request
   *
   * This function closely associates a certain irqchip with a certain
   * gpiochip, providing an irq domain to translate the local IRQs to
   * global irqs in the gpiolib core, and making sure that the gpiochip
   * is passed as chip data to all related functions. Driver callbacks
   * need to use gpiochip_get_data() to get their local state containers back
   * from the gpiochip passed as chip data. An irqdomain will be stored
   * in the gpiochip that shall be used by the driver to handle IRQ number
   * translation. The gpiochip will need to be initialized and registered
   * before calling this function.
   *
   * This function will handle two cell:ed simple IRQs and assumes all
   * the pins on the gpiochip can generate a unique IRQ. Everything else
   * need to be open coded.
   */
  int gpiochip_irqchip_add_key(struct gpio_chip *gpiochip,
  			     struct irq_chip *irqchip,
  			     unsigned int first_irq,
  			     irq_flow_handler_t handler,
  			     unsigned int type,
  			     bool threaded,
  			     struct lock_class_key *lock_key,
  			     struct lock_class_key *request_key)
  {
  	struct device_node *of_node;
  
  	if (!gpiochip || !irqchip)
  		return -EINVAL;
  
  	if (!gpiochip->parent) {
  		pr_err("missing gpiochip .dev parent pointer\n");
  		return -EINVAL;
  	}
  	gpiochip->irq.threaded = threaded;
  	of_node = gpiochip->parent->of_node;
  #ifdef CONFIG_OF_GPIO
  	/*
  	 * If the gpiochip has an assigned OF node this takes precedence
  	 * FIXME: get rid of this and use gpiochip->parent->of_node
  	 * everywhere
  	 */
  	if (gpiochip->of_node)
  		of_node = gpiochip->of_node;
  #endif
  	/*
  	 * Specifying a default trigger is a terrible idea if DT or ACPI is
  	 * used to configure the interrupts, as you may end-up with
  	 * conflicting triggers. Tell the user, and reset to NONE.
  	 */
  	if (WARN(of_node && type != IRQ_TYPE_NONE,
  		 "%pOF: Ignoring %d default trigger\n", of_node, type))
  		type = IRQ_TYPE_NONE;
  	if (has_acpi_companion(gpiochip->parent) && type != IRQ_TYPE_NONE) {
  		acpi_handle_warn(ACPI_HANDLE(gpiochip->parent),
  				 "Ignoring %d default trigger\n", type);
  		type = IRQ_TYPE_NONE;
  	}
  
  	gpiochip->irq.chip = irqchip;
  	gpiochip->irq.handler = handler;
  	gpiochip->irq.default_type = type;
  	gpiochip->to_irq = gpiochip_to_irq;
  	gpiochip->irq.lock_key = lock_key;
  	gpiochip->irq.request_key = request_key;
  	gpiochip->irq.domain = irq_domain_add_simple(of_node,
  					gpiochip->ngpio, first_irq,
  					&gpiochip_domain_ops, gpiochip);
  	if (!gpiochip->irq.domain) {
  		gpiochip->irq.chip = NULL;
  		return -EINVAL;
  	}
  
  	gpiochip_set_irq_hooks(gpiochip);
  
  	acpi_gpiochip_request_interrupts(gpiochip);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(gpiochip_irqchip_add_key);
  
  #else /* CONFIG_GPIOLIB_IRQCHIP */
  
  static inline int gpiochip_add_irqchip(struct gpio_chip *gpiochip,
  				       struct lock_class_key *lock_key,
  				       struct lock_class_key *request_key)
  {
  	return 0;
  }
  
  static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip) {}
  static inline int gpiochip_irqchip_init_valid_mask(struct gpio_chip *gpiochip)
  {
  	return 0;
  }
  static inline void gpiochip_irqchip_free_valid_mask(struct gpio_chip *gpiochip)
  { }
  
  #endif /* CONFIG_GPIOLIB_IRQCHIP */
  
  /**
   * gpiochip_generic_request() - request the gpio function for a pin
   * @chip: the gpiochip owning the GPIO
   * @offset: the offset of the GPIO to request for GPIO function
   */
  int gpiochip_generic_request(struct gpio_chip *chip, unsigned offset)
  {
  	return pinctrl_gpio_request(chip->gpiodev->base + offset);
  }
  EXPORT_SYMBOL_GPL(gpiochip_generic_request);
  
  /**
   * gpiochip_generic_free() - free the gpio function from a pin
   * @chip: the gpiochip to request the gpio function for
   * @offset: the offset of the GPIO to free from GPIO function
   */
  void gpiochip_generic_free(struct gpio_chip *chip, unsigned offset)
  {
  	pinctrl_gpio_free(chip->gpiodev->base + offset);
  }
  EXPORT_SYMBOL_GPL(gpiochip_generic_free);
  
  /**
   * gpiochip_generic_config() - apply configuration for a pin
   * @chip: the gpiochip owning the GPIO
   * @offset: the offset of the GPIO to apply the configuration
   * @config: the configuration to be applied
   */
  int gpiochip_generic_config(struct gpio_chip *chip, unsigned offset,
  			    unsigned long config)
  {
  	return pinctrl_gpio_set_config(chip->gpiodev->base + offset, config);
  }
  EXPORT_SYMBOL_GPL(gpiochip_generic_config);
  
  #ifdef CONFIG_PINCTRL
  
  /**
   * gpiochip_add_pingroup_range() - add a range for GPIO <-> pin mapping
   * @chip: the gpiochip to add the range for
   * @pctldev: the pin controller to map to
   * @gpio_offset: the start offset in the current gpio_chip number space
   * @pin_group: name of the pin group inside the pin controller
   *
   * Calling this function directly from a DeviceTree-supported
   * pinctrl driver is DEPRECATED. Please see Section 2.1 of
   * Documentation/devicetree/bindings/gpio/gpio.txt on how to
   * bind pinctrl and gpio drivers via the "gpio-ranges" property.
   */
  int gpiochip_add_pingroup_range(struct gpio_chip *chip,
  			struct pinctrl_dev *pctldev,
  			unsigned int gpio_offset, const char *pin_group)
  {
  	struct gpio_pin_range *pin_range;
  	struct gpio_device *gdev = chip->gpiodev;
  	int ret;
  
  	pin_range = kzalloc(sizeof(*pin_range), GFP_KERNEL);
  	if (!pin_range) {
  		chip_err(chip, "failed to allocate pin ranges\n");
  		return -ENOMEM;
  	}
  
  	/* Use local offset as range ID */
  	pin_range->range.id = gpio_offset;
  	pin_range->range.gc = chip;
  	pin_range->range.name = chip->label;
  	pin_range->range.base = gdev->base + gpio_offset;
  	pin_range->pctldev = pctldev;
  
  	ret = pinctrl_get_group_pins(pctldev, pin_group,
  					&pin_range->range.pins,
  					&pin_range->range.npins);
  	if (ret < 0) {
  		kfree(pin_range);
  		return ret;
  	}
  
  	pinctrl_add_gpio_range(pctldev, &pin_range->range);
  
  	chip_dbg(chip, "created GPIO range %d->%d ==> %s PINGRP %s\n",
  		 gpio_offset, gpio_offset + pin_range->range.npins - 1,
  		 pinctrl_dev_get_devname(pctldev), pin_group);
  
  	list_add_tail(&pin_range->node, &gdev->pin_ranges);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(gpiochip_add_pingroup_range);
  
  /**
   * gpiochip_add_pin_range() - add a range for GPIO <-> pin mapping
   * @chip: the gpiochip to add the range for
   * @pinctl_name: the dev_name() of the pin controller to map to
   * @gpio_offset: the start offset in the current gpio_chip number space
   * @pin_offset: the start offset in the pin controller number space
   * @npins: the number of pins from the offset of each pin space (GPIO and
   *	pin controller) to accumulate in this range
   *
   * Returns:
   * 0 on success, or a negative error-code on failure.
   *
   * Calling this function directly from a DeviceTree-supported
   * pinctrl driver is DEPRECATED. Please see Section 2.1 of
   * Documentation/devicetree/bindings/gpio/gpio.txt on how to
   * bind pinctrl and gpio drivers via the "gpio-ranges" property.
   */
  int gpiochip_add_pin_range(struct gpio_chip *chip, const char *pinctl_name,
  			   unsigned int gpio_offset, unsigned int pin_offset,
  			   unsigned int npins)
  {
  	struct gpio_pin_range *pin_range;
  	struct gpio_device *gdev = chip->gpiodev;
  	int ret;
  
  	pin_range = kzalloc(sizeof(*pin_range), GFP_KERNEL);
  	if (!pin_range) {
  		chip_err(chip, "failed to allocate pin ranges\n");
  		return -ENOMEM;
  	}
  
  	/* Use local offset as range ID */
  	pin_range->range.id = gpio_offset;
  	pin_range->range.gc = chip;
  	pin_range->range.name = chip->label;
  	pin_range->range.base = gdev->base + gpio_offset;
  	pin_range->range.pin_base = pin_offset;
  	pin_range->range.npins = npins;
  	pin_range->pctldev = pinctrl_find_and_add_gpio_range(pinctl_name,
  			&pin_range->range);
  	if (IS_ERR(pin_range->pctldev)) {
  		ret = PTR_ERR(pin_range->pctldev);
  		chip_err(chip, "could not create pin range\n");
  		kfree(pin_range);
  		return ret;
  	}
  	chip_dbg(chip, "created GPIO range %d->%d ==> %s PIN %d->%d\n",
  		 gpio_offset, gpio_offset + npins - 1,
  		 pinctl_name,
  		 pin_offset, pin_offset + npins - 1);
  
  	list_add_tail(&pin_range->node, &gdev->pin_ranges);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(gpiochip_add_pin_range);
  
  /**
   * gpiochip_remove_pin_ranges() - remove all the GPIO <-> pin mappings
   * @chip: the chip to remove all the mappings for
   */
  void gpiochip_remove_pin_ranges(struct gpio_chip *chip)
  {
  	struct gpio_pin_range *pin_range, *tmp;
  	struct gpio_device *gdev = chip->gpiodev;
  
  	list_for_each_entry_safe(pin_range, tmp, &gdev->pin_ranges, node) {
  		list_del(&pin_range->node);
  		pinctrl_remove_gpio_range(pin_range->pctldev,
  				&pin_range->range);
  		kfree(pin_range);
  	}
  }
  EXPORT_SYMBOL_GPL(gpiochip_remove_pin_ranges);
  
  #endif /* CONFIG_PINCTRL */
  
  /* These "optional" allocation calls help prevent drivers from stomping
   * on each other, and help provide better diagnostics in debugfs.
   * They're called even less than the "set direction" calls.
   */
  static int gpiod_request_commit(struct gpio_desc *desc, const char *label)
  {
  	struct gpio_chip	*chip = desc->gdev->chip;
  	int			status;
  	unsigned long		flags;
  	unsigned		offset;
  
  	if (label) {
  		label = kstrdup_const(label, GFP_KERNEL);
  		if (!label)
  			return -ENOMEM;
  	}
  
  	spin_lock_irqsave(&gpio_lock, flags);
  
  	/* NOTE:  gpio_request() can be called in early boot,
  	 * before IRQs are enabled, for non-sleeping (SOC) GPIOs.
  	 */
  
  	if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
  		desc_set_label(desc, label ? : "?");
  		status = 0;
  	} else {
  		kfree_const(label);
  		status = -EBUSY;
  		goto done;
  	}
  
  	if (chip->request) {
  		/* chip->request may sleep */
  		spin_unlock_irqrestore(&gpio_lock, flags);
  		offset = gpio_chip_hwgpio(desc);
  		if (gpiochip_line_is_valid(chip, offset))
  			status = chip->request(chip, offset);
  		else
  			status = -EINVAL;
  		spin_lock_irqsave(&gpio_lock, flags);
  
  		if (status < 0) {
  			desc_set_label(desc, NULL);
  			kfree_const(label);
  			clear_bit(FLAG_REQUESTED, &desc->flags);
  			goto done;
  		}
  	}
  	if (chip->get_direction) {
  		/* chip->get_direction may sleep */
  		spin_unlock_irqrestore(&gpio_lock, flags);
  		gpiod_get_direction(desc);
  		spin_lock_irqsave(&gpio_lock, flags);
  	}
  done:
  	spin_unlock_irqrestore(&gpio_lock, flags);
  	return status;
  }
  
  /*
   * This descriptor validation needs to be inserted verbatim into each
   * function taking a descriptor, so we need to use a preprocessor
   * macro to avoid endless duplication. If the desc is NULL it is an
   * optional GPIO and calls should just bail out.
   */
  static int validate_desc(const struct gpio_desc *desc, const char *func)
  {
  	if (!desc)
  		return 0;
  	if (IS_ERR(desc)) {
  		pr_warn("%s: invalid GPIO (errorpointer)\n", func);
  		return PTR_ERR(desc);
  	}
  	if (!desc->gdev) {
  		pr_warn("%s: invalid GPIO (no device)\n", func);
  		return -EINVAL;
  	}
  	if (!desc->gdev->chip) {
  		dev_warn(&desc->gdev->dev,
  			 "%s: backing chip is gone\n", func);
  		return 0;
  	}
  	return 1;
  }
  
  #define VALIDATE_DESC(desc) do { \
  	int __valid = validate_desc(desc, __func__); \
  	if (__valid <= 0) \
  		return __valid; \
  	} while (0)
  
  #define VALIDATE_DESC_VOID(desc) do { \
  	int __valid = validate_desc(desc, __func__); \
  	if (__valid <= 0) \
  		return; \
  	} while (0)
  
  int gpiod_request(struct gpio_desc *desc, const char *label)
  {
  	int status = -EPROBE_DEFER;
  	struct gpio_device *gdev;
  
  	VALIDATE_DESC(desc);
  	gdev = desc->gdev;
  
  	if (try_module_get(gdev->owner)) {
  		status = gpiod_request_commit(desc, label);
  		if (status < 0)
  			module_put(gdev->owner);
  		else
  			get_device(&gdev->dev);
  	}
  
  	if (status)
  		gpiod_dbg(desc, "%s: status %d\n", __func__, status);
  
  	return status;
  }
  
  static bool gpiod_free_commit(struct gpio_desc *desc)
  {
  	bool			ret = false;
  	unsigned long		flags;
  	struct gpio_chip	*chip;
  
  	might_sleep();
  
  	gpiod_unexport(desc);
  
  	spin_lock_irqsave(&gpio_lock, flags);
  
  	chip = desc->gdev->chip;
  	if (chip && test_bit(FLAG_REQUESTED, &desc->flags)) {
  		if (chip->free) {
  			spin_unlock_irqrestore(&gpio_lock, flags);
  			might_sleep_if(chip->can_sleep);
  			chip->free(chip, gpio_chip_hwgpio(desc));
  			spin_lock_irqsave(&gpio_lock, flags);
  		}
  		kfree_const(desc->label);
  		desc_set_label(desc, NULL);
  		clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
  		clear_bit(FLAG_REQUESTED, &desc->flags);
  		clear_bit(FLAG_OPEN_DRAIN, &desc->flags);
  		clear_bit(FLAG_OPEN_SOURCE, &desc->flags);
  		clear_bit(FLAG_IS_HOGGED, &desc->flags);
  		ret = true;
  	}
  
  	spin_unlock_irqrestore(&gpio_lock, flags);
  	return ret;
  }
  
  void gpiod_free(struct gpio_desc *desc)
  {
  	if (desc && desc->gdev && gpiod_free_commit(desc)) {
  		module_put(desc->gdev->owner);
  		put_device(&desc->gdev->dev);
  	} else {
  		WARN_ON(extra_checks);
  	}
  }
  
  /**
   * gpiochip_is_requested - return string iff signal was requested
   * @chip: controller managing the signal
   * @offset: of signal within controller's 0..(ngpio - 1) range
   *
   * Returns NULL if the GPIO is not currently requested, else a string.
   * The string returned is the label passed to gpio_request(); if none has been
   * passed it is a meaningless, non-NULL constant.
   *
   * This function is for use by GPIO controller drivers.  The label can
   * help with diagnostics, and knowing that the signal is used as a GPIO
   * can help avoid accidentally multiplexing it to another controller.
   */
  const char *gpiochip_is_requested(struct gpio_chip *chip, unsigned offset)
  {
  	struct gpio_desc *desc;
  
  	if (offset >= chip->ngpio)
  		return NULL;
  
  	desc = &chip->gpiodev->descs[offset];
  
  	if (test_bit(FLAG_REQUESTED, &desc->flags) == 0)
  		return NULL;
  	return desc->label;
  }
  EXPORT_SYMBOL_GPL(gpiochip_is_requested);
  
  /**
   * gpiochip_request_own_desc - Allow GPIO chip to request its own descriptor
   * @chip: GPIO chip
   * @hwnum: hardware number of the GPIO for which to request the descriptor
   * @label: label for the GPIO
   * @flags: flags for this GPIO or 0 if default
   *
   * Function allows GPIO chip drivers to request and use their own GPIO
   * descriptors via gpiolib API. Difference to gpiod_request() is that this
   * function will not increase reference count of the GPIO chip module. This
   * allows the GPIO chip module to be unloaded as needed (we assume that the
   * GPIO chip driver handles freeing the GPIOs it has requested).
   *
   * Returns:
   * A pointer to the GPIO descriptor, or an ERR_PTR()-encoded negative error
   * code on failure.
   */
  struct gpio_desc *gpiochip_request_own_desc(struct gpio_chip *chip, u16 hwnum,
  					    const char *label,
  					    enum gpiod_flags flags)
  {
  	struct gpio_desc *desc = gpiochip_get_desc(chip, hwnum);
  	int err;
  
  	if (IS_ERR(desc)) {
  		chip_err(chip, "failed to get GPIO descriptor\n");
  		return desc;
  	}
  
  	err = gpiod_request_commit(desc, label);
  	if (err < 0)
  		return ERR_PTR(err);
  
  	err = gpiod_configure_flags(desc, label, 0, flags);
  	if (err) {
  		chip_err(chip, "setup of own GPIO %s failed\n", label);
  		gpiod_free_commit(desc);
  		return ERR_PTR(err);
  	}
  
  	return desc;
  }
  EXPORT_SYMBOL_GPL(gpiochip_request_own_desc);
  
  /**
   * gpiochip_free_own_desc - Free GPIO requested by the chip driver
   * @desc: GPIO descriptor to free
   *
   * Function frees the given GPIO requested previously with
   * gpiochip_request_own_desc().
   */
  void gpiochip_free_own_desc(struct gpio_desc *desc)
  {
  	if (desc)
  		gpiod_free_commit(desc);
  }
  EXPORT_SYMBOL_GPL(gpiochip_free_own_desc);
  
  /*
   * Drivers MUST set GPIO direction before making get/set calls.  In
   * some cases this is done in early boot, before IRQs are enabled.
   *
   * As a rule these aren't called more than once (except for drivers
   * using the open-drain emulation idiom) so these are natural places
   * to accumulate extra debugging checks.  Note that we can't (yet)
   * rely on gpio_request() having been called beforehand.
   */
  
  /**
   * gpiod_direction_input - set the GPIO direction to input
   * @desc:	GPIO to set to input
   *
   * Set the direction of the passed GPIO to input, such as gpiod_get_value() can
   * be called safely on it.
   *
   * Return 0 in case of success, else an error code.
   */
  int gpiod_direction_input(struct gpio_desc *desc)
  {
  	struct gpio_chip	*chip;
  	int			status = 0;
  
  	VALIDATE_DESC(desc);
  	chip = desc->gdev->chip;
  
  	/*
  	 * It is legal to have no .get() and .direction_input() specified if
  	 * the chip is output-only, but you can't specify .direction_input()
  	 * and not support the .get() operation, that doesn't make sense.
  	 */
  	if (!chip->get && chip->direction_input) {
  		gpiod_warn(desc,
  			   "%s: missing get() but have direction_input()\n",
  			   __func__);
  		return -EIO;
  	}
  
  	/*
  	 * If we have a .direction_input() callback, things are simple,
  	 * just call it. Else we are some input-only chip so try to check the
  	 * direction (if .get_direction() is supported) else we silently
  	 * assume we are in input mode after this.
  	 */
  	if (chip->direction_input) {
  		status = chip->direction_input(chip, gpio_chip_hwgpio(desc));
  	} else if (chip->get_direction &&
  		  (chip->get_direction(chip, gpio_chip_hwgpio(desc)) != 1)) {
  		gpiod_warn(desc,
  			   "%s: missing direction_input() operation and line is output\n",
  			   __func__);
  		return -EIO;
  	}
  	if (status == 0)
  		clear_bit(FLAG_IS_OUT, &desc->flags);
  
  	trace_gpio_direction(desc_to_gpio(desc), 1, status);
  
  	return status;
  }
  EXPORT_SYMBOL_GPL(gpiod_direction_input);
  
  static int gpio_set_drive_single_ended(struct gpio_chip *gc, unsigned offset,
  				       enum pin_config_param mode)
  {
  	unsigned long config = { PIN_CONF_PACKED(mode, 0) };
  
  	return gc->set_config ? gc->set_config(gc, offset, config) : -ENOTSUPP;
  }
  
  static int gpiod_direction_output_raw_commit(struct gpio_desc *desc, int value)
  {
  	struct gpio_chip *gc = desc->gdev->chip;
  	int val = !!value;
  	int ret = 0;
  
  	/*
  	 * It's OK not to specify .direction_output() if the gpiochip is
  	 * output-only, but if there is then not even a .set() operation it
  	 * is pretty tricky to drive the output line.
  	 */
  	if (!gc->set && !gc->direction_output) {
  		gpiod_warn(desc,
  			   "%s: missing set() and direction_output() operations\n",
  			   __func__);
  		return -EIO;
  	}
  
  	if (gc->direction_output) {
  		ret = gc->direction_output(gc, gpio_chip_hwgpio(desc), val);
  	} else {
  		/* Check that we are in output mode if we can */
  		if (gc->get_direction &&
  		    gc->get_direction(gc, gpio_chip_hwgpio(desc))) {
  			gpiod_warn(desc,
  				"%s: missing direction_output() operation\n",
  				__func__);
  			return -EIO;
  		}
  		/*
  		 * If we can't actively set the direction, we are some
  		 * output-only chip, so just drive the output as desired.
  		 */
  		gc->set(gc, gpio_chip_hwgpio(desc), val);
  	}
  
  	if (!ret)
  		set_bit(FLAG_IS_OUT, &desc->flags);
  	trace_gpio_value(desc_to_gpio(desc), 0, val);
  	trace_gpio_direction(desc_to_gpio(desc), 0, ret);
  	return ret;
  }
  
  /**
   * gpiod_direction_output_raw - set the GPIO direction to output
   * @desc:	GPIO to set to output
   * @value:	initial output value of the GPIO
   *
   * Set the direction of the passed GPIO to output, such as gpiod_set_value() can
   * be called safely on it. The initial value of the output must be specified
   * as raw value on the physical line without regard for the ACTIVE_LOW status.
   *
   * Return 0 in case of success, else an error code.
   */
  int gpiod_direction_output_raw(struct gpio_desc *desc, int value)
  {
  	VALIDATE_DESC(desc);
  	return gpiod_direction_output_raw_commit(desc, value);
  }
  EXPORT_SYMBOL_GPL(gpiod_direction_output_raw);
  
  /**
   * gpiod_direction_output - set the GPIO direction to output
   * @desc:	GPIO to set to output
   * @value:	initial output value of the GPIO
   *
   * Set the direction of the passed GPIO to output, such as gpiod_set_value() can
   * be called safely on it. The initial value of the output must be specified
   * as the logical value of the GPIO, i.e. taking its ACTIVE_LOW status into
   * account.
   *
   * Return 0 in case of success, else an error code.
   */
  int gpiod_direction_output(struct gpio_desc *desc, int value)
  {
  	struct gpio_chip *gc;
  	int ret;
  
  	VALIDATE_DESC(desc);
  	if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
  		value = !value;
  	else
  		value = !!value;
  
  	/* GPIOs used for enabled IRQs shall not be set as output */
  	if (test_bit(FLAG_USED_AS_IRQ, &desc->flags) &&
  	    test_bit(FLAG_IRQ_IS_ENABLED, &desc->flags)) {
  		gpiod_err(desc,
  			  "%s: tried to set a GPIO tied to an IRQ as output\n",
  			  __func__);
  		return -EIO;
  	}
  
  	gc = desc->gdev->chip;
  	if (test_bit(FLAG_OPEN_DRAIN, &desc->flags)) {
  		/* First see if we can enable open drain in hardware */
  		ret = gpio_set_drive_single_ended(gc, gpio_chip_hwgpio(desc),
  						  PIN_CONFIG_DRIVE_OPEN_DRAIN);
  		if (!ret)
  			goto set_output_value;
  		/* Emulate open drain by not actively driving the line high */
  		if (value)
  			return gpiod_direction_input(desc);
  	}
  	else if (test_bit(FLAG_OPEN_SOURCE, &desc->flags)) {
  		ret = gpio_set_drive_single_ended(gc, gpio_chip_hwgpio(desc),
  						  PIN_CONFIG_DRIVE_OPEN_SOURCE);
  		if (!ret)
  			goto set_output_value;
  		/* Emulate open source by not actively driving the line low */
  		if (!value)
  			return gpiod_direction_input(desc);
  	} else {
  		gpio_set_drive_single_ended(gc, gpio_chip_hwgpio(desc),
  					    PIN_CONFIG_DRIVE_PUSH_PULL);
  	}
  
  set_output_value:
  	return gpiod_direction_output_raw_commit(desc, value);
  }
  EXPORT_SYMBOL_GPL(gpiod_direction_output);
  
  /**
   * gpiod_set_debounce - sets @debounce time for a GPIO
   * @desc: descriptor of the GPIO for which to set debounce time
   * @debounce: debounce time in microseconds
   *
   * Returns:
   * 0 on success, %-ENOTSUPP if the controller doesn't support setting the
   * debounce time.
   */
  int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce)
  {
  	struct gpio_chip	*chip;
  	unsigned long		config;
  
  	VALIDATE_DESC(desc);
  	chip = desc->gdev->chip;
  	if (!chip->set || !chip->set_config) {
  		gpiod_dbg(desc,
  			  "%s: missing set() or set_config() operations\n",
  			  __func__);
  		return -ENOTSUPP;
  	}
  
  	config = pinconf_to_config_packed(PIN_CONFIG_INPUT_DEBOUNCE, debounce);
  	return chip->set_config(chip, gpio_chip_hwgpio(desc), config);
  }
  EXPORT_SYMBOL_GPL(gpiod_set_debounce);
  
  /**
   * gpiod_set_transitory - Lose or retain GPIO state on suspend or reset
   * @desc: descriptor of the GPIO for which to configure persistence
   * @transitory: True to lose state on suspend or reset, false for persistence
   *
   * Returns:
   * 0 on success, otherwise a negative error code.
   */
  int gpiod_set_transitory(struct gpio_desc *desc, bool transitory)
  {
  	struct gpio_chip *chip;
  	unsigned long packed;
  	int gpio;
  	int rc;
  
  	VALIDATE_DESC(desc);
  	/*
  	 * Handle FLAG_TRANSITORY first, enabling queries to gpiolib for
  	 * persistence state.
  	 */
  	if (transitory)
  		set_bit(FLAG_TRANSITORY, &desc->flags);
  	else
  		clear_bit(FLAG_TRANSITORY, &desc->flags);
  
  	/* If the driver supports it, set the persistence state now */
  	chip = desc->gdev->chip;
  	if (!chip->set_config)
  		return 0;
  
  	packed = pinconf_to_config_packed(PIN_CONFIG_PERSIST_STATE,
  					  !transitory);
  	gpio = gpio_chip_hwgpio(desc);
  	rc = chip->set_config(chip, gpio, packed);
  	if (rc == -ENOTSUPP) {
  		dev_dbg(&desc->gdev->dev, "Persistence not supported for GPIO %d\n",
  				gpio);
  		return 0;
  	}
  
  	return rc;
  }
  EXPORT_SYMBOL_GPL(gpiod_set_transitory);
  
  /**
   * gpiod_is_active_low - test whether a GPIO is active-low or not
   * @desc: the gpio descriptor to test
   *
   * Returns 1 if the GPIO is active-low, 0 otherwise.
   */
  int gpiod_is_active_low(const struct gpio_desc *desc)
  {
  	VALIDATE_DESC(desc);
  	return test_bit(FLAG_ACTIVE_LOW, &desc->flags);
  }
  EXPORT_SYMBOL_GPL(gpiod_is_active_low);
  
  /* I/O calls are only valid after configuration completed; the relevant
   * "is this a valid GPIO" error checks should already have been done.
   *
   * "Get" operations are often inlinable as reading a pin value register,
   * and masking the relevant bit in that register.
   *
   * When "set" operations are inlinable, they involve writing that mask to
   * one register to set a low value, or a different register to set it high.
   * Otherwise locking is needed, so there may be little value to inlining.
   *
   *------------------------------------------------------------------------
   *
   * IMPORTANT!!!  The hot paths -- get/set value -- assume that callers
   * have requested the GPIO.  That can include implicit requesting by
   * a direction setting call.  Marking a gpio as requested locks its chip
   * in memory, guaranteeing that these table lookups need no more locking
   * and that gpiochip_remove() will fail.
   *
   * REVISIT when debugging, consider adding some instrumentation to ensure
   * that the GPIO was actually requested.
   */
  
  static int gpiod_get_raw_value_commit(const struct gpio_desc *desc)
  {
  	struct gpio_chip	*chip;
  	int offset;
  	int value;
  
  	chip = desc->gdev->chip;
  	offset = gpio_chip_hwgpio(desc);
  	value = chip->get ? chip->get(chip, offset) : -EIO;
  	value = value < 0 ? value : !!value;
  	trace_gpio_value(desc_to_gpio(desc), 1, value);
  	return value;
  }
  
  static int gpio_chip_get_multiple(struct gpio_chip *chip,
  				  unsigned long *mask, unsigned long *bits)
  {
  	if (chip->get_multiple) {
  		return chip->get_multiple(chip, mask, bits);
  	} else if (chip->get) {
  		int i, value;
  
  		for_each_set_bit(i, mask, chip->ngpio) {
  			value = chip->get(chip, i);
  			if (value < 0)
  				return value;
  			__assign_bit(i, bits, value);
  		}
  		return 0;
  	}
  	return -EIO;
  }
  
  int gpiod_get_array_value_complex(bool raw, bool can_sleep,
  				  unsigned int array_size,
  				  struct gpio_desc **desc_array,
  				  struct gpio_array *array_info,
  				  unsigned long *value_bitmap)
  {
  	int err, i = 0;
  
  	/*
  	 * Validate array_info against desc_array and its size.
  	 * It should immediately follow desc_array if both
  	 * have been obtained from the same gpiod_get_array() call.
  	 */
  	if (array_info && array_info->desc == desc_array &&
  	    array_size <= array_info->size &&
  	    (void *)array_info == desc_array + array_info->size) {
  		if (!can_sleep)
  			WARN_ON(array_info->chip->can_sleep);
  
  		err = gpio_chip_get_multiple(array_info->chip,
  					     array_info->get_mask,
  					     value_bitmap);
  		if (err)
  			return err;
  
  		if (!raw && !bitmap_empty(array_info->invert_mask, array_size))
  			bitmap_xor(value_bitmap, value_bitmap,
  				   array_info->invert_mask, array_size);
  
  		if (bitmap_full(array_info->get_mask, array_size))
  			return 0;
  
  		i = find_first_zero_bit(array_info->get_mask, array_size);
  	} else {
  		array_info = NULL;
  	}
  
  	while (i < array_size) {
  		struct gpio_chip *chip = desc_array[i]->gdev->chip;
  		unsigned long fastpath[2 * BITS_TO_LONGS(FASTPATH_NGPIO)];
  		unsigned long *mask, *bits;
  		int first, j, ret;
  
  		if (likely(chip->ngpio <= FASTPATH_NGPIO)) {
  			mask = fastpath;
  		} else {
  			mask = kmalloc_array(2 * BITS_TO_LONGS(chip->ngpio),
  					   sizeof(*mask),
  					   can_sleep ? GFP_KERNEL : GFP_ATOMIC);
  			if (!mask)
  				return -ENOMEM;
  		}
  
  		bits = mask + BITS_TO_LONGS(chip->ngpio);
  		bitmap_zero(mask, chip->ngpio);
  
  		if (!can_sleep)
  			WARN_ON(chip->can_sleep);
  
  		/* collect all inputs belonging to the same chip */
  		first = i;
  		do {
  			const struct gpio_desc *desc = desc_array[i];
  			int hwgpio = gpio_chip_hwgpio(desc);
  
  			__set_bit(hwgpio, mask);
  			i++;
  
  			if (array_info)
  				i = find_next_zero_bit(array_info->get_mask,
  						       array_size, i);
  		} while ((i < array_size) &&
  			 (desc_array[i]->gdev->chip == chip));
  
  		ret = gpio_chip_get_multiple(chip, mask, bits);
  		if (ret) {
  			if (mask != fastpath)
  				kfree(mask);
  			return ret;
  		}
  
  		for (j = first; j < i; ) {
  			const struct gpio_desc *desc = desc_array[j];
  			int hwgpio = gpio_chip_hwgpio(desc);
  			int value = test_bit(hwgpio, bits);
  
  			if (!raw && test_bit(FLAG_ACTIVE_LOW, &desc->flags))
  				value = !value;
  			__assign_bit(j, value_bitmap, value);
  			trace_gpio_value(desc_to_gpio(desc), 1, value);
  			j++;
  
  			if (array_info)
  				j = find_next_zero_bit(array_info->get_mask, i,
  						       j);
  		}
  
  		if (mask != fastpath)
  			kfree(mask);
  	}
  	return 0;
  }
  
  /**
   * gpiod_get_raw_value() - return a gpio's raw value
   * @desc: gpio whose value will be returned
   *
   * Return the GPIO's raw value, i.e. the value of the physical line disregarding
   * its ACTIVE_LOW status, or negative errno on failure.
   *
   * This function should be called from contexts where we cannot sleep, and will
   * complain if the GPIO chip functions potentially sleep.
   */
  int gpiod_get_raw_value(const struct gpio_desc *desc)
  {
  	VALIDATE_DESC(desc);
  	/* Should be using gpio_get_value_cansleep() */
  	WARN_ON(desc->gdev->chip->can_sleep);
  	return gpiod_get_raw_value_commit(desc);
  }
  EXPORT_SYMBOL_GPL(gpiod_get_raw_value);
  
  /**
   * gpiod_get_value() - return a gpio's value
   * @desc: gpio whose value will be returned
   *
   * Return the GPIO's logical value, i.e. taking the ACTIVE_LOW status into
   * account, or negative errno on failure.
   *
   * This function should be called from contexts where we cannot sleep, and will
   * complain if the GPIO chip functions potentially sleep.
   */
  int gpiod_get_value(const struct gpio_desc *desc)
  {
  	int value;
  
  	VALIDATE_DESC(desc);
  	/* Should be using gpio_get_value_cansleep() */
  	WARN_ON(desc->gdev->chip->can_sleep);
  
  	value = gpiod_get_raw_value_commit(desc);
  	if (value < 0)
  		return value;
  
  	if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
  		value = !value;
  
  	return value;
  }
  EXPORT_SYMBOL_GPL(gpiod_get_value);
  
  /**
   * gpiod_get_raw_array_value() - read raw values from an array of GPIOs
   * @array_size: number of elements in the descriptor array / value bitmap
   * @desc_array: array of GPIO descriptors whose values will be read
   * @array_info: information on applicability of fast bitmap processing path
   * @value_bitmap: bitmap to store the read values
   *
   * Read the raw values of the GPIOs, i.e. the values of the physical lines
   * without regard for their ACTIVE_LOW status.  Return 0 in case of success,
   * else an error code.
   *
   * This function should be called from contexts where we cannot sleep,
   * and it will complain if the GPIO chip functions potentially sleep.
   */
  int gpiod_get_raw_array_value(unsigned int array_size,
  			      struct gpio_desc **desc_array,
  			      struct gpio_array *array_info,
  			      unsigned long *value_bitmap)
  {
  	if (!desc_array)
  		return -EINVAL;
  	return gpiod_get_array_value_complex(true, false, array_size,
  					     desc_array, array_info,
  					     value_bitmap);
  }
  EXPORT_SYMBOL_GPL(gpiod_get_raw_array_value);
  
  /**
   * gpiod_get_array_value() - read values from an array of GPIOs
   * @array_size: number of elements in the descriptor array / value bitmap
   * @desc_array: array of GPIO descriptors whose values will be read
   * @array_info: information on applicability of fast bitmap processing path
   * @value_bitmap: bitmap to store the read values
   *
   * Read the logical values of the GPIOs, i.e. taking their ACTIVE_LOW status
   * into account.  Return 0 in case of success, else an error code.
   *
   * This function should be called from contexts where we cannot sleep,
   * and it will complain if the GPIO chip functions potentially sleep.
   */
  int gpiod_get_array_value(unsigned int array_size,
  			  struct gpio_desc **desc_array,
  			  struct gpio_array *array_info,
  			  unsigned long *value_bitmap)
  {
  	if (!desc_array)
  		return -EINVAL;
  	return gpiod_get_array_value_complex(false, false, array_size,
  					     desc_array, array_info,
  					     value_bitmap);
  }
  EXPORT_SYMBOL_GPL(gpiod_get_array_value);
  
  /*
   *  gpio_set_open_drain_value_commit() - Set the open drain gpio's value.
   * @desc: gpio descriptor whose state need to be set.
   * @value: Non-zero for setting it HIGH otherwise it will set to LOW.
   */
  static void gpio_set_open_drain_value_commit(struct gpio_desc *desc, bool value)
  {
  	int err = 0;
  	struct gpio_chip *chip = desc->gdev->chip;
  	int offset = gpio_chip_hwgpio(desc);
  
  	if (value) {
  		err = chip->direction_input(chip, offset);
  		if (!err)
  			clear_bit(FLAG_IS_OUT, &desc->flags);
  	} else {
  		err = chip->direction_output(chip, offset, 0);
  		if (!err)
  			set_bit(FLAG_IS_OUT, &desc->flags);
  	}
  	trace_gpio_direction(desc_to_gpio(desc), value, err);
  	if (err < 0)
  		gpiod_err(desc,
  			  "%s: Error in set_value for open drain err %d\n",
  			  __func__, err);
  }
  
  /*
   *  _gpio_set_open_source_value() - Set the open source gpio's value.
   * @desc: gpio descriptor whose state need to be set.
   * @value: Non-zero for setting it HIGH otherwise it will set to LOW.
   */
  static void gpio_set_open_source_value_commit(struct gpio_desc *desc, bool value)
  {
  	int err = 0;
  	struct gpio_chip *chip = desc->gdev->chip;
  	int offset = gpio_chip_hwgpio(desc);
  
  	if (value) {
  		err = chip->direction_output(chip, offset, 1);
  		if (!err)
  			set_bit(FLAG_IS_OUT, &desc->flags);
  	} else {
  		err = chip->direction_input(chip, offset);
  		if (!err)
  			clear_bit(FLAG_IS_OUT, &desc->flags);
  	}
  	trace_gpio_direction(desc_to_gpio(desc), !value, err);
  	if (err < 0)
  		gpiod_err(desc,
  			  "%s: Error in set_value for open source err %d\n",
  			  __func__, err);
  }
  
  static void gpiod_set_raw_value_commit(struct gpio_desc *desc, bool value)
  {
  	struct gpio_chip	*chip;
  
  	chip = desc->gdev->chip;
  	trace_gpio_value(desc_to_gpio(desc), 0, value);
  	chip->set(chip, gpio_chip_hwgpio(desc), value);
  }
  
  /*
   * set multiple outputs on the same chip;
   * use the chip's set_multiple function if available;
   * otherwise set the outputs sequentially;
   * @mask: bit mask array; one bit per output; BITS_PER_LONG bits per word
   *        defines which outputs are to be changed
   * @bits: bit value array; one bit per output; BITS_PER_LONG bits per word
   *        defines the values the outputs specified by mask are to be set to
   */
  static void gpio_chip_set_multiple(struct gpio_chip *chip,
  				   unsigned long *mask, unsigned long *bits)
  {
  	if (chip->set_multiple) {
  		chip->set_multiple(chip, mask, bits);
  	} else {
  		unsigned int i;
  
  		/* set outputs if the corresponding mask bit is set */
  		for_each_set_bit(i, mask, chip->ngpio)
  			chip->set(chip, i, test_bit(i, bits));
  	}
  }
  
  int gpiod_set_array_value_complex(bool raw, bool can_sleep,
  				  unsigned int array_size,
  				  struct gpio_desc **desc_array,
  				  struct gpio_array *array_info,
  				  unsigned long *value_bitmap)
  {
  	int i = 0;
  
  	/*
  	 * Validate array_info against desc_array and its size.
  	 * It should immediately follow desc_array if both
  	 * have been obtained from the same gpiod_get_array() call.
  	 */
  	if (array_info && array_info->desc == desc_array &&
  	    array_size <= array_info->size &&
  	    (void *)array_info == desc_array + array_info->size) {
  		if (!can_sleep)
  			WARN_ON(array_info->chip->can_sleep);
  
  		if (!raw && !bitmap_empty(array_info->invert_mask, array_size))
  			bitmap_xor(value_bitmap, value_bitmap,
  				   array_info->invert_mask, array_size);
  
  		gpio_chip_set_multiple(array_info->chip, array_info->set_mask,
  				       value_bitmap);
  
  		if (bitmap_full(array_info->set_mask, array_size))
  			return 0;
  
  		i = find_first_zero_bit(array_info->set_mask, array_size);
  	} else {
  		array_info = NULL;
  	}
  
  	while (i < array_size) {
  		struct gpio_chip *chip = desc_array[i]->gdev->chip;
  		unsigned long fastpath[2 * BITS_TO_LONGS(FASTPATH_NGPIO)];
  		unsigned long *mask, *bits;
  		int count = 0;
  
  		if (likely(chip->ngpio <= FASTPATH_NGPIO)) {
  			mask = fastpath;
  		} else {
  			mask = kmalloc_array(2 * BITS_TO_LONGS(chip->ngpio),
  					   sizeof(*mask),
  					   can_sleep ? GFP_KERNEL : GFP_ATOMIC);
  			if (!mask)
  				return -ENOMEM;
  		}
  
  		bits = mask + BITS_TO_LONGS(chip->ngpio);
  		bitmap_zero(mask, chip->ngpio);
  
  		if (!can_sleep)
  			WARN_ON(chip->can_sleep);
  
  		do {
  			struct gpio_desc *desc = desc_array[i];
  			int hwgpio = gpio_chip_hwgpio(desc);
  			int value = test_bit(i, value_bitmap);
  
  			/*
  			 * Pins applicable for fast input but not for
  			 * fast output processing may have been already
  			 * inverted inside the fast path, skip them.
  			 */
  			if (!raw && !(array_info &&
  			    test_bit(i, array_info->invert_mask)) &&
  			    test_bit(FLAG_ACTIVE_LOW, &desc->flags))
  				value = !value;
  			trace_gpio_value(desc_to_gpio(desc), 0, value);
  			/*
  			 * collect all normal outputs belonging to the same chip
  			 * open drain and open source outputs are set individually
  			 */
  			if (test_bit(FLAG_OPEN_DRAIN, &desc->flags) && !raw) {
  				gpio_set_open_drain_value_commit(desc, value);
  			} else if (test_bit(FLAG_OPEN_SOURCE, &desc->flags) && !raw) {
  				gpio_set_open_source_value_commit(desc, value);
  			} else {
  				__set_bit(hwgpio, mask);
  				if (value)
  					__set_bit(hwgpio, bits);
  				else
  					__clear_bit(hwgpio, bits);
  				count++;
  			}
  			i++;
  
  			if (array_info)
  				i = find_next_zero_bit(array_info->set_mask,
  						       array_size, i);
  		} while ((i < array_size) &&
  			 (desc_array[i]->gdev->chip == chip));
  		/* push collected bits to outputs */
  		if (count != 0)
  			gpio_chip_set_multiple(chip, mask, bits);
  
  		if (mask != fastpath)
  			kfree(mask);
  	}
  	return 0;
  }
  
  /**
   * gpiod_set_raw_value() - assign a gpio's raw value
   * @desc: gpio whose value will be assigned
   * @value: value to assign
   *
   * Set the raw value of the GPIO, i.e. the value of its physical line without
   * regard for its ACTIVE_LOW status.
   *
   * This function should be called from contexts where we cannot sleep, and will
   * complain if the GPIO chip functions potentially sleep.
   */
  void gpiod_set_raw_value(struct gpio_desc *desc, int value)
  {
  	VALIDATE_DESC_VOID(desc);
  	/* Should be using gpiod_set_value_cansleep() */
  	WARN_ON(desc->gdev->chip->can_sleep);
  	gpiod_set_raw_value_commit(desc, value);
  }
  EXPORT_SYMBOL_GPL(gpiod_set_raw_value);
  
  /**
   * gpiod_set_value_nocheck() - set a GPIO line value without checking
   * @desc: the descriptor to set the value on
   * @value: value to set
   *
   * This sets the value of a GPIO line backing a descriptor, applying
   * different semantic quirks like active low and open drain/source
   * handling.
   */
  static void gpiod_set_value_nocheck(struct gpio_desc *desc, int value)
  {
  	if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
  		value = !value;
  	if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
  		gpio_set_open_drain_value_commit(desc, value);
  	else if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
  		gpio_set_open_source_value_commit(desc, value);
  	else
  		gpiod_set_raw_value_commit(desc, value);
  }
  
  /**
   * gpiod_set_value() - assign a gpio's value
   * @desc: gpio whose value will be assigned
   * @value: value to assign
   *
   * Set the logical value of the GPIO, i.e. taking its ACTIVE_LOW,
   * OPEN_DRAIN and OPEN_SOURCE flags into account.
   *
   * This function should be called from contexts where we cannot sleep, and will
   * complain if the GPIO chip functions potentially sleep.
   */
  void gpiod_set_value(struct gpio_desc *desc, int value)
  {
  	VALIDATE_DESC_VOID(desc);
  	WARN_ON(desc->gdev->chip->can_sleep);
  	gpiod_set_value_nocheck(desc, value);
  }
  EXPORT_SYMBOL_GPL(gpiod_set_value);
  
  /**
   * gpiod_set_raw_array_value() - assign values to an array of GPIOs
   * @array_size: number of elements in the descriptor array / value bitmap
   * @desc_array: array of GPIO descriptors whose values will be assigned
   * @array_info: information on applicability of fast bitmap processing path
   * @value_bitmap: bitmap of values to assign
   *
   * Set the raw values of the GPIOs, i.e. the values of the physical lines
   * without regard for their ACTIVE_LOW status.
   *
   * This function should be called from contexts where we cannot sleep, and will
   * complain if the GPIO chip functions potentially sleep.
   */
  int gpiod_set_raw_array_value(unsigned int array_size,
  			      struct gpio_desc **desc_array,
  			      struct gpio_array *array_info,
  			      unsigned long *value_bitmap)
  {
  	if (!desc_array)
  		return -EINVAL;
  	return gpiod_set_array_value_complex(true, false, array_size,
  					desc_array, array_info, value_bitmap);
  }
  EXPORT_SYMBOL_GPL(gpiod_set_raw_array_value);
  
  /**
   * gpiod_set_array_value() - assign values to an array of GPIOs
   * @array_size: number of elements in the descriptor array / value bitmap
   * @desc_array: array of GPIO descriptors whose values will be assigned
   * @array_info: information on applicability of fast bitmap processing path
   * @value_bitmap: bitmap of values to assign
   *
   * Set the logical values of the GPIOs, i.e. taking their ACTIVE_LOW status
   * into account.
   *
   * This function should be called from contexts where we cannot sleep, and will
   * complain if the GPIO chip functions potentially sleep.
   */
  int gpiod_set_array_value(unsigned int array_size,
  			  struct gpio_desc **desc_array,
  			  struct gpio_array *array_info,
  			  unsigned long *value_bitmap)
  {
  	if (!desc_array)
  		return -EINVAL;
  	return gpiod_set_array_value_complex(false, false, array_size,
  					     desc_array, array_info,
  					     value_bitmap);
  }
  EXPORT_SYMBOL_GPL(gpiod_set_array_value);
  
  /**
   * gpiod_cansleep() - report whether gpio value access may sleep
   * @desc: gpio to check
   *
   */
  int gpiod_cansleep(const struct gpio_desc *desc)
  {
  	VALIDATE_DESC(desc);
  	return desc->gdev->chip->can_sleep;
  }
  EXPORT_SYMBOL_GPL(gpiod_cansleep);
  
  /**
   * gpiod_set_consumer_name() - set the consumer name for the descriptor
   * @desc: gpio to set the consumer name on
   * @name: the new consumer name
   */
  int gpiod_set_consumer_name(struct gpio_desc *desc, const char *name)
  {
  	VALIDATE_DESC(desc);
  	if (name) {
  		name = kstrdup_const(name, GFP_KERNEL);
  		if (!name)
  			return -ENOMEM;
  	}
  
  	kfree_const(desc->label);
  	desc_set_label(desc, name);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(gpiod_set_consumer_name);
  
  /**
   * gpiod_to_irq() - return the IRQ corresponding to a GPIO
   * @desc: gpio whose IRQ will be returned (already requested)
   *
   * Return the IRQ corresponding to the passed GPIO, or an error code in case of
   * error.
   */
  int gpiod_to_irq(const struct gpio_desc *desc)
  {
  	struct gpio_chip *chip;
  	int offset;
  
  	/*
  	 * Cannot VALIDATE_DESC() here as gpiod_to_irq() consumer semantics
  	 * requires this function to not return zero on an invalid descriptor
  	 * but rather a negative error number.
  	 */
  	if (!desc || IS_ERR(desc) || !desc->gdev || !desc->gdev->chip)
  		return -EINVAL;
  
  	chip = desc->gdev->chip;
  	offset = gpio_chip_hwgpio(desc);
  	if (chip->to_irq) {
  		int retirq = chip->to_irq(chip, offset);
  
  		/* Zero means NO_IRQ */
  		if (!retirq)
  			return -ENXIO;
  
  		return retirq;
  	}
  	return -ENXIO;
  }
  EXPORT_SYMBOL_GPL(gpiod_to_irq);
  
  /**
   * gpiochip_lock_as_irq() - lock a GPIO to be used as IRQ
   * @chip: the chip the GPIO to lock belongs to
   * @offset: the offset of the GPIO to lock as IRQ
   *
   * This is used directly by GPIO drivers that want to lock down
   * a certain GPIO line to be used for IRQs.
   */
  int gpiochip_lock_as_irq(struct gpio_chip *chip, unsigned int offset)
  {
  	struct gpio_desc *desc;
  
  	desc = gpiochip_get_desc(chip, offset);
  	if (IS_ERR(desc))
  		return PTR_ERR(desc);
  
  	/*
  	 * If it's fast: flush the direction setting if something changed
  	 * behind our back
  	 */
  	if (!chip->can_sleep && chip->get_direction) {
  		int dir = gpiod_get_direction(desc);
  
  		if (dir < 0) {
  			chip_err(chip, "%s: cannot get GPIO direction\n",
  				 __func__);
  			return dir;
  		}
  	}
  
  	if (test_bit(FLAG_IS_OUT, &desc->flags)) {
  		chip_err(chip,
  			 "%s: tried to flag a GPIO set as output for IRQ\n",
  			 __func__);
  		return -EIO;
  	}
  
  	set_bit(FLAG_USED_AS_IRQ, &desc->flags);
  	set_bit(FLAG_IRQ_IS_ENABLED, &desc->flags);
  
  	/*
  	 * If the consumer has not set up a label (such as when the
  	 * IRQ is referenced from .to_irq()) we set up a label here
  	 * so it is clear this is used as an interrupt.
  	 */
  	if (!desc->label)
  		desc_set_label(desc, "interrupt");
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(gpiochip_lock_as_irq);
  
  /**
   * gpiochip_unlock_as_irq() - unlock a GPIO used as IRQ
   * @chip: the chip the GPIO to lock belongs to
   * @offset: the offset of the GPIO to lock as IRQ
   *
   * This is used directly by GPIO drivers that want to indicate
   * that a certain GPIO is no longer used exclusively for IRQ.
   */
  void gpiochip_unlock_as_irq(struct gpio_chip *chip, unsigned int offset)
  {
  	struct gpio_desc *desc;
  
  	desc = gpiochip_get_desc(chip, offset);
  	if (IS_ERR(desc))
  		return;
  
  	clear_bit(FLAG_USED_AS_IRQ, &desc->flags);
  	clear_bit(FLAG_IRQ_IS_ENABLED, &desc->flags);
  
  	/* If we only had this marking, erase it */
  	if (desc->label && !strcmp(desc->label, "interrupt"))
  		desc_set_label(desc, NULL);
  }
  EXPORT_SYMBOL_GPL(gpiochip_unlock_as_irq);
  
  void gpiochip_disable_irq(struct gpio_chip *chip, unsigned int offset)
  {
  	struct gpio_desc *desc = gpiochip_get_desc(chip, offset);
  
  	if (!IS_ERR(desc) &&
  	    !WARN_ON(!test_bit(FLAG_USED_AS_IRQ, &desc->flags)))
  		clear_bit(FLAG_IRQ_IS_ENABLED, &desc->flags);
  }
  EXPORT_SYMBOL_GPL(gpiochip_disable_irq);
  
  void gpiochip_enable_irq(struct gpio_chip *chip, unsigned int offset)
  {
  	struct gpio_desc *desc = gpiochip_get_desc(chip, offset);
  
  	if (!IS_ERR(desc) &&
  	    !WARN_ON(!test_bit(FLAG_USED_AS_IRQ, &desc->flags))) {
  		WARN_ON(test_bit(FLAG_IS_OUT, &desc->flags));
  		set_bit(FLAG_IRQ_IS_ENABLED, &desc->flags);
  	}
  }
  EXPORT_SYMBOL_GPL(gpiochip_enable_irq);
  
  bool gpiochip_line_is_irq(struct gpio_chip *chip, unsigned int offset)
  {
  	if (offset >= chip->ngpio)
  		return false;
  
  	return test_bit(FLAG_USED_AS_IRQ, &chip->gpiodev->descs[offset].flags);
  }
  EXPORT_SYMBOL_GPL(gpiochip_line_is_irq);
  
  int gpiochip_reqres_irq(struct gpio_chip *chip, unsigned int offset)
  {
  	int ret;
  
  	if (!try_module_get(chip->gpiodev->owner))
  		return -ENODEV;
  
  	ret = gpiochip_lock_as_irq(chip, offset);
  	if (ret) {
  		chip_err(chip, "unable to lock HW IRQ %u for IRQ\n", offset);
  		module_put(chip->gpiodev->owner);
  		return ret;
  	}
  	return 0;
  }
  EXPORT_SYMBOL_GPL(gpiochip_reqres_irq);
  
  void gpiochip_relres_irq(struct gpio_chip *chip, unsigned int offset)
  {
  	gpiochip_unlock_as_irq(chip, offset);
  	module_put(chip->gpiodev->owner);
  }
  EXPORT_SYMBOL_GPL(gpiochip_relres_irq);
  
  bool gpiochip_line_is_open_drain(struct gpio_chip *chip, unsigned int offset)
  {
  	if (offset >= chip->ngpio)
  		return false;
  
  	return test_bit(FLAG_OPEN_DRAIN, &chip->gpiodev->descs[offset].flags);
  }
  EXPORT_SYMBOL_GPL(gpiochip_line_is_open_drain);
  
  bool gpiochip_line_is_open_source(struct gpio_chip *chip, unsigned int offset)
  {
  	if (offset >= chip->ngpio)
  		return false;
  
  	return test_bit(FLAG_OPEN_SOURCE, &chip->gpiodev->descs[offset].flags);
  }
  EXPORT_SYMBOL_GPL(gpiochip_line_is_open_source);
  
  bool gpiochip_line_is_persistent(struct gpio_chip *chip, unsigned int offset)
  {
  	if (offset >= chip->ngpio)
  		return false;
  
  	return !test_bit(FLAG_TRANSITORY, &chip->gpiodev->descs[offset].flags);
  }
  EXPORT_SYMBOL_GPL(gpiochip_line_is_persistent);
  
  /**
   * gpiod_get_raw_value_cansleep() - return a gpio's raw value
   * @desc: gpio whose value will be returned
   *
   * Return the GPIO's raw value, i.e. the value of the physical line disregarding
   * its ACTIVE_LOW status, or negative errno on failure.
   *
   * This function is to be called from contexts that can sleep.
   */
  int gpiod_get_raw_value_cansleep(const struct gpio_desc *desc)
  {
  	might_sleep_if(extra_checks);
  	VALIDATE_DESC(desc);
  	return gpiod_get_raw_value_commit(desc);
  }
  EXPORT_SYMBOL_GPL(gpiod_get_raw_value_cansleep);
  
  /**
   * gpiod_get_value_cansleep() - return a gpio's value
   * @desc: gpio whose value will be returned
   *
   * Return the GPIO's logical value, i.e. taking the ACTIVE_LOW status into
   * account, or negative errno on failure.
   *
   * This function is to be called from contexts that can sleep.
   */
  int gpiod_get_value_cansleep(const struct gpio_desc *desc)
  {
  	int value;
  
  	might_sleep_if(extra_checks);
  	VALIDATE_DESC(desc);
  	value = gpiod_get_raw_value_commit(desc);
  	if (value < 0)
  		return value;
  
  	if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
  		value = !value;
  
  	return value;
  }
  EXPORT_SYMBOL_GPL(gpiod_get_value_cansleep);
  
  /**
   * gpiod_get_raw_array_value_cansleep() - read raw values from an array of GPIOs
   * @array_size: number of elements in the descriptor array / value bitmap
   * @desc_array: array of GPIO descriptors whose values will be read
   * @array_info: information on applicability of fast bitmap processing path
   * @value_bitmap: bitmap to store the read values
   *
   * Read the raw values of the GPIOs, i.e. the values of the physical lines
   * without regard for their ACTIVE_LOW status.  Return 0 in case of success,
   * else an error code.
   *
   * This function is to be called from contexts that can sleep.
   */
  int gpiod_get_raw_array_value_cansleep(unsigned int array_size,
  				       struct gpio_desc **desc_array,
  				       struct gpio_array *array_info,
  				       unsigned long *value_bitmap)
  {
  	might_sleep_if(extra_checks);
  	if (!desc_array)
  		return -EINVAL;
  	return gpiod_get_array_value_complex(true, true, array_size,
  					     desc_array, array_info,
  					     value_bitmap);
  }
  EXPORT_SYMBOL_GPL(gpiod_get_raw_array_value_cansleep);
  
  /**
   * gpiod_get_array_value_cansleep() - read values from an array of GPIOs
   * @array_size: number of elements in the descriptor array / value bitmap
   * @desc_array: array of GPIO descriptors whose values will be read
   * @array_info: information on applicability of fast bitmap processing path
   * @value_bitmap: bitmap to store the read values
   *
   * Read the logical values of the GPIOs, i.e. taking their ACTIVE_LOW status
   * into account.  Return 0 in case of success, else an error code.
   *
   * This function is to be called from contexts that can sleep.
   */
  int gpiod_get_array_value_cansleep(unsigned int array_size,
  				   struct gpio_desc **desc_array,
  				   struct gpio_array *array_info,
  				   unsigned long *value_bitmap)
  {
  	might_sleep_if(extra_checks);
  	if (!desc_array)
  		return -EINVAL;
  	return gpiod_get_array_value_complex(false, true, array_size,
  					     desc_array, array_info,
  					     value_bitmap);
  }
  EXPORT_SYMBOL_GPL(gpiod_get_array_value_cansleep);
  
  /**
   * gpiod_set_raw_value_cansleep() - assign a gpio's raw value
   * @desc: gpio whose value will be assigned
   * @value: value to assign
   *
   * Set the raw value of the GPIO, i.e. the value of its physical line without
   * regard for its ACTIVE_LOW status.
   *
   * This function is to be called from contexts that can sleep.
   */
  void gpiod_set_raw_value_cansleep(struct gpio_desc *desc, int value)
  {
  	might_sleep_if(extra_checks);
  	VALIDATE_DESC_VOID(desc);
  	gpiod_set_raw_value_commit(desc, value);
  }
  EXPORT_SYMBOL_GPL(gpiod_set_raw_value_cansleep);
  
  /**
   * gpiod_set_value_cansleep() - assign a gpio's value
   * @desc: gpio whose value will be assigned
   * @value: value to assign
   *
   * Set the logical value of the GPIO, i.e. taking its ACTIVE_LOW status into
   * account
   *
   * This function is to be called from contexts that can sleep.
   */
  void gpiod_set_value_cansleep(struct gpio_desc *desc, int value)
  {
  	might_sleep_if(extra_checks);
  	VALIDATE_DESC_VOID(desc);
  	gpiod_set_value_nocheck(desc, value);
  }
  EXPORT_SYMBOL_GPL(gpiod_set_value_cansleep);
  
  /**
   * gpiod_set_raw_array_value_cansleep() - assign values to an array of GPIOs
   * @array_size: number of elements in the descriptor array / value bitmap
   * @desc_array: array of GPIO descriptors whose values will be assigned
   * @array_info: information on applicability of fast bitmap processing path
   * @value_bitmap: bitmap of values to assign
   *
   * Set the raw values of the GPIOs, i.e. the values of the physical lines
   * without regard for their ACTIVE_LOW status.
   *
   * This function is to be called from contexts that can sleep.
   */
  int gpiod_set_raw_array_value_cansleep(unsigned int array_size,
  				       struct gpio_desc **desc_array,
  				       struct gpio_array *array_info,
  				       unsigned long *value_bitmap)
  {
  	might_sleep_if(extra_checks);
  	if (!desc_array)
  		return -EINVAL;
  	return gpiod_set_array_value_complex(true, true, array_size, desc_array,
  				      array_info, value_bitmap);
  }
  EXPORT_SYMBOL_GPL(gpiod_set_raw_array_value_cansleep);
  
  /**
   * gpiod_add_lookup_tables() - register GPIO device consumers
   * @tables: list of tables of consumers to register
   * @n: number of tables in the list
   */
  void gpiod_add_lookup_tables(struct gpiod_lookup_table **tables, size_t n)
  {
  	unsigned int i;
  
  	mutex_lock(&gpio_lookup_lock);
  
  	for (i = 0; i < n; i++)
  		list_add_tail(&tables[i]->list, &gpio_lookup_list);
  
  	mutex_unlock(&gpio_lookup_lock);
  }
  
  /**
   * gpiod_set_array_value_cansleep() - assign values to an array of GPIOs
   * @array_size: number of elements in the descriptor array / value bitmap
   * @desc_array: array of GPIO descriptors whose values will be assigned
   * @array_info: information on applicability of fast bitmap processing path
   * @value_bitmap: bitmap of values to assign
   *
   * Set the logical values of the GPIOs, i.e. taking their ACTIVE_LOW status
   * into account.
   *
   * This function is to be called from contexts that can sleep.
   */
  int gpiod_set_array_value_cansleep(unsigned int array_size,
  				   struct gpio_desc **desc_array,
  				   struct gpio_array *array_info,
  				   unsigned long *value_bitmap)
  {
  	might_sleep_if(extra_checks);
  	if (!desc_array)
  		return -EINVAL;
  	return gpiod_set_array_value_complex(false, true, array_size,
  					     desc_array, array_info,
  					     value_bitmap);
  }
  EXPORT_SYMBOL_GPL(gpiod_set_array_value_cansleep);
  
  /**
   * gpiod_add_lookup_table() - register GPIO device consumers
   * @table: table of consumers to register
   */
  void gpiod_add_lookup_table(struct gpiod_lookup_table *table)
  {
  	mutex_lock(&gpio_lookup_lock);
  
  	list_add_tail(&table->list, &gpio_lookup_list);
  
  	mutex_unlock(&gpio_lookup_lock);
  }
  EXPORT_SYMBOL_GPL(gpiod_add_lookup_table);
  
  /**
   * gpiod_remove_lookup_table() - unregister GPIO device consumers
   * @table: table of consumers to unregister
   */
  void gpiod_remove_lookup_table(struct gpiod_lookup_table *table)
  {
  	mutex_lock(&gpio_lookup_lock);
  
  	list_del(&table->list);
  
  	mutex_unlock(&gpio_lookup_lock);
  }
  EXPORT_SYMBOL_GPL(gpiod_remove_lookup_table);
  
  /**
   * gpiod_add_hogs() - register a set of GPIO hogs from machine code
   * @hogs: table of gpio hog entries with a zeroed sentinel at the end
   */
  void gpiod_add_hogs(struct gpiod_hog *hogs)
  {
  	struct gpio_chip *chip;
  	struct gpiod_hog *hog;
  
  	mutex_lock(&gpio_machine_hogs_mutex);
  
  	for (hog = &hogs[0]; hog->chip_label; hog++) {
  		list_add_tail(&hog->list, &gpio_machine_hogs);
  
  		/*
  		 * The chip may have been registered earlier, so check if it
  		 * exists and, if so, try to hog the line now.
  		 */
  		chip = find_chip_by_name(hog->chip_label);
  		if (chip)
  			gpiochip_machine_hog(chip, hog);
  	}
  
  	mutex_unlock(&gpio_machine_hogs_mutex);
  }
  EXPORT_SYMBOL_GPL(gpiod_add_hogs);
  
  static struct gpiod_lookup_table *gpiod_find_lookup_table(struct device *dev)
  {
  	const char *dev_id = dev ? dev_name(dev) : NULL;
  	struct gpiod_lookup_table *table;
  
  	mutex_lock(&gpio_lookup_lock);
  
  	list_for_each_entry(table, &gpio_lookup_list, list) {
  		if (table->dev_id && dev_id) {
  			/*
  			 * Valid strings on both ends, must be identical to have
  			 * a match
  			 */
  			if (!strcmp(table->dev_id, dev_id))
  				goto found;
  		} else {
  			/*
  			 * One of the pointers is NULL, so both must be to have
  			 * a match
  			 */
  			if (dev_id == table->dev_id)
  				goto found;
  		}
  	}
  	table = NULL;
  
  found:
  	mutex_unlock(&gpio_lookup_lock);
  	return table;
  }
  
  static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
  				    unsigned int idx,
  				    enum gpio_lookup_flags *flags)
  {
  	struct gpio_desc *desc = ERR_PTR(-ENOENT);
  	struct gpiod_lookup_table *table;
  	struct gpiod_lookup *p;
  
  	table = gpiod_find_lookup_table(dev);
  	if (!table)
  		return desc;
  
  	for (p = &table->table[0]; p->chip_label; p++) {
  		struct gpio_chip *chip;
  
  		/* idx must always match exactly */
  		if (p->idx != idx)
  			continue;
  
  		/* If the lookup entry has a con_id, require exact match */
  		if (p->con_id && (!con_id || strcmp(p->con_id, con_id)))
  			continue;
  
  		chip = find_chip_by_name(p->chip_label);
  
  		if (!chip) {
  			/*
  			 * As the lookup table indicates a chip with
  			 * p->chip_label should exist, assume it may
  			 * still appear later and let the interested
  			 * consumer be probed again or let the Deferred
  			 * Probe infrastructure handle the error.
  			 */
  			dev_warn(dev, "cannot find GPIO chip %s, deferring\n",
  				 p->chip_label);
  			return ERR_PTR(-EPROBE_DEFER);
  		}
  
  		if (chip->ngpio <= p->chip_hwnum) {
  			dev_err(dev,
  				"requested GPIO %d is out of range [0..%d] for chip %s\n",
  				idx, chip->ngpio, chip->label);
  			return ERR_PTR(-EINVAL);
  		}
  
  		desc = gpiochip_get_desc(chip, p->chip_hwnum);
  		*flags = p->flags;
  
  		return desc;
  	}
  
  	return desc;
  }
  
  static int dt_gpio_count(struct device *dev, const char *con_id)
  {
  	int ret;
  	char propname[32];
  	unsigned int i;
  
  	for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
  		if (con_id)
  			snprintf(propname, sizeof(propname), "%s-%s",
  				 con_id, gpio_suffixes[i]);
  		else
  			snprintf(propname, sizeof(propname), "%s",
  				 gpio_suffixes[i]);
  
  		ret = of_gpio_named_count(dev->of_node, propname);
  		if (ret > 0)
  			break;
  	}
  	return ret ? ret : -ENOENT;
  }
  
  static int platform_gpio_count(struct device *dev, const char *con_id)
  {
  	struct gpiod_lookup_table *table;
  	struct gpiod_lookup *p;
  	unsigned int count = 0;
  
  	table = gpiod_find_lookup_table(dev);
  	if (!table)
  		return -ENOENT;
  
  	for (p = &table->table[0]; p->chip_label; p++) {
  		if ((con_id && p->con_id && !strcmp(con_id, p->con_id)) ||
  		    (!con_id && !p->con_id))
  			count++;
  	}
  	if (!count)
  		return -ENOENT;
  
  	return count;
  }
  
  /**
   * gpiod_count - return the number of GPIOs associated with a device / function
   *		or -ENOENT if no GPIO has been assigned to the requested function
   * @dev:	GPIO consumer, can be NULL for system-global GPIOs
   * @con_id:	function within the GPIO consumer
   */
  int gpiod_count(struct device *dev, const char *con_id)
  {
  	int count = -ENOENT;
  
  	if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node)
  		count = dt_gpio_count(dev, con_id);
  	else if (IS_ENABLED(CONFIG_ACPI) && dev && ACPI_HANDLE(dev))
  		count = acpi_gpio_count(dev, con_id);
  
  	if (count < 0)
  		count = platform_gpio_count(dev, con_id);
  
  	return count;
  }
  EXPORT_SYMBOL_GPL(gpiod_count);
  
  /**
   * gpiod_get - obtain a GPIO for a given GPIO function
   * @dev:	GPIO consumer, can be NULL for system-global GPIOs
   * @con_id:	function within the GPIO consumer
   * @flags:	optional GPIO initialization flags
   *
   * Return the GPIO descriptor corresponding to the function con_id of device
   * dev, -ENOENT if no GPIO has been assigned to the requested function, or
   * another IS_ERR() code if an error occurred while trying to acquire the GPIO.
   */
  struct gpio_desc *__must_check gpiod_get(struct device *dev, const char *con_id,
  					 enum gpiod_flags flags)
  {
  	return gpiod_get_index(dev, con_id, 0, flags);
  }
  EXPORT_SYMBOL_GPL(gpiod_get);
  
  /**
   * gpiod_get_optional - obtain an optional GPIO for a given GPIO function
   * @dev: GPIO consumer, can be NULL for system-global GPIOs
   * @con_id: function within the GPIO consumer
   * @flags: optional GPIO initialization flags
   *
   * This is equivalent to gpiod_get(), except that when no GPIO was assigned to
   * the requested function it will return NULL. This is convenient for drivers
   * that need to handle optional GPIOs.
   */
  struct gpio_desc *__must_check gpiod_get_optional(struct device *dev,
  						  const char *con_id,
  						  enum gpiod_flags flags)
  {
  	return gpiod_get_index_optional(dev, con_id, 0, flags);
  }
  EXPORT_SYMBOL_GPL(gpiod_get_optional);
  
  
  /**
   * gpiod_configure_flags - helper function to configure a given GPIO
   * @desc:	gpio whose value will be assigned
   * @con_id:	function within the GPIO consumer
   * @lflags:	gpio_lookup_flags - returned from of_find_gpio() or
   *		of_get_gpio_hog()
   * @dflags:	gpiod_flags - optional GPIO initialization flags
   *
   * Return 0 on success, -ENOENT if no GPIO has been assigned to the
   * requested function and/or index, or another IS_ERR() code if an error
   * occurred while trying to acquire the GPIO.
   */
  int gpiod_configure_flags(struct gpio_desc *desc, const char *con_id,
  		unsigned long lflags, enum gpiod_flags dflags)
  {
  	int status;
  
  	if (lflags & GPIO_ACTIVE_LOW)
  		set_bit(FLAG_ACTIVE_LOW, &desc->flags);
  
  	if (lflags & GPIO_OPEN_DRAIN)
  		set_bit(FLAG_OPEN_DRAIN, &desc->flags);
  	else if (dflags & GPIOD_FLAGS_BIT_OPEN_DRAIN) {
  		/*
  		 * This enforces open drain mode from the consumer side.
  		 * This is necessary for some busses like I2C, but the lookup
  		 * should *REALLY* have specified them as open drain in the
  		 * first place, so print a little warning here.
  		 */
  		set_bit(FLAG_OPEN_DRAIN, &desc->flags);
  		gpiod_warn(desc,
  			   "enforced open drain please flag it properly in DT/ACPI DSDT/board file\n");
  	}
  
  	if (lflags & GPIO_OPEN_SOURCE)
  		set_bit(FLAG_OPEN_SOURCE, &desc->flags);
  
  	status = gpiod_set_transitory(desc, (lflags & GPIO_TRANSITORY));
  	if (status < 0)
  		return status;
  
  	/* No particular flag request, return here... */
  	if (!(dflags & GPIOD_FLAGS_BIT_DIR_SET)) {
  		pr_debug("no flags found for %s\n", con_id);
  		return 0;
  	}
  
  	/* Process flags */
  	if (dflags & GPIOD_FLAGS_BIT_DIR_OUT)
  		status = gpiod_direction_output(desc,
  				!!(dflags & GPIOD_FLAGS_BIT_DIR_VAL));
  	else
  		status = gpiod_direction_input(desc);
  
  	return status;
  }
  
  /**
   * gpiod_get_index - obtain a GPIO from a multi-index GPIO function
   * @dev:	GPIO consumer, can be NULL for system-global GPIOs
   * @con_id:	function within the GPIO consumer
   * @idx:	index of the GPIO to obtain in the consumer
   * @flags:	optional GPIO initialization flags
   *
   * This variant of gpiod_get() allows to access GPIOs other than the first
   * defined one for functions that define several GPIOs.
   *
   * Return a valid GPIO descriptor, -ENOENT if no GPIO has been assigned to the
   * requested function and/or index, or another IS_ERR() code if an error
   * occurred while trying to acquire the GPIO.
   */
  struct gpio_desc *__must_check gpiod_get_index(struct device *dev,
  					       const char *con_id,
  					       unsigned int idx,
  					       enum gpiod_flags flags)
  {
  	struct gpio_desc *desc = NULL;
  	int status;
  	enum gpio_lookup_flags lookupflags = 0;
  	/* Maybe we have a device name, maybe not */
  	const char *devname = dev ? dev_name(dev) : "?";
  
  	dev_dbg(dev, "GPIO lookup for consumer %s\n", con_id);
  
  	if (dev) {
  		/* Using device tree? */
  		if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
  			dev_dbg(dev, "using device tree for GPIO lookup\n");
  			desc = of_find_gpio(dev, con_id, idx, &lookupflags);
  		} else if (ACPI_COMPANION(dev)) {
  			dev_dbg(dev, "using ACPI for GPIO lookup\n");
  			desc = acpi_find_gpio(dev, con_id, idx, &flags, &lookupflags);
  		}
  	}
  
  	/*
  	 * Either we are not using DT or ACPI, or their lookup did not return
  	 * a result. In that case, use platform lookup as a fallback.
  	 */
  	if (!desc || desc == ERR_PTR(-ENOENT)) {
  		dev_dbg(dev, "using lookup tables for GPIO lookup\n");
  		desc = gpiod_find(dev, con_id, idx, &lookupflags);
  	}
  
  	if (IS_ERR(desc)) {
  		dev_dbg(dev, "No GPIO consumer %s found\n", con_id);
  		return desc;
  	}
  
  	/*
  	 * If a connection label was passed use that, else attempt to use
  	 * the device name as label
  	 */
  	status = gpiod_request(desc, con_id ? con_id : devname);
  	if (status < 0) {
  		if (status == -EBUSY && flags & GPIOD_FLAGS_BIT_NONEXCLUSIVE) {
  			/*
  			 * This happens when there are several consumers for
  			 * the same GPIO line: we just return here without
  			 * further initialization. It is a bit if a hack.
  			 * This is necessary to support fixed regulators.
  			 *
  			 * FIXME: Make this more sane and safe.
  			 */
  			dev_info(dev, "nonexclusive access to GPIO for %s\n",
  				 con_id ? con_id : devname);
  			return desc;
  		} else {
  			return ERR_PTR(status);
  		}
  	}
  
  	status = gpiod_configure_flags(desc, con_id, lookupflags, flags);
  	if (status < 0) {
  		dev_dbg(dev, "setup of GPIO %s failed\n", con_id);
  		gpiod_put(desc);
  		return ERR_PTR(status);
  	}
  
  	return desc;
  }
  EXPORT_SYMBOL_GPL(gpiod_get_index);
  
  /**
   * gpiod_get_from_of_node() - obtain a GPIO from an OF node
   * @node:	handle of the OF node
   * @propname:	name of the DT property representing the GPIO
   * @index:	index of the GPIO to obtain for the consumer
   * @dflags:	GPIO initialization flags
   * @label:	label to attach to the requested GPIO
   *
   * Returns:
   * On successful request the GPIO pin is configured in accordance with
   * provided @dflags. If the node does not have the requested GPIO
   * property, NULL is returned.
   *
   * In case of error an ERR_PTR() is returned.
   */
  struct gpio_desc *gpiod_get_from_of_node(struct device_node *node,
  					 const char *propname, int index,
  					 enum gpiod_flags dflags,
  					 const char *label)
  {
  	struct gpio_desc *desc;
  	unsigned long lflags = 0;
  	enum of_gpio_flags flags;
  	bool active_low = false;
  	bool single_ended = false;
  	bool open_drain = false;
  	bool transitory = false;
  	int ret;
  
  	desc = of_get_named_gpiod_flags(node, propname,
  					index, &flags);
  
  	if (!desc || IS_ERR(desc)) {
  		/* If it is not there, just return NULL */
  		if (PTR_ERR(desc) == -ENOENT)
  			return NULL;
  		return desc;
  	}
  
  	active_low = flags & OF_GPIO_ACTIVE_LOW;
  	single_ended = flags & OF_GPIO_SINGLE_ENDED;
  	open_drain = flags & OF_GPIO_OPEN_DRAIN;
  	transitory = flags & OF_GPIO_TRANSITORY;
  
  	ret = gpiod_request(desc, label);
  	if (ret == -EBUSY && (flags & GPIOD_FLAGS_BIT_NONEXCLUSIVE))
  		return desc;
  	if (ret)
  		return ERR_PTR(ret);
  
  	if (active_low)
  		lflags |= GPIO_ACTIVE_LOW;
  
  	if (single_ended) {
  		if (open_drain)
  			lflags |= GPIO_OPEN_DRAIN;
  		else
  			lflags |= GPIO_OPEN_SOURCE;
  	}
  
  	if (transitory)
  		lflags |= GPIO_TRANSITORY;
  
  	ret = gpiod_configure_flags(desc, propname, lflags, dflags);
  	if (ret < 0) {
  		gpiod_put(desc);
  		return ERR_PTR(ret);
  	}
  
  	return desc;
  }
  EXPORT_SYMBOL(gpiod_get_from_of_node);
  
  /**
   * fwnode_get_named_gpiod - obtain a GPIO from firmware node
   * @fwnode:	handle of the firmware node
   * @propname:	name of the firmware property representing the GPIO
   * @index:	index of the GPIO to obtain for the consumer
   * @dflags:	GPIO initialization flags
   * @label:	label to attach to the requested GPIO
   *
   * This function can be used for drivers that get their configuration
   * from opaque firmware.
   *
   * The function properly finds the corresponding GPIO using whatever is the
   * underlying firmware interface and then makes sure that the GPIO
   * descriptor is requested before it is returned to the caller.
   *
   * Returns:
   * On successful request the GPIO pin is configured in accordance with
   * provided @dflags.
   *
   * In case of error an ERR_PTR() is returned.
   */
  struct gpio_desc *fwnode_get_named_gpiod(struct fwnode_handle *fwnode,
  					 const char *propname, int index,
  					 enum gpiod_flags dflags,
  					 const char *label)
  {
  	struct gpio_desc *desc = ERR_PTR(-ENODEV);
  	unsigned long lflags = 0;
  	int ret;
  
  	if (!fwnode)
  		return ERR_PTR(-EINVAL);
  
  	if (is_of_node(fwnode)) {
  		desc = gpiod_get_from_of_node(to_of_node(fwnode),
  					      propname, index,
  					      dflags,
  					      label);
  		return desc;
  	} else if (is_acpi_node(fwnode)) {
  		struct acpi_gpio_info info;
  
  		desc = acpi_node_get_gpiod(fwnode, propname, index, &info);
  		if (IS_ERR(desc))
  			return desc;
  
  		acpi_gpio_update_gpiod_flags(&dflags, &info);
  
  		if (info.polarity == GPIO_ACTIVE_LOW)
  			lflags |= GPIO_ACTIVE_LOW;
  	}
  
  	/* Currently only ACPI takes this path */
  	ret = gpiod_request(desc, label);
  	if (ret)
  		return ERR_PTR(ret);
  
  	ret = gpiod_configure_flags(desc, propname, lflags, dflags);
  	if (ret < 0) {
  		gpiod_put(desc);
  		return ERR_PTR(ret);
  	}
  
  	return desc;
  }
  EXPORT_SYMBOL_GPL(fwnode_get_named_gpiod);
  
  /**
   * gpiod_get_index_optional - obtain an optional GPIO from a multi-index GPIO
   *                            function
   * @dev: GPIO consumer, can be NULL for system-global GPIOs
   * @con_id: function within the GPIO consumer
   * @index: index of the GPIO to obtain in the consumer
   * @flags: optional GPIO initialization flags
   *
   * This is equivalent to gpiod_get_index(), except that when no GPIO with the
   * specified index was assigned to the requested function it will return NULL.
   * This is convenient for drivers that need to handle optional GPIOs.
   */
  struct gpio_desc *__must_check gpiod_get_index_optional(struct device *dev,
  							const char *con_id,
  							unsigned int index,
  							enum gpiod_flags flags)
  {
  	struct gpio_desc *desc;
  
  	desc = gpiod_get_index(dev, con_id, index, flags);
  	if (IS_ERR(desc)) {
  		if (PTR_ERR(desc) == -ENOENT)
  			return NULL;
  	}
  
  	return desc;
  }
  EXPORT_SYMBOL_GPL(gpiod_get_index_optional);
  
  /**
   * gpiod_hog - Hog the specified GPIO desc given the provided flags
   * @desc:	gpio whose value will be assigned
   * @name:	gpio line name
   * @lflags:	gpio_lookup_flags - returned from of_find_gpio() or
   *		of_get_gpio_hog()
   * @dflags:	gpiod_flags - optional GPIO initialization flags
   */
  int gpiod_hog(struct gpio_desc *desc, const char *name,
  	      unsigned long lflags, enum gpiod_flags dflags)
  {
  	struct gpio_chip *chip;
  	struct gpio_desc *local_desc;
  	int hwnum;
  	int status;
  
  	chip = gpiod_to_chip(desc);
  	hwnum = gpio_chip_hwgpio(desc);
  
  	/*
  	 * FIXME: not very elegant that we call gpiod_configure_flags()
  	 * twice here (once inside gpiochip_request_own_desc() and
  	 * again here), but the gpiochip_request_own_desc() is external
  	 * and cannot really pass the lflags so this is the lesser evil
  	 * at the moment. Pass zero as dflags on this first call so we
  	 * don't screw anything up.
  	 */
  	local_desc = gpiochip_request_own_desc(chip, hwnum, name, 0);
  	if (IS_ERR(local_desc)) {
  		status = PTR_ERR(local_desc);
  		pr_err("requesting hog GPIO %s (chip %s, offset %d) failed, %d\n",
  		       name, chip->label, hwnum, status);
  		return status;
  	}
  
  	status = gpiod_configure_flags(desc, name, lflags, dflags);
  	if (status < 0) {
  		pr_err("setup of hog GPIO %s (chip %s, offset %d) failed, %d\n",
  		       name, chip->label, hwnum, status);
  		gpiochip_free_own_desc(desc);
  		return status;
  	}
  
  	/* Mark GPIO as hogged so it can be identified and removed later */
  	set_bit(FLAG_IS_HOGGED, &desc->flags);
  
  	pr_info("GPIO line %d (%s) hogged as %s%s\n",
  		desc_to_gpio(desc), name,
  		(dflags&GPIOD_FLAGS_BIT_DIR_OUT) ? "output" : "input",
  		(dflags&GPIOD_FLAGS_BIT_DIR_OUT) ?
  		  (dflags&GPIOD_FLAGS_BIT_DIR_VAL) ? "/high" : "/low":"");
  
  	return 0;
  }
  
  /**
   * gpiochip_free_hogs - Scan gpio-controller chip and release GPIO hog
   * @chip:	gpio chip to act on
   *
   * This is only used by of_gpiochip_remove to free hogged gpios
   */
  static void gpiochip_free_hogs(struct gpio_chip *chip)
  {
  	int id;
  
  	for (id = 0; id < chip->ngpio; id++) {
  		if (test_bit(FLAG_IS_HOGGED, &chip->gpiodev->descs[id].flags))
  			gpiochip_free_own_desc(&chip->gpiodev->descs[id]);
  	}
  }
  
  /**
   * gpiod_get_array - obtain multiple GPIOs from a multi-index GPIO function
   * @dev:	GPIO consumer, can be NULL for system-global GPIOs
   * @con_id:	function within the GPIO consumer
   * @flags:	optional GPIO initialization flags
   *
   * This function acquires all the GPIOs defined under a given function.
   *
   * Return a struct gpio_descs containing an array of descriptors, -ENOENT if
   * no GPIO has been assigned to the requested function, or another IS_ERR()
   * code if an error occurred while trying to acquire the GPIOs.
   */
  struct gpio_descs *__must_check gpiod_get_array(struct device *dev,
  						const char *con_id,
  						enum gpiod_flags flags)
  {
  	struct gpio_desc *desc;
  	struct gpio_descs *descs;
  	struct gpio_array *array_info = NULL;
  	struct gpio_chip *chip;
  	int count, bitmap_size;
  
  	count = gpiod_count(dev, con_id);
  	if (count < 0)
  		return ERR_PTR(count);
  
  	descs = kzalloc(struct_size(descs, desc, count), GFP_KERNEL);
  	if (!descs)
  		return ERR_PTR(-ENOMEM);
  
  	for (descs->ndescs = 0; descs->ndescs < count; ) {
  		desc = gpiod_get_index(dev, con_id, descs->ndescs, flags);
  		if (IS_ERR(desc)) {
  			gpiod_put_array(descs);
  			return ERR_CAST(desc);
  		}
  
  		descs->desc[descs->ndescs] = desc;
  
  		chip = gpiod_to_chip(desc);
  		/*
  		 * If pin hardware number of array member 0 is also 0, select
  		 * its chip as a candidate for fast bitmap processing path.
  		 */
  		if (descs->ndescs == 0 && gpio_chip_hwgpio(desc) == 0) {
  			struct gpio_descs *array;
  
  			bitmap_size = BITS_TO_LONGS(chip->ngpio > count ?
  						    chip->ngpio : count);
  
  			array = kzalloc(struct_size(descs, desc, count) +
  					struct_size(array_info, invert_mask,
  					3 * bitmap_size), GFP_KERNEL);
  			if (!array) {
  				gpiod_put_array(descs);
  				return ERR_PTR(-ENOMEM);
  			}
  
  			memcpy(array, descs,
  			       struct_size(descs, desc, descs->ndescs + 1));
  			kfree(descs);
  
  			descs = array;
  			array_info = (void *)(descs->desc + count);
  			array_info->get_mask = array_info->invert_mask +
  						  bitmap_size;
  			array_info->set_mask = array_info->get_mask +
  						  bitmap_size;
  
  			array_info->desc = descs->desc;
  			array_info->size = count;
  			array_info->chip = chip;
  			bitmap_set(array_info->get_mask, descs->ndescs,
  				   count - descs->ndescs);
  			bitmap_set(array_info->set_mask, descs->ndescs,
  				   count - descs->ndescs);
  			descs->info = array_info;
  		}
  		/* Unmark array members which don't belong to the 'fast' chip */
  		if (array_info && array_info->chip != chip) {
  			__clear_bit(descs->ndescs, array_info->get_mask);
  			__clear_bit(descs->ndescs, array_info->set_mask);
  		}
  		/*
  		 * Detect array members which belong to the 'fast' chip
  		 * but their pins are not in hardware order.
  		 */
  		else if (array_info &&
  			   gpio_chip_hwgpio(desc) != descs->ndescs) {
  			/*
  			 * Don't use fast path if all array members processed so
  			 * far belong to the same chip as this one but its pin
  			 * hardware number is different from its array index.
  			 */
  			if (bitmap_full(array_info->get_mask, descs->ndescs)) {
  				array_info = NULL;
  			} else {
  				__clear_bit(descs->ndescs,
  					    array_info->get_mask);
  				__clear_bit(descs->ndescs,
  					    array_info->set_mask);
  			}
  		} else if (array_info) {
  			/* Exclude open drain or open source from fast output */
  			if (gpiochip_line_is_open_drain(chip, descs->ndescs) ||
  			    gpiochip_line_is_open_source(chip, descs->ndescs))
  				__clear_bit(descs->ndescs,
  					    array_info->set_mask);
  			/* Identify 'fast' pins which require invertion */
  			if (gpiod_is_active_low(desc))
  				__set_bit(descs->ndescs,
  					  array_info->invert_mask);
  		}
  
  		descs->ndescs++;
  	}
  	if (array_info)
  		dev_dbg(dev,
  			"GPIO array info: chip=%s, size=%d, get_mask=%lx, set_mask=%lx, invert_mask=%lx\n",
  			array_info->chip->label, array_info->size,
  			*array_info->get_mask, *array_info->set_mask,
  			*array_info->invert_mask);
  	return descs;
  }
  EXPORT_SYMBOL_GPL(gpiod_get_array);
  
  /**
   * gpiod_get_array_optional - obtain multiple GPIOs from a multi-index GPIO
   *                            function
   * @dev:	GPIO consumer, can be NULL for system-global GPIOs
   * @con_id:	function within the GPIO consumer
   * @flags:	optional GPIO initialization flags
   *
   * This is equivalent to gpiod_get_array(), except that when no GPIO was
   * assigned to the requested function it will return NULL.
   */
  struct gpio_descs *__must_check gpiod_get_array_optional(struct device *dev,
  							const char *con_id,
  							enum gpiod_flags flags)
  {
  	struct gpio_descs *descs;
  
  	descs = gpiod_get_array(dev, con_id, flags);
  	if (IS_ERR(descs) && (PTR_ERR(descs) == -ENOENT))
  		return NULL;
  
  	return descs;
  }
  EXPORT_SYMBOL_GPL(gpiod_get_array_optional);
  
  /**
   * gpiod_put - dispose of a GPIO descriptor
   * @desc:	GPIO descriptor to dispose of
   *
   * No descriptor can be used after gpiod_put() has been called on it.
   */
  void gpiod_put(struct gpio_desc *desc)
  {
  	gpiod_free(desc);
  }
  EXPORT_SYMBOL_GPL(gpiod_put);
  
  /**
   * gpiod_put_array - dispose of multiple GPIO descriptors
   * @descs:	struct gpio_descs containing an array of descriptors
   */
  void gpiod_put_array(struct gpio_descs *descs)
  {
  	unsigned int i;
  
  	for (i = 0; i < descs->ndescs; i++)
  		gpiod_put(descs->desc[i]);
  
  	kfree(descs);
  }
  EXPORT_SYMBOL_GPL(gpiod_put_array);
  
  static int __init gpiolib_dev_init(void)
  {
  	int ret;
  
  	/* Register GPIO sysfs bus */
  	ret = bus_register(&gpio_bus_type);
  	if (ret < 0) {
  		pr_err("gpiolib: could not register GPIO bus type\n");
  		return ret;
  	}
  
  	ret = alloc_chrdev_region(&gpio_devt, 0, GPIO_DEV_MAX, "gpiochip");
  	if (ret < 0) {
  		pr_err("gpiolib: failed to allocate char dev region\n");
  		bus_unregister(&gpio_bus_type);
  	} else {
  		gpiolib_initialized = true;
  		gpiochip_setup_devs();
  	}
  	return ret;
  }
  core_initcall(gpiolib_dev_init);
  
  #ifdef CONFIG_DEBUG_FS
  
  static void gpiolib_dbg_show(struct seq_file *s, struct gpio_device *gdev)
  {
  	unsigned		i;
  	struct gpio_chip	*chip = gdev->chip;
  	unsigned		gpio = gdev->base;
  	struct gpio_desc	*gdesc = &gdev->descs[0];
  	bool			is_out;
  	bool			is_irq;
  	bool			active_low;
  
  	for (i = 0; i < gdev->ngpio; i++, gpio++, gdesc++) {
  		if (!test_bit(FLAG_REQUESTED, &gdesc->flags)) {
  			if (gdesc->name) {
  				seq_printf(s, " gpio-%-3d (%-20.20s)\n",
  					   gpio, gdesc->name);
  			}
  			continue;
  		}
  
  		gpiod_get_direction(gdesc);
  		is_out = test_bit(FLAG_IS_OUT, &gdesc->flags);
  		is_irq = test_bit(FLAG_USED_AS_IRQ, &gdesc->flags);
  		active_low = test_bit(FLAG_ACTIVE_LOW, &gdesc->flags);
  		seq_printf(s, " gpio-%-3d (%-20.20s|%-20.20s) %s %s %s%s",
  			gpio, gdesc->name ? gdesc->name : "", gdesc->label,
  			is_out ? "out" : "in ",
  			chip->get ? (chip->get(chip, i) ? "hi" : "lo") : "?  ",
  			is_irq ? "IRQ " : "",
  			active_low ? "ACTIVE LOW" : "");
  		seq_printf(s, "\n");
  	}
  }
  
  static void *gpiolib_seq_start(struct seq_file *s, loff_t *pos)
  {
  	unsigned long flags;
  	struct gpio_device *gdev = NULL;
  	loff_t index = *pos;
  
  	s->private = "";
  
  	spin_lock_irqsave(&gpio_lock, flags);
  	list_for_each_entry(gdev, &gpio_devices, list)
  		if (index-- == 0) {
  			spin_unlock_irqrestore(&gpio_lock, flags);
  			return gdev;
  		}
  	spin_unlock_irqrestore(&gpio_lock, flags);
  
  	return NULL;
  }
  
  static void *gpiolib_seq_next(struct seq_file *s, void *v, loff_t *pos)
  {
  	unsigned long flags;
  	struct gpio_device *gdev = v;
  	void *ret = NULL;
  
  	spin_lock_irqsave(&gpio_lock, flags);
  	if (list_is_last(&gdev->list, &gpio_devices))
  		ret = NULL;
  	else
  		ret = list_entry(gdev->list.next, struct gpio_device, list);
  	spin_unlock_irqrestore(&gpio_lock, flags);
  
  	s->private = "\n";
  	++*pos;
  
  	return ret;
  }
  
  static void gpiolib_seq_stop(struct seq_file *s, void *v)
  {
  }
  
  static int gpiolib_seq_show(struct seq_file *s, void *v)
  {
  	struct gpio_device *gdev = v;
  	struct gpio_chip *chip = gdev->chip;
  	struct device *parent;
  
  	if (!chip) {
  		seq_printf(s, "%s%s: (dangling chip)", (char *)s->private,
  			   dev_name(&gdev->dev));
  		return 0;
  	}
  
  	seq_printf(s, "%s%s: GPIOs %d-%d", (char *)s->private,
  		   dev_name(&gdev->dev),
  		   gdev->base, gdev->base + gdev->ngpio - 1);
  	parent = chip->parent;
  	if (parent)
  		seq_printf(s, ", parent: %s/%s",
  			   parent->bus ? parent->bus->name : "no-bus",
  			   dev_name(parent));
  	if (chip->label)
  		seq_printf(s, ", %s", chip->label);
  	if (chip->can_sleep)
  		seq_printf(s, ", can sleep");
  	seq_printf(s, ":\n");
  
  	if (chip->dbg_show)
  		chip->dbg_show(s, chip);
  	else
  		gpiolib_dbg_show(s, gdev);
  
  	return 0;
  }
  
  static const struct seq_operations gpiolib_seq_ops = {
  	.start = gpiolib_seq_start,
  	.next = gpiolib_seq_next,
  	.stop = gpiolib_seq_stop,
  	.show = gpiolib_seq_show,
  };
  
  static int gpiolib_open(struct inode *inode, struct file *file)
  {
  	return seq_open(file, &gpiolib_seq_ops);
  }
  
  static const struct file_operations gpiolib_operations = {
  	.owner		= THIS_MODULE,
  	.open		= gpiolib_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= seq_release,
  };
  
  static int __init gpiolib_debugfs_init(void)
  {
  	/* /sys/kernel/debug/gpio */
  	(void) debugfs_create_file("gpio", S_IFREG | S_IRUGO,
  				NULL, NULL, &gpiolib_operations);
  	return 0;
  }
  subsys_initcall(gpiolib_debugfs_init);
  
  #endif	/* DEBUG_FS */
  