gpiolib.c 80.4 KB
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#include <linux/kernel.h>
#include <linux/module.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
#include <linux/spinlock.h>
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#include <linux/list.h>
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#include <linux/device.h>
#include <linux/err.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/gpio.h>
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#include <linux/of_gpio.h>
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#include <linux/idr.h>
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#include <linux/slab.h>
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#include <linux/acpi.h>
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#include <linux/gpio/driver.h>
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#include <linux/gpio/machine.h>
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#include <linux/pinctrl/consumer.h>
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#include <linux/idr.h>
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#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <uapi/linux/gpio.h>
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#include "gpiolib.h"

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


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

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


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static inline void desc_set_label(struct gpio_desc *d, const char *label)
{
	d->label = label;
}

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

	spin_lock_irqsave(&gpio_lock, flags);

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

	spin_unlock_irqrestore(&gpio_lock, flags);

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

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

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

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

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

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

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

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

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

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

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

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

	spin_lock_irqsave(&gpio_lock, flags);

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

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

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

	spin_unlock_irqrestore(&gpio_lock, flags);

	return NULL;
}

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

	if (!gc->names)
		return 0;

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

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

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

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/**
 * gpio_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;
	int __user *ip = (int __user *)arg;

	/* We fail any subsequent ioctl():s when the chip is gone */
	if (!chip)
		return -ENODEV;

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

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

		if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
			return -EFAULT;
		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) {
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			strncpy(lineinfo.consumer, desc->label,
				sizeof(lineinfo.consumer));
			lineinfo.consumer[sizeof(lineinfo.consumer)-1] = '\0';
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		} else {
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			lineinfo.consumer[0] = '\0';
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		}

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

		if (copy_to_user(ip, &lineinfo, sizeof(lineinfo)))
			return -EFAULT;
		return 0;
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	}
	return -EINVAL;
}

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

	/* Fail on open if the backing gpiochip is gone */
	if (!gdev || !gdev->chip)
		return -ENODEV;
	get_device(&gdev->dev);
	filp->private_data = gdev;
	return 0;
}

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

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


static const struct file_operations gpio_fileops = {
	.release = gpio_chrdev_release,
	.open = gpio_chrdev_open,
	.owner = THIS_MODULE,
	.llseek = noop_llseek,
	.unlocked_ioctl = gpio_ioctl,
	.compat_ioctl = gpio_ioctl,
};

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

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

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

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

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

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	/*
	 * TODO: this allocates a Linux GPIO number base in the global
	 * GPIO numberspace for this chip. In the long run we want to
	 * get *rid* of this numberspace and use only descriptors, but
	 * it may be a pipe dream. It will not happen before we get rid
	 * of the sysfs interface anyways.
	 */
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	if (base < 0) {
		base = gpiochip_find_base(chip->ngpio);
		if (base < 0) {
			status = base;
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			spin_unlock_irqrestore(&gpio_lock, flags);
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			goto err_free_label;
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		}
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		/*
		 * TODO: it should not be necessary to reflect the assigned
		 * base outside of the GPIO subsystem. Go over drivers and
		 * see if anyone makes use of this, else drop this and assign
		 * a poison instead.
		 */
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		chip->base = base;
	}
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	gdev->base = base;
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	status = gpiodev_add_to_list(gdev);
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	if (status) {
		spin_unlock_irqrestore(&gpio_lock, flags);
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		goto err_free_label;
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	}
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	for (i = 0; i < chip->ngpio; i++) {
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		struct gpio_desc *desc = &gdev->descs[i];
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		desc->gdev = gdev;
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		/* REVISIT: most hardware initializes GPIOs as inputs (often
		 * with pullups enabled) so power usage is minimized. Linux
		 * code should set the gpio direction first thing; but until
		 * it does, and in case chip->get_direction is not set, we may
		 * expose the wrong direction in sysfs.
		 */
		desc->flags = !chip->direction_input ? (1 << FLAG_IS_OUT) : 0;
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	}
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	spin_unlock_irqrestore(&gpio_lock, flags);

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

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

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

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

	/* From this point, the .release() function cleans up gpio_device */
	gdev->dev.release = gpiodevice_release;
	get_device(&gdev->dev);
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	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), chip->label ? : "generic");
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	return 0;
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err_remove_device:
	device_del(&gdev->dev);
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err_remove_chardev:
	cdev_del(&gdev->chrdev);
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err_remove_chip:
	acpi_gpiochip_remove(chip);
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	gpiochip_free_hogs(chip);
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	of_gpiochip_remove(chip);
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err_remove_from_list:
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	spin_lock_irqsave(&gpio_lock, flags);
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	list_del(&gdev->list);
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	spin_unlock_irqrestore(&gpio_lock, flags);
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err_free_label:
	kfree(gdev->label);
err_free_descs:
	kfree(gdev->descs);
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err_free_gdev:
	ida_simple_remove(&gpio_ida, gdev->id);
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	/* failures here can mean systems won't boot... */
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	pr_err("%s: GPIOs %d..%d (%s) failed to register\n", __func__,
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	       gdev->base, gdev->base + gdev->ngpio - 1,
	       chip->label ? : "generic");
	kfree(gdev);
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	return status;
}
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EXPORT_SYMBOL_GPL(gpiochip_add_data);
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/**
 * gpiochip_get_data() - get per-subdriver data for the chip
 */
void *gpiochip_get_data(struct gpio_chip *chip)
{
	return chip->gpiodev->data;
}
EXPORT_SYMBOL_GPL(gpiochip_get_data);

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/**
 * gpiochip_remove() - unregister a gpio_chip
 * @chip: the chip to unregister
 *
 * A gpio_chip with any GPIOs still requested may not be removed.
 */
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void gpiochip_remove(struct gpio_chip *chip)
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{
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	struct gpio_device *gdev = chip->gpiodev;
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	struct gpio_desc *desc;
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	unsigned long	flags;
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	unsigned	i;
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	bool		requested = false;
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	/* FIXME: should the legacy sysfs handling be moved to gpio_device? */
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	gpiochip_sysfs_unregister(gdev);
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	/* Numb the device, cancelling all outstanding operations */
	gdev->chip = NULL;
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	gpiochip_irqchip_remove(chip);
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	acpi_gpiochip_remove(chip);
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	gpiochip_remove_pin_ranges(chip);
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	gpiochip_free_hogs(chip);
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	of_gpiochip_remove(chip);
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	/*
	 * We accept no more calls into the driver from this point, so
	 * NULL the driver data pointer
	 */
	gdev->data = NULL;
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	spin_lock_irqsave(&gpio_lock, flags);
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	for (i = 0; i < gdev->ngpio; i++) {
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		desc = &gdev->descs[i];
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		if (test_bit(FLAG_REQUESTED, &desc->flags))
			requested = true;
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	}
	spin_unlock_irqrestore(&gpio_lock, flags);
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	if (requested)
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		dev_crit(&gdev->dev,
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			 "REMOVING GPIOCHIP WITH GPIOS STILL REQUESTED\n");
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	/*
	 * 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.
	 */
	put_device(&gdev->dev);
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}
EXPORT_SYMBOL_GPL(gpiochip_remove);

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static void devm_gpio_chip_release(struct device *dev, void *res)
{
	struct gpio_chip *chip = *(struct gpio_chip **)res;

	gpiochip_remove(chip);
}

static int devm_gpio_chip_match(struct device *dev, void *res, void *data)

{
	struct gpio_chip **r = res;

	if (!r || !*r) {
		WARN_ON(!r || !*r);
		return 0;
	}

	return *r == data;
}

/**
 * devm_gpiochip_add_data() - Resource manager piochip_add_data()
 * @dev: the device pointer on which irq_chip belongs to.
 * @chip: the chip to register, with chip->base initialized
 * Context: potentially before irqs will work
 *
 * 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.
 *
 * The gpio chip automatically be released when the device is unbound.
 */
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);

/**
 * devm_gpiochip_remove() - Resource manager of gpiochip_remove()
 * @dev: device for which which resource was allocated
 * @chip: the chip to remove
 *
 * A gpio_chip with any GPIOs still requested may not be removed.
 */
void devm_gpiochip_remove(struct device *dev, struct gpio_chip *chip)
{
	int ret;

	ret = devres_release(dev, devm_gpio_chip_release,
			     devm_gpio_chip_match, chip);
	if (!ret)
		WARN_ON(ret);
}
EXPORT_SYMBOL_GPL(devm_gpiochip_remove);

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/**
 * gpiochip_find() - iterator for locating a specific gpio_chip
 * @data: data to pass to match function
 * @callback: 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.
 */
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struct gpio_chip *gpiochip_find(void *data,
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				int (*match)(struct gpio_chip *chip,
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					     void *data))
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{
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	struct gpio_device *gdev;
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	struct gpio_chip *chip;
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	unsigned long flags;

	spin_lock_irqsave(&gpio_lock, flags);
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	list_for_each_entry(gdev, &gpio_devices, list)
		if (match(gdev->chip, data))
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			break;
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	/* No match? */
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	if (&gdev->list == &gpio_devices)
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		chip = NULL;
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	else
		chip = gdev->chip;

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	spin_unlock_irqrestore(&gpio_lock, flags);

	return chip;
}
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EXPORT_SYMBOL_GPL(gpiochip_find);
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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);
}

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#ifdef CONFIG_GPIOLIB_IRQCHIP

/*
 * The following is irqchip helper code for gpiochips.
 */

/**
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 * gpiochip_set_chained_irqchip() - sets a chained irqchip to a gpiochip
 * @gpiochip: the gpiochip to set the irqchip chain to
 * @irqchip: the irqchip to chain to the gpiochip
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 * @parent_irq: the irq number corresponding to the parent IRQ for this
 * chained irqchip
 * @parent_handler: the parent interrupt handler for the accumulated IRQ
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 * coming out of the gpiochip. If the interrupt is nested rather than
 * cascaded, pass NULL in this handler argument
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 */
void gpiochip_set_chained_irqchip(struct gpio_chip *gpiochip,
				  struct irq_chip *irqchip,
				  int parent_irq,
				  irq_flow_handler_t parent_handler)
{
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	unsigned int offset;

	if (!gpiochip->irqdomain) {
		chip_err(gpiochip, "called %s before setting up irqchip\n",
			 __func__);
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		return;
	}

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	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.
		 */
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		irq_set_chained_handler_and_data(parent_irq, parent_handler,
						 gpiochip);
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		gpiochip->irq_parent = parent_irq;
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	}
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	/* Set the parent IRQ for all affected IRQs */
	for (offset = 0; offset < gpiochip->ngpio; offset++)
		irq_set_parent(irq_find_mapping(gpiochip->irqdomain, offset),
			       parent_irq);
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}
EXPORT_SYMBOL_GPL(gpiochip_set_chained_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.
 */
static int gpiochip_irq_map(struct irq_domain *d, unsigned int irq,
			    irq_hw_number_t hwirq)
{
	struct gpio_chip *chip = d->host_data;

	irq_set_chip_data(irq, chip);
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	/*
	 * 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->lock_key);
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	irq_set_chip_and_handler(irq, chip->irqchip, chip->irq_handler);
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	/* Chips that can sleep need nested thread handlers */
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	if (chip->can_sleep && !chip->irq_not_threaded)
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		irq_set_nested_thread(irq, 1);
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	irq_set_noprobe(irq);
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	/*
	 * 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);
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	return 0;
}

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static void gpiochip_irq_unmap(struct irq_domain *d, unsigned int irq)
{
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	struct gpio_chip *chip = d->host_data;

	if (chip->can_sleep)
		irq_set_nested_thread(irq, 0);
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	irq_set_chip_and_handler(irq, NULL, NULL);
	irq_set_chip_data(irq, NULL);
}

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static const struct irq_domain_ops gpiochip_domain_ops = {
	.map	= gpiochip_irq_map,
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	.unmap	= gpiochip_irq_unmap,
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	/* Virtually all GPIO irqchips are twocell:ed */
	.xlate	= irq_domain_xlate_twocell,
};

static int gpiochip_irq_reqres(struct irq_data *d)
{
	struct gpio_chip *chip = irq_data_get_irq_chip_data(d);

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	if (!try_module_get(chip->gpiodev->owner))
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		return -ENODEV;

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	if (gpiochip_lock_as_irq(chip, d->hwirq)) {
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		chip_err(chip,
			"unable to lock HW IRQ %lu for IRQ\n",
			d->hwirq);
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		module_put(chip->gpiodev->owner);
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		return -EINVAL;
	}
	return 0;
}

static void gpiochip_irq_relres(struct irq_data *d)
{
	struct gpio_chip *chip = irq_data_get_irq_chip_data(d);

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	gpiochip_unlock_as_irq(chip, d->hwirq);
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	module_put(chip->gpiodev->owner);
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}

static int gpiochip_to_irq(struct gpio_chip *chip, unsigned offset)
{
	return irq_find_mapping(chip->irqdomain, offset);
}

/**
 * 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)
{
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	unsigned int offset;

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	acpi_gpiochip_free_interrupts(gpiochip);

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	if (gpiochip->irq_parent) {
		irq_set_chained_handler(gpiochip->irq_parent, NULL);
		irq_set_handler_data(gpiochip->irq_parent, NULL);
	}

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	/* Remove all IRQ mappings and delete the domain */
	if (gpiochip->irqdomain) {
		for (offset = 0; offset < gpiochip->ngpio; offset++)
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			irq_dispose_mapping(
				irq_find_mapping(gpiochip->irqdomain, offset));
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		irq_domain_remove(gpiochip->irqdomain);
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	}
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	if (gpiochip->irqchip) {
		gpiochip->irqchip->irq_request_resources = NULL;
		gpiochip->irqchip->irq_release_resources = NULL;
		gpiochip->irqchip = NULL;
	}
}

/**
 * gpiochip_irqchip_add() - 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)
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 * @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.
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 * @lock_key: lockdep class
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 *
 * 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
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 * need to use gpiochip_get_data() to get their local state containers back
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 * 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.
 *
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 * This function will handle two cell:ed simple IRQs and assumes all
 * the pins on the gpiochip can generate a unique IRQ. Everything else
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 * need to be open coded.
 */
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int _gpiochip_irqchip_add(struct gpio_chip *gpiochip,
			  struct irq_chip *irqchip,
			  unsigned int first_irq,
			  irq_flow_handler_t handler,
			  unsigned int type,
			  struct lock_class_key *lock_key)
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{
	struct device_node *of_node;
	unsigned int offset;
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	unsigned irq_base = 0;
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	if (!gpiochip || !irqchip)
		return -EINVAL;

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	if (!gpiochip->parent) {
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		pr_err("missing gpiochip .dev parent pointer\n");
		return -EINVAL;
	}
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	of_node = gpiochip->parent->of_node;
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#ifdef CONFIG_OF_GPIO
	/*
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	 * If the gpiochip has an assigned OF node this takes precedence
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	 * FIXME: get rid of this and use gpiochip->parent->of_node
	 * everywhere
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	 */
	if (gpiochip->of_node)
		of_node = gpiochip->of_node;
#endif
	gpiochip->irqchip = irqchip;
	gpiochip->irq_handler = handler;
	gpiochip->irq_default_type = type;
	gpiochip->to_irq = gpiochip_to_irq;
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	gpiochip->lock_key = lock_key;
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	gpiochip->irqdomain = irq_domain_add_simple(of_node,
					gpiochip->ngpio, first_irq,
					&gpiochip_domain_ops, gpiochip);
	if (!gpiochip->irqdomain) {
		gpiochip->irqchip = NULL;
		return -EINVAL;
	}