gpiolib.c 49.9 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 "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

/* 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 struct gpio_desc gpio_desc[ARCH_NR_GPIOS];

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#define GPIO_OFFSET_VALID(chip, offset) (offset >= 0 && offset < chip->ngpio)

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static DEFINE_MUTEX(gpio_lookup_lock);
static LIST_HEAD(gpio_lookup_list);
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LIST_HEAD(gpio_chips);
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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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{
	if (WARN(!gpio_is_valid(gpio), "invalid GPIO %d\n", gpio))
		return NULL;
	else
		return &gpio_desc[gpio];
}
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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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	if (hwnum >= chip->ngpio)
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		return ERR_PTR(-EINVAL);
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	return &chip->desc[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 - &gpio_desc[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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	return desc ? desc->chip : NULL;
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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_chip *chip;
	int base = ARCH_NR_GPIOS - ngpio;
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	list_for_each_entry_reverse(chip, &gpio_chips, list) {
		/* found a free space? */
		if (chip->base + chip->ngpio <= base)
			break;
		else
			/* nope, check the space right before the chip */
			base = chip->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.
 */
int gpiod_get_direction(const 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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		/* FLAG_IS_OUT is just a cache of the result of get_direction(),
		 * so it does not affect constness per se */
		clear_bit(FLAG_IS_OUT, &((struct gpio_desc *)desc)->flags);
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	}
	if (status == 0) {
		/* GPIOF_DIR_OUT */
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		set_bit(FLAG_IS_OUT, &((struct gpio_desc *)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
 * by base order.
 *
 * Return -EBUSY if the new chip overlaps with some other chip's integer
 * space.
 */
static int gpiochip_add_to_list(struct gpio_chip *chip)
{
	struct list_head *pos = &gpio_chips;
	struct gpio_chip *_chip;
	int err = 0;

	/* find where to insert our chip */
	list_for_each(pos, &gpio_chips) {
		_chip = list_entry(pos, struct gpio_chip, list);
		/* shall we insert before _chip? */
		if (_chip->base >= chip->base + chip->ngpio)
			break;
	}

	/* are we stepping on the chip right before? */
	if (pos != &gpio_chips && pos->prev != &gpio_chips) {
		_chip = list_entry(pos->prev, struct gpio_chip, list);
		if (_chip->base + _chip->ngpio > chip->base) {
			dev_err(chip->dev,
			       "GPIO integer space overlap, cannot add chip\n");
			err = -EBUSY;
		}
	}

	if (!err)
		list_add_tail(&chip->list, pos);

	return err;
}

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/**
 * gpiochip_add() - register a gpio_chip
 * @chip: the chip to register, with chip->base initialized
 * Context: potentially before irqs or kmalloc 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.
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 *
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 * When gpiochip_add() is called very early during boot, so that GPIOs
 * can be freely used, the chip->dev device must be registered before
 * 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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 */
int gpiochip_add(struct gpio_chip *chip)
{
	unsigned long	flags;
	int		status = 0;
	unsigned	id;
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	int		base = chip->base;
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	if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))
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			&& base >= 0) {
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		status = -EINVAL;
		goto fail;
	}

	spin_lock_irqsave(&gpio_lock, flags);

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	if (base < 0) {
		base = gpiochip_find_base(chip->ngpio);
		if (base < 0) {
			status = base;
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			goto unlock;
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		}
		chip->base = base;
	}

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	status = gpiochip_add_to_list(chip);

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	if (status == 0) {
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		chip->desc = &gpio_desc[chip->base];

		for (id = 0; id < chip->ngpio; id++) {
			struct gpio_desc *desc = &chip->desc[id];
			desc->chip = chip;
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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,
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			 * and in case chip->get_direction is not set,
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			 * we may expose the wrong direction in sysfs.
			 */
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			desc->flags = !chip->direction_input
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				? (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
	INIT_LIST_HEAD(&chip->pin_ranges);
#endif

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	of_gpiochip_add(chip);
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	acpi_gpiochip_add(chip);
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	if (status)
		goto fail;

	status = gpiochip_export(chip);
	if (status)
		goto fail;

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	pr_debug("%s: registered GPIOs %d to %d on device: %s\n", __func__,
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		chip->base, chip->base + chip->ngpio - 1,
		chip->label ? : "generic");

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	return 0;
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unlock:
	spin_unlock_irqrestore(&gpio_lock, flags);
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fail:
	/* 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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		chip->base, chip->base + chip->ngpio - 1,
		chip->label ? : "generic");
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	return status;
}
EXPORT_SYMBOL_GPL(gpiochip_add);

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/* Forward-declaration */
static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip);

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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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{
	unsigned long	flags;
	unsigned	id;

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	acpi_gpiochip_remove(chip);

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	spin_lock_irqsave(&gpio_lock, flags);

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	gpiochip_irqchip_remove(chip);
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	gpiochip_remove_pin_ranges(chip);
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	of_gpiochip_remove(chip);

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	for (id = 0; id < chip->ngpio; id++) {
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		if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags))
			dev_crit(chip->dev, "REMOVING GPIOCHIP WITH GPIOS STILL REQUESTED\n");
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	}
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	for (id = 0; id < chip->ngpio; id++)
		chip->desc[id].chip = NULL;
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	list_del(&chip->list);
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	spin_unlock_irqrestore(&gpio_lock, flags);
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	gpiochip_unexport(chip);
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}
EXPORT_SYMBOL_GPL(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_chip *chip;
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	unsigned long flags;

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

/**
 * gpiochip_add_chained_irqchip() - adds a chained irqchip to a gpiochip
 * @gpiochip: the gpiochip to add the irqchip to
 * @irqchip: the irqchip to add 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,
				  int parent_irq,
				  irq_flow_handler_t parent_handler)
{
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	unsigned int offset;

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	if (gpiochip->can_sleep) {
		chip_err(gpiochip, "you cannot have chained interrupts on a chip that may sleep\n");
		return;
	}
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	if (!gpiochip->irqdomain) {
		chip_err(gpiochip, "called %s before setting up irqchip\n",
			 __func__);
		return;
	}
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	irq_set_chained_handler(parent_irq, parent_handler);
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	/*
	 * The parent irqchip is already using the chip_data for this
	 * irqchip, so our callbacks simply use the handler_data.
	 */
	irq_set_handler_data(parent_irq, gpiochip);
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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);

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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.
 */
static struct lock_class_key gpiochip_irq_lock_class;

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/**
 * 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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	irq_set_lockdep_class(irq, &gpiochip_irq_lock_class);
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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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#ifdef CONFIG_ARM
	set_irq_flags(irq, IRQF_VALID);
#else
	irq_set_noprobe(irq);
#endif
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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;

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#ifdef CONFIG_ARM
	set_irq_flags(irq, 0);
#endif
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	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);

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

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

	gpio_unlock_as_irq(chip, d->hwirq);
}

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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	/* 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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 *
 * 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 container_of() 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.
 *
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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.
 */
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 device_node *of_node;
	unsigned int offset;
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	unsigned irq_base = 0;
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	if (!gpiochip || !irqchip)
		return -EINVAL;

	if (!gpiochip->dev) {
		pr_err("missing gpiochip .dev parent pointer\n");
		return -EINVAL;
	}
	of_node = gpiochip->dev->of_node;
#ifdef CONFIG_OF_GPIO
	/*
	 * If the gpiochip has an assigned OF node this takes precendence
	 * FIXME: get rid of this and use gpiochip->dev->of_node everywhere
	 */
	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;
	gpiochip->irqdomain = irq_domain_add_simple(of_node,
					gpiochip->ngpio, first_irq,
					&gpiochip_domain_ops, gpiochip);
	if (!gpiochip->irqdomain) {
		gpiochip->irqchip = NULL;
		return -EINVAL;
	}
	irqchip->irq_request_resources = gpiochip_irq_reqres;
	irqchip->irq_release_resources = gpiochip_irq_relres;

	/*
	 * Prepare the mapping since the irqchip shall be orthogonal to
	 * any gpiochip calls. If the first_irq was zero, this is
	 * necessary to allocate descriptors for all IRQs.
	 */
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	for (offset = 0; offset < gpiochip->ngpio; offset++) {
		irq_base = irq_create_mapping(gpiochip->irqdomain, offset);
		if (offset == 0)
			/*
			 * Store the base into the gpiochip to be used when
			 * unmapping the irqs.
			 */
			gpiochip->irq_base = irq_base;
	}
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	acpi_gpiochip_request_interrupts(gpiochip);

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	return 0;
}
EXPORT_SYMBOL_GPL(gpiochip_irqchip_add);

#else /* CONFIG_GPIOLIB_IRQCHIP */

static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip) {}

#endif /* CONFIG_GPIOLIB_IRQCHIP */

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#ifdef CONFIG_PINCTRL
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/**
 * gpiochip_add_pingroup_range() - add a range for GPIO <-> pin mapping
 * @chip: the gpiochip to add the range for
 * @pinctrl: the dev_name() of 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
 */
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;
	int ret;

	pin_range = kzalloc(sizeof(*pin_range), GFP_KERNEL);
	if (!pin_range) {
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		chip_err(chip, "failed to allocate pin ranges\n");
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		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 = chip->base + gpio_offset;
	pin_range->pctldev = pctldev;

	ret = pinctrl_get_group_pins(pctldev, pin_group,
					&pin_range->range.pins,
					&pin_range->range.npins);
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	if (ret < 0) {
		kfree(pin_range);
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		return ret;
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	}
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	pinctrl_add_gpio_range(pctldev, &pin_range->range);

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	chip_dbg(chip, "created GPIO range %d->%d ==> %s PINGRP %s\n",
		 gpio_offset, gpio_offset + pin_range->range.npins - 1,
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		 pinctrl_dev_get_devname(pctldev), pin_group);

	list_add_tail(&pin_range->node, &chip->pin_ranges);

	return 0;
}
EXPORT_SYMBOL_GPL(gpiochip_add_pingroup_range);

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/**
 * gpiochip_add_pin_range() - add a range for GPIO <-> pin mapping
 * @chip: the gpiochip to add the range for
 * @pinctrl_name: the dev_name() of the pin controller to map to
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 * @gpio_offset: the start offset in the current gpio_chip number space
 * @pin_offset: the start offset in the pin controller number space
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 * @npins: the number of pins from the offset of each pin space (GPIO and
 *	pin controller) to accumulate in this range
 */
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int gpiochip_add_pin_range(struct gpio_chip *chip, const char *pinctl_name,
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			   unsigned int gpio_offset, unsigned int pin_offset,
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			   unsigned int npins)
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{
	struct gpio_pin_range *pin_range;
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	int ret;
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	pin_range = kzalloc(sizeof(*pin_range), GFP_KERNEL);
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	if (!pin_range) {
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		chip_err(chip, "failed to allocate pin ranges\n");
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		return -ENOMEM;
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	}

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	/* Use local offset as range ID */
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	pin_range->range.id = gpio_offset;
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	pin_range->range.gc = chip;
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	pin_range->range.name = chip->label;
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	pin_range->range.base = chip->base + gpio_offset;
	pin_range->range.pin_base = pin_offset;
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	pin_range->range.npins = npins;
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	pin_range->pctldev = pinctrl_find_and_add_gpio_range(pinctl_name,
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			&pin_range->range);
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	if (IS_ERR(pin_range->pctldev)) {
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		ret = PTR_ERR(pin_range->pctldev);
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		chip_err(chip, "could not create pin range\n");
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		kfree(pin_range);
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		return ret;
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	}
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	chip_dbg(chip, "created GPIO range %d->%d ==> %s PIN %d->%d\n",
		 gpio_offset, gpio_offset + npins - 1,
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		 pinctl_name,
		 pin_offset, pin_offset + npins - 1);
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	list_add_tail(&pin_range->node, &chip->pin_ranges);
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	return 0;
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}
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EXPORT_SYMBOL_GPL(gpiochip_add_pin_range);
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/**
 * gpiochip_remove_pin_ranges() - remove all the GPIO <-> pin mappings
 * @chip: the chip to remove all the mappings for
 */
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void gpiochip_remove_pin_ranges(struct gpio_chip *chip)
{
	struct gpio_pin_range *pin_range, *tmp;

	list_for_each_entry_safe(pin_range, tmp, &chip->pin_ranges, node) {
		list_del(&pin_range->node);
		pinctrl_remove_gpio_range(pin_range->pctldev,
				&pin_range->range);
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		kfree(pin_range);
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	}
}
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EXPORT_SYMBOL_GPL(gpiochip_remove_pin_ranges);

#endif /* CONFIG_PINCTRL */
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/* 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.
 */
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static int __gpiod_request(struct gpio_desc *desc, const char *label)
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{
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	struct gpio_chip	*chip = desc->chip;
	int			status;
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	unsigned long		flags;

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	spin_lock_irqsave(&gpio_lock, flags);

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	/* NOTE:  gpio_request() can be called in early boot,
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	 * before IRQs are enabled, for non-sleeping (SOC) GPIOs.
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	 */

	if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
		desc_set_label(desc, label ? : "?");
		status = 0;
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	} else {
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		status = -EBUSY;
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		goto done;
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	}

	if (chip->request) {
		/* chip->request may sleep */
		spin_unlock_irqrestore(&gpio_lock, flags);
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		status = chip->request(chip, gpio_chip_hwgpio(desc));
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		spin_lock_irqsave(&gpio_lock, flags);

		if (status < 0) {
			desc_set_label(desc, NULL);
			clear_bit(FLAG_REQUESTED, &desc->flags);
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			goto done;
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		}
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	}
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	if (chip->get_direction) {
		/* chip->get_direction may sleep */
		spin_unlock_irqrestore(&gpio_lock, flags);
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		gpiod_get_direction(desc);
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		spin_lock_irqsave(&gpio_lock, flags);
	}
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done:
	spin_unlock_irqrestore(&gpio_lock, flags);
	return status;
}

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int gpiod_request(struct gpio_desc *desc, const char *label)
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{
	int status = -EPROBE_DEFER;
	struct gpio_chip *chip;

	if (!desc) {
		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
	}

	chip = desc->chip;
	if (!chip)
		goto done;

	if (try_module_get(chip->owner)) {
		status = __gpiod_request(desc, label);
		if (status < 0)
			module_put(chip->owner);
	}

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done:
	if (status)
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		gpiod_dbg(desc, "%s: status %d\n", __func__, status);
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	return status;
}
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static bool __gpiod_free(struct gpio_desc *desc)
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{
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	bool			ret = false;
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	unsigned long		flags;
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	struct gpio_chip	*chip;
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	might_sleep();

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	gpiod_unexport(desc);
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	spin_lock_irqsave(&gpio_lock, flags);

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	chip = desc->chip;
	if (chip && test_bit(FLAG_REQUESTED, &desc->flags)) {
		if (chip->free) {
			spin_unlock_irqrestore(&gpio_lock, flags);
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			might_sleep_if(chip->can_sleep);
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			chip->free(chip, gpio_chip_hwgpio(desc));
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			spin_lock_irqsave(&gpio_lock, flags);
		}
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		desc_set_label(desc, NULL);
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		clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
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		clear_bit(FLAG_REQUESTED, &desc->flags);
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		clear_bit(FLAG_OPEN_DRAIN, &desc->flags);
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		clear_bit(FLAG_OPEN_SOURCE, &desc->flags);
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		ret = true;
	}
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	spin_unlock_irqrestore(&gpio_lock, flags);
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	return ret;
}

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void gpiod_free(struct gpio_desc *desc)
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{
	if (desc && __gpiod_free(desc))
		module_put(desc->chip->owner);
	else
		WARN_ON(extra_checks);
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}
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/**
 * 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.
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 * The string returned is the label passed to gpio_request(); if none has been
 * passed it is a meaningless, non-NULL constant.
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 *
 * 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)
{
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	struct gpio_desc *desc;
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	if (!GPIO_OFFSET_VALID(chip, offset))
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		return NULL;
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	desc = &chip->desc[offset];

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	if (test_bit(FLAG_REQUESTED, &desc->flags) == 0)
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		return NULL;
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	return desc->label;
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}
EXPORT_SYMBOL_GPL(gpiochip_is_requested);

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/**
 * gpiochip_request_own_desc - Allow GPIO chip to request its own descriptor
 * @desc: GPIO descriptor to request
 * @label: label for the GPIO
 *
 * 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).
 */
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struct gpio_desc *gpiochip_request_own_desc(struct gpio_chip *chip, u16 hwnum,
					    const char *label)
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{
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	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(desc, label);
	if (err < 0)
		return ERR_PTR(err);
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	return desc;
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}
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EXPORT_SYMBOL_GPL(gpiochip_request_own_desc);
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/**
 * 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(desc);
}
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EXPORT_SYMBOL_GPL(gpiochip_free_own_desc);
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/* 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.
 */

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/**
 * 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)
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{
	struct gpio_chip	*chip;
	int			status = -EINVAL;

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	if (!desc || !desc->chip) {
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		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
	}

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	chip = desc->chip;
	if (!chip->get || !chip->direction_input) {
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		gpiod_warn(desc,
			"%s: missing get() or direction_input() operations\n",
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			__func__);
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		return -EIO;
	}

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	status = chip->direction_input(chip, gpio_chip_hwgpio(desc));
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	if (status == 0)
		clear_bit(FLAG_IS_OUT, &desc->flags);
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	trace_gpio_direction(desc_to_gpio(desc), 1, status);
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	return status;
}
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EXPORT_SYMBOL_GPL(gpiod_direction_input);
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static int _gpiod_direction_output_raw(struct gpio_desc *desc, int value)
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{
	struct gpio_chip	*chip;
	int			status = -EINVAL;

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	/* GPIOs used for IRQs shall not be set as output */
	if (test_bit(FLAG_USED_AS_IRQ, &desc->flags)) {
		gpiod_err(desc,
			  "%s: tried to set a GPIO tied to an IRQ as output\n",
			  __func__);
		return -EIO;
	}

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	/* Open drain pin should not be driven to 1 */
	if (value && test_bit(FLAG_OPEN_DRAIN,  &desc->flags))
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		return gpiod_direction_input(desc);
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	/* Open source pin should not be driven to 0 */
	if (!value && test_bit(FLAG_OPEN_SOURCE,  &desc->flags))
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		return gpiod_direction_input(desc);
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	chip = desc->chip;
	if (!chip->set || !chip->direction_output) {
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		gpiod_warn(desc,
		       "%s: missing set() or direction_output() operations\n",
		       __func__);
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		return -EIO;
	}

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	status = chip->direction_output(chip, gpio_chip_hwgpio(desc), value);
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	if (status == 0)
		set_bit(FLAG_IS_OUT, &desc->flags);
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	trace_gpio_value(desc_to_gpio(desc), 0, value);
	trace_gpio_direction(desc_to_gpio(desc), 0, status);
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	return status;
}
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/**
 * 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)
{
	if (!desc || !desc->chip) {
		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
	}
	return _gpiod_direction_output_raw(desc, value);
}
EXPORT_SYMBOL_GPL(gpiod_direction_output_raw);

/**
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 * gpiod_direction_output - set the GPIO direction to output
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 * @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)
{
	if (!desc || !desc->chip) {
		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
	}
	if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
		value = !value;
	return _gpiod_direction_output_raw(desc, value);
}
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EXPORT_SYMBOL_GPL(gpiod_direction_output);
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1063
/**
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 * gpiod_set_debounce - sets @debounce time for a @gpio
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 * @gpio: the gpio to set debounce time
 * @debounce: debounce time is microseconds
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 *
 * returns -ENOTSUPP if the controller does not support setting
 * debounce.
1070
 */
1071
int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce)
1072 1073 1074
{
	struct gpio_chip	*chip;

1075
	if (!desc || !desc->chip) {
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		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
	}

1080
	chip = desc->chip;
1081
	if (!chip->set || !chip->set_debounce) {
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		gpiod_dbg(desc,
			  "%s: missing set() or set_debounce() operations\n",
			  __func__);
1085
		return -ENOTSUPP;
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	}

1088
	return chip->set_debounce(chip, gpio_chip_hwgpio(desc), debounce);
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}
1090
EXPORT_SYMBOL_GPL(gpiod_set_debounce);
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/**
 * 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)
1099
{
1100
	return test_bit(FLAG_ACTIVE_LOW, &desc->flags);
1101
}
1102
EXPORT_SYMBOL_GPL(gpiod_is_active_low);
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