gpiolib.c 53.4 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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#define CREATE_TRACE_POINTS
#include <trace/events/gpio.h>
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/* Optional implementation infrastructure for GPIO interfaces.
 *
 * Platforms may want to use this if they tend to use very many GPIOs
 * that aren't part of a System-On-Chip core; or across I2C/SPI/etc.
 *
 * When kernel footprint or instruction count is an issue, simpler
 * implementations may be preferred.  The GPIO programming interface
 * allows for inlining speed-critical get/set operations for common
 * cases, so that access to SOC-integrated GPIOs can sometimes cost
 * only an instruction or two per bit.
 */


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

/* 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.
 */
static DEFINE_SPINLOCK(gpio_lock);

struct gpio_desc {
	struct gpio_chip	*chip;
	unsigned long		flags;
/* flag symbols are bit numbers */
#define FLAG_REQUESTED	0
#define FLAG_IS_OUT	1
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#define FLAG_EXPORT	2	/* protected by sysfs_lock */
#define FLAG_SYSFS	3	/* exported via /sys/class/gpio/control */
#define FLAG_TRIG_FALL	4	/* trigger on falling edge */
#define FLAG_TRIG_RISE	5	/* trigger on rising edge */
#define FLAG_ACTIVE_LOW	6	/* sysfs value has active low */
#define FLAG_OPEN_DRAIN	7	/* Gpio is open drain type */
#define FLAG_OPEN_SOURCE 8	/* Gpio is open source type */
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#define ID_SHIFT	16	/* add new flags before this one */
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#define GPIO_FLAGS_MASK		((1 << ID_SHIFT) - 1)
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#define GPIO_TRIGGER_MASK	(BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE))
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#ifdef CONFIG_DEBUG_FS
	const char		*label;
#endif
};
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 LIST_HEAD(gpio_chips);

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#ifdef CONFIG_GPIO_SYSFS
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static DEFINE_IDR(dirent_idr);
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#endif

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/*
 * Internal gpiod_* API using descriptors instead of the integer namespace.
 * Most of this should eventually go public.
 */
static int gpiod_request(struct gpio_desc *desc, const char *label);
static void gpiod_free(struct gpio_desc *desc);
static int gpiod_direction_input(struct gpio_desc *desc);
static int gpiod_direction_output(struct gpio_desc *desc, int value);
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static int gpiod_get_direction(const struct gpio_desc *desc);
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static int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce);
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static int gpiod_get_value_cansleep(const struct gpio_desc *desc);
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static void gpiod_set_value_cansleep(struct gpio_desc *desc, int value);
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static int gpiod_get_value(const struct gpio_desc *desc);
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static void gpiod_set_value(struct gpio_desc *desc, int value);
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static int gpiod_cansleep(const struct gpio_desc *desc);
static int gpiod_to_irq(const struct gpio_desc *desc);
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static int gpiod_export(struct gpio_desc *desc, bool direction_may_change);
static int gpiod_export_link(struct device *dev, const char *name,
			     struct gpio_desc *desc);
static int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value);
static void gpiod_unexport(struct gpio_desc *desc);


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

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/*
 * Return the GPIO number of the passed descriptor relative to its chip
 */
static int gpio_chip_hwgpio(const struct gpio_desc *desc)
{
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	return desc - &desc->chip->desc[0];
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}

/**
 * Convert a GPIO number to its descriptor
 */
static struct gpio_desc *gpio_to_desc(unsigned gpio)
{
	if (WARN(!gpio_is_valid(gpio), "invalid GPIO %d\n", gpio))
		return NULL;
	else
		return &gpio_desc[gpio];
}

/**
 * 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
 */
static int desc_to_gpio(const struct gpio_desc *desc)
{
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	return desc->chip->base + gpio_chip_hwgpio(desc);
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}


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/* Warn when drivers omit gpio_request() calls -- legal but ill-advised
 * when setting direction, and otherwise illegal.  Until board setup code
 * and drivers use explicit requests everywhere (which won't happen when
 * those calls have no teeth) we can't avoid autorequesting.  This nag
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 * message should motivate switching to explicit requests... so should
 * the weaker cleanup after faults, compared to gpio_request().
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 *
 * NOTE: the autorequest mechanism is going away; at this point it's
 * only "legal" in the sense that (old) code using it won't break yet,
 * but instead only triggers a WARN() stack dump.
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 */
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static int gpio_ensure_requested(struct gpio_desc *desc)
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{
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	const struct gpio_chip *chip = desc->chip;
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	const int gpio = desc_to_gpio(desc);
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	if (WARN(test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0,
			"autorequest GPIO-%d\n", gpio)) {
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		if (!try_module_get(chip->owner)) {
			pr_err("GPIO-%d: module can't be gotten \n", gpio);
			clear_bit(FLAG_REQUESTED, &desc->flags);
			/* lose */
			return -EIO;
		}
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		desc_set_label(desc, "[auto]");
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		/* caller must chip->request() w/o spinlock */
		if (chip->request)
			return 1;
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	}
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	return 0;
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}

/* caller holds gpio_lock *OR* gpio is marked as requested */
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static 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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struct gpio_chip *gpio_to_chip(unsigned gpio)
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{
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	return gpiod_to_chip(gpio_to_desc(gpio));
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}

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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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/* caller ensures gpio is valid and requested, chip->get_direction may sleep  */
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static 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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#ifdef CONFIG_GPIO_SYSFS

/* lock protects against unexport_gpio() being called while
 * sysfs files are active.
 */
static DEFINE_MUTEX(sysfs_lock);

/*
 * /sys/class/gpio/gpioN... only for GPIOs that are exported
 *   /direction
 *      * MAY BE OMITTED if kernel won't allow direction changes
 *      * is read/write as "in" or "out"
 *      * may also be written as "high" or "low", initializing
 *        output value as specified ("out" implies "low")
 *   /value
 *      * always readable, subject to hardware behavior
 *      * may be writable, as zero/nonzero
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 *   /edge
 *      * configures behavior of poll(2) on /value
 *      * available only if pin can generate IRQs on input
 *      * is read/write as "none", "falling", "rising", or "both"
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 *   /active_low
 *      * configures polarity of /value
 *      * is read/write as zero/nonzero
 *      * also affects existing and subsequent "falling" and "rising"
 *        /edge configuration
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 */

static ssize_t gpio_direction_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
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	const struct gpio_desc	*desc = dev_get_drvdata(dev);
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	ssize_t			status;

	mutex_lock(&sysfs_lock);

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	if (!test_bit(FLAG_EXPORT, &desc->flags)) {
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		status = -EIO;
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	} else {
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		gpiod_get_direction(desc);
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		status = sprintf(buf, "%s\n",
			test_bit(FLAG_IS_OUT, &desc->flags)
				? "out" : "in");
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	}
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	mutex_unlock(&sysfs_lock);
	return status;
}

static ssize_t gpio_direction_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t size)
{
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	struct gpio_desc	*desc = dev_get_drvdata(dev);
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	ssize_t			status;

	mutex_lock(&sysfs_lock);

	if (!test_bit(FLAG_EXPORT, &desc->flags))
		status = -EIO;
	else if (sysfs_streq(buf, "high"))
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		status = gpiod_direction_output(desc, 1);
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	else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
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		status = gpiod_direction_output(desc, 0);
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	else if (sysfs_streq(buf, "in"))
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		status = gpiod_direction_input(desc);
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	else
		status = -EINVAL;

	mutex_unlock(&sysfs_lock);
	return status ? : size;
}

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static /* const */ DEVICE_ATTR(direction, 0644,
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		gpio_direction_show, gpio_direction_store);

static ssize_t gpio_value_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
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	struct gpio_desc	*desc = dev_get_drvdata(dev);
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	ssize_t			status;

	mutex_lock(&sysfs_lock);

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	if (!test_bit(FLAG_EXPORT, &desc->flags)) {
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		status = -EIO;
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	} else {
		int value;

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		value = !!gpiod_get_value_cansleep(desc);
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		if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
			value = !value;

		status = sprintf(buf, "%d\n", value);
	}
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	mutex_unlock(&sysfs_lock);
	return status;
}

static ssize_t gpio_value_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t size)
{
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	struct gpio_desc	*desc = dev_get_drvdata(dev);
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	ssize_t			status;

	mutex_lock(&sysfs_lock);

	if (!test_bit(FLAG_EXPORT, &desc->flags))
		status = -EIO;
	else if (!test_bit(FLAG_IS_OUT, &desc->flags))
		status = -EPERM;
	else {
		long		value;

		status = strict_strtol(buf, 0, &value);
		if (status == 0) {
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			if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
				value = !value;
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			gpiod_set_value_cansleep(desc, value != 0);
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			status = size;
		}
	}

	mutex_unlock(&sysfs_lock);
	return status;
}

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static const DEVICE_ATTR(value, 0644,
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		gpio_value_show, gpio_value_store);

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static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
{
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	struct sysfs_dirent	*value_sd = priv;
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	sysfs_notify_dirent(value_sd);
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	return IRQ_HANDLED;
}

static int gpio_setup_irq(struct gpio_desc *desc, struct device *dev,
		unsigned long gpio_flags)
{
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	struct sysfs_dirent	*value_sd;
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	unsigned long		irq_flags;
	int			ret, irq, id;

	if ((desc->flags & GPIO_TRIGGER_MASK) == gpio_flags)
		return 0;

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	irq = gpiod_to_irq(desc);
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	if (irq < 0)
		return -EIO;

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	id = desc->flags >> ID_SHIFT;
	value_sd = idr_find(&dirent_idr, id);
	if (value_sd)
		free_irq(irq, value_sd);
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	desc->flags &= ~GPIO_TRIGGER_MASK;

	if (!gpio_flags) {
		ret = 0;
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		goto free_id;
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	}

	irq_flags = IRQF_SHARED;
	if (test_bit(FLAG_TRIG_FALL, &gpio_flags))
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		irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
			IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
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	if (test_bit(FLAG_TRIG_RISE, &gpio_flags))
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		irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
			IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
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	if (!value_sd) {
		value_sd = sysfs_get_dirent(dev->kobj.sd, NULL, "value");
		if (!value_sd) {
			ret = -ENODEV;
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			goto err_out;
		}

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		ret = idr_alloc(&dirent_idr, value_sd, 1, 0, GFP_KERNEL);
		if (ret < 0)
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			goto free_sd;
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		id = ret;
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		desc->flags &= GPIO_FLAGS_MASK;
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		desc->flags |= (unsigned long)id << ID_SHIFT;
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		if (desc->flags >> ID_SHIFT != id) {
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			ret = -ERANGE;
			goto free_id;
		}
	}

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	ret = request_any_context_irq(irq, gpio_sysfs_irq, irq_flags,
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				"gpiolib", value_sd);
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	if (ret < 0)
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		goto free_id;
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	desc->flags |= gpio_flags;
	return 0;

free_id:
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	idr_remove(&dirent_idr, id);
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	desc->flags &= GPIO_FLAGS_MASK;
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free_sd:
	if (value_sd)
		sysfs_put(value_sd);
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err_out:
	return ret;
}

static const struct {
	const char *name;
	unsigned long flags;
} trigger_types[] = {
	{ "none",    0 },
	{ "falling", BIT(FLAG_TRIG_FALL) },
	{ "rising",  BIT(FLAG_TRIG_RISE) },
	{ "both",    BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE) },
};

static ssize_t gpio_edge_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	const struct gpio_desc	*desc = dev_get_drvdata(dev);
	ssize_t			status;

	mutex_lock(&sysfs_lock);

	if (!test_bit(FLAG_EXPORT, &desc->flags))
		status = -EIO;
	else {
		int i;

		status = 0;
		for (i = 0; i < ARRAY_SIZE(trigger_types); i++)
			if ((desc->flags & GPIO_TRIGGER_MASK)
					== trigger_types[i].flags) {
				status = sprintf(buf, "%s\n",
						 trigger_types[i].name);
				break;
			}
	}

	mutex_unlock(&sysfs_lock);
	return status;
}

static ssize_t gpio_edge_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t size)
{
	struct gpio_desc	*desc = dev_get_drvdata(dev);
	ssize_t			status;
	int			i;

	for (i = 0; i < ARRAY_SIZE(trigger_types); i++)
		if (sysfs_streq(trigger_types[i].name, buf))
			goto found;
	return -EINVAL;

found:
	mutex_lock(&sysfs_lock);

	if (!test_bit(FLAG_EXPORT, &desc->flags))
		status = -EIO;
	else {
		status = gpio_setup_irq(desc, dev, trigger_types[i].flags);
		if (!status)
			status = size;
	}

	mutex_unlock(&sysfs_lock);

	return status;
}

static DEVICE_ATTR(edge, 0644, gpio_edge_show, gpio_edge_store);

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static int sysfs_set_active_low(struct gpio_desc *desc, struct device *dev,
				int value)
{
	int			status = 0;

	if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
		return 0;

	if (value)
		set_bit(FLAG_ACTIVE_LOW, &desc->flags);
	else
		clear_bit(FLAG_ACTIVE_LOW, &desc->flags);

	/* reconfigure poll(2) support if enabled on one edge only */
	if (dev != NULL && (!!test_bit(FLAG_TRIG_RISE, &desc->flags) ^
				!!test_bit(FLAG_TRIG_FALL, &desc->flags))) {
		unsigned long trigger_flags = desc->flags & GPIO_TRIGGER_MASK;

		gpio_setup_irq(desc, dev, 0);
		status = gpio_setup_irq(desc, dev, trigger_flags);
	}

	return status;
}

static ssize_t gpio_active_low_show(struct device *dev,
		struct device_attribute *attr, char *buf)
{
	const struct gpio_desc	*desc = dev_get_drvdata(dev);
	ssize_t			status;

	mutex_lock(&sysfs_lock);

	if (!test_bit(FLAG_EXPORT, &desc->flags))
		status = -EIO;
	else
		status = sprintf(buf, "%d\n",
				!!test_bit(FLAG_ACTIVE_LOW, &desc->flags));

	mutex_unlock(&sysfs_lock);

	return status;
}

static ssize_t gpio_active_low_store(struct device *dev,
		struct device_attribute *attr, const char *buf, size_t size)
{
	struct gpio_desc	*desc = dev_get_drvdata(dev);
	ssize_t			status;

	mutex_lock(&sysfs_lock);

	if (!test_bit(FLAG_EXPORT, &desc->flags)) {
		status = -EIO;
	} else {
		long		value;

		status = strict_strtol(buf, 0, &value);
		if (status == 0)
			status = sysfs_set_active_low(desc, dev, value != 0);
	}

	mutex_unlock(&sysfs_lock);

	return status ? : size;
}

static const DEVICE_ATTR(active_low, 0644,
		gpio_active_low_show, gpio_active_low_store);

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static const struct attribute *gpio_attrs[] = {
	&dev_attr_value.attr,
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	&dev_attr_active_low.attr,
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	NULL,
};

static const struct attribute_group gpio_attr_group = {
	.attrs = (struct attribute **) gpio_attrs,
};

/*
 * /sys/class/gpio/gpiochipN/
 *   /base ... matching gpio_chip.base (N)
 *   /label ... matching gpio_chip.label
 *   /ngpio ... matching gpio_chip.ngpio
 */

static ssize_t chip_base_show(struct device *dev,
			       struct device_attribute *attr, char *buf)
{
	const struct gpio_chip	*chip = dev_get_drvdata(dev);

	return sprintf(buf, "%d\n", chip->base);
}
static DEVICE_ATTR(base, 0444, chip_base_show, NULL);

static ssize_t chip_label_show(struct device *dev,
			       struct device_attribute *attr, char *buf)
{
	const struct gpio_chip	*chip = dev_get_drvdata(dev);

	return sprintf(buf, "%s\n", chip->label ? : "");
}
static DEVICE_ATTR(label, 0444, chip_label_show, NULL);

static ssize_t chip_ngpio_show(struct device *dev,
			       struct device_attribute *attr, char *buf)
{
	const struct gpio_chip	*chip = dev_get_drvdata(dev);

	return sprintf(buf, "%u\n", chip->ngpio);
}
static DEVICE_ATTR(ngpio, 0444, chip_ngpio_show, NULL);

static const struct attribute *gpiochip_attrs[] = {
	&dev_attr_base.attr,
	&dev_attr_label.attr,
	&dev_attr_ngpio.attr,
	NULL,
};

static const struct attribute_group gpiochip_attr_group = {
	.attrs = (struct attribute **) gpiochip_attrs,
};

/*
 * /sys/class/gpio/export ... write-only
 *	integer N ... number of GPIO to export (full access)
 * /sys/class/gpio/unexport ... write-only
 *	integer N ... number of GPIO to unexport
 */
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static ssize_t export_store(struct class *class,
				struct class_attribute *attr,
				const char *buf, size_t len)
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650
{
651 652 653
	long			gpio;
	struct gpio_desc	*desc;
	int			status;
D
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654 655 656 657 658

	status = strict_strtol(buf, 0, &gpio);
	if (status < 0)
		goto done;

659
	desc = gpio_to_desc(gpio);
660 661 662 663 664
	/* reject invalid GPIOs */
	if (!desc) {
		pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
		return -EINVAL;
	}
665

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666 667 668 669 670
	/* No extra locking here; FLAG_SYSFS just signifies that the
	 * request and export were done by on behalf of userspace, so
	 * they may be undone on its behalf too.
	 */

671
	status = gpiod_request(desc, "sysfs");
672 673 674
	if (status < 0) {
		if (status == -EPROBE_DEFER)
			status = -ENODEV;
D
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675
		goto done;
676
	}
677
	status = gpiod_export(desc, true);
D
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678
	if (status < 0)
679
		gpiod_free(desc);
D
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680
	else
681
		set_bit(FLAG_SYSFS, &desc->flags);
D
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682 683 684 685 686 687 688

done:
	if (status)
		pr_debug("%s: status %d\n", __func__, status);
	return status ? : len;
}

689 690 691
static ssize_t unexport_store(struct class *class,
				struct class_attribute *attr,
				const char *buf, size_t len)
D
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692
{
693 694 695
	long			gpio;
	struct gpio_desc	*desc;
	int			status;
D
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696 697 698 699 700

	status = strict_strtol(buf, 0, &gpio);
	if (status < 0)
		goto done;

701
	desc = gpio_to_desc(gpio);
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702
	/* reject bogus commands (gpio_unexport ignores them) */
703 704 705 706 707 708
	if (!desc) {
		pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
		return -EINVAL;
	}

	status = -EINVAL;
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709 710 711 712 713

	/* No extra locking here; FLAG_SYSFS just signifies that the
	 * request and export were done by on behalf of userspace, so
	 * they may be undone on its behalf too.
	 */
714
	if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
D
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		status = 0;
716
		gpiod_free(desc);
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717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752
	}
done:
	if (status)
		pr_debug("%s: status %d\n", __func__, status);
	return status ? : len;
}

static struct class_attribute gpio_class_attrs[] = {
	__ATTR(export, 0200, NULL, export_store),
	__ATTR(unexport, 0200, NULL, unexport_store),
	__ATTR_NULL,
};

static struct class gpio_class = {
	.name =		"gpio",
	.owner =	THIS_MODULE,

	.class_attrs =	gpio_class_attrs,
};


/**
 * gpio_export - export a GPIO through sysfs
 * @gpio: gpio to make available, already requested
 * @direction_may_change: true if userspace may change gpio direction
 * Context: arch_initcall or later
 *
 * When drivers want to make a GPIO accessible to userspace after they
 * have requested it -- perhaps while debugging, or as part of their
 * public interface -- they may use this routine.  If the GPIO can
 * change direction (some can't) and the caller allows it, userspace
 * will see "direction" sysfs attribute which may be used to change
 * the gpio's direction.  A "value" attribute will always be provided.
 *
 * Returns zero on success, else an error.
 */
753
static int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
D
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754 755
{
	unsigned long		flags;
R
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756
	int			status;
757
	const char		*ioname = NULL;
R
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758
	struct device		*dev;
759
	int			offset;
D
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760 761 762 763 764 765 766

	/* can't export until sysfs is available ... */
	if (!gpio_class.p) {
		pr_debug("%s: called too early!\n", __func__);
		return -ENOENT;
	}

767 768
	if (!desc) {
		pr_debug("%s: invalid gpio descriptor\n", __func__);
R
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769 770
		return -EINVAL;
	}
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771 772 773 774

	mutex_lock(&sysfs_lock);

	spin_lock_irqsave(&gpio_lock, flags);
R
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775 776 777 778
	if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
	     test_bit(FLAG_EXPORT, &desc->flags)) {
		spin_unlock_irqrestore(&gpio_lock, flags);
		pr_debug("%s: gpio %d unavailable (requested=%d, exported=%d)\n",
779
				__func__, desc_to_gpio(desc),
R
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780 781
				test_bit(FLAG_REQUESTED, &desc->flags),
				test_bit(FLAG_EXPORT, &desc->flags));
782 783
		status = -EPERM;
		goto fail_unlock;
D
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	}
R
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785 786 787

	if (!desc->chip->direction_input || !desc->chip->direction_output)
		direction_may_change = false;
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788 789
	spin_unlock_irqrestore(&gpio_lock, flags);

790 791 792
	offset = gpio_chip_hwgpio(desc);
	if (desc->chip->names && desc->chip->names[offset])
		ioname = desc->chip->names[offset];
793

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	dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
795 796
			    desc, ioname ? ioname : "gpio%u",
			    desc_to_gpio(desc));
R
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797 798 799
	if (IS_ERR(dev)) {
		status = PTR_ERR(dev);
		goto fail_unlock;
D
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800 801
	}

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802
	status = sysfs_create_group(&dev->kobj, &gpio_attr_group);
D
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803
	if (status)
R
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804
		goto fail_unregister_device;
D
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805

R
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806 807 808 809 810 811
	if (direction_may_change) {
		status = device_create_file(dev, &dev_attr_direction);
		if (status)
			goto fail_unregister_device;
	}

812
	if (gpiod_to_irq(desc) >= 0 && (direction_may_change ||
R
Ryan Mallon 已提交
813 814 815 816 817
				       !test_bit(FLAG_IS_OUT, &desc->flags))) {
		status = device_create_file(dev, &dev_attr_edge);
		if (status)
			goto fail_unregister_device;
	}
D
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818

R
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819 820 821 822 823 824 825 826
	set_bit(FLAG_EXPORT, &desc->flags);
	mutex_unlock(&sysfs_lock);
	return 0;

fail_unregister_device:
	device_unregister(dev);
fail_unlock:
	mutex_unlock(&sysfs_lock);
827 828
	pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
		 status);
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829 830
	return status;
}
831 832 833 834 835

int gpio_export(unsigned gpio, bool direction_may_change)
{
	return gpiod_export(gpio_to_desc(gpio), direction_may_change);
}
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836 837
EXPORT_SYMBOL_GPL(gpio_export);

838
static int match_export(struct device *dev, const void *data)
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839 840 841 842
{
	return dev_get_drvdata(dev) == data;
}

843 844 845 846 847 848 849 850 851 852 853
/**
 * gpio_export_link - create a sysfs link to an exported GPIO node
 * @dev: device under which to create symlink
 * @name: name of the symlink
 * @gpio: gpio to create symlink to, already exported
 *
 * Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN
 * node. Caller is responsible for unlinking.
 *
 * Returns zero on success, else an error.
 */
854 855
static int gpiod_export_link(struct device *dev, const char *name,
			     struct gpio_desc *desc)
856 857 858
{
	int			status = -EINVAL;

859 860 861 862
	if (!desc) {
		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
	}
863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880

	mutex_lock(&sysfs_lock);

	if (test_bit(FLAG_EXPORT, &desc->flags)) {
		struct device *tdev;

		tdev = class_find_device(&gpio_class, NULL, desc, match_export);
		if (tdev != NULL) {
			status = sysfs_create_link(&dev->kobj, &tdev->kobj,
						name);
		} else {
			status = -ENODEV;
		}
	}

	mutex_unlock(&sysfs_lock);

	if (status)
881 882
		pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
			 status);
883 884 885 886

	return status;
}

887 888 889 890 891
int gpio_export_link(struct device *dev, const char *name, unsigned gpio)
{
	return gpiod_export_link(dev, name, gpio_to_desc(gpio));
}
EXPORT_SYMBOL_GPL(gpio_export_link);
892 893 894 895 896 897 898 899 900 901 902 903 904

/**
 * gpio_sysfs_set_active_low - set the polarity of gpio sysfs value
 * @gpio: gpio to change
 * @value: non-zero to use active low, i.e. inverted values
 *
 * Set the polarity of /sys/class/gpio/gpioN/value sysfs attribute.
 * The GPIO does not have to be exported yet.  If poll(2) support has
 * been enabled for either rising or falling edge, it will be
 * reconfigured to follow the new polarity.
 *
 * Returns zero on success, else an error.
 */
905
static int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value)
906 907 908 909
{
	struct device		*dev = NULL;
	int			status = -EINVAL;

910 911 912 913
	if (!desc) {
		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
	}
914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930

	mutex_lock(&sysfs_lock);

	if (test_bit(FLAG_EXPORT, &desc->flags)) {
		dev = class_find_device(&gpio_class, NULL, desc, match_export);
		if (dev == NULL) {
			status = -ENODEV;
			goto unlock;
		}
	}

	status = sysfs_set_active_low(desc, dev, value);

unlock:
	mutex_unlock(&sysfs_lock);

	if (status)
931 932
		pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
			 status);
933 934 935

	return status;
}
936 937 938 939 940

int gpio_sysfs_set_active_low(unsigned gpio, int value)
{
	return gpiod_sysfs_set_active_low(gpio_to_desc(gpio), value);
}
941 942
EXPORT_SYMBOL_GPL(gpio_sysfs_set_active_low);

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943 944 945 946 947 948
/**
 * gpio_unexport - reverse effect of gpio_export()
 * @gpio: gpio to make unavailable
 *
 * This is implicit on gpio_free().
 */
949
static void gpiod_unexport(struct gpio_desc *desc)
D
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950
{
951
	int			status = 0;
952
	struct device		*dev = NULL;
D
David Brownell 已提交
953

954
	if (!desc) {
955 956
		pr_warn("%s: invalid GPIO\n", __func__);
		return;
957
	}
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958 959 960 961 962 963 964

	mutex_lock(&sysfs_lock);

	if (test_bit(FLAG_EXPORT, &desc->flags)) {

		dev = class_find_device(&gpio_class, NULL, desc, match_export);
		if (dev) {
965
			gpio_setup_irq(desc, dev, 0);
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David Brownell 已提交
966 967 968 969 970 971
			clear_bit(FLAG_EXPORT, &desc->flags);
		} else
			status = -ENODEV;
	}

	mutex_unlock(&sysfs_lock);
972

973 974 975 976
	if (dev) {
		device_unregister(dev);
		put_device(dev);
	}
977

D
David Brownell 已提交
978
	if (status)
979 980 981 982 983 984 985
		pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
			 status);
}

void gpio_unexport(unsigned gpio)
{
	gpiod_unexport(gpio_to_desc(gpio));
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986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005
}
EXPORT_SYMBOL_GPL(gpio_unexport);

static int gpiochip_export(struct gpio_chip *chip)
{
	int		status;
	struct device	*dev;

	/* Many systems register gpio chips for SOC support very early,
	 * before driver model support is available.  In those cases we
	 * export this later, in gpiolib_sysfs_init() ... here we just
	 * verify that _some_ field of gpio_class got initialized.
	 */
	if (!gpio_class.p)
		return 0;

	/* use chip->base for the ID; it's already known to be unique */
	mutex_lock(&sysfs_lock);
	dev = device_create(&gpio_class, chip->dev, MKDEV(0, 0), chip,
				"gpiochip%d", chip->base);
1006
	if (!IS_ERR(dev)) {
D
David Brownell 已提交
1007 1008 1009
		status = sysfs_create_group(&dev->kobj,
				&gpiochip_attr_group);
	} else
1010
		status = PTR_ERR(dev);
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1011 1012 1013 1014 1015 1016 1017 1018
	chip->exported = (status == 0);
	mutex_unlock(&sysfs_lock);

	if (status) {
		unsigned long	flags;
		unsigned	gpio;

		spin_lock_irqsave(&gpio_lock, flags);
1019 1020 1021
		gpio = 0;
		while (gpio < chip->ngpio)
			chip->desc[gpio++].chip = NULL;
D
David Brownell 已提交
1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055
		spin_unlock_irqrestore(&gpio_lock, flags);

		pr_debug("%s: chip %s status %d\n", __func__,
				chip->label, status);
	}

	return status;
}

static void gpiochip_unexport(struct gpio_chip *chip)
{
	int			status;
	struct device		*dev;

	mutex_lock(&sysfs_lock);
	dev = class_find_device(&gpio_class, NULL, chip, match_export);
	if (dev) {
		put_device(dev);
		device_unregister(dev);
		chip->exported = 0;
		status = 0;
	} else
		status = -ENODEV;
	mutex_unlock(&sysfs_lock);

	if (status)
		pr_debug("%s: chip %s status %d\n", __func__,
				chip->label, status);
}

static int __init gpiolib_sysfs_init(void)
{
	int		status;
	unsigned long	flags;
1056
	struct gpio_chip *chip;
D
David Brownell 已提交
1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068

	status = class_register(&gpio_class);
	if (status < 0)
		return status;

	/* Scan and register the gpio_chips which registered very
	 * early (e.g. before the class_register above was called).
	 *
	 * We run before arch_initcall() so chip->dev nodes can have
	 * registered, and so arch_initcall() can always gpio_export().
	 */
	spin_lock_irqsave(&gpio_lock, flags);
1069
	list_for_each_entry(chip, &gpio_chips, list) {
D
David Brownell 已提交
1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093
		if (!chip || chip->exported)
			continue;

		spin_unlock_irqrestore(&gpio_lock, flags);
		status = gpiochip_export(chip);
		spin_lock_irqsave(&gpio_lock, flags);
	}
	spin_unlock_irqrestore(&gpio_lock, flags);


	return status;
}
postcore_initcall(gpiolib_sysfs_init);

#else
static inline int gpiochip_export(struct gpio_chip *chip)
{
	return 0;
}

static inline void gpiochip_unexport(struct gpio_chip *chip)
{
}

1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114
static inline int gpiod_export(struct gpio_desc *desc,
			       bool direction_may_change)
{
	return -ENOSYS;
}

static inline int gpiod_export_link(struct device *dev, const char *name,
				    struct gpio_desc *desc)
{
	return -ENOSYS;
}

static inline int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value)
{
	return -ENOSYS;
}

static inline void gpiod_unexport(struct gpio_desc *desc)
{
}

D
David Brownell 已提交
1115 1116
#endif /* CONFIG_GPIO_SYSFS */

1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153
/*
 * 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;
}

1154 1155 1156 1157 1158 1159 1160 1161
/**
 * 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.
1162
 *
D
David Brownell 已提交
1163 1164 1165 1166 1167
 * 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.
 *
1168 1169
 * If chip->base is negative, this requests dynamic assignment of
 * a range of valid GPIOs.
1170 1171 1172 1173 1174 1175
 */
int gpiochip_add(struct gpio_chip *chip)
{
	unsigned long	flags;
	int		status = 0;
	unsigned	id;
1176
	int		base = chip->base;
1177

T
Trent Piepho 已提交
1178
	if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))
1179
			&& base >= 0) {
1180 1181 1182 1183 1184 1185
		status = -EINVAL;
		goto fail;
	}

	spin_lock_irqsave(&gpio_lock, flags);

1186 1187 1188 1189
	if (base < 0) {
		base = gpiochip_find_base(chip->ngpio);
		if (base < 0) {
			status = base;
D
David Brownell 已提交
1190
			goto unlock;
1191 1192 1193 1194
		}
		chip->base = base;
	}

1195 1196
	status = gpiochip_add_to_list(chip);

1197
	if (status == 0) {
1198 1199 1200 1201 1202
		chip->desc = &gpio_desc[chip->base];

		for (id = 0; id < chip->ngpio; id++) {
			struct gpio_desc *desc = &chip->desc[id];
			desc->chip = chip;
D
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1203 1204 1205 1206 1207

			/* 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,
1208
			 * and in case chip->get_direction is not set,
D
David Brownell 已提交
1209 1210
			 * we may expose the wrong direction in sysfs.
			 */
1211
			desc->flags = !chip->direction_input
D
David Brownell 已提交
1212 1213
				? (1 << FLAG_IS_OUT)
				: 0;
1214 1215 1216
		}
	}

1217 1218 1219 1220
#ifdef CONFIG_PINCTRL
	INIT_LIST_HEAD(&chip->pin_ranges);
#endif

1221 1222
	of_gpiochip_add(chip);

D
David Brownell 已提交
1223
unlock:
1224
	spin_unlock_irqrestore(&gpio_lock, flags);
1225 1226 1227 1228 1229 1230 1231 1232

	if (status)
		goto fail;

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

1233
	pr_debug("gpiochip_add: registered GPIOs %d to %d on device: %s\n",
1234 1235 1236
		chip->base, chip->base + chip->ngpio - 1,
		chip->label ? : "generic");

1237
	return 0;
1238 1239
fail:
	/* failures here can mean systems won't boot... */
1240 1241 1242
	pr_err("gpiochip_add: gpios %d..%d (%s) failed to register\n",
		chip->base, chip->base + chip->ngpio - 1,
		chip->label ? : "generic");
1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260
	return status;
}
EXPORT_SYMBOL_GPL(gpiochip_add);

/**
 * gpiochip_remove() - unregister a gpio_chip
 * @chip: the chip to unregister
 *
 * A gpio_chip with any GPIOs still requested may not be removed.
 */
int gpiochip_remove(struct gpio_chip *chip)
{
	unsigned long	flags;
	int		status = 0;
	unsigned	id;

	spin_lock_irqsave(&gpio_lock, flags);

1261
	gpiochip_remove_pin_ranges(chip);
1262 1263
	of_gpiochip_remove(chip);

1264 1265
	for (id = 0; id < chip->ngpio; id++) {
		if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) {
1266 1267 1268 1269 1270
			status = -EBUSY;
			break;
		}
	}
	if (status == 0) {
1271 1272
		for (id = 0; id < chip->ngpio; id++)
			chip->desc[id].chip = NULL;
1273 1274

		list_del(&chip->list);
1275 1276 1277
	}

	spin_unlock_irqrestore(&gpio_lock, flags);
D
David Brownell 已提交
1278 1279 1280 1281

	if (status == 0)
		gpiochip_unexport(chip);

1282 1283 1284 1285
	return status;
}
EXPORT_SYMBOL_GPL(gpiochip_remove);

1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296
/**
 * 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.
 */
1297
struct gpio_chip *gpiochip_find(void *data,
1298
				int (*match)(struct gpio_chip *chip,
1299
					     void *data))
1300
{
1301
	struct gpio_chip *chip;
1302 1303 1304
	unsigned long flags;

	spin_lock_irqsave(&gpio_lock, flags);
1305 1306
	list_for_each_entry(chip, &gpio_chips, list)
		if (match(chip, data))
1307
			break;
1308 1309 1310 1311

	/* No match? */
	if (&chip->list == &gpio_chips)
		chip = NULL;
1312 1313 1314 1315
	spin_unlock_irqrestore(&gpio_lock, flags);

	return chip;
}
J
Jean Delvare 已提交
1316
EXPORT_SYMBOL_GPL(gpiochip_find);
1317

1318
#ifdef CONFIG_PINCTRL
1319

1320 1321 1322 1323
/**
 * 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
1324 1325
 * @gpio_offset: the start offset in the current gpio_chip number space
 * @pin_offset: the start offset in the pin controller number space
1326 1327 1328
 * @npins: the number of pins from the offset of each pin space (GPIO and
 *	pin controller) to accumulate in this range
 */
1329
int gpiochip_add_pin_range(struct gpio_chip *chip, const char *pinctl_name,
1330
			   unsigned int gpio_offset, unsigned int pin_offset,
1331
			   unsigned int npins)
1332 1333
{
	struct gpio_pin_range *pin_range;
1334
	int ret;
1335

1336
	pin_range = kzalloc(sizeof(*pin_range), GFP_KERNEL);
1337 1338 1339
	if (!pin_range) {
		pr_err("%s: GPIO chip: failed to allocate pin ranges\n",
				chip->label);
1340
		return -ENOMEM;
1341 1342
	}

1343
	/* Use local offset as range ID */
1344
	pin_range->range.id = gpio_offset;
1345
	pin_range->range.gc = chip;
1346
	pin_range->range.name = chip->label;
1347 1348
	pin_range->range.base = chip->base + gpio_offset;
	pin_range->range.pin_base = pin_offset;
1349
	pin_range->range.npins = npins;
L
Linus Walleij 已提交
1350
	pin_range->pctldev = pinctrl_find_and_add_gpio_range(pinctl_name,
1351
			&pin_range->range);
1352
	if (IS_ERR(pin_range->pctldev)) {
1353
		ret = PTR_ERR(pin_range->pctldev);
1354 1355 1356
		pr_err("%s: GPIO chip: could not create pin range\n",
		       chip->label);
		kfree(pin_range);
1357
		return ret;
1358
	}
1359 1360 1361 1362
	pr_debug("GPIO chip %s: created GPIO range %d->%d ==> %s PIN %d->%d\n",
		 chip->label, gpio_offset, gpio_offset + npins - 1,
		 pinctl_name,
		 pin_offset, pin_offset + npins - 1);
1363 1364

	list_add_tail(&pin_range->node, &chip->pin_ranges);
1365 1366

	return 0;
1367
}
1368
EXPORT_SYMBOL_GPL(gpiochip_add_pin_range);
1369

1370 1371 1372 1373
/**
 * gpiochip_remove_pin_ranges() - remove all the GPIO <-> pin mappings
 * @chip: the chip to remove all the mappings for
 */
1374 1375 1376 1377 1378 1379 1380 1381
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);
1382
		kfree(pin_range);
1383 1384
	}
}
1385 1386 1387
EXPORT_SYMBOL_GPL(gpiochip_remove_pin_ranges);

#endif /* CONFIG_PINCTRL */
1388

1389 1390 1391 1392
/* 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.
 */
1393
static int gpiod_request(struct gpio_desc *desc, const char *label)
1394
{
D
David Brownell 已提交
1395
	struct gpio_chip	*chip;
1396
	int			status = -EPROBE_DEFER;
1397 1398
	unsigned long		flags;

1399
	if (!desc) {
1400 1401
		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
1402
	}
1403 1404 1405

	spin_lock_irqsave(&gpio_lock, flags);

D
David Brownell 已提交
1406 1407
	chip = desc->chip;
	if (chip == NULL)
1408 1409
		goto done;

D
David Brownell 已提交
1410
	if (!try_module_get(chip->owner))
1411 1412
		goto done;

1413
	/* NOTE:  gpio_request() can be called in early boot,
D
David Brownell 已提交
1414
	 * before IRQs are enabled, for non-sleeping (SOC) GPIOs.
1415 1416 1417 1418 1419
	 */

	if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
		desc_set_label(desc, label ? : "?");
		status = 0;
1420
	} else {
1421
		status = -EBUSY;
D
David Brownell 已提交
1422
		module_put(chip->owner);
M
Magnus Damm 已提交
1423
		goto done;
D
David Brownell 已提交
1424 1425 1426 1427 1428
	}

	if (chip->request) {
		/* chip->request may sleep */
		spin_unlock_irqrestore(&gpio_lock, flags);
1429
		status = chip->request(chip, gpio_chip_hwgpio(desc));
D
David Brownell 已提交
1430 1431 1432 1433 1434 1435
		spin_lock_irqsave(&gpio_lock, flags);

		if (status < 0) {
			desc_set_label(desc, NULL);
			module_put(chip->owner);
			clear_bit(FLAG_REQUESTED, &desc->flags);
1436
			goto done;
D
David Brownell 已提交
1437
		}
1438
	}
1439 1440 1441
	if (chip->get_direction) {
		/* chip->get_direction may sleep */
		spin_unlock_irqrestore(&gpio_lock, flags);
1442
		gpiod_get_direction(desc);
1443 1444
		spin_lock_irqsave(&gpio_lock, flags);
	}
1445 1446
done:
	if (status)
1447
		pr_debug("_gpio_request: gpio-%d (%s) status %d\n",
1448
			 desc_to_gpio(desc), label ? : "?", status);
1449 1450 1451
	spin_unlock_irqrestore(&gpio_lock, flags);
	return status;
}
1452 1453 1454 1455 1456

int gpio_request(unsigned gpio, const char *label)
{
	return gpiod_request(gpio_to_desc(gpio), label);
}
1457 1458
EXPORT_SYMBOL_GPL(gpio_request);

1459
static void gpiod_free(struct gpio_desc *desc)
1460 1461
{
	unsigned long		flags;
D
David Brownell 已提交
1462
	struct gpio_chip	*chip;
1463

1464 1465
	might_sleep();

1466
	if (!desc) {
1467 1468 1469 1470
		WARN_ON(extra_checks);
		return;
	}

1471
	gpiod_unexport(desc);
D
David Brownell 已提交
1472

1473 1474
	spin_lock_irqsave(&gpio_lock, flags);

D
David Brownell 已提交
1475 1476 1477 1478
	chip = desc->chip;
	if (chip && test_bit(FLAG_REQUESTED, &desc->flags)) {
		if (chip->free) {
			spin_unlock_irqrestore(&gpio_lock, flags);
1479
			might_sleep_if(chip->can_sleep);
1480
			chip->free(chip, gpio_chip_hwgpio(desc));
D
David Brownell 已提交
1481 1482
			spin_lock_irqsave(&gpio_lock, flags);
		}
1483
		desc_set_label(desc, NULL);
1484
		module_put(desc->chip->owner);
1485
		clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
D
David Brownell 已提交
1486
		clear_bit(FLAG_REQUESTED, &desc->flags);
1487
		clear_bit(FLAG_OPEN_DRAIN, &desc->flags);
1488
		clear_bit(FLAG_OPEN_SOURCE, &desc->flags);
1489
	} else
1490 1491 1492 1493
		WARN_ON(extra_checks);

	spin_unlock_irqrestore(&gpio_lock, flags);
}
1494 1495 1496 1497 1498

void gpio_free(unsigned gpio)
{
	gpiod_free(gpio_to_desc(gpio));
}
1499 1500
EXPORT_SYMBOL_GPL(gpio_free);

1501 1502 1503 1504 1505 1506 1507 1508
/**
 * gpio_request_one - request a single GPIO with initial configuration
 * @gpio:	the GPIO number
 * @flags:	GPIO configuration as specified by GPIOF_*
 * @label:	a literal description string of this GPIO
 */
int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
{
1509
	struct gpio_desc *desc;
1510 1511
	int err;

1512 1513 1514
	desc = gpio_to_desc(gpio);

	err = gpiod_request(desc, label);
1515 1516 1517
	if (err)
		return err;

1518
	if (flags & GPIOF_OPEN_DRAIN)
1519
		set_bit(FLAG_OPEN_DRAIN, &desc->flags);
1520

1521
	if (flags & GPIOF_OPEN_SOURCE)
1522
		set_bit(FLAG_OPEN_SOURCE, &desc->flags);
1523

1524
	if (flags & GPIOF_DIR_IN)
1525
		err = gpiod_direction_input(desc);
1526
	else
1527
		err = gpiod_direction_output(desc,
1528 1529
				(flags & GPIOF_INIT_HIGH) ? 1 : 0);

1530
	if (err)
1531 1532 1533
		goto free_gpio;

	if (flags & GPIOF_EXPORT) {
1534
		err = gpiod_export(desc, flags & GPIOF_EXPORT_CHANGEABLE);
1535 1536 1537 1538 1539
		if (err)
			goto free_gpio;
	}

	return 0;
1540

1541
 free_gpio:
1542
	gpiod_free(desc);
1543 1544 1545 1546 1547 1548 1549 1550 1551
	return err;
}
EXPORT_SYMBOL_GPL(gpio_request_one);

/**
 * gpio_request_array - request multiple GPIOs in a single call
 * @array:	array of the 'struct gpio'
 * @num:	how many GPIOs in the array
 */
1552
int gpio_request_array(const struct gpio *array, size_t num)
1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574
{
	int i, err;

	for (i = 0; i < num; i++, array++) {
		err = gpio_request_one(array->gpio, array->flags, array->label);
		if (err)
			goto err_free;
	}
	return 0;

err_free:
	while (i--)
		gpio_free((--array)->gpio);
	return err;
}
EXPORT_SYMBOL_GPL(gpio_request_array);

/**
 * gpio_free_array - release multiple GPIOs in a single call
 * @array:	array of the 'struct gpio'
 * @num:	how many GPIOs in the array
 */
1575
void gpio_free_array(const struct gpio *array, size_t num)
1576 1577 1578 1579 1580
{
	while (num--)
		gpio_free((array++)->gpio);
}
EXPORT_SYMBOL_GPL(gpio_free_array);
1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596

/**
 * 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.
 * If debugfs support is enabled, the string returned is the label passed
 * to gpio_request(); otherwise it is a meaningless constant.
 *
 * This function is for use by GPIO controller drivers.  The label can
 * help with diagnostics, and knowing that the signal is used as a GPIO
 * can help avoid accidentally multiplexing it to another controller.
 */
const char *gpiochip_is_requested(struct gpio_chip *chip, unsigned offset)
{
1597
	struct gpio_desc *desc;
1598

1599
	if (!GPIO_OFFSET_VALID(chip, offset))
1600
		return NULL;
1601 1602 1603

	desc = &chip->desc[offset];

1604
	if (test_bit(FLAG_REQUESTED, &desc->flags) == 0)
1605 1606
		return NULL;
#ifdef CONFIG_DEBUG_FS
1607
	return desc->label;
1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623
#else
	return "?";
#endif
}
EXPORT_SYMBOL_GPL(gpiochip_is_requested);


/* 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.
 */

1624
static int gpiod_direction_input(struct gpio_desc *desc)
1625 1626 1627 1628
{
	unsigned long		flags;
	struct gpio_chip	*chip;
	int			status = -EINVAL;
1629
	int			offset;
1630

1631 1632 1633 1634 1635
	if (!desc) {
		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
	}

1636 1637 1638 1639 1640
	spin_lock_irqsave(&gpio_lock, flags);

	chip = desc->chip;
	if (!chip || !chip->get || !chip->direction_input)
		goto fail;
1641
	status = gpio_ensure_requested(desc);
D
David Brownell 已提交
1642 1643
	if (status < 0)
		goto fail;
1644 1645 1646 1647 1648

	/* now we know the gpio is valid and chip won't vanish */

	spin_unlock_irqrestore(&gpio_lock, flags);

1649
	might_sleep_if(chip->can_sleep);
1650

1651
	offset = gpio_chip_hwgpio(desc);
D
David Brownell 已提交
1652
	if (status) {
1653
		status = chip->request(chip, offset);
D
David Brownell 已提交
1654 1655
		if (status < 0) {
			pr_debug("GPIO-%d: chip request fail, %d\n",
1656
				desc_to_gpio(desc), status);
D
David Brownell 已提交
1657 1658 1659 1660 1661 1662 1663
			/* and it's not available to anyone else ...
			 * gpio_request() is the fully clean solution.
			 */
			goto lose;
		}
	}

1664
	status = chip->direction_input(chip, offset);
1665 1666
	if (status == 0)
		clear_bit(FLAG_IS_OUT, &desc->flags);
1667

1668
	trace_gpio_direction(desc_to_gpio(desc), 1, status);
D
David Brownell 已提交
1669
lose:
1670 1671 1672
	return status;
fail:
	spin_unlock_irqrestore(&gpio_lock, flags);
1673 1674 1675
	if (status)
		pr_debug("%s: gpio-%d status %d\n", __func__,
			 desc_to_gpio(desc), status);
1676 1677
	return status;
}
1678 1679 1680 1681 1682

int gpio_direction_input(unsigned gpio)
{
	return gpiod_direction_input(gpio_to_desc(gpio));
}
1683 1684
EXPORT_SYMBOL_GPL(gpio_direction_input);

1685
static int gpiod_direction_output(struct gpio_desc *desc, int value)
1686 1687 1688 1689
{
	unsigned long		flags;
	struct gpio_chip	*chip;
	int			status = -EINVAL;
1690
	int offset;
1691

1692 1693 1694 1695 1696
	if (!desc) {
		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
	}

1697 1698
	/* Open drain pin should not be driven to 1 */
	if (value && test_bit(FLAG_OPEN_DRAIN,  &desc->flags))
1699
		return gpiod_direction_input(desc);
1700

1701 1702
	/* Open source pin should not be driven to 0 */
	if (!value && test_bit(FLAG_OPEN_SOURCE,  &desc->flags))
1703
		return gpiod_direction_input(desc);
1704

1705 1706 1707 1708 1709
	spin_lock_irqsave(&gpio_lock, flags);

	chip = desc->chip;
	if (!chip || !chip->set || !chip->direction_output)
		goto fail;
1710
	status = gpio_ensure_requested(desc);
D
David Brownell 已提交
1711 1712
	if (status < 0)
		goto fail;
1713 1714 1715 1716 1717

	/* now we know the gpio is valid and chip won't vanish */

	spin_unlock_irqrestore(&gpio_lock, flags);

1718
	might_sleep_if(chip->can_sleep);
1719

1720
	offset = gpio_chip_hwgpio(desc);
D
David Brownell 已提交
1721
	if (status) {
1722
		status = chip->request(chip, offset);
D
David Brownell 已提交
1723 1724
		if (status < 0) {
			pr_debug("GPIO-%d: chip request fail, %d\n",
1725
				desc_to_gpio(desc), status);
D
David Brownell 已提交
1726 1727 1728 1729 1730 1731 1732
			/* and it's not available to anyone else ...
			 * gpio_request() is the fully clean solution.
			 */
			goto lose;
		}
	}

1733
	status = chip->direction_output(chip, offset, value);
1734 1735
	if (status == 0)
		set_bit(FLAG_IS_OUT, &desc->flags);
1736 1737
	trace_gpio_value(desc_to_gpio(desc), 0, value);
	trace_gpio_direction(desc_to_gpio(desc), 0, status);
D
David Brownell 已提交
1738
lose:
1739 1740 1741
	return status;
fail:
	spin_unlock_irqrestore(&gpio_lock, flags);
1742 1743 1744
	if (status)
		pr_debug("%s: gpio-%d status %d\n", __func__,
			 desc_to_gpio(desc), status);
1745 1746
	return status;
}
1747 1748 1749 1750 1751

int gpio_direction_output(unsigned gpio, int value)
{
	return gpiod_direction_output(gpio_to_desc(gpio), value);
}
1752 1753
EXPORT_SYMBOL_GPL(gpio_direction_output);

1754 1755 1756 1757 1758
/**
 * gpio_set_debounce - sets @debounce time for a @gpio
 * @gpio: the gpio to set debounce time
 * @debounce: debounce time is microseconds
 */
1759
static int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce)
1760 1761 1762 1763
{
	unsigned long		flags;
	struct gpio_chip	*chip;
	int			status = -EINVAL;
1764
	int			offset;
1765

1766 1767 1768 1769 1770
	if (!desc) {
		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
	}

1771 1772 1773 1774 1775
	spin_lock_irqsave(&gpio_lock, flags);

	chip = desc->chip;
	if (!chip || !chip->set || !chip->set_debounce)
		goto fail;
1776 1777

	status = gpio_ensure_requested(desc);
1778 1779 1780 1781 1782 1783 1784
	if (status < 0)
		goto fail;

	/* now we know the gpio is valid and chip won't vanish */

	spin_unlock_irqrestore(&gpio_lock, flags);

1785
	might_sleep_if(chip->can_sleep);
1786

1787 1788
	offset = gpio_chip_hwgpio(desc);
	return chip->set_debounce(chip, offset, debounce);
1789 1790 1791

fail:
	spin_unlock_irqrestore(&gpio_lock, flags);
1792 1793 1794
	if (status)
		pr_debug("%s: gpio-%d status %d\n", __func__,
			 desc_to_gpio(desc), status);
1795 1796 1797

	return status;
}
1798 1799 1800 1801 1802

int gpio_set_debounce(unsigned gpio, unsigned debounce)
{
	return gpiod_set_debounce(gpio_to_desc(gpio), debounce);
}
1803
EXPORT_SYMBOL_GPL(gpio_set_debounce);
1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835

/* I/O calls are only valid after configuration completed; the relevant
 * "is this a valid GPIO" error checks should already have been done.
 *
 * "Get" operations are often inlinable as reading a pin value register,
 * and masking the relevant bit in that register.
 *
 * When "set" operations are inlinable, they involve writing that mask to
 * one register to set a low value, or a different register to set it high.
 * Otherwise locking is needed, so there may be little value to inlining.
 *
 *------------------------------------------------------------------------
 *
 * IMPORTANT!!!  The hot paths -- get/set value -- assume that callers
 * have requested the GPIO.  That can include implicit requesting by
 * a direction setting call.  Marking a gpio as requested locks its chip
 * in memory, guaranteeing that these table lookups need no more locking
 * and that gpiochip_remove() will fail.
 *
 * REVISIT when debugging, consider adding some instrumentation to ensure
 * that the GPIO was actually requested.
 */

/**
 * __gpio_get_value() - return a gpio's value
 * @gpio: gpio whose value will be returned
 * Context: any
 *
 * This is used directly or indirectly to implement gpio_get_value().
 * It returns the zero or nonzero value provided by the associated
 * gpio_chip.get() method; or zero if no such method is provided.
 */
1836
static int gpiod_get_value(const struct gpio_desc *desc)
1837 1838
{
	struct gpio_chip	*chip;
1839
	int value;
1840
	int offset;
1841

1842 1843
	if (!desc)
		return 0;
1844 1845
	chip = desc->chip;
	offset = gpio_chip_hwgpio(desc);
1846
	/* Should be using gpio_get_value_cansleep() */
1847
	WARN_ON(chip->can_sleep);
1848 1849
	value = chip->get ? chip->get(chip, offset) : 0;
	trace_gpio_value(desc_to_gpio(desc), 1, value);
1850
	return value;
1851
}
1852 1853 1854 1855 1856

int __gpio_get_value(unsigned gpio)
{
	return gpiod_get_value(gpio_to_desc(gpio));
}
1857 1858
EXPORT_SYMBOL_GPL(__gpio_get_value);

1859 1860 1861 1862 1863 1864
/*
 *  _gpio_set_open_drain_value() - Set the open drain gpio's value.
 * @gpio: Gpio whose state need to be set.
 * @chip: Gpio chip.
 * @value: Non-zero for setting it HIGH otherise it will set to LOW.
 */
1865
static void _gpio_set_open_drain_value(struct gpio_desc *desc, int value)
1866 1867
{
	int err = 0;
1868 1869 1870
	struct gpio_chip *chip = desc->chip;
	int offset = gpio_chip_hwgpio(desc);

1871
	if (value) {
1872
		err = chip->direction_input(chip, offset);
1873
		if (!err)
1874
			clear_bit(FLAG_IS_OUT, &desc->flags);
1875
	} else {
1876
		err = chip->direction_output(chip, offset, 0);
1877
		if (!err)
1878
			set_bit(FLAG_IS_OUT, &desc->flags);
1879
	}
1880
	trace_gpio_direction(desc_to_gpio(desc), value, err);
1881 1882
	if (err < 0)
		pr_err("%s: Error in set_value for open drain gpio%d err %d\n",
1883
					__func__, desc_to_gpio(desc), err);
1884 1885
}

1886 1887 1888 1889 1890 1891
/*
 *  _gpio_set_open_source() - Set the open source gpio's value.
 * @gpio: Gpio whose state need to be set.
 * @chip: Gpio chip.
 * @value: Non-zero for setting it HIGH otherise it will set to LOW.
 */
1892
static void _gpio_set_open_source_value(struct gpio_desc *desc, int value)
1893 1894
{
	int err = 0;
1895 1896 1897
	struct gpio_chip *chip = desc->chip;
	int offset = gpio_chip_hwgpio(desc);

1898
	if (value) {
1899
		err = chip->direction_output(chip, offset, 1);
1900
		if (!err)
1901
			set_bit(FLAG_IS_OUT, &desc->flags);
1902
	} else {
1903
		err = chip->direction_input(chip, offset);
1904
		if (!err)
1905
			clear_bit(FLAG_IS_OUT, &desc->flags);
1906
	}
1907
	trace_gpio_direction(desc_to_gpio(desc), !value, err);
1908 1909
	if (err < 0)
		pr_err("%s: Error in set_value for open source gpio%d err %d\n",
1910
					__func__, desc_to_gpio(desc), err);
1911 1912
}

1913 1914 1915 1916 1917 1918 1919 1920 1921
/**
 * __gpio_set_value() - assign a gpio's value
 * @gpio: gpio whose value will be assigned
 * @value: value to assign
 * Context: any
 *
 * This is used directly or indirectly to implement gpio_set_value().
 * It invokes the associated gpio_chip.set() method.
 */
1922
static void gpiod_set_value(struct gpio_desc *desc, int value)
1923 1924 1925
{
	struct gpio_chip	*chip;

1926 1927
	if (!desc)
		return;
1928
	chip = desc->chip;
1929
	/* Should be using gpio_set_value_cansleep() */
1930
	WARN_ON(chip->can_sleep);
1931 1932 1933 1934 1935
	trace_gpio_value(desc_to_gpio(desc), 0, value);
	if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
		_gpio_set_open_drain_value(desc, value);
	else if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
		_gpio_set_open_source_value(desc, value);
1936
	else
1937 1938 1939 1940 1941 1942
		chip->set(chip, gpio_chip_hwgpio(desc), value);
}

void __gpio_set_value(unsigned gpio, int value)
{
	return gpiod_set_value(gpio_to_desc(gpio), value);
1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953
}
EXPORT_SYMBOL_GPL(__gpio_set_value);

/**
 * __gpio_cansleep() - report whether gpio value access will sleep
 * @gpio: gpio in question
 * Context: any
 *
 * This is used directly or indirectly to implement gpio_cansleep().  It
 * returns nonzero if access reading or writing the GPIO value can sleep.
 */
1954
static int gpiod_cansleep(const struct gpio_desc *desc)
1955
{
1956 1957
	if (!desc)
		return 0;
1958
	/* only call this on GPIOs that are valid! */
1959 1960
	return desc->chip->can_sleep;
}
1961

1962 1963 1964
int __gpio_cansleep(unsigned gpio)
{
	return gpiod_cansleep(gpio_to_desc(gpio));
1965 1966 1967
}
EXPORT_SYMBOL_GPL(__gpio_cansleep);

D
David Brownell 已提交
1968 1969 1970 1971 1972 1973 1974 1975 1976
/**
 * __gpio_to_irq() - return the IRQ corresponding to a GPIO
 * @gpio: gpio whose IRQ will be returned (already requested)
 * Context: any
 *
 * This is used directly or indirectly to implement gpio_to_irq().
 * It returns the number of the IRQ signaled by this (input) GPIO,
 * or a negative errno.
 */
1977
static int gpiod_to_irq(const struct gpio_desc *desc)
D
David Brownell 已提交
1978 1979
{
	struct gpio_chip	*chip;
1980
	int			offset;
D
David Brownell 已提交
1981

1982 1983
	if (!desc)
		return -EINVAL;
1984 1985 1986
	chip = desc->chip;
	offset = gpio_chip_hwgpio(desc);
	return chip->to_irq ? chip->to_irq(chip, offset) : -ENXIO;
D
David Brownell 已提交
1987 1988
}

1989 1990 1991 1992 1993
int __gpio_to_irq(unsigned gpio)
{
	return gpiod_to_irq(gpio_to_desc(gpio));
}
EXPORT_SYMBOL_GPL(__gpio_to_irq);
1994 1995 1996 1997 1998 1999


/* There's no value in making it easy to inline GPIO calls that may sleep.
 * Common examples include ones connected to I2C or SPI chips.
 */

2000
static int gpiod_get_value_cansleep(const struct gpio_desc *desc)
2001 2002
{
	struct gpio_chip	*chip;
2003
	int value;
2004
	int offset;
2005 2006

	might_sleep_if(extra_checks);
2007 2008
	if (!desc)
		return 0;
2009 2010 2011 2012
	chip = desc->chip;
	offset = gpio_chip_hwgpio(desc);
	value = chip->get ? chip->get(chip, offset) : 0;
	trace_gpio_value(desc_to_gpio(desc), 1, value);
2013
	return value;
2014
}
2015 2016 2017 2018 2019

int gpio_get_value_cansleep(unsigned gpio)
{
	return gpiod_get_value_cansleep(gpio_to_desc(gpio));
}
2020 2021
EXPORT_SYMBOL_GPL(gpio_get_value_cansleep);

2022
static void gpiod_set_value_cansleep(struct gpio_desc *desc, int value)
2023 2024 2025 2026
{
	struct gpio_chip	*chip;

	might_sleep_if(extra_checks);
2027 2028
	if (!desc)
		return;
2029 2030 2031 2032 2033 2034
	chip = desc->chip;
	trace_gpio_value(desc_to_gpio(desc), 0, value);
	if (test_bit(FLAG_OPEN_DRAIN,  &desc->flags))
		_gpio_set_open_drain_value(desc, value);
	else if (test_bit(FLAG_OPEN_SOURCE,  &desc->flags))
		_gpio_set_open_source_value(desc, value);
2035
	else
2036
		chip->set(chip, gpio_chip_hwgpio(desc), value);
2037 2038
}

2039 2040 2041 2042 2043
void gpio_set_value_cansleep(unsigned gpio, int value)
{
	return gpiod_set_value_cansleep(gpio_to_desc(gpio), value);
}
EXPORT_SYMBOL_GPL(gpio_set_value_cansleep);
2044 2045 2046 2047 2048 2049 2050

#ifdef CONFIG_DEBUG_FS

static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
{
	unsigned		i;
	unsigned		gpio = chip->base;
2051
	struct gpio_desc	*gdesc = &chip->desc[0];
2052 2053 2054 2055 2056 2057
	int			is_out;

	for (i = 0; i < chip->ngpio; i++, gpio++, gdesc++) {
		if (!test_bit(FLAG_REQUESTED, &gdesc->flags))
			continue;

2058
		gpiod_get_direction(gdesc);
2059
		is_out = test_bit(FLAG_IS_OUT, &gdesc->flags);
2060
		seq_printf(s, " gpio-%-3d (%-20.20s) %s %s",
2061 2062 2063 2064 2065 2066 2067 2068 2069
			gpio, gdesc->label,
			is_out ? "out" : "in ",
			chip->get
				? (chip->get(chip, i) ? "hi" : "lo")
				: "?  ");
		seq_printf(s, "\n");
	}
}

2070
static void *gpiolib_seq_start(struct seq_file *s, loff_t *pos)
2071
{
2072
	unsigned long flags;
2073
	struct gpio_chip *chip = NULL;
2074
	loff_t index = *pos;
2075

2076
	s->private = "";
2077

2078
	spin_lock_irqsave(&gpio_lock, flags);
2079
	list_for_each_entry(chip, &gpio_chips, list)
2080 2081
		if (index-- == 0) {
			spin_unlock_irqrestore(&gpio_lock, flags);
2082
			return chip;
2083
		}
2084
	spin_unlock_irqrestore(&gpio_lock, flags);
2085

2086
	return NULL;
2087 2088 2089 2090
}

static void *gpiolib_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
2091
	unsigned long flags;
2092 2093 2094
	struct gpio_chip *chip = v;
	void *ret = NULL;

2095
	spin_lock_irqsave(&gpio_lock, flags);
2096 2097 2098 2099
	if (list_is_last(&chip->list, &gpio_chips))
		ret = NULL;
	else
		ret = list_entry(chip->list.next, struct gpio_chip, list);
2100
	spin_unlock_irqrestore(&gpio_lock, flags);
2101 2102 2103 2104 2105 2106 2107 2108 2109 2110 2111 2112 2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133

	s->private = "\n";
	++*pos;

	return ret;
}

static void gpiolib_seq_stop(struct seq_file *s, void *v)
{
}

static int gpiolib_seq_show(struct seq_file *s, void *v)
{
	struct gpio_chip *chip = v;
	struct device *dev;

	seq_printf(s, "%sGPIOs %d-%d", (char *)s->private,
			chip->base, chip->base + chip->ngpio - 1);
	dev = chip->dev;
	if (dev)
		seq_printf(s, ", %s/%s", dev->bus ? dev->bus->name : "no-bus",
			dev_name(dev));
	if (chip->label)
		seq_printf(s, ", %s", chip->label);
	if (chip->can_sleep)
		seq_printf(s, ", can sleep");
	seq_printf(s, ":\n");

	if (chip->dbg_show)
		chip->dbg_show(s, chip);
	else
		gpiolib_dbg_show(s, chip);

2134 2135 2136
	return 0;
}

2137 2138 2139 2140 2141 2142 2143
static const struct seq_operations gpiolib_seq_ops = {
	.start = gpiolib_seq_start,
	.next = gpiolib_seq_next,
	.stop = gpiolib_seq_stop,
	.show = gpiolib_seq_show,
};

2144 2145
static int gpiolib_open(struct inode *inode, struct file *file)
{
2146
	return seq_open(file, &gpiolib_seq_ops);
2147 2148
}

2149
static const struct file_operations gpiolib_operations = {
2150
	.owner		= THIS_MODULE,
2151 2152 2153
	.open		= gpiolib_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
2154
	.release	= seq_release,
2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166
};

static int __init gpiolib_debugfs_init(void)
{
	/* /sys/kernel/debug/gpio */
	(void) debugfs_create_file("gpio", S_IFREG | S_IRUGO,
				NULL, NULL, &gpiolib_operations);
	return 0;
}
subsys_initcall(gpiolib_debugfs_init);

#endif	/* DEBUG_FS */