gpiolib.c 47.9 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/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_RESERVED	2
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#define FLAG_EXPORT	3	/* protected by sysfs_lock */
#define FLAG_SYSFS	4	/* exported via /sys/class/gpio/control */
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#define FLAG_TRIG_FALL	5	/* trigger on falling edge */
#define FLAG_TRIG_RISE	6	/* trigger on rising edge */
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#define FLAG_ACTIVE_LOW	7	/* sysfs value has active low */
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#define FLAG_OPEN_DRAIN	8	/* Gpio is open drain type */
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#define FLAG_OPEN_SOURCE 9	/* 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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#ifdef CONFIG_GPIO_SYSFS
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static DEFINE_IDR(dirent_idr);
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#endif

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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
}

/* 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, unsigned offset)
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{
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	const struct gpio_chip *chip = desc->chip;
	const int gpio = chip->base + offset;
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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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struct gpio_chip *gpio_to_chip(unsigned gpio)
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{
	return gpio_desc[gpio].chip;
}

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/* dynamic allocation of GPIOs, e.g. on a hotplugged device */
static int gpiochip_find_base(int ngpio)
{
	int i;
	int spare = 0;
	int base = -ENOSPC;

	for (i = ARCH_NR_GPIOS - 1; i >= 0 ; i--) {
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		struct gpio_desc *desc = &gpio_desc[i];
		struct gpio_chip *chip = desc->chip;
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		if (!chip && !test_bit(FLAG_RESERVED, &desc->flags)) {
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			spare++;
			if (spare == ngpio) {
				base = i;
				break;
			}
		} else {
			spare = 0;
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			if (chip)
				i -= chip->ngpio - 1;
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		}
	}

	if (gpio_is_valid(base))
		pr_debug("%s: found new base at %d\n", __func__, base);
	return base;
}

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/**
 * gpiochip_reserve() - reserve range of gpios to use with platform code only
 * @start: starting gpio number
 * @ngpio: number of gpios to reserve
 * Context: platform init, potentially before irqs or kmalloc will work
 *
 * Returns a negative errno if any gpio within the range is already reserved
 * or registered, else returns zero as a success code.  Use this function
 * to mark a range of gpios as unavailable for dynamic gpio number allocation,
 * for example because its driver support is not yet loaded.
 */
int __init gpiochip_reserve(int start, int ngpio)
{
	int ret = 0;
	unsigned long flags;
	int i;

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	if (!gpio_is_valid(start) || !gpio_is_valid(start + ngpio - 1))
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		return -EINVAL;

	spin_lock_irqsave(&gpio_lock, flags);

	for (i = start; i < start + ngpio; i++) {
		struct gpio_desc *desc = &gpio_desc[i];

		if (desc->chip || test_bit(FLAG_RESERVED, &desc->flags)) {
			ret = -EBUSY;
			goto err;
		}

		set_bit(FLAG_RESERVED, &desc->flags);
	}

	pr_debug("%s: reserved gpios from %d to %d\n",
		 __func__, start, start + ngpio - 1);
err:
	spin_unlock_irqrestore(&gpio_lock, flags);

	return ret;
}

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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)
{
	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, "%s\n",
			test_bit(FLAG_IS_OUT, &desc->flags)
				? "out" : "in");

	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)
{
	const struct gpio_desc	*desc = dev_get_drvdata(dev);
	unsigned		gpio = desc - gpio_desc;
	ssize_t			status;

	mutex_lock(&sysfs_lock);

	if (!test_bit(FLAG_EXPORT, &desc->flags))
		status = -EIO;
	else if (sysfs_streq(buf, "high"))
		status = gpio_direction_output(gpio, 1);
	else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
		status = gpio_direction_output(gpio, 0);
	else if (sysfs_streq(buf, "in"))
		status = gpio_direction_input(gpio);
	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)
{
	const struct gpio_desc	*desc = dev_get_drvdata(dev);
	unsigned		gpio = desc - gpio_desc;
	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;

		value = !!gpio_get_value_cansleep(gpio);
		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)
{
	const struct gpio_desc	*desc = dev_get_drvdata(dev);
	unsigned		gpio = desc - gpio_desc;
	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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			gpio_set_value_cansleep(gpio, value != 0);
			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;

	irq = gpio_to_irq(desc - gpio_desc);
	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;
		}

		do {
			ret = -ENOMEM;
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			if (idr_pre_get(&dirent_idr, GFP_KERNEL))
				ret = idr_get_new_above(&dirent_idr, value_sd,
							1, &id);
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		} while (ret == -EAGAIN);

		if (ret)
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			goto free_sd;
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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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{
	long	gpio;
	int	status;

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

	/* 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.
	 */

	status = gpio_request(gpio, "sysfs");
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	if (status < 0) {
		if (status == -EPROBE_DEFER)
			status = -ENODEV;
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		goto done;
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	}
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	status = gpio_export(gpio, true);
	if (status < 0)
		gpio_free(gpio);
	else
		set_bit(FLAG_SYSFS, &gpio_desc[gpio].flags);

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

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static ssize_t unexport_store(struct class *class,
				struct class_attribute *attr,
				const char *buf, size_t len)
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{
	long	gpio;
	int	status;

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

	status = -EINVAL;

	/* reject bogus commands (gpio_unexport ignores them) */
	if (!gpio_is_valid(gpio))
		goto done;

	/* 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.
	 */
	if (test_and_clear_bit(FLAG_SYSFS, &gpio_desc[gpio].flags)) {
		status = 0;
		gpio_free(gpio);
	}
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.
 */
int gpio_export(unsigned gpio, bool direction_may_change)
{
	unsigned long		flags;
	struct gpio_desc	*desc;
	int			status = -EINVAL;
708
	const char		*ioname = NULL;
D
David Brownell 已提交
709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731

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

	if (!gpio_is_valid(gpio))
		goto done;

	mutex_lock(&sysfs_lock);

	spin_lock_irqsave(&gpio_lock, flags);
	desc = &gpio_desc[gpio];
	if (test_bit(FLAG_REQUESTED, &desc->flags)
			&& !test_bit(FLAG_EXPORT, &desc->flags)) {
		status = 0;
		if (!desc->chip->direction_input
				|| !desc->chip->direction_output)
			direction_may_change = false;
	}
	spin_unlock_irqrestore(&gpio_lock, flags);

732 733 734
	if (desc->chip->names && desc->chip->names[gpio - desc->chip->base])
		ioname = desc->chip->names[gpio - desc->chip->base];

D
David Brownell 已提交
735 736 737 738
	if (status == 0) {
		struct device	*dev;

		dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
739
				desc, ioname ? ioname : "gpio%u", gpio);
740
		if (!IS_ERR(dev)) {
741
			status = sysfs_create_group(&dev->kobj,
D
David Brownell 已提交
742
						&gpio_attr_group);
743 744

			if (!status && direction_may_change)
D
David Brownell 已提交
745
				status = device_create_file(dev,
746
						&dev_attr_direction);
747 748 749 750 751 752 753 754

			if (!status && gpio_to_irq(gpio) >= 0
					&& (direction_may_change
						|| !test_bit(FLAG_IS_OUT,
							&desc->flags)))
				status = device_create_file(dev,
						&dev_attr_edge);

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			if (status != 0)
				device_unregister(dev);
		} else
758
			status = PTR_ERR(dev);
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759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777
		if (status == 0)
			set_bit(FLAG_EXPORT, &desc->flags);
	}

	mutex_unlock(&sysfs_lock);

done:
	if (status)
		pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);

	return status;
}
EXPORT_SYMBOL_GPL(gpio_export);

static int match_export(struct device *dev, void *data)
{
	return dev_get_drvdata(dev) == data;
}

778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822
/**
 * 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.
 */
int gpio_export_link(struct device *dev, const char *name, unsigned gpio)
{
	struct gpio_desc	*desc;
	int			status = -EINVAL;

	if (!gpio_is_valid(gpio))
		goto done;

	mutex_lock(&sysfs_lock);

	desc = &gpio_desc[gpio];

	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);

done:
	if (status)
		pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);

	return status;
}
EXPORT_SYMBOL_GPL(gpio_export_link);

823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869

/**
 * 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.
 */
int gpio_sysfs_set_active_low(unsigned gpio, int value)
{
	struct gpio_desc	*desc;
	struct device		*dev = NULL;
	int			status = -EINVAL;

	if (!gpio_is_valid(gpio))
		goto done;

	mutex_lock(&sysfs_lock);

	desc = &gpio_desc[gpio];

	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);

done:
	if (status)
		pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);

	return status;
}
EXPORT_SYMBOL_GPL(gpio_sysfs_set_active_low);

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David Brownell 已提交
870 871 872 873 874 875 876 877 878
/**
 * gpio_unexport - reverse effect of gpio_export()
 * @gpio: gpio to make unavailable
 *
 * This is implicit on gpio_free().
 */
void gpio_unexport(unsigned gpio)
{
	struct gpio_desc	*desc;
879
	int			status = 0;
880
	struct device		*dev = NULL;
D
David Brownell 已提交
881

882 883
	if (!gpio_is_valid(gpio)) {
		status = -EINVAL;
D
David Brownell 已提交
884
		goto done;
885
	}
D
David Brownell 已提交
886 887 888 889

	mutex_lock(&sysfs_lock);

	desc = &gpio_desc[gpio];
890

D
David Brownell 已提交
891 892 893 894
	if (test_bit(FLAG_EXPORT, &desc->flags)) {

		dev = class_find_device(&gpio_class, NULL, desc, match_export);
		if (dev) {
895
			gpio_setup_irq(desc, dev, 0);
D
David Brownell 已提交
896 897 898 899 900 901
			clear_bit(FLAG_EXPORT, &desc->flags);
		} else
			status = -ENODEV;
	}

	mutex_unlock(&sysfs_lock);
902 903 904 905
	if (dev) {
		device_unregister(dev);
		put_device(dev);
	}
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906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928
done:
	if (status)
		pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
}
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);
929
	if (!IS_ERR(dev)) {
D
David Brownell 已提交
930 931 932
		status = sysfs_create_group(&dev->kobj,
				&gpiochip_attr_group);
	} else
933
		status = PTR_ERR(dev);
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David Brownell 已提交
934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021
	chip->exported = (status == 0);
	mutex_unlock(&sysfs_lock);

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

		spin_lock_irqsave(&gpio_lock, flags);
		gpio = chip->base;
		while (gpio_desc[gpio].chip == chip)
			gpio_desc[gpio++].chip = NULL;
		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;
	unsigned	gpio;

	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);
	for (gpio = 0; gpio < ARCH_NR_GPIOS; gpio++) {
		struct gpio_chip	*chip;

		chip = gpio_desc[gpio].chip;
		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)
{
}

#endif /* CONFIG_GPIO_SYSFS */

1022 1023 1024 1025 1026 1027 1028 1029
/**
 * 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.
1030
 *
D
David Brownell 已提交
1031 1032 1033 1034 1035
 * 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.
 *
1036 1037
 * If chip->base is negative, this requests dynamic assignment of
 * a range of valid GPIOs.
1038 1039 1040 1041 1042 1043
 */
int gpiochip_add(struct gpio_chip *chip)
{
	unsigned long	flags;
	int		status = 0;
	unsigned	id;
1044
	int		base = chip->base;
1045

T
Trent Piepho 已提交
1046
	if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))
1047
			&& base >= 0) {
1048 1049 1050 1051 1052 1053
		status = -EINVAL;
		goto fail;
	}

	spin_lock_irqsave(&gpio_lock, flags);

1054 1055 1056 1057
	if (base < 0) {
		base = gpiochip_find_base(chip->ngpio);
		if (base < 0) {
			status = base;
D
David Brownell 已提交
1058
			goto unlock;
1059 1060 1061 1062
		}
		chip->base = base;
	}

1063
	/* these GPIO numbers must not be managed by another gpio_chip */
1064
	for (id = base; id < base + chip->ngpio; id++) {
1065 1066 1067 1068 1069 1070
		if (gpio_desc[id].chip != NULL) {
			status = -EBUSY;
			break;
		}
	}
	if (status == 0) {
1071
		for (id = base; id < base + chip->ngpio; id++) {
1072
			gpio_desc[id].chip = chip;
D
David Brownell 已提交
1073 1074 1075 1076 1077 1078 1079 1080 1081 1082

			/* 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,
			 * we may expose the wrong direction in sysfs.
			 */
			gpio_desc[id].flags = !chip->direction_input
				? (1 << FLAG_IS_OUT)
				: 0;
1083 1084 1085
		}
	}

1086 1087 1088 1089
#ifdef CONFIG_PINCTRL
	INIT_LIST_HEAD(&chip->pin_ranges);
#endif

1090 1091
	of_gpiochip_add(chip);

D
David Brownell 已提交
1092
unlock:
1093
	spin_unlock_irqrestore(&gpio_lock, flags);
1094 1095 1096 1097 1098 1099 1100 1101

	if (status)
		goto fail;

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

1102
	pr_debug("gpiochip_add: registered GPIOs %d to %d on device: %s\n",
1103 1104 1105
		chip->base, chip->base + chip->ngpio - 1,
		chip->label ? : "generic");

1106
	return 0;
1107 1108
fail:
	/* failures here can mean systems won't boot... */
1109 1110 1111
	pr_err("gpiochip_add: gpios %d..%d (%s) failed to register\n",
		chip->base, chip->base + chip->ngpio - 1,
		chip->label ? : "generic");
1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129
	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);

1130
	gpiochip_remove_pin_ranges(chip);
1131 1132
	of_gpiochip_remove(chip);

1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144
	for (id = chip->base; id < chip->base + chip->ngpio; id++) {
		if (test_bit(FLAG_REQUESTED, &gpio_desc[id].flags)) {
			status = -EBUSY;
			break;
		}
	}
	if (status == 0) {
		for (id = chip->base; id < chip->base + chip->ngpio; id++)
			gpio_desc[id].chip = NULL;
	}

	spin_unlock_irqrestore(&gpio_lock, flags);
D
David Brownell 已提交
1145 1146 1147 1148

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

1149 1150 1151 1152
	return status;
}
EXPORT_SYMBOL_GPL(gpiochip_remove);

1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163
/**
 * 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.
 */
1164
struct gpio_chip *gpiochip_find(void *data,
1165
				int (*match)(struct gpio_chip *chip,
1166
					     void *data))
1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185
{
	struct gpio_chip *chip = NULL;
	unsigned long flags;
	int i;

	spin_lock_irqsave(&gpio_lock, flags);
	for (i = 0; i < ARCH_NR_GPIOS; i++) {
		if (!gpio_desc[i].chip)
			continue;

		if (match(gpio_desc[i].chip, data)) {
			chip = gpio_desc[i].chip;
			break;
		}
	}
	spin_unlock_irqrestore(&gpio_lock, flags);

	return chip;
}
J
Jean Delvare 已提交
1186
EXPORT_SYMBOL_GPL(gpiochip_find);
1187

1188
#ifdef CONFIG_PINCTRL
1189

1190 1191 1192 1193 1194 1195 1196 1197 1198
/**
 * 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
 * @offset: the start offset in the current gpio_chip number space
 * @pin_base: the start offset in the pin controller number space
 * @npins: the number of pins from the offset of each pin space (GPIO and
 *	pin controller) to accumulate in this range
 */
1199
int gpiochip_add_pin_range(struct gpio_chip *chip, const char *pinctl_name,
1200 1201
			   unsigned int offset, unsigned int pin_base,
			   unsigned int npins)
1202 1203 1204
{
	struct gpio_pin_range *pin_range;

1205
	pin_range = kzalloc(sizeof(*pin_range), GFP_KERNEL);
1206 1207 1208
	if (!pin_range) {
		pr_err("%s: GPIO chip: failed to allocate pin ranges\n",
				chip->label);
1209
		return -ENOMEM;
1210 1211
	}

1212 1213 1214
	/* Use local offset as range ID */
	pin_range->range.id = offset;
	pin_range->range.gc = chip;
1215
	pin_range->range.name = chip->label;
1216
	pin_range->range.base = chip->base + offset;
1217 1218
	pin_range->range.pin_base = pin_base;
	pin_range->range.npins = npins;
L
Linus Walleij 已提交
1219
	pin_range->pctldev = pinctrl_find_and_add_gpio_range(pinctl_name,
1220
			&pin_range->range);
1221 1222 1223 1224 1225 1226 1227 1228
	if (!pin_range->pctldev) {
		pr_err("%s: GPIO chip: could not create pin range\n",
		       chip->label);
		kfree(pin_range);
	}
	pr_debug("%s: GPIO chip: created GPIO range %d->%d ==> PIN %d->%d\n",
		 chip->label, offset, offset + npins - 1,
		 pin_base, pin_base + npins - 1);
1229 1230

	list_add_tail(&pin_range->node, &chip->pin_ranges);
1231 1232

	return 0;
1233
}
1234
EXPORT_SYMBOL_GPL(gpiochip_add_pin_range);
1235

1236 1237 1238 1239
/**
 * gpiochip_remove_pin_ranges() - remove all the GPIO <-> pin mappings
 * @chip: the chip to remove all the mappings for
 */
1240 1241 1242 1243 1244 1245 1246 1247
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);
1248
		kfree(pin_range);
1249 1250
	}
}
1251 1252 1253
EXPORT_SYMBOL_GPL(gpiochip_remove_pin_ranges);

#endif /* CONFIG_PINCTRL */
1254

1255 1256 1257 1258 1259 1260 1261
/* 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.
 */
int gpio_request(unsigned gpio, const char *label)
{
	struct gpio_desc	*desc;
D
David Brownell 已提交
1262
	struct gpio_chip	*chip;
1263
	int			status = -EPROBE_DEFER;
1264 1265 1266 1267
	unsigned long		flags;

	spin_lock_irqsave(&gpio_lock, flags);

1268 1269
	if (!gpio_is_valid(gpio)) {
		status = -EINVAL;
1270
		goto done;
1271
	}
1272
	desc = &gpio_desc[gpio];
D
David Brownell 已提交
1273 1274
	chip = desc->chip;
	if (chip == NULL)
1275 1276
		goto done;

D
David Brownell 已提交
1277
	if (!try_module_get(chip->owner))
1278 1279
		goto done;

1280
	/* NOTE:  gpio_request() can be called in early boot,
D
David Brownell 已提交
1281
	 * before IRQs are enabled, for non-sleeping (SOC) GPIOs.
1282 1283 1284 1285 1286
	 */

	if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
		desc_set_label(desc, label ? : "?");
		status = 0;
1287
	} else {
1288
		status = -EBUSY;
D
David Brownell 已提交
1289
		module_put(chip->owner);
M
Magnus Damm 已提交
1290
		goto done;
D
David Brownell 已提交
1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303
	}

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

		if (status < 0) {
			desc_set_label(desc, NULL);
			module_put(chip->owner);
			clear_bit(FLAG_REQUESTED, &desc->flags);
		}
1304
	}
1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318

done:
	if (status)
		pr_debug("gpio_request: gpio-%d (%s) status %d\n",
			gpio, label ? : "?", status);
	spin_unlock_irqrestore(&gpio_lock, flags);
	return status;
}
EXPORT_SYMBOL_GPL(gpio_request);

void gpio_free(unsigned gpio)
{
	unsigned long		flags;
	struct gpio_desc	*desc;
D
David Brownell 已提交
1319
	struct gpio_chip	*chip;
1320

1321 1322
	might_sleep();

1323
	if (!gpio_is_valid(gpio)) {
1324 1325 1326 1327
		WARN_ON(extra_checks);
		return;
	}

D
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1328 1329
	gpio_unexport(gpio);

1330 1331 1332
	spin_lock_irqsave(&gpio_lock, flags);

	desc = &gpio_desc[gpio];
D
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1333 1334 1335 1336
	chip = desc->chip;
	if (chip && test_bit(FLAG_REQUESTED, &desc->flags)) {
		if (chip->free) {
			spin_unlock_irqrestore(&gpio_lock, flags);
1337
			might_sleep_if(chip->can_sleep);
D
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1338 1339 1340
			chip->free(chip, gpio - chip->base);
			spin_lock_irqsave(&gpio_lock, flags);
		}
1341
		desc_set_label(desc, NULL);
1342
		module_put(desc->chip->owner);
1343
		clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
D
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1344
		clear_bit(FLAG_REQUESTED, &desc->flags);
1345
		clear_bit(FLAG_OPEN_DRAIN, &desc->flags);
1346
		clear_bit(FLAG_OPEN_SOURCE, &desc->flags);
1347
	} else
1348 1349 1350 1351 1352 1353
		WARN_ON(extra_checks);

	spin_unlock_irqrestore(&gpio_lock, flags);
}
EXPORT_SYMBOL_GPL(gpio_free);

1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367
/**
 * 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)
{
	int err;

	err = gpio_request(gpio, label);
	if (err)
		return err;

1368 1369 1370
	if (flags & GPIOF_OPEN_DRAIN)
		set_bit(FLAG_OPEN_DRAIN, &gpio_desc[gpio].flags);

1371 1372 1373
	if (flags & GPIOF_OPEN_SOURCE)
		set_bit(FLAG_OPEN_SOURCE, &gpio_desc[gpio].flags);

1374 1375 1376 1377 1378 1379
	if (flags & GPIOF_DIR_IN)
		err = gpio_direction_input(gpio);
	else
		err = gpio_direction_output(gpio,
				(flags & GPIOF_INIT_HIGH) ? 1 : 0);

1380
	if (err)
1381 1382 1383 1384 1385 1386 1387 1388 1389
		goto free_gpio;

	if (flags & GPIOF_EXPORT) {
		err = gpio_export(gpio, flags & GPIOF_EXPORT_CHANGEABLE);
		if (err)
			goto free_gpio;
	}

	return 0;
1390

1391 1392
 free_gpio:
	gpio_free(gpio);
1393 1394 1395 1396 1397 1398 1399 1400 1401
	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
 */
1402
int gpio_request_array(const struct gpio *array, size_t num)
1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424
{
	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
 */
1425
void gpio_free_array(const struct gpio *array, size_t num)
1426 1427 1428 1429 1430
{
	while (num--)
		gpio_free((array++)->gpio);
}
EXPORT_SYMBOL_GPL(gpio_free_array);
1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448

/**
 * 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)
{
	unsigned gpio = chip->base + offset;

1449
	if (!gpio_is_valid(gpio) || gpio_desc[gpio].chip != chip)
1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479
		return NULL;
	if (test_bit(FLAG_REQUESTED, &gpio_desc[gpio].flags) == 0)
		return NULL;
#ifdef CONFIG_DEBUG_FS
	return gpio_desc[gpio].label;
#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.
 */

int gpio_direction_input(unsigned gpio)
{
	unsigned long		flags;
	struct gpio_chip	*chip;
	struct gpio_desc	*desc = &gpio_desc[gpio];
	int			status = -EINVAL;

	spin_lock_irqsave(&gpio_lock, flags);

1480
	if (!gpio_is_valid(gpio))
1481 1482 1483 1484 1485 1486 1487
		goto fail;
	chip = desc->chip;
	if (!chip || !chip->get || !chip->direction_input)
		goto fail;
	gpio -= chip->base;
	if (gpio >= chip->ngpio)
		goto fail;
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1488 1489 1490
	status = gpio_ensure_requested(desc, gpio);
	if (status < 0)
		goto fail;
1491 1492 1493 1494 1495

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

	spin_unlock_irqrestore(&gpio_lock, flags);

1496
	might_sleep_if(chip->can_sleep);
1497

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1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509
	if (status) {
		status = chip->request(chip, gpio);
		if (status < 0) {
			pr_debug("GPIO-%d: chip request fail, %d\n",
				chip->base + gpio, status);
			/* and it's not available to anyone else ...
			 * gpio_request() is the fully clean solution.
			 */
			goto lose;
		}
	}

1510 1511 1512
	status = chip->direction_input(chip, gpio);
	if (status == 0)
		clear_bit(FLAG_IS_OUT, &desc->flags);
1513 1514

	trace_gpio_direction(chip->base + gpio, 1, status);
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1515
lose:
1516 1517 1518 1519 1520
	return status;
fail:
	spin_unlock_irqrestore(&gpio_lock, flags);
	if (status)
		pr_debug("%s: gpio-%d status %d\n",
1521
			__func__, gpio, status);
1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532
	return status;
}
EXPORT_SYMBOL_GPL(gpio_direction_input);

int gpio_direction_output(unsigned gpio, int value)
{
	unsigned long		flags;
	struct gpio_chip	*chip;
	struct gpio_desc	*desc = &gpio_desc[gpio];
	int			status = -EINVAL;

1533 1534 1535 1536
	/* Open drain pin should not be driven to 1 */
	if (value && test_bit(FLAG_OPEN_DRAIN,  &desc->flags))
		return gpio_direction_input(gpio);

1537 1538 1539 1540
	/* Open source pin should not be driven to 0 */
	if (!value && test_bit(FLAG_OPEN_SOURCE,  &desc->flags))
		return gpio_direction_input(gpio);

1541 1542
	spin_lock_irqsave(&gpio_lock, flags);

1543
	if (!gpio_is_valid(gpio))
1544 1545 1546 1547 1548 1549 1550
		goto fail;
	chip = desc->chip;
	if (!chip || !chip->set || !chip->direction_output)
		goto fail;
	gpio -= chip->base;
	if (gpio >= chip->ngpio)
		goto fail;
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1551 1552 1553
	status = gpio_ensure_requested(desc, gpio);
	if (status < 0)
		goto fail;
1554 1555 1556 1557 1558

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

	spin_unlock_irqrestore(&gpio_lock, flags);

1559
	might_sleep_if(chip->can_sleep);
1560

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1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572
	if (status) {
		status = chip->request(chip, gpio);
		if (status < 0) {
			pr_debug("GPIO-%d: chip request fail, %d\n",
				chip->base + gpio, status);
			/* and it's not available to anyone else ...
			 * gpio_request() is the fully clean solution.
			 */
			goto lose;
		}
	}

1573 1574 1575
	status = chip->direction_output(chip, gpio, value);
	if (status == 0)
		set_bit(FLAG_IS_OUT, &desc->flags);
1576 1577
	trace_gpio_value(chip->base + gpio, 0, value);
	trace_gpio_direction(chip->base + gpio, 0, status);
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1578
lose:
1579 1580 1581 1582 1583
	return status;
fail:
	spin_unlock_irqrestore(&gpio_lock, flags);
	if (status)
		pr_debug("%s: gpio-%d status %d\n",
1584
			__func__, gpio, status);
1585 1586 1587 1588
	return status;
}
EXPORT_SYMBOL_GPL(gpio_direction_output);

1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618
/**
 * gpio_set_debounce - sets @debounce time for a @gpio
 * @gpio: the gpio to set debounce time
 * @debounce: debounce time is microseconds
 */
int gpio_set_debounce(unsigned gpio, unsigned debounce)
{
	unsigned long		flags;
	struct gpio_chip	*chip;
	struct gpio_desc	*desc = &gpio_desc[gpio];
	int			status = -EINVAL;

	spin_lock_irqsave(&gpio_lock, flags);

	if (!gpio_is_valid(gpio))
		goto fail;
	chip = desc->chip;
	if (!chip || !chip->set || !chip->set_debounce)
		goto fail;
	gpio -= chip->base;
	if (gpio >= chip->ngpio)
		goto fail;
	status = gpio_ensure_requested(desc, gpio);
	if (status < 0)
		goto fail;

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

	spin_unlock_irqrestore(&gpio_lock, flags);

1619
	might_sleep_if(chip->can_sleep);
1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631

	return chip->set_debounce(chip, gpio, debounce);

fail:
	spin_unlock_irqrestore(&gpio_lock, flags);
	if (status)
		pr_debug("%s: gpio-%d status %d\n",
			__func__, gpio, status);

	return status;
}
EXPORT_SYMBOL_GPL(gpio_set_debounce);
1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666

/* 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.
 */
int __gpio_get_value(unsigned gpio)
{
	struct gpio_chip	*chip;
1667
	int value;
1668 1669

	chip = gpio_to_chip(gpio);
1670
	/* Should be using gpio_get_value_cansleep() */
1671
	WARN_ON(chip->can_sleep);
1672 1673 1674
	value = chip->get ? chip->get(chip, gpio - chip->base) : 0;
	trace_gpio_value(gpio, 1, value);
	return value;
1675 1676 1677
}
EXPORT_SYMBOL_GPL(__gpio_get_value);

1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702
/*
 *  _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.
 */
static void _gpio_set_open_drain_value(unsigned gpio,
			struct gpio_chip *chip, int value)
{
	int err = 0;
	if (value) {
		err = chip->direction_input(chip, gpio - chip->base);
		if (!err)
			clear_bit(FLAG_IS_OUT, &gpio_desc[gpio].flags);
	} else {
		err = chip->direction_output(chip, gpio - chip->base, 0);
		if (!err)
			set_bit(FLAG_IS_OUT, &gpio_desc[gpio].flags);
	}
	trace_gpio_direction(gpio, value, err);
	if (err < 0)
		pr_err("%s: Error in set_value for open drain gpio%d err %d\n",
					__func__, gpio, err);
}

1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728
/*
 *  _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.
 */
static void _gpio_set_open_source_value(unsigned gpio,
			struct gpio_chip *chip, int value)
{
	int err = 0;
	if (value) {
		err = chip->direction_output(chip, gpio - chip->base, 1);
		if (!err)
			set_bit(FLAG_IS_OUT, &gpio_desc[gpio].flags);
	} else {
		err = chip->direction_input(chip, gpio - chip->base);
		if (!err)
			clear_bit(FLAG_IS_OUT, &gpio_desc[gpio].flags);
	}
	trace_gpio_direction(gpio, !value, err);
	if (err < 0)
		pr_err("%s: Error in set_value for open source gpio%d err %d\n",
					__func__, gpio, err);
}


1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742
/**
 * __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.
 */
void __gpio_set_value(unsigned gpio, int value)
{
	struct gpio_chip	*chip;

	chip = gpio_to_chip(gpio);
1743
	/* Should be using gpio_set_value_cansleep() */
1744
	WARN_ON(chip->can_sleep);
1745
	trace_gpio_value(gpio, 0, value);
1746 1747
	if (test_bit(FLAG_OPEN_DRAIN,  &gpio_desc[gpio].flags))
		_gpio_set_open_drain_value(gpio, chip, value);
1748 1749
	else if (test_bit(FLAG_OPEN_SOURCE,  &gpio_desc[gpio].flags))
		_gpio_set_open_source_value(gpio, chip, value);
1750 1751
	else
		chip->set(chip, gpio - chip->base, value);
1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773
}
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.
 */
int __gpio_cansleep(unsigned gpio)
{
	struct gpio_chip	*chip;

	/* only call this on GPIOs that are valid! */
	chip = gpio_to_chip(gpio);

	return chip->can_sleep;
}
EXPORT_SYMBOL_GPL(__gpio_cansleep);

D
David Brownell 已提交
1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791
/**
 * __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.
 */
int __gpio_to_irq(unsigned gpio)
{
	struct gpio_chip	*chip;

	chip = gpio_to_chip(gpio);
	return chip->to_irq ? chip->to_irq(chip, gpio - chip->base) : -ENXIO;
}
EXPORT_SYMBOL_GPL(__gpio_to_irq);

1792 1793 1794 1795 1796 1797 1798 1799 1800


/* 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.
 */

int gpio_get_value_cansleep(unsigned gpio)
{
	struct gpio_chip	*chip;
1801
	int value;
1802 1803 1804

	might_sleep_if(extra_checks);
	chip = gpio_to_chip(gpio);
1805 1806 1807
	value = chip->get ? chip->get(chip, gpio - chip->base) : 0;
	trace_gpio_value(gpio, 1, value);
	return value;
1808 1809 1810 1811 1812 1813 1814 1815 1816
}
EXPORT_SYMBOL_GPL(gpio_get_value_cansleep);

void gpio_set_value_cansleep(unsigned gpio, int value)
{
	struct gpio_chip	*chip;

	might_sleep_if(extra_checks);
	chip = gpio_to_chip(gpio);
1817
	trace_gpio_value(gpio, 0, value);
1818 1819
	if (test_bit(FLAG_OPEN_DRAIN,  &gpio_desc[gpio].flags))
		_gpio_set_open_drain_value(gpio, chip, value);
1820 1821
	else if (test_bit(FLAG_OPEN_SOURCE,  &gpio_desc[gpio].flags))
		_gpio_set_open_source_value(gpio, chip, value);
1822 1823
	else
		chip->set(chip, gpio - chip->base, value);
1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841
}
EXPORT_SYMBOL_GPL(gpio_set_value_cansleep);


#ifdef CONFIG_DEBUG_FS

static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
{
	unsigned		i;
	unsigned		gpio = chip->base;
	struct gpio_desc	*gdesc = &gpio_desc[gpio];
	int			is_out;

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

		is_out = test_bit(FLAG_IS_OUT, &gdesc->flags);
1842
		seq_printf(s, " gpio-%-3d (%-20.20s) %s %s",
1843 1844 1845 1846 1847 1848 1849 1850 1851
			gpio, gdesc->label,
			is_out ? "out" : "in ",
			chip->get
				? (chip->get(chip, i) ? "hi" : "lo")
				: "?  ");
		seq_printf(s, "\n");
	}
}

1852
static void *gpiolib_seq_start(struct seq_file *s, loff_t *pos)
1853
{
1854 1855 1856 1857
	struct gpio_chip *chip = NULL;
	unsigned int gpio;
	void *ret = NULL;
	loff_t index = 0;
1858 1859 1860

	/* REVISIT this isn't locked against gpio_chip removal ... */

1861
	for (gpio = 0; gpio_is_valid(gpio); gpio++) {
1862
		if (gpio_desc[gpio].chip == chip)
1863
			continue;
1864

1865 1866 1867 1868
		chip = gpio_desc[gpio].chip;
		if (!chip)
			continue;

1869 1870 1871 1872
		if (index++ >= *pos) {
			ret = chip;
			break;
		}
1873
	}
1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926

	s->private = "";

	return ret;
}

static void *gpiolib_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
	struct gpio_chip *chip = v;
	unsigned int gpio;
	void *ret = NULL;

	/* skip GPIOs provided by the current chip */
	for (gpio = chip->base + chip->ngpio; gpio_is_valid(gpio); gpio++) {
		chip = gpio_desc[gpio].chip;
		if (chip) {
			ret = chip;
			break;
		}
	}

	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);

1927 1928 1929
	return 0;
}

1930 1931 1932 1933 1934 1935 1936
static const struct seq_operations gpiolib_seq_ops = {
	.start = gpiolib_seq_start,
	.next = gpiolib_seq_next,
	.stop = gpiolib_seq_stop,
	.show = gpiolib_seq_show,
};

1937 1938
static int gpiolib_open(struct inode *inode, struct file *file)
{
1939
	return seq_open(file, &gpiolib_seq_ops);
1940 1941
}

1942
static const struct file_operations gpiolib_operations = {
1943
	.owner		= THIS_MODULE,
1944 1945 1946
	.open		= gpiolib_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
1947
	.release	= seq_release,
1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959
};

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 */