gpiolib.c 53.1 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);
static int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce);
static int gpiod_get_value_cansleep(struct gpio_desc *desc);
static void gpiod_set_value_cansleep(struct gpio_desc *desc, int value);
static int gpiod_get_value(struct gpio_desc *desc);
static void gpiod_set_value(struct gpio_desc *desc, int value);
static int gpiod_cansleep(struct gpio_desc *desc);
static int gpiod_to_irq(struct gpio_desc *desc);
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(struct gpio_desc *desc)
{
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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(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;
		clear_bit(FLAG_IS_OUT, &desc->flags);
	}
	if (status == 0) {
		/* GPIOF_DIR_OUT */
		set_bit(FLAG_IS_OUT, &desc->flags);
	}
	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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	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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{
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	long			gpio;
	struct gpio_desc	*desc;
	int			status;
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	status = strict_strtol(buf, 0, &gpio);
	if (status < 0)
		goto done;

656
	desc = gpio_to_desc(gpio);
657 658 659 660 661
	/* reject invalid GPIOs */
	if (!desc) {
		pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
		return -EINVAL;
	}
662

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663 664 665 666 667
	/* 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.
	 */

668
	status = gpiod_request(desc, "sysfs");
669 670 671
	if (status < 0) {
		if (status == -EPROBE_DEFER)
			status = -ENODEV;
D
David Brownell 已提交
672
		goto done;
673
	}
674
	status = gpiod_export(desc, true);
D
David Brownell 已提交
675
	if (status < 0)
676
		gpiod_free(desc);
D
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677
	else
678
		set_bit(FLAG_SYSFS, &desc->flags);
D
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679 680 681 682 683 684 685

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

686 687 688
static ssize_t unexport_store(struct class *class,
				struct class_attribute *attr,
				const char *buf, size_t len)
D
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689
{
690 691 692
	long			gpio;
	struct gpio_desc	*desc;
	int			status;
D
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693 694 695 696 697

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

698
	desc = gpio_to_desc(gpio);
D
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699
	/* reject bogus commands (gpio_unexport ignores them) */
700 701 702 703 704 705
	if (!desc) {
		pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
		return -EINVAL;
	}

	status = -EINVAL;
D
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706 707 708 709 710

	/* 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.
	 */
711
	if (test_and_clear_bit(FLAG_SYSFS, &desc->flags)) {
D
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712
		status = 0;
713
		gpiod_free(desc);
D
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714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749
	}
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.
 */
750
static int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
D
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751 752
{
	unsigned long		flags;
R
Ryan Mallon 已提交
753
	int			status;
754
	const char		*ioname = NULL;
R
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755
	struct device		*dev;
756
	int			offset;
D
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757 758 759 760 761 762 763

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

764 765
	if (!desc) {
		pr_debug("%s: invalid gpio descriptor\n", __func__);
R
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766 767
		return -EINVAL;
	}
D
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768 769 770 771

	mutex_lock(&sysfs_lock);

	spin_lock_irqsave(&gpio_lock, flags);
R
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772 773 774 775
	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",
776
				__func__, desc_to_gpio(desc),
R
Ryan Mallon 已提交
777 778
				test_bit(FLAG_REQUESTED, &desc->flags),
				test_bit(FLAG_EXPORT, &desc->flags));
779 780
		status = -EPERM;
		goto fail_unlock;
D
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781
	}
R
Ryan Mallon 已提交
782 783 784

	if (!desc->chip->direction_input || !desc->chip->direction_output)
		direction_may_change = false;
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785 786
	spin_unlock_irqrestore(&gpio_lock, flags);

787 788 789
	offset = gpio_chip_hwgpio(desc);
	if (desc->chip->names && desc->chip->names[offset])
		ioname = desc->chip->names[offset];
790

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791
	dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
792 793
			    desc, ioname ? ioname : "gpio%u",
			    desc_to_gpio(desc));
R
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794 795 796
	if (IS_ERR(dev)) {
		status = PTR_ERR(dev);
		goto fail_unlock;
D
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797 798
	}

R
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799
	status = sysfs_create_group(&dev->kobj, &gpio_attr_group);
D
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800
	if (status)
R
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801
		goto fail_unregister_device;
D
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802

R
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803 804 805 806 807 808
	if (direction_may_change) {
		status = device_create_file(dev, &dev_attr_direction);
		if (status)
			goto fail_unregister_device;
	}

809
	if (gpiod_to_irq(desc) >= 0 && (direction_may_change ||
R
Ryan Mallon 已提交
810 811 812 813 814
				       !test_bit(FLAG_IS_OUT, &desc->flags))) {
		status = device_create_file(dev, &dev_attr_edge);
		if (status)
			goto fail_unregister_device;
	}
D
David Brownell 已提交
815

R
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816 817 818 819 820 821 822 823
	set_bit(FLAG_EXPORT, &desc->flags);
	mutex_unlock(&sysfs_lock);
	return 0;

fail_unregister_device:
	device_unregister(dev);
fail_unlock:
	mutex_unlock(&sysfs_lock);
824 825
	pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
		 status);
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826 827
	return status;
}
828 829 830 831 832

int gpio_export(unsigned gpio, bool direction_may_change)
{
	return gpiod_export(gpio_to_desc(gpio), direction_may_change);
}
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833 834
EXPORT_SYMBOL_GPL(gpio_export);

835
static int match_export(struct device *dev, const void *data)
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836 837 838 839
{
	return dev_get_drvdata(dev) == data;
}

840 841 842 843 844 845 846 847 848 849 850
/**
 * 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.
 */
851 852
static int gpiod_export_link(struct device *dev, const char *name,
			     struct gpio_desc *desc)
853 854 855
{
	int			status = -EINVAL;

856 857 858 859
	if (!desc) {
		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
	}
860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877

	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)
878 879
		pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
			 status);
880 881 882 883

	return status;
}

884 885 886 887 888
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);
889 890 891 892 893 894 895 896 897 898 899 900 901

/**
 * 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.
 */
902
static int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value)
903 904 905 906
{
	struct device		*dev = NULL;
	int			status = -EINVAL;

907 908 909 910
	if (!desc) {
		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
	}
911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927

	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)
928 929
		pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
			 status);
930 931 932

	return status;
}
933 934 935 936 937

int gpio_sysfs_set_active_low(unsigned gpio, int value)
{
	return gpiod_sysfs_set_active_low(gpio_to_desc(gpio), value);
}
938 939
EXPORT_SYMBOL_GPL(gpio_sysfs_set_active_low);

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940 941 942 943 944 945
/**
 * gpio_unexport - reverse effect of gpio_export()
 * @gpio: gpio to make unavailable
 *
 * This is implicit on gpio_free().
 */
946
static void gpiod_unexport(struct gpio_desc *desc)
D
David Brownell 已提交
947
{
948
	int			status = 0;
949
	struct device		*dev = NULL;
D
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950

951
	if (!desc) {
952 953
		pr_warn("%s: invalid GPIO\n", __func__);
		return;
954
	}
D
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955 956 957 958 959 960 961

	mutex_lock(&sysfs_lock);

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

		dev = class_find_device(&gpio_class, NULL, desc, match_export);
		if (dev) {
962
			gpio_setup_irq(desc, dev, 0);
D
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963 964 965 966 967 968
			clear_bit(FLAG_EXPORT, &desc->flags);
		} else
			status = -ENODEV;
	}

	mutex_unlock(&sysfs_lock);
969

970 971 972 973
	if (dev) {
		device_unregister(dev);
		put_device(dev);
	}
974

D
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975
	if (status)
976 977 978 979 980 981 982
		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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983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002
}
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);
1003
	if (!IS_ERR(dev)) {
D
David Brownell 已提交
1004 1005 1006
		status = sysfs_create_group(&dev->kobj,
				&gpiochip_attr_group);
	} else
1007
		status = PTR_ERR(dev);
D
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1008 1009 1010 1011 1012 1013 1014 1015
	chip->exported = (status == 0);
	mutex_unlock(&sysfs_lock);

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

		spin_lock_irqsave(&gpio_lock, flags);
1016 1017 1018
		gpio = 0;
		while (gpio < chip->ngpio)
			chip->desc[gpio++].chip = NULL;
D
David Brownell 已提交
1019 1020 1021 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
		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;
1053
	struct gpio_chip *chip;
D
David Brownell 已提交
1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065

	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);
1066
	list_for_each_entry(chip, &gpio_chips, list) {
D
David Brownell 已提交
1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090
		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)
{
}

1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111
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
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1112 1113
#endif /* CONFIG_GPIO_SYSFS */

1114 1115 1116 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
/*
 * 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;
}

1151 1152 1153 1154 1155 1156 1157 1158
/**
 * 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.
1159
 *
D
David Brownell 已提交
1160 1161 1162 1163 1164
 * 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.
 *
1165 1166
 * If chip->base is negative, this requests dynamic assignment of
 * a range of valid GPIOs.
1167 1168 1169 1170 1171 1172
 */
int gpiochip_add(struct gpio_chip *chip)
{
	unsigned long	flags;
	int		status = 0;
	unsigned	id;
1173
	int		base = chip->base;
1174

T
Trent Piepho 已提交
1175
	if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))
1176
			&& base >= 0) {
1177 1178 1179 1180 1181 1182
		status = -EINVAL;
		goto fail;
	}

	spin_lock_irqsave(&gpio_lock, flags);

1183 1184 1185 1186
	if (base < 0) {
		base = gpiochip_find_base(chip->ngpio);
		if (base < 0) {
			status = base;
D
David Brownell 已提交
1187
			goto unlock;
1188 1189 1190 1191
		}
		chip->base = base;
	}

1192 1193
	status = gpiochip_add_to_list(chip);

1194
	if (status == 0) {
1195 1196 1197 1198 1199
		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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1200 1201 1202 1203 1204

			/* 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,
1205
			 * and in case chip->get_direction is not set,
D
David Brownell 已提交
1206 1207
			 * we may expose the wrong direction in sysfs.
			 */
1208
			desc->flags = !chip->direction_input
D
David Brownell 已提交
1209 1210
				? (1 << FLAG_IS_OUT)
				: 0;
1211 1212 1213
		}
	}

1214 1215 1216 1217
#ifdef CONFIG_PINCTRL
	INIT_LIST_HEAD(&chip->pin_ranges);
#endif

1218 1219
	of_gpiochip_add(chip);

D
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1220
unlock:
1221
	spin_unlock_irqrestore(&gpio_lock, flags);
1222 1223 1224 1225 1226 1227 1228 1229

	if (status)
		goto fail;

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

1230
	pr_debug("gpiochip_add: registered GPIOs %d to %d on device: %s\n",
1231 1232 1233
		chip->base, chip->base + chip->ngpio - 1,
		chip->label ? : "generic");

1234
	return 0;
1235 1236
fail:
	/* failures here can mean systems won't boot... */
1237 1238 1239
	pr_err("gpiochip_add: gpios %d..%d (%s) failed to register\n",
		chip->base, chip->base + chip->ngpio - 1,
		chip->label ? : "generic");
1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257
	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);

1258
	gpiochip_remove_pin_ranges(chip);
1259 1260
	of_gpiochip_remove(chip);

1261 1262
	for (id = 0; id < chip->ngpio; id++) {
		if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) {
1263 1264 1265 1266 1267
			status = -EBUSY;
			break;
		}
	}
	if (status == 0) {
1268 1269
		for (id = 0; id < chip->ngpio; id++)
			chip->desc[id].chip = NULL;
1270 1271

		list_del(&chip->list);
1272 1273 1274
	}

	spin_unlock_irqrestore(&gpio_lock, flags);
D
David Brownell 已提交
1275 1276 1277 1278

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

1279 1280 1281 1282
	return status;
}
EXPORT_SYMBOL_GPL(gpiochip_remove);

1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293
/**
 * 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.
 */
1294
struct gpio_chip *gpiochip_find(void *data,
1295
				int (*match)(struct gpio_chip *chip,
1296
					     void *data))
1297
{
1298
	struct gpio_chip *chip;
1299 1300 1301
	unsigned long flags;

	spin_lock_irqsave(&gpio_lock, flags);
1302 1303
	list_for_each_entry(chip, &gpio_chips, list)
		if (match(chip, data))
1304
			break;
1305 1306 1307 1308

	/* No match? */
	if (&chip->list == &gpio_chips)
		chip = NULL;
1309 1310 1311 1312
	spin_unlock_irqrestore(&gpio_lock, flags);

	return chip;
}
J
Jean Delvare 已提交
1313
EXPORT_SYMBOL_GPL(gpiochip_find);
1314

1315
#ifdef CONFIG_PINCTRL
1316

1317 1318 1319 1320
/**
 * 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
1321 1322
 * @gpio_offset: the start offset in the current gpio_chip number space
 * @pin_offset: the start offset in the pin controller number space
1323 1324 1325
 * @npins: the number of pins from the offset of each pin space (GPIO and
 *	pin controller) to accumulate in this range
 */
1326
int gpiochip_add_pin_range(struct gpio_chip *chip, const char *pinctl_name,
1327
			   unsigned int gpio_offset, unsigned int pin_offset,
1328
			   unsigned int npins)
1329 1330
{
	struct gpio_pin_range *pin_range;
1331
	int ret;
1332

1333
	pin_range = kzalloc(sizeof(*pin_range), GFP_KERNEL);
1334 1335 1336
	if (!pin_range) {
		pr_err("%s: GPIO chip: failed to allocate pin ranges\n",
				chip->label);
1337
		return -ENOMEM;
1338 1339
	}

1340
	/* Use local offset as range ID */
1341
	pin_range->range.id = gpio_offset;
1342
	pin_range->range.gc = chip;
1343
	pin_range->range.name = chip->label;
1344 1345
	pin_range->range.base = chip->base + gpio_offset;
	pin_range->range.pin_base = pin_offset;
1346
	pin_range->range.npins = npins;
L
Linus Walleij 已提交
1347
	pin_range->pctldev = pinctrl_find_and_add_gpio_range(pinctl_name,
1348
			&pin_range->range);
1349
	if (IS_ERR(pin_range->pctldev)) {
1350
		ret = PTR_ERR(pin_range->pctldev);
1351 1352 1353
		pr_err("%s: GPIO chip: could not create pin range\n",
		       chip->label);
		kfree(pin_range);
1354
		return ret;
1355
	}
1356 1357 1358 1359
	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);
1360 1361

	list_add_tail(&pin_range->node, &chip->pin_ranges);
1362 1363

	return 0;
1364
}
1365
EXPORT_SYMBOL_GPL(gpiochip_add_pin_range);
1366

1367 1368 1369 1370
/**
 * gpiochip_remove_pin_ranges() - remove all the GPIO <-> pin mappings
 * @chip: the chip to remove all the mappings for
 */
1371 1372 1373 1374 1375 1376 1377 1378
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);
1379
		kfree(pin_range);
1380 1381
	}
}
1382 1383 1384
EXPORT_SYMBOL_GPL(gpiochip_remove_pin_ranges);

#endif /* CONFIG_PINCTRL */
1385

1386 1387 1388 1389
/* 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.
 */
1390
static int gpiod_request(struct gpio_desc *desc, const char *label)
1391
{
D
David Brownell 已提交
1392
	struct gpio_chip	*chip;
1393
	int			status = -EPROBE_DEFER;
1394 1395
	unsigned long		flags;

1396
	if (!desc) {
1397 1398
		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
1399
	}
1400 1401 1402

	spin_lock_irqsave(&gpio_lock, flags);

D
David Brownell 已提交
1403 1404
	chip = desc->chip;
	if (chip == NULL)
1405 1406
		goto done;

D
David Brownell 已提交
1407
	if (!try_module_get(chip->owner))
1408 1409
		goto done;

1410
	/* NOTE:  gpio_request() can be called in early boot,
D
David Brownell 已提交
1411
	 * before IRQs are enabled, for non-sleeping (SOC) GPIOs.
1412 1413 1414 1415 1416
	 */

	if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
		desc_set_label(desc, label ? : "?");
		status = 0;
1417
	} else {
1418
		status = -EBUSY;
D
David Brownell 已提交
1419
		module_put(chip->owner);
M
Magnus Damm 已提交
1420
		goto done;
D
David Brownell 已提交
1421 1422 1423 1424 1425
	}

	if (chip->request) {
		/* chip->request may sleep */
		spin_unlock_irqrestore(&gpio_lock, flags);
1426
		status = chip->request(chip, gpio_chip_hwgpio(desc));
D
David Brownell 已提交
1427 1428 1429 1430 1431 1432
		spin_lock_irqsave(&gpio_lock, flags);

		if (status < 0) {
			desc_set_label(desc, NULL);
			module_put(chip->owner);
			clear_bit(FLAG_REQUESTED, &desc->flags);
1433
			goto done;
D
David Brownell 已提交
1434
		}
1435
	}
1436 1437 1438
	if (chip->get_direction) {
		/* chip->get_direction may sleep */
		spin_unlock_irqrestore(&gpio_lock, flags);
1439
		gpiod_get_direction(desc);
1440 1441
		spin_lock_irqsave(&gpio_lock, flags);
	}
1442 1443
done:
	if (status)
1444
		pr_debug("_gpio_request: gpio-%d (%s) status %d\n",
1445
			 desc_to_gpio(desc), label ? : "?", status);
1446 1447 1448
	spin_unlock_irqrestore(&gpio_lock, flags);
	return status;
}
1449 1450 1451 1452 1453

int gpio_request(unsigned gpio, const char *label)
{
	return gpiod_request(gpio_to_desc(gpio), label);
}
1454 1455
EXPORT_SYMBOL_GPL(gpio_request);

1456
static void gpiod_free(struct gpio_desc *desc)
1457 1458
{
	unsigned long		flags;
D
David Brownell 已提交
1459
	struct gpio_chip	*chip;
1460

1461 1462
	might_sleep();

1463
	if (!desc) {
1464 1465 1466 1467
		WARN_ON(extra_checks);
		return;
	}

1468
	gpiod_unexport(desc);
D
David Brownell 已提交
1469

1470 1471
	spin_lock_irqsave(&gpio_lock, flags);

D
David Brownell 已提交
1472 1473 1474 1475
	chip = desc->chip;
	if (chip && test_bit(FLAG_REQUESTED, &desc->flags)) {
		if (chip->free) {
			spin_unlock_irqrestore(&gpio_lock, flags);
1476
			might_sleep_if(chip->can_sleep);
1477
			chip->free(chip, gpio_chip_hwgpio(desc));
D
David Brownell 已提交
1478 1479
			spin_lock_irqsave(&gpio_lock, flags);
		}
1480
		desc_set_label(desc, NULL);
1481
		module_put(desc->chip->owner);
1482
		clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
D
David Brownell 已提交
1483
		clear_bit(FLAG_REQUESTED, &desc->flags);
1484
		clear_bit(FLAG_OPEN_DRAIN, &desc->flags);
1485
		clear_bit(FLAG_OPEN_SOURCE, &desc->flags);
1486
	} else
1487 1488 1489 1490
		WARN_ON(extra_checks);

	spin_unlock_irqrestore(&gpio_lock, flags);
}
1491 1492 1493 1494 1495

void gpio_free(unsigned gpio)
{
	gpiod_free(gpio_to_desc(gpio));
}
1496 1497
EXPORT_SYMBOL_GPL(gpio_free);

1498 1499 1500 1501 1502 1503 1504 1505
/**
 * 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)
{
1506
	struct gpio_desc *desc;
1507 1508
	int err;

1509 1510 1511
	desc = gpio_to_desc(gpio);

	err = gpiod_request(desc, label);
1512 1513 1514
	if (err)
		return err;

1515
	if (flags & GPIOF_OPEN_DRAIN)
1516
		set_bit(FLAG_OPEN_DRAIN, &desc->flags);
1517

1518
	if (flags & GPIOF_OPEN_SOURCE)
1519
		set_bit(FLAG_OPEN_SOURCE, &desc->flags);
1520

1521
	if (flags & GPIOF_DIR_IN)
1522
		err = gpiod_direction_input(desc);
1523
	else
1524
		err = gpiod_direction_output(desc,
1525 1526
				(flags & GPIOF_INIT_HIGH) ? 1 : 0);

1527
	if (err)
1528 1529 1530
		goto free_gpio;

	if (flags & GPIOF_EXPORT) {
1531
		err = gpiod_export(desc, flags & GPIOF_EXPORT_CHANGEABLE);
1532 1533 1534 1535 1536
		if (err)
			goto free_gpio;
	}

	return 0;
1537

1538
 free_gpio:
1539
	gpiod_free(desc);
1540 1541 1542 1543 1544 1545 1546 1547 1548
	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
 */
1549
int gpio_request_array(const struct gpio *array, size_t num)
1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571
{
	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
 */
1572
void gpio_free_array(const struct gpio *array, size_t num)
1573 1574 1575 1576 1577
{
	while (num--)
		gpio_free((array++)->gpio);
}
EXPORT_SYMBOL_GPL(gpio_free_array);
1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593

/**
 * 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)
{
1594
	struct gpio_desc *desc;
1595

1596
	if (!GPIO_OFFSET_VALID(chip, offset))
1597
		return NULL;
1598 1599 1600

	desc = &chip->desc[offset];

1601
	if (test_bit(FLAG_REQUESTED, &desc->flags) == 0)
1602 1603
		return NULL;
#ifdef CONFIG_DEBUG_FS
1604
	return desc->label;
1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620
#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.
 */

1621
static int gpiod_direction_input(struct gpio_desc *desc)
1622 1623 1624 1625
{
	unsigned long		flags;
	struct gpio_chip	*chip;
	int			status = -EINVAL;
1626
	int			offset;
1627

1628 1629 1630 1631 1632
	if (!desc) {
		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
	}

1633 1634 1635 1636 1637
	spin_lock_irqsave(&gpio_lock, flags);

	chip = desc->chip;
	if (!chip || !chip->get || !chip->direction_input)
		goto fail;
1638
	status = gpio_ensure_requested(desc);
D
David Brownell 已提交
1639 1640
	if (status < 0)
		goto fail;
1641 1642 1643 1644 1645

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

	spin_unlock_irqrestore(&gpio_lock, flags);

1646
	might_sleep_if(chip->can_sleep);
1647

1648
	offset = gpio_chip_hwgpio(desc);
D
David Brownell 已提交
1649
	if (status) {
1650
		status = chip->request(chip, offset);
D
David Brownell 已提交
1651 1652
		if (status < 0) {
			pr_debug("GPIO-%d: chip request fail, %d\n",
1653
				desc_to_gpio(desc), status);
D
David Brownell 已提交
1654 1655 1656 1657 1658 1659 1660
			/* and it's not available to anyone else ...
			 * gpio_request() is the fully clean solution.
			 */
			goto lose;
		}
	}

1661
	status = chip->direction_input(chip, offset);
1662 1663
	if (status == 0)
		clear_bit(FLAG_IS_OUT, &desc->flags);
1664

1665
	trace_gpio_direction(desc_to_gpio(desc), 1, status);
D
David Brownell 已提交
1666
lose:
1667 1668 1669
	return status;
fail:
	spin_unlock_irqrestore(&gpio_lock, flags);
1670 1671 1672
	if (status)
		pr_debug("%s: gpio-%d status %d\n", __func__,
			 desc_to_gpio(desc), status);
1673 1674
	return status;
}
1675 1676 1677 1678 1679

int gpio_direction_input(unsigned gpio)
{
	return gpiod_direction_input(gpio_to_desc(gpio));
}
1680 1681
EXPORT_SYMBOL_GPL(gpio_direction_input);

1682
static int gpiod_direction_output(struct gpio_desc *desc, int value)
1683 1684 1685 1686
{
	unsigned long		flags;
	struct gpio_chip	*chip;
	int			status = -EINVAL;
1687
	int offset;
1688

1689 1690 1691 1692 1693
	if (!desc) {
		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
	}

1694 1695
	/* Open drain pin should not be driven to 1 */
	if (value && test_bit(FLAG_OPEN_DRAIN,  &desc->flags))
1696
		return gpiod_direction_input(desc);
1697

1698 1699
	/* Open source pin should not be driven to 0 */
	if (!value && test_bit(FLAG_OPEN_SOURCE,  &desc->flags))
1700
		return gpiod_direction_input(desc);
1701

1702 1703 1704 1705 1706
	spin_lock_irqsave(&gpio_lock, flags);

	chip = desc->chip;
	if (!chip || !chip->set || !chip->direction_output)
		goto fail;
1707
	status = gpio_ensure_requested(desc);
D
David Brownell 已提交
1708 1709
	if (status < 0)
		goto fail;
1710 1711 1712 1713 1714

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

	spin_unlock_irqrestore(&gpio_lock, flags);

1715
	might_sleep_if(chip->can_sleep);
1716

1717
	offset = gpio_chip_hwgpio(desc);
D
David Brownell 已提交
1718
	if (status) {
1719
		status = chip->request(chip, offset);
D
David Brownell 已提交
1720 1721
		if (status < 0) {
			pr_debug("GPIO-%d: chip request fail, %d\n",
1722
				desc_to_gpio(desc), status);
D
David Brownell 已提交
1723 1724 1725 1726 1727 1728 1729
			/* and it's not available to anyone else ...
			 * gpio_request() is the fully clean solution.
			 */
			goto lose;
		}
	}

1730
	status = chip->direction_output(chip, offset, value);
1731 1732
	if (status == 0)
		set_bit(FLAG_IS_OUT, &desc->flags);
1733 1734
	trace_gpio_value(desc_to_gpio(desc), 0, value);
	trace_gpio_direction(desc_to_gpio(desc), 0, status);
D
David Brownell 已提交
1735
lose:
1736 1737 1738
	return status;
fail:
	spin_unlock_irqrestore(&gpio_lock, flags);
1739 1740 1741
	if (status)
		pr_debug("%s: gpio-%d status %d\n", __func__,
			 desc_to_gpio(desc), status);
1742 1743
	return status;
}
1744 1745 1746 1747 1748

int gpio_direction_output(unsigned gpio, int value)
{
	return gpiod_direction_output(gpio_to_desc(gpio), value);
}
1749 1750
EXPORT_SYMBOL_GPL(gpio_direction_output);

1751 1752 1753 1754 1755
/**
 * gpio_set_debounce - sets @debounce time for a @gpio
 * @gpio: the gpio to set debounce time
 * @debounce: debounce time is microseconds
 */
1756
static int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce)
1757 1758 1759 1760
{
	unsigned long		flags;
	struct gpio_chip	*chip;
	int			status = -EINVAL;
1761
	int			offset;
1762

1763 1764 1765 1766 1767
	if (!desc) {
		pr_warn("%s: invalid GPIO\n", __func__);
		return -EINVAL;
	}

1768 1769 1770 1771 1772
	spin_lock_irqsave(&gpio_lock, flags);

	chip = desc->chip;
	if (!chip || !chip->set || !chip->set_debounce)
		goto fail;
1773 1774

	status = gpio_ensure_requested(desc);
1775 1776 1777 1778 1779 1780 1781
	if (status < 0)
		goto fail;

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

	spin_unlock_irqrestore(&gpio_lock, flags);

1782
	might_sleep_if(chip->can_sleep);
1783

1784 1785
	offset = gpio_chip_hwgpio(desc);
	return chip->set_debounce(chip, offset, debounce);
1786 1787 1788

fail:
	spin_unlock_irqrestore(&gpio_lock, flags);
1789 1790 1791
	if (status)
		pr_debug("%s: gpio-%d status %d\n", __func__,
			 desc_to_gpio(desc), status);
1792 1793 1794

	return status;
}
1795 1796 1797 1798 1799

int gpio_set_debounce(unsigned gpio, unsigned debounce)
{
	return gpiod_set_debounce(gpio_to_desc(gpio), debounce);
}
1800
EXPORT_SYMBOL_GPL(gpio_set_debounce);
1801 1802 1803 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

/* 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.
 */
1833
static int gpiod_get_value(struct gpio_desc *desc)
1834 1835
{
	struct gpio_chip	*chip;
1836
	int value;
1837
	int offset;
1838

1839 1840
	if (!desc)
		return 0;
1841 1842
	chip = desc->chip;
	offset = gpio_chip_hwgpio(desc);
1843
	/* Should be using gpio_get_value_cansleep() */
1844
	WARN_ON(chip->can_sleep);
1845 1846
	value = chip->get ? chip->get(chip, offset) : 0;
	trace_gpio_value(desc_to_gpio(desc), 1, value);
1847
	return value;
1848
}
1849 1850 1851 1852 1853

int __gpio_get_value(unsigned gpio)
{
	return gpiod_get_value(gpio_to_desc(gpio));
}
1854 1855
EXPORT_SYMBOL_GPL(__gpio_get_value);

1856 1857 1858 1859 1860 1861
/*
 *  _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.
 */
1862
static void _gpio_set_open_drain_value(struct gpio_desc *desc, int value)
1863 1864
{
	int err = 0;
1865 1866 1867
	struct gpio_chip *chip = desc->chip;
	int offset = gpio_chip_hwgpio(desc);

1868
	if (value) {
1869
		err = chip->direction_input(chip, offset);
1870
		if (!err)
1871
			clear_bit(FLAG_IS_OUT, &desc->flags);
1872
	} else {
1873
		err = chip->direction_output(chip, offset, 0);
1874
		if (!err)
1875
			set_bit(FLAG_IS_OUT, &desc->flags);
1876
	}
1877
	trace_gpio_direction(desc_to_gpio(desc), value, err);
1878 1879
	if (err < 0)
		pr_err("%s: Error in set_value for open drain gpio%d err %d\n",
1880
					__func__, desc_to_gpio(desc), err);
1881 1882
}

1883 1884 1885 1886 1887 1888
/*
 *  _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.
 */
1889
static void _gpio_set_open_source_value(struct gpio_desc *desc, int value)
1890 1891
{
	int err = 0;
1892 1893 1894
	struct gpio_chip *chip = desc->chip;
	int offset = gpio_chip_hwgpio(desc);

1895
	if (value) {
1896
		err = chip->direction_output(chip, offset, 1);
1897
		if (!err)
1898
			set_bit(FLAG_IS_OUT, &desc->flags);
1899
	} else {
1900
		err = chip->direction_input(chip, offset);
1901
		if (!err)
1902
			clear_bit(FLAG_IS_OUT, &desc->flags);
1903
	}
1904
	trace_gpio_direction(desc_to_gpio(desc), !value, err);
1905 1906
	if (err < 0)
		pr_err("%s: Error in set_value for open source gpio%d err %d\n",
1907
					__func__, desc_to_gpio(desc), err);
1908 1909
}

1910 1911 1912 1913 1914 1915 1916 1917 1918
/**
 * __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.
 */
1919
static void gpiod_set_value(struct gpio_desc *desc, int value)
1920 1921 1922
{
	struct gpio_chip	*chip;

1923 1924
	if (!desc)
		return;
1925
	chip = desc->chip;
1926
	/* Should be using gpio_set_value_cansleep() */
1927
	WARN_ON(chip->can_sleep);
1928 1929 1930 1931 1932
	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);
1933
	else
1934 1935 1936 1937 1938 1939
		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);
1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950
}
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.
 */
1951
static int gpiod_cansleep(struct gpio_desc *desc)
1952
{
1953 1954
	if (!desc)
		return 0;
1955
	/* only call this on GPIOs that are valid! */
1956 1957
	return desc->chip->can_sleep;
}
1958

1959 1960 1961
int __gpio_cansleep(unsigned gpio)
{
	return gpiod_cansleep(gpio_to_desc(gpio));
1962 1963 1964
}
EXPORT_SYMBOL_GPL(__gpio_cansleep);

D
David Brownell 已提交
1965 1966 1967 1968 1969 1970 1971 1972 1973
/**
 * __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.
 */
1974
static int gpiod_to_irq(struct gpio_desc *desc)
D
David Brownell 已提交
1975 1976
{
	struct gpio_chip	*chip;
1977
	int			offset;
D
David Brownell 已提交
1978

1979 1980
	if (!desc)
		return -EINVAL;
1981 1982 1983
	chip = desc->chip;
	offset = gpio_chip_hwgpio(desc);
	return chip->to_irq ? chip->to_irq(chip, offset) : -ENXIO;
D
David Brownell 已提交
1984 1985
}

1986 1987 1988 1989 1990
int __gpio_to_irq(unsigned gpio)
{
	return gpiod_to_irq(gpio_to_desc(gpio));
}
EXPORT_SYMBOL_GPL(__gpio_to_irq);
1991 1992 1993 1994 1995 1996


/* 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.
 */

1997
static int gpiod_get_value_cansleep(struct gpio_desc *desc)
1998 1999
{
	struct gpio_chip	*chip;
2000
	int value;
2001
	int offset;
2002 2003

	might_sleep_if(extra_checks);
2004 2005
	if (!desc)
		return 0;
2006 2007 2008 2009
	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);
2010
	return value;
2011
}
2012 2013 2014 2015 2016

int gpio_get_value_cansleep(unsigned gpio)
{
	return gpiod_get_value_cansleep(gpio_to_desc(gpio));
}
2017 2018
EXPORT_SYMBOL_GPL(gpio_get_value_cansleep);

2019
static void gpiod_set_value_cansleep(struct gpio_desc *desc, int value)
2020 2021 2022 2023
{
	struct gpio_chip	*chip;

	might_sleep_if(extra_checks);
2024 2025
	if (!desc)
		return;
2026 2027 2028 2029 2030 2031
	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);
2032
	else
2033
		chip->set(chip, gpio_chip_hwgpio(desc), value);
2034 2035
}

2036 2037 2038 2039 2040
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);
2041 2042 2043 2044 2045 2046 2047

#ifdef CONFIG_DEBUG_FS

static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
{
	unsigned		i;
	unsigned		gpio = chip->base;
2048
	struct gpio_desc	*gdesc = &chip->desc[0];
2049 2050 2051 2052 2053 2054
	int			is_out;

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

2055
		gpiod_get_direction(gdesc);
2056
		is_out = test_bit(FLAG_IS_OUT, &gdesc->flags);
2057
		seq_printf(s, " gpio-%-3d (%-20.20s) %s %s",
2058 2059 2060 2061 2062 2063 2064 2065 2066
			gpio, gdesc->label,
			is_out ? "out" : "in ",
			chip->get
				? (chip->get(chip, i) ? "hi" : "lo")
				: "?  ");
		seq_printf(s, "\n");
	}
}

2067
static void *gpiolib_seq_start(struct seq_file *s, loff_t *pos)
2068
{
2069
	unsigned long flags;
2070
	struct gpio_chip *chip = NULL;
2071
	loff_t index = *pos;
2072

2073
	s->private = "";
2074

2075
	spin_lock_irqsave(&gpio_lock, flags);
2076
	list_for_each_entry(chip, &gpio_chips, list)
2077 2078
		if (index-- == 0) {
			spin_unlock_irqrestore(&gpio_lock, flags);
2079
			return chip;
2080
		}
2081
	spin_unlock_irqrestore(&gpio_lock, flags);
2082

2083
	return NULL;
2084 2085 2086 2087
}

static void *gpiolib_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
2088
	unsigned long flags;
2089 2090 2091
	struct gpio_chip *chip = v;
	void *ret = NULL;

2092
	spin_lock_irqsave(&gpio_lock, flags);
2093 2094 2095 2096
	if (list_is_last(&chip->list, &gpio_chips))
		ret = NULL;
	else
		ret = list_entry(chip->list.next, struct gpio_chip, list);
2097
	spin_unlock_irqrestore(&gpio_lock, flags);
2098 2099 2100 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

	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);

2131 2132 2133
	return 0;
}

2134 2135 2136 2137 2138 2139 2140
static const struct seq_operations gpiolib_seq_ops = {
	.start = gpiolib_seq_start,
	.next = gpiolib_seq_next,
	.stop = gpiolib_seq_stop,
	.show = gpiolib_seq_show,
};

2141 2142
static int gpiolib_open(struct inode *inode, struct file *file)
{
2143
	return seq_open(file, &gpiolib_seq_ops);
2144 2145
}

2146
static const struct file_operations gpiolib_operations = {
2147
	.owner		= THIS_MODULE,
2148 2149 2150
	.open		= gpiolib_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
2151
	.release	= seq_release,
2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163
};

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 */