gpiolib.c 48.9 KB
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#include <linux/kernel.h>
#include <linux/module.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
#include <linux/spinlock.h>
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#include <linux/list.h>
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#include <linux/device.h>
#include <linux/err.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/gpio.h>
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#include <linux/of_gpio.h>
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#include <linux/idr.h>
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#include <linux/slab.h>
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#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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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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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) {
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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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/* caller ensures gpio is valid and requested, chip->get_direction may sleep  */
static int gpio_get_direction(unsigned gpio)
{
	struct gpio_chip	*chip;
	struct gpio_desc	*desc = &gpio_desc[gpio];
	int			status = -EINVAL;

	chip = gpio_to_chip(gpio);
	gpio -= chip->base;

	if (!chip->get_direction)
		return status;

	status = chip->get_direction(chip, gpio);
	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)
{
	const struct gpio_desc	*desc = dev_get_drvdata(dev);
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	unsigned		gpio = desc - gpio_desc;
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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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		gpio_get_direction(gpio);
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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)
{
	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;
R
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	int			status;
698
	const char		*ioname = NULL;
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	struct device		*dev;
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700 701 702 703 704 705 706

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

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	if (!gpio_is_valid(gpio)) {
		pr_debug("%s: gpio %d is not valid\n", __func__, gpio);
		return -EINVAL;
	}
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	mutex_lock(&sysfs_lock);

	spin_lock_irqsave(&gpio_lock, flags);
	desc = &gpio_desc[gpio];
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	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",
				__func__, gpio,
				test_bit(FLAG_REQUESTED, &desc->flags),
				test_bit(FLAG_EXPORT, &desc->flags));
723 724
		status = -EPERM;
		goto fail_unlock;
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David Brownell 已提交
725
	}
R
Ryan Mallon 已提交
726 727 728

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

731 732 733
	if (desc->chip->names && desc->chip->names[gpio - desc->chip->base])
		ioname = desc->chip->names[gpio - desc->chip->base];

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	dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
			    desc, ioname ? ioname : "gpio%u", gpio);
	if (IS_ERR(dev)) {
		status = PTR_ERR(dev);
		goto fail_unlock;
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739 740
	}

R
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741
	status = sysfs_create_group(&dev->kobj, &gpio_attr_group);
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742
	if (status)
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		goto fail_unregister_device;
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744

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745 746 747 748 749 750 751 752 753 754 755 756
	if (direction_may_change) {
		status = device_create_file(dev, &dev_attr_direction);
		if (status)
			goto fail_unregister_device;
	}

	if (gpio_to_irq(gpio) >= 0 && (direction_may_change ||
				       !test_bit(FLAG_IS_OUT, &desc->flags))) {
		status = device_create_file(dev, &dev_attr_edge);
		if (status)
			goto fail_unregister_device;
	}
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758 759 760 761 762 763 764 765 766
	set_bit(FLAG_EXPORT, &desc->flags);
	mutex_unlock(&sysfs_lock);
	return 0;

fail_unregister_device:
	device_unregister(dev);
fail_unlock:
	mutex_unlock(&sysfs_lock);
	pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
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	return status;
}
EXPORT_SYMBOL_GPL(gpio_export);

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

776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820
/**
 * 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);

821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867

/**
 * 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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/**
 * 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;
877
	int			status = 0;
878
	struct device		*dev = NULL;
D
David Brownell 已提交
879

880 881
	if (!gpio_is_valid(gpio)) {
		status = -EINVAL;
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882
		goto done;
883
	}
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884 885 886 887

	mutex_lock(&sysfs_lock);

	desc = &gpio_desc[gpio];
888

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889 890 891 892
	if (test_bit(FLAG_EXPORT, &desc->flags)) {

		dev = class_find_device(&gpio_class, NULL, desc, match_export);
		if (dev) {
893
			gpio_setup_irq(desc, dev, 0);
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David Brownell 已提交
894 895 896 897 898 899
			clear_bit(FLAG_EXPORT, &desc->flags);
		} else
			status = -ENODEV;
	}

	mutex_unlock(&sysfs_lock);
900 901 902 903
	if (dev) {
		device_unregister(dev);
		put_device(dev);
	}
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904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926
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);
927
	if (!IS_ERR(dev)) {
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David Brownell 已提交
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		status = sysfs_create_group(&dev->kobj,
				&gpiochip_attr_group);
	} else
931
		status = PTR_ERR(dev);
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932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976
	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;
977
	struct gpio_chip *chip;
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978 979 980 981 982 983 984 985 986 987 988 989

	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);
990
	list_for_each_entry(chip, &gpio_chips, list) {
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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
		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 */

1017 1018 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 1053
/*
 * 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;
}

1054 1055 1056 1057 1058 1059 1060 1061
/**
 * 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.
1062
 *
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David Brownell 已提交
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 * When gpiochip_add() is called very early during boot, so that GPIOs
 * can be freely used, the chip->dev device must be registered before
 * the gpio framework's arch_initcall().  Otherwise sysfs initialization
 * for GPIOs will fail rudely.
 *
1068 1069
 * If chip->base is negative, this requests dynamic assignment of
 * a range of valid GPIOs.
1070 1071 1072 1073 1074 1075
 */
int gpiochip_add(struct gpio_chip *chip)
{
	unsigned long	flags;
	int		status = 0;
	unsigned	id;
1076
	int		base = chip->base;
1077

T
Trent Piepho 已提交
1078
	if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))
1079
			&& base >= 0) {
1080 1081 1082 1083 1084 1085
		status = -EINVAL;
		goto fail;
	}

	spin_lock_irqsave(&gpio_lock, flags);

1086 1087 1088 1089
	if (base < 0) {
		base = gpiochip_find_base(chip->ngpio);
		if (base < 0) {
			status = base;
D
David Brownell 已提交
1090
			goto unlock;
1091 1092 1093 1094
		}
		chip->base = base;
	}

1095 1096
	status = gpiochip_add_to_list(chip);

1097
	if (status == 0) {
1098
		for (id = base; id < base + chip->ngpio; id++) {
1099
			gpio_desc[id].chip = chip;
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1100 1101 1102 1103 1104

			/* 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,
1105
			 * and in case chip->get_direction is not set,
D
David Brownell 已提交
1106 1107 1108 1109 1110
			 * we may expose the wrong direction in sysfs.
			 */
			gpio_desc[id].flags = !chip->direction_input
				? (1 << FLAG_IS_OUT)
				: 0;
1111 1112 1113
		}
	}

1114 1115 1116 1117
#ifdef CONFIG_PINCTRL
	INIT_LIST_HEAD(&chip->pin_ranges);
#endif

1118 1119
	of_gpiochip_add(chip);

D
David Brownell 已提交
1120
unlock:
1121
	spin_unlock_irqrestore(&gpio_lock, flags);
1122 1123 1124 1125 1126 1127 1128 1129

	if (status)
		goto fail;

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

1130
	pr_debug("gpiochip_add: registered GPIOs %d to %d on device: %s\n",
1131 1132 1133
		chip->base, chip->base + chip->ngpio - 1,
		chip->label ? : "generic");

1134
	return 0;
1135 1136
fail:
	/* failures here can mean systems won't boot... */
1137 1138 1139
	pr_err("gpiochip_add: gpios %d..%d (%s) failed to register\n",
		chip->base, chip->base + chip->ngpio - 1,
		chip->label ? : "generic");
1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157
	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);

1158
	gpiochip_remove_pin_ranges(chip);
1159 1160
	of_gpiochip_remove(chip);

1161 1162 1163 1164 1165 1166 1167 1168 1169
	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;
1170 1171

		list_del(&chip->list);
1172 1173 1174
	}

	spin_unlock_irqrestore(&gpio_lock, flags);
D
David Brownell 已提交
1175 1176 1177 1178

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

1179 1180 1181 1182
	return status;
}
EXPORT_SYMBOL_GPL(gpiochip_remove);

1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193
/**
 * 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.
 */
1194
struct gpio_chip *gpiochip_find(void *data,
1195
				int (*match)(struct gpio_chip *chip,
1196
					     void *data))
1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215
{
	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
1216
EXPORT_SYMBOL_GPL(gpiochip_find);
1217

1218
#ifdef CONFIG_PINCTRL
1219

1220 1221 1222 1223
/**
 * 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
1224 1225
 * @gpio_offset: the start offset in the current gpio_chip number space
 * @pin_offset: the start offset in the pin controller number space
1226 1227 1228
 * @npins: the number of pins from the offset of each pin space (GPIO and
 *	pin controller) to accumulate in this range
 */
1229
int gpiochip_add_pin_range(struct gpio_chip *chip, const char *pinctl_name,
1230
			   unsigned int gpio_offset, unsigned int pin_offset,
1231
			   unsigned int npins)
1232 1233
{
	struct gpio_pin_range *pin_range;
1234
	int ret;
1235

1236
	pin_range = kzalloc(sizeof(*pin_range), GFP_KERNEL);
1237 1238 1239
	if (!pin_range) {
		pr_err("%s: GPIO chip: failed to allocate pin ranges\n",
				chip->label);
1240
		return -ENOMEM;
1241 1242
	}

1243
	/* Use local offset as range ID */
1244
	pin_range->range.id = gpio_offset;
1245
	pin_range->range.gc = chip;
1246
	pin_range->range.name = chip->label;
1247 1248
	pin_range->range.base = chip->base + gpio_offset;
	pin_range->range.pin_base = pin_offset;
1249
	pin_range->range.npins = npins;
L
Linus Walleij 已提交
1250
	pin_range->pctldev = pinctrl_find_and_add_gpio_range(pinctl_name,
1251
			&pin_range->range);
1252
	if (IS_ERR(pin_range->pctldev)) {
1253
		ret = PTR_ERR(pin_range->pctldev);
1254 1255 1256
		pr_err("%s: GPIO chip: could not create pin range\n",
		       chip->label);
		kfree(pin_range);
1257
		return ret;
1258
	}
1259 1260 1261 1262
	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);
1263 1264

	list_add_tail(&pin_range->node, &chip->pin_ranges);
1265 1266

	return 0;
1267
}
1268
EXPORT_SYMBOL_GPL(gpiochip_add_pin_range);
1269

1270 1271 1272 1273
/**
 * gpiochip_remove_pin_ranges() - remove all the GPIO <-> pin mappings
 * @chip: the chip to remove all the mappings for
 */
1274 1275 1276 1277 1278 1279 1280 1281
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);
1282
		kfree(pin_range);
1283 1284
	}
}
1285 1286 1287
EXPORT_SYMBOL_GPL(gpiochip_remove_pin_ranges);

#endif /* CONFIG_PINCTRL */
1288

1289 1290 1291 1292 1293 1294 1295
/* 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
1296
	struct gpio_chip	*chip;
1297
	int			status = -EPROBE_DEFER;
1298 1299 1300 1301
	unsigned long		flags;

	spin_lock_irqsave(&gpio_lock, flags);

1302 1303
	if (!gpio_is_valid(gpio)) {
		status = -EINVAL;
1304
		goto done;
1305
	}
1306
	desc = &gpio_desc[gpio];
D
David Brownell 已提交
1307 1308
	chip = desc->chip;
	if (chip == NULL)
1309 1310
		goto done;

D
David Brownell 已提交
1311
	if (!try_module_get(chip->owner))
1312 1313
		goto done;

1314
	/* NOTE:  gpio_request() can be called in early boot,
D
David Brownell 已提交
1315
	 * before IRQs are enabled, for non-sleeping (SOC) GPIOs.
1316 1317 1318 1319 1320
	 */

	if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
		desc_set_label(desc, label ? : "?");
		status = 0;
1321
	} else {
1322
		status = -EBUSY;
D
David Brownell 已提交
1323
		module_put(chip->owner);
M
Magnus Damm 已提交
1324
		goto done;
D
David Brownell 已提交
1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336
	}

	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);
1337
			goto done;
D
David Brownell 已提交
1338
		}
1339
	}
1340 1341 1342 1343 1344 1345
	if (chip->get_direction) {
		/* chip->get_direction may sleep */
		spin_unlock_irqrestore(&gpio_lock, flags);
		gpio_get_direction(gpio);
		spin_lock_irqsave(&gpio_lock, flags);
	}
1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358
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
1359
	struct gpio_chip	*chip;
1360

1361 1362
	might_sleep();

1363
	if (!gpio_is_valid(gpio)) {
1364 1365 1366 1367
		WARN_ON(extra_checks);
		return;
	}

D
David Brownell 已提交
1368 1369
	gpio_unexport(gpio);

1370 1371 1372
	spin_lock_irqsave(&gpio_lock, flags);

	desc = &gpio_desc[gpio];
D
David Brownell 已提交
1373 1374 1375 1376
	chip = desc->chip;
	if (chip && test_bit(FLAG_REQUESTED, &desc->flags)) {
		if (chip->free) {
			spin_unlock_irqrestore(&gpio_lock, flags);
1377
			might_sleep_if(chip->can_sleep);
D
David Brownell 已提交
1378 1379 1380
			chip->free(chip, gpio - chip->base);
			spin_lock_irqsave(&gpio_lock, flags);
		}
1381
		desc_set_label(desc, NULL);
1382
		module_put(desc->chip->owner);
1383
		clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
D
David Brownell 已提交
1384
		clear_bit(FLAG_REQUESTED, &desc->flags);
1385
		clear_bit(FLAG_OPEN_DRAIN, &desc->flags);
1386
		clear_bit(FLAG_OPEN_SOURCE, &desc->flags);
1387
	} else
1388 1389 1390 1391 1392 1393
		WARN_ON(extra_checks);

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

1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407
/**
 * 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;

1408 1409 1410
	if (flags & GPIOF_OPEN_DRAIN)
		set_bit(FLAG_OPEN_DRAIN, &gpio_desc[gpio].flags);

1411 1412 1413
	if (flags & GPIOF_OPEN_SOURCE)
		set_bit(FLAG_OPEN_SOURCE, &gpio_desc[gpio].flags);

1414 1415 1416 1417 1418 1419
	if (flags & GPIOF_DIR_IN)
		err = gpio_direction_input(gpio);
	else
		err = gpio_direction_output(gpio,
				(flags & GPIOF_INIT_HIGH) ? 1 : 0);

1420
	if (err)
1421 1422 1423 1424 1425 1426 1427 1428 1429
		goto free_gpio;

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

	return 0;
1430

1431 1432
 free_gpio:
	gpio_free(gpio);
1433 1434 1435 1436 1437 1438 1439 1440 1441
	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
 */
1442
int gpio_request_array(const struct gpio *array, size_t num)
1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464
{
	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
 */
1465
void gpio_free_array(const struct gpio *array, size_t num)
1466 1467 1468 1469 1470
{
	while (num--)
		gpio_free((array++)->gpio);
}
EXPORT_SYMBOL_GPL(gpio_free_array);
1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488

/**
 * 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;

1489
	if (!gpio_is_valid(gpio) || gpio_desc[gpio].chip != chip)
1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519
		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);

1520
	if (!gpio_is_valid(gpio))
1521 1522 1523 1524 1525 1526 1527
		goto fail;
	chip = desc->chip;
	if (!chip || !chip->get || !chip->direction_input)
		goto fail;
	gpio -= chip->base;
	if (gpio >= chip->ngpio)
		goto fail;
D
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1528 1529 1530
	status = gpio_ensure_requested(desc, gpio);
	if (status < 0)
		goto fail;
1531 1532 1533 1534 1535

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

	spin_unlock_irqrestore(&gpio_lock, flags);

1536
	might_sleep_if(chip->can_sleep);
1537

D
David Brownell 已提交
1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549
	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;
		}
	}

1550 1551 1552
	status = chip->direction_input(chip, gpio);
	if (status == 0)
		clear_bit(FLAG_IS_OUT, &desc->flags);
1553 1554

	trace_gpio_direction(chip->base + gpio, 1, status);
D
David Brownell 已提交
1555
lose:
1556 1557 1558 1559 1560
	return status;
fail:
	spin_unlock_irqrestore(&gpio_lock, flags);
	if (status)
		pr_debug("%s: gpio-%d status %d\n",
1561
			__func__, gpio, status);
1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572
	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;

1573 1574 1575 1576
	/* Open drain pin should not be driven to 1 */
	if (value && test_bit(FLAG_OPEN_DRAIN,  &desc->flags))
		return gpio_direction_input(gpio);

1577 1578 1579 1580
	/* Open source pin should not be driven to 0 */
	if (!value && test_bit(FLAG_OPEN_SOURCE,  &desc->flags))
		return gpio_direction_input(gpio);

1581 1582
	spin_lock_irqsave(&gpio_lock, flags);

1583
	if (!gpio_is_valid(gpio))
1584 1585 1586 1587 1588 1589 1590
		goto fail;
	chip = desc->chip;
	if (!chip || !chip->set || !chip->direction_output)
		goto fail;
	gpio -= chip->base;
	if (gpio >= chip->ngpio)
		goto fail;
D
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1591 1592 1593
	status = gpio_ensure_requested(desc, gpio);
	if (status < 0)
		goto fail;
1594 1595 1596 1597 1598

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

	spin_unlock_irqrestore(&gpio_lock, flags);

1599
	might_sleep_if(chip->can_sleep);
1600

D
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1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612
	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;
		}
	}

1613 1614 1615
	status = chip->direction_output(chip, gpio, value);
	if (status == 0)
		set_bit(FLAG_IS_OUT, &desc->flags);
1616 1617
	trace_gpio_value(chip->base + gpio, 0, value);
	trace_gpio_direction(chip->base + gpio, 0, status);
D
David Brownell 已提交
1618
lose:
1619 1620 1621 1622 1623
	return status;
fail:
	spin_unlock_irqrestore(&gpio_lock, flags);
	if (status)
		pr_debug("%s: gpio-%d status %d\n",
1624
			__func__, gpio, status);
1625 1626 1627 1628
	return status;
}
EXPORT_SYMBOL_GPL(gpio_direction_output);

1629 1630 1631 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
/**
 * 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);

1659
	might_sleep_if(chip->can_sleep);
1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671

	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);
1672 1673 1674 1675 1676 1677 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 1703 1704 1705 1706

/* 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;
1707
	int value;
1708 1709

	chip = gpio_to_chip(gpio);
1710
	/* Should be using gpio_get_value_cansleep() */
1711
	WARN_ON(chip->can_sleep);
1712 1713 1714
	value = chip->get ? chip->get(chip, gpio - chip->base) : 0;
	trace_gpio_value(gpio, 1, value);
	return value;
1715 1716 1717
}
EXPORT_SYMBOL_GPL(__gpio_get_value);

1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742
/*
 *  _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);
}

1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768
/*
 *  _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);
}


1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782
/**
 * __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);
1783
	/* Should be using gpio_set_value_cansleep() */
1784
	WARN_ON(chip->can_sleep);
1785
	trace_gpio_value(gpio, 0, value);
1786 1787
	if (test_bit(FLAG_OPEN_DRAIN,  &gpio_desc[gpio].flags))
		_gpio_set_open_drain_value(gpio, chip, value);
1788 1789
	else if (test_bit(FLAG_OPEN_SOURCE,  &gpio_desc[gpio].flags))
		_gpio_set_open_source_value(gpio, chip, value);
1790 1791
	else
		chip->set(chip, gpio - chip->base, value);
1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813
}
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
1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831
/**
 * __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);

1832 1833 1834 1835 1836 1837 1838 1839 1840


/* 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;
1841
	int value;
1842 1843 1844

	might_sleep_if(extra_checks);
	chip = gpio_to_chip(gpio);
1845 1846 1847
	value = chip->get ? chip->get(chip, gpio - chip->base) : 0;
	trace_gpio_value(gpio, 1, value);
	return value;
1848 1849 1850 1851 1852 1853 1854 1855 1856
}
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);
1857
	trace_gpio_value(gpio, 0, value);
1858 1859
	if (test_bit(FLAG_OPEN_DRAIN,  &gpio_desc[gpio].flags))
		_gpio_set_open_drain_value(gpio, chip, value);
1860 1861
	else if (test_bit(FLAG_OPEN_SOURCE,  &gpio_desc[gpio].flags))
		_gpio_set_open_source_value(gpio, chip, value);
1862 1863
	else
		chip->set(chip, gpio - chip->base, value);
1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880
}
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;

1881
		gpio_get_direction(gpio);
1882
		is_out = test_bit(FLAG_IS_OUT, &gdesc->flags);
1883
		seq_printf(s, " gpio-%-3d (%-20.20s) %s %s",
1884 1885 1886 1887 1888 1889 1890 1891 1892
			gpio, gdesc->label,
			is_out ? "out" : "in ",
			chip->get
				? (chip->get(chip, i) ? "hi" : "lo")
				: "?  ");
		seq_printf(s, "\n");
	}
}

1893
static void *gpiolib_seq_start(struct seq_file *s, loff_t *pos)
1894
{
1895 1896 1897 1898
	struct gpio_chip *chip = NULL;
	unsigned int gpio;
	void *ret = NULL;
	loff_t index = 0;
1899 1900 1901

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

1902
	for (gpio = 0; gpio_is_valid(gpio); gpio++) {
1903
		if (gpio_desc[gpio].chip == chip)
1904
			continue;
1905

1906 1907 1908 1909
		chip = gpio_desc[gpio].chip;
		if (!chip)
			continue;

1910 1911 1912 1913
		if (index++ >= *pos) {
			ret = chip;
			break;
		}
1914
	}
1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967

	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);

1968 1969 1970
	return 0;
}

1971 1972 1973 1974 1975 1976 1977
static const struct seq_operations gpiolib_seq_ops = {
	.start = gpiolib_seq_start,
	.next = gpiolib_seq_next,
	.stop = gpiolib_seq_stop,
	.show = gpiolib_seq_show,
};

1978 1979
static int gpiolib_open(struct inode *inode, struct file *file)
{
1980
	return seq_open(file, &gpiolib_seq_ops);
1981 1982
}

1983
static const struct file_operations gpiolib_operations = {
1984
	.owner		= THIS_MODULE,
1985 1986 1987
	.open		= gpiolib_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
1988
	.release	= seq_release,
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000
};

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 */