// SPDX-License-Identifier: GPL-2.0

#include <linux/bitops.h>
#include <linux/cleanup.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kdev_t.h>
#include <linux/kstrtox.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/srcu.h>
#include <linux/sysfs.h>
#include <linux/types.h>

#include <linux/gpio/consumer.h>
#include <linux/gpio/driver.h>

#include <uapi/linux/gpio.h>

#include "gpiolib.h"
#include "gpiolib-sysfs.h"

#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)

struct kernfs_node;

#define GPIO_IRQF_TRIGGER_NONE          0
#define GPIO_IRQF_TRIGGER_FALLING       BIT(0)
#define GPIO_IRQF_TRIGGER_RISING        BIT(1)
#define GPIO_IRQF_TRIGGER_BOTH          (GPIO_IRQF_TRIGGER_FALLING | \
                                         GPIO_IRQF_TRIGGER_RISING)

enum {
        GPIO_SYSFS_LINE_CLASS_ATTR_DIRECTION = 0,
        GPIO_SYSFS_LINE_CLASS_ATTR_VALUE,
        GPIO_SYSFS_LINE_CLASS_ATTR_EDGE,
        GPIO_SYSFS_LINE_CLASS_ATTR_ACTIVE_LOW,
        GPIO_SYSFS_LINE_CLASS_ATTR_SENTINEL,
        GPIO_SYSFS_LINE_CLASS_ATTR_SIZE,
};

#endif /* CONFIG_GPIO_SYSFS_LEGACY */

enum {
        GPIO_SYSFS_LINE_CHIP_ATTR_DIRECTION = 0,
        GPIO_SYSFS_LINE_CHIP_ATTR_VALUE,
        GPIO_SYSFS_LINE_CHIP_ATTR_SENTINEL,
        GPIO_SYSFS_LINE_CHIP_ATTR_SIZE,
};

struct gpiod_data {
        struct list_head list;

        struct gpio_desc *desc;
        struct device *dev;

        struct mutex mutex;
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
        struct kernfs_node *value_kn;
        int irq;
        unsigned char irq_flags;
#endif /* CONFIG_GPIO_SYSFS_LEGACY */

        bool direction_can_change;

        struct kobject *parent;
        struct device_attribute dir_attr;
        struct device_attribute val_attr;

#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
        struct device_attribute edge_attr;
        struct device_attribute active_low_attr;

        struct attribute *class_attrs[GPIO_SYSFS_LINE_CLASS_ATTR_SIZE];
        struct attribute_group class_attr_group;
        const struct attribute_group *class_attr_groups[2];
#endif /* CONFIG_GPIO_SYSFS_LEGACY */

        struct attribute *chip_attrs[GPIO_SYSFS_LINE_CHIP_ATTR_SIZE];
        struct attribute_group chip_attr_group;
        const struct attribute_group *chip_attr_groups[2];
};

struct gpiodev_data {
        struct list_head exported_lines;
        struct gpio_device *gdev;
        struct device *cdev_id; /* Class device by GPIO device ID */
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
        struct device *cdev_base; /* Class device by GPIO base */
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
};

/*
 * Lock to serialise gpiod export and unexport, and prevent re-export of
 * gpiod whose chip is being unregistered.
 */
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
 *   /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"
 *   /active_low
 *      * configures polarity of /value
 *      * is read/write as zero/nonzero
 *      * also affects existing and subsequent "falling" and "rising"
 *        /edge configuration
 */

static ssize_t direction_show(struct device *dev,
                              struct device_attribute *attr, char *buf)
{
        struct gpiod_data *data = container_of(attr, struct gpiod_data,
                                               dir_attr);
        struct gpio_desc *desc = data->desc;
        int value;

        scoped_guard(mutex, &data->mutex) {
                gpiod_get_direction(desc);
                value = !!test_bit(GPIOD_FLAG_IS_OUT, &desc->flags);
        }

        return sysfs_emit(buf, "%s\n", value ? "out" : "in");
}

static ssize_t direction_store(struct device *dev,
                               struct device_attribute *attr, const char *buf,
                               size_t size)
{
        struct gpiod_data *data = container_of(attr, struct gpiod_data,
                                               dir_attr);
        struct gpio_desc *desc = data->desc;
        ssize_t status;

        guard(mutex)(&data->mutex);

        if (sysfs_streq(buf, "high"))
                status = gpiod_direction_output_raw(desc, 1);
        else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
                status = gpiod_direction_output_raw(desc, 0);
        else if (sysfs_streq(buf, "in"))
                status = gpiod_direction_input(desc);
        else
                status = -EINVAL;

        return status ? : size;
}

static ssize_t value_show(struct device *dev, struct device_attribute *attr,
                          char *buf)
{
        struct gpiod_data *data = container_of(attr, struct gpiod_data,
                                               val_attr);
        struct gpio_desc *desc = data->desc;
        ssize_t status;

        scoped_guard(mutex, &data->mutex)
                status = gpiod_get_value_cansleep(desc);

        if (status < 0)
                return status;

        return sysfs_emit(buf, "%zd\n", status);
}

static ssize_t value_store(struct device *dev, struct device_attribute *attr,
                           const char *buf, size_t size)
{
        struct gpiod_data *data = container_of(attr, struct gpiod_data,
                                               val_attr);
        struct gpio_desc *desc = data->desc;
        ssize_t status;
        long value;

        status = kstrtol(buf, 0, &value);
        if (status)
                return status;

        guard(mutex)(&data->mutex);

        status = gpiod_set_value_cansleep(desc, value);
        if (status)
                return status;

        return size;
}

#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
{
        struct gpiod_data *data = priv;

        sysfs_notify_dirent(data->value_kn);

        return IRQ_HANDLED;
}

/* Caller holds gpiod-data mutex. */
static int gpio_sysfs_request_irq(struct gpiod_data *data, unsigned char flags)
{
        struct gpio_desc *desc = data->desc;
        unsigned long irq_flags;
        int ret;

        CLASS(gpio_chip_guard, guard)(desc);
        if (!guard.gc)
                return -ENODEV;

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

        irq_flags = IRQF_SHARED;
        if (flags & GPIO_IRQF_TRIGGER_FALLING) {
                irq_flags |= test_bit(GPIOD_FLAG_ACTIVE_LOW, &desc->flags) ?
                                IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
                set_bit(GPIOD_FLAG_EDGE_FALLING, &desc->flags);
        }
        if (flags & GPIO_IRQF_TRIGGER_RISING) {
                irq_flags |= test_bit(GPIOD_FLAG_ACTIVE_LOW, &desc->flags) ?
                                IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
                set_bit(GPIOD_FLAG_EDGE_RISING, &desc->flags);
        }

        /*
         * FIXME: This should be done in the irq_request_resources callback
         * when the irq is requested, but a few drivers currently fail to do
         * so.
         *
         * Remove this redundant call (along with the corresponding unlock)
         * when those drivers have been fixed.
         */
        ret = gpiochip_lock_as_irq(guard.gc, gpiod_hwgpio(desc));
        if (ret < 0)
                goto err_clr_bits;

        ret = request_any_context_irq(data->irq, gpio_sysfs_irq, irq_flags,
                                "gpiolib", data);
        if (ret < 0)
                goto err_unlock;

        data->irq_flags = flags;

        return 0;

err_unlock:
        gpiochip_unlock_as_irq(guard.gc, gpiod_hwgpio(desc));
err_clr_bits:
        clear_bit(GPIOD_FLAG_EDGE_RISING, &desc->flags);
        clear_bit(GPIOD_FLAG_EDGE_FALLING, &desc->flags);

        return ret;
}

/*
 * Caller holds gpiod-data mutex (unless called after class-device
 * deregistration).
 */
static void gpio_sysfs_free_irq(struct gpiod_data *data)
{
        struct gpio_desc *desc = data->desc;

        CLASS(gpio_chip_guard, guard)(desc);
        if (!guard.gc)
                return;

        data->irq_flags = 0;
        free_irq(data->irq, data);
        gpiochip_unlock_as_irq(guard.gc, gpiod_hwgpio(desc));
        clear_bit(GPIOD_FLAG_EDGE_RISING, &desc->flags);
        clear_bit(GPIOD_FLAG_EDGE_FALLING, &desc->flags);
}

static const char *const trigger_names[] = {
        [GPIO_IRQF_TRIGGER_NONE]        = "none",
        [GPIO_IRQF_TRIGGER_FALLING]     = "falling",
        [GPIO_IRQF_TRIGGER_RISING]      = "rising",
        [GPIO_IRQF_TRIGGER_BOTH]        = "both",
};

static ssize_t edge_show(struct device *dev, struct device_attribute *attr,
                         char *buf)
{
        struct gpiod_data *data = container_of(attr, struct gpiod_data,
                                               edge_attr);
        int flags;

        scoped_guard(mutex, &data->mutex)
                flags = data->irq_flags;

        if (flags >= ARRAY_SIZE(trigger_names))
                return 0;

        return sysfs_emit(buf, "%s\n", trigger_names[flags]);
}

static ssize_t edge_store(struct device *dev, struct device_attribute *attr,
                          const char *buf, size_t size)
{
        struct gpiod_data *data = container_of(attr, struct gpiod_data,
                                               edge_attr);
        ssize_t status = size;
        int flags;

        flags = sysfs_match_string(trigger_names, buf);
        if (flags < 0)
                return flags;

        guard(mutex)(&data->mutex);

        if (flags == data->irq_flags)
                return size;

        if (data->irq_flags)
                gpio_sysfs_free_irq(data);

        if (!flags)
                return size;

        status = gpio_sysfs_request_irq(data, flags);
        if (status)
                return status;

        gpiod_line_state_notify(data->desc, GPIO_V2_LINE_CHANGED_CONFIG);

        return size;
}

/* Caller holds gpiod-data mutex. */
static int gpio_sysfs_set_active_low(struct gpiod_data *data, int value)
{
        unsigned int flags = data->irq_flags;
        struct gpio_desc *desc = data->desc;
        int status = 0;

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

        assign_bit(GPIOD_FLAG_ACTIVE_LOW, &desc->flags, value);

        /* reconfigure poll(2) support if enabled on one edge only */
        if (flags == GPIO_IRQF_TRIGGER_FALLING ||
            flags == GPIO_IRQF_TRIGGER_RISING) {
                gpio_sysfs_free_irq(data);
                status = gpio_sysfs_request_irq(data, flags);
        }

        gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_CONFIG);

        return status;
}

static ssize_t active_low_show(struct device *dev,
                               struct device_attribute *attr, char *buf)
{
        struct gpiod_data *data = container_of(attr, struct gpiod_data,
                                               active_low_attr);
        struct gpio_desc *desc = data->desc;
        int value;

        scoped_guard(mutex, &data->mutex)
                value = !!test_bit(GPIOD_FLAG_ACTIVE_LOW, &desc->flags);

        return sysfs_emit(buf, "%d\n", value);
}

static ssize_t active_low_store(struct device *dev,
                                struct device_attribute *attr,
                                const char *buf, size_t size)
{
        struct gpiod_data *data = container_of(attr, struct gpiod_data,
                                               active_low_attr);
        ssize_t status;
        long value;

        status = kstrtol(buf, 0, &value);
        if (status)
                return status;

        guard(mutex)(&data->mutex);

        return gpio_sysfs_set_active_low(data, value) ?: size;
}
#endif /* CONFIG_GPIO_SYSFS_LEGACY */

static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
                               int n)
{
        struct device_attribute *dev_attr = container_of(attr,
                                                struct device_attribute, attr);
        umode_t mode = attr->mode;
        struct gpiod_data *data;

        if (strcmp(attr->name, "direction") == 0) {
                data = container_of(dev_attr, struct gpiod_data, dir_attr);

                if (!data->direction_can_change)
                        mode = 0;
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
        } else if (strcmp(attr->name, "edge") == 0) {
                data = container_of(dev_attr, struct gpiod_data, edge_attr);

                if (gpiod_to_irq(data->desc) < 0)
                        mode = 0;

                if (!data->direction_can_change &&
                    test_bit(GPIOD_FLAG_IS_OUT, &data->desc->flags))
                        mode = 0;
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
        }

        return mode;
}

/*
 * /sys/class/gpio/gpiochipN/
 *   /base ... matching gpio_chip.base (N)
 *   /label ... matching gpio_chip.label
 *   /ngpio ... matching gpio_chip.ngpio
 *
 * AND
 *
 * /sys/class/gpio/chipX/
 *   /export ... export GPIO at given offset
 *   /unexport ... unexport GPIO at given offset
 *   /label ... matching gpio_chip.label
 *   /ngpio ... matching gpio_chip.ngpio
 */

#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
static ssize_t base_show(struct device *dev, struct device_attribute *attr,
                         char *buf)
{
        const struct gpiodev_data *data = dev_get_drvdata(dev);

        return sysfs_emit(buf, "%u\n", data->gdev->base);
}
static DEVICE_ATTR_RO(base);
#endif /* CONFIG_GPIO_SYSFS_LEGACY */

static ssize_t label_show(struct device *dev, struct device_attribute *attr,
                          char *buf)
{
        const struct gpiodev_data *data = dev_get_drvdata(dev);

        return sysfs_emit(buf, "%s\n", data->gdev->label);
}
static DEVICE_ATTR_RO(label);

static ssize_t ngpio_show(struct device *dev, struct device_attribute *attr,
                          char *buf)
{
        const struct gpiodev_data *data = dev_get_drvdata(dev);

        return sysfs_emit(buf, "%u\n", data->gdev->ngpio);
}
static DEVICE_ATTR_RO(ngpio);

static int export_gpio_desc(struct gpio_desc *desc)
{
        int offset, ret;

        CLASS(gpio_chip_guard, guard)(desc);
        if (!guard.gc)
                return -ENODEV;

        offset = gpiod_hwgpio(desc);
        if (!gpiochip_line_is_valid(guard.gc, offset)) {
                pr_debug_ratelimited("%s: GPIO %d masked\n", __func__,
                                     gpiod_hwgpio(desc));
                return -EINVAL;
        }

        /*
         * No extra locking here; GPIOD_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.
         */

        ret = gpiod_request_user(desc, "sysfs");
        if (ret)
                return ret;

        ret = gpiod_set_transitory(desc, false);
        if (ret) {
                gpiod_free(desc);
                return ret;
        }

        ret = gpiod_export(desc, true);
        if (ret < 0) {
                gpiod_free(desc);
        } else {
                set_bit(GPIOD_FLAG_SYSFS, &desc->flags);
                gpiod_line_state_notify(desc, GPIO_V2_LINE_CHANGED_REQUESTED);
        }

        return ret;
}

static int unexport_gpio_desc(struct gpio_desc *desc)
{
        /*
         * No extra locking here; GPIOD_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(GPIOD_FLAG_SYSFS, &desc->flags))
                return -EINVAL;

        gpiod_unexport(desc);
        gpiod_free(desc);

        return 0;
}

static ssize_t do_chip_export_store(struct device *dev,
                                    struct device_attribute *attr,
                                    const char *buf, ssize_t size,
                                    int (*handler)(struct gpio_desc *desc))
{
        struct gpiodev_data *data = dev_get_drvdata(dev);
        struct gpio_device *gdev = data->gdev;
        struct gpio_desc *desc;
        unsigned int gpio;
        int ret;

        ret = kstrtouint(buf, 0, &gpio);
        if (ret)
                return ret;

        desc = gpio_device_get_desc(gdev, gpio);
        if (IS_ERR(desc))
                return PTR_ERR(desc);

        ret = handler(desc);
        if (ret)
                return ret;

        return size;
}

static ssize_t chip_export_store(struct device *dev,
                                 struct device_attribute *attr,
                                 const char *buf, size_t size)
{
        return do_chip_export_store(dev, attr, buf, size, export_gpio_desc);
}

static struct device_attribute dev_attr_export = __ATTR(export, 0200, NULL,
                                                        chip_export_store);

static ssize_t chip_unexport_store(struct device *dev,
                                   struct device_attribute *attr,
                                   const char *buf, size_t size)
{
        return do_chip_export_store(dev, attr, buf, size, unexport_gpio_desc);
}

static struct device_attribute dev_attr_unexport = __ATTR(unexport, 0200,
                                                          NULL,
                                                          chip_unexport_store);

#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
static struct attribute *gpiochip_attrs[] = {
        &dev_attr_base.attr,
        &dev_attr_label.attr,
        &dev_attr_ngpio.attr,
        NULL,
};
ATTRIBUTE_GROUPS(gpiochip);
#endif /* CONFIG_GPIO_SYSFS_LEGACY */

static struct attribute *gpiochip_ext_attrs[] = {
        &dev_attr_label.attr,
        &dev_attr_ngpio.attr,
        &dev_attr_export.attr,
        &dev_attr_unexport.attr,
        NULL
};
ATTRIBUTE_GROUPS(gpiochip_ext);

#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
/*
 * /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
 */
static ssize_t export_store(const struct class *class,
                            const struct class_attribute *attr,
                            const char *buf, size_t len)
{
        struct gpio_desc *desc;
        int status;
        long gpio;

        status = kstrtol(buf, 0, &gpio);
        if (status)
                return status;

        desc = gpio_to_desc(gpio);
        /* reject invalid GPIOs */
        if (!desc) {
                pr_debug_ratelimited("%s: invalid GPIO %ld\n", __func__, gpio);
                return -EINVAL;
        }

        status = export_gpio_desc(desc);
        if (status)
                pr_debug("%s: status %d\n", __func__, status);
        return status ? : len;
}
static CLASS_ATTR_WO(export);

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

        status = kstrtol(buf, 0, &gpio);
        if (status < 0)
                return status;

        desc = gpio_to_desc(gpio);
        /* reject bogus commands (gpiod_unexport() ignores them) */
        if (!desc) {
                pr_debug_ratelimited("%s: invalid GPIO %ld\n", __func__, gpio);
                return -EINVAL;
        }

        status = unexport_gpio_desc(desc);
        if (status)
                pr_debug("%s: status %d\n", __func__, status);
        return status ? : len;
}
static CLASS_ATTR_WO(unexport);

static struct attribute *gpio_class_attrs[] = {
        &class_attr_export.attr,
        &class_attr_unexport.attr,
        NULL,
};
ATTRIBUTE_GROUPS(gpio_class);
#endif /* CONFIG_GPIO_SYSFS_LEGACY */

static const struct class gpio_class = {
        .name =         "gpio",
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
        .class_groups = gpio_class_groups,
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
};

static int match_gdev(struct device *dev, const void *desc)
{
        struct gpiodev_data *data = dev_get_drvdata(dev);
        const struct gpio_device *gdev = desc;

        return data && data->gdev == gdev;
}

static struct gpiodev_data *
gdev_get_data(struct gpio_device *gdev) __must_hold(&sysfs_lock)
{
        /*
         * Find the first device in GPIO class that matches. Whether that's
         * the one indexed by GPIO base or device ID doesn't matter, it has
         * the same address set as driver data.
         */
        struct device *cdev __free(put_device) = class_find_device(&gpio_class,
                                                                   NULL, gdev,
                                                                   match_gdev);
        if (!cdev)
                return NULL;

        return dev_get_drvdata(cdev);
};

static void gpiod_attr_init(struct device_attribute *dev_attr, const char *name,
                            ssize_t (*show)(struct device *dev,
                                            struct device_attribute *attr,
                                            char *buf),
                            ssize_t (*store)(struct device *dev,
                                             struct device_attribute *attr,
                                             const char *buf, size_t count))
{
        sysfs_attr_init(&dev_attr->attr);
        dev_attr->attr.name = name;
        dev_attr->attr.mode = 0644;
        dev_attr->show = show;
        dev_attr->store = store;
}

/**
 * gpiod_export - export a GPIO through sysfs
 * @desc: 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:
 * 0 on success, or negative errno on failure.
 */
int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
{
        char *path __free(kfree) = NULL;
        struct gpiodev_data *gdev_data;
        struct gpiod_data *desc_data;
        struct gpio_device *gdev;
        struct attribute **attrs;
        int status;

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

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

        CLASS(gpio_chip_guard, guard)(desc);
        if (!guard.gc)
                return -ENODEV;

        if (test_and_set_bit(GPIOD_FLAG_EXPORT, &desc->flags))
                return -EPERM;

        gdev = desc->gdev;

        guard(mutex)(&sysfs_lock);

        if (!test_bit(GPIOD_FLAG_REQUESTED, &desc->flags)) {
                gpiod_dbg(desc, "%s: unavailable (not requested)\n", __func__);
                status = -EPERM;
                goto err_clear_bit;
        }

        desc_data = kzalloc_obj(*desc_data);
        if (!desc_data) {
                status = -ENOMEM;
                goto err_clear_bit;
        }

        desc_data->desc = desc;
        mutex_init(&desc_data->mutex);
        if (guard.gc->direction_input && guard.gc->direction_output)
                desc_data->direction_can_change = direction_may_change;
        else
                desc_data->direction_can_change = false;

        gpiod_attr_init(&desc_data->dir_attr, "direction",
                        direction_show, direction_store);
        gpiod_attr_init(&desc_data->val_attr, "value", value_show, value_store);

#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
        gpiod_attr_init(&desc_data->edge_attr, "edge", edge_show, edge_store);
        gpiod_attr_init(&desc_data->active_low_attr, "active_low",
                        active_low_show, active_low_store);

        attrs = desc_data->class_attrs;
        desc_data->class_attr_group.is_visible = gpio_is_visible;
        attrs[GPIO_SYSFS_LINE_CLASS_ATTR_DIRECTION] = &desc_data->dir_attr.attr;
        attrs[GPIO_SYSFS_LINE_CLASS_ATTR_VALUE] = &desc_data->val_attr.attr;
        attrs[GPIO_SYSFS_LINE_CLASS_ATTR_EDGE] = &desc_data->edge_attr.attr;
        attrs[GPIO_SYSFS_LINE_CLASS_ATTR_ACTIVE_LOW] = &desc_data->active_low_attr.attr;

        desc_data->class_attr_group.attrs = desc_data->class_attrs;
        desc_data->class_attr_groups[0] = &desc_data->class_attr_group;

        /*
         * Note: we need to continue passing desc_data here as there's still
         * at least one known user of gpiod_export_link() in the tree. This
         * function still uses class_find_device() internally.
         */
        desc_data->dev = device_create_with_groups(&gpio_class, &gdev->dev,
                                                   MKDEV(0, 0), desc_data,
                                                   desc_data->class_attr_groups,
                                                   "gpio%u",
                                                   desc_to_gpio(desc));
        if (IS_ERR(desc_data->dev)) {
                status = PTR_ERR(desc_data->dev);
                goto err_free_data;
        }

        desc_data->value_kn = sysfs_get_dirent(desc_data->dev->kobj.sd,
                                                       "value");
        if (!desc_data->value_kn) {
                status = -ENODEV;
                goto err_unregister_device;
        }
#endif /* CONFIG_GPIO_SYSFS_LEGACY */

        gdev_data = gdev_get_data(gdev);
        if (!gdev_data) {
                status = -ENODEV;
                goto err_put_dirent;
        }

        desc_data->chip_attr_group.name = kasprintf(GFP_KERNEL, "gpio%u",
                                                    gpiod_hwgpio(desc));
        if (!desc_data->chip_attr_group.name) {
                status = -ENOMEM;
                goto err_put_dirent;
        }

        attrs = desc_data->chip_attrs;
        desc_data->chip_attr_group.is_visible = gpio_is_visible;
        attrs[GPIO_SYSFS_LINE_CHIP_ATTR_DIRECTION] = &desc_data->dir_attr.attr;
        attrs[GPIO_SYSFS_LINE_CHIP_ATTR_VALUE] = &desc_data->val_attr.attr;

        desc_data->chip_attr_group.attrs = attrs;
        desc_data->chip_attr_groups[0] = &desc_data->chip_attr_group;

        desc_data->parent = &gdev_data->cdev_id->kobj;
        status = sysfs_create_groups(desc_data->parent,
                                     desc_data->chip_attr_groups);
        if (status)
                goto err_free_name;

        path = kasprintf(GFP_KERNEL, "gpio%u/value", gpiod_hwgpio(desc));
        if (!path) {
                status = -ENOMEM;
                goto err_remove_groups;
        }

        list_add(&desc_data->list, &gdev_data->exported_lines);

        return 0;

err_remove_groups:
        sysfs_remove_groups(desc_data->parent, desc_data->chip_attr_groups);
err_free_name:
        kfree(desc_data->chip_attr_group.name);
err_put_dirent:
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
        sysfs_put(desc_data->value_kn);
err_unregister_device:
        device_unregister(desc_data->dev);
err_free_data:
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
        kfree(desc_data);
err_clear_bit:
        clear_bit(GPIOD_FLAG_EXPORT, &desc->flags);
        gpiod_dbg(desc, "%s: status %d\n", __func__, status);
        return status;
}
EXPORT_SYMBOL_GPL(gpiod_export);

#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
static int match_export(struct device *dev, const void *desc)
{
        struct gpiod_data *data = dev_get_drvdata(dev);

        return gpiod_is_equal(data->desc, desc);
}
#endif /* CONFIG_GPIO_SYSFS_LEGACY */

/**
 * gpiod_export_link - create a sysfs link to an exported GPIO node
 * @dev: device under which to create symlink
 * @name: name of the symlink
 * @desc: 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:
 * 0 on success, or negative errno on failure.
 */
int gpiod_export_link(struct device *dev, const char *name,
                      struct gpio_desc *desc)
{
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
        struct device *cdev;
        int ret;

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

        cdev = class_find_device(&gpio_class, NULL, desc, match_export);
        if (!cdev)
                return -ENODEV;

        ret = sysfs_create_link(&dev->kobj, &cdev->kobj, name);
        put_device(cdev);

        return ret;
#else
        return -EOPNOTSUPP;
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
}
EXPORT_SYMBOL_GPL(gpiod_export_link);

static void gpiod_unexport_unlocked(struct gpio_desc *desc)
{
        struct gpiod_data *tmp, *desc_data = NULL;
        struct gpiodev_data *gdev_data;
        struct gpio_device *gdev;

        if (!test_bit(GPIOD_FLAG_EXPORT, &desc->flags))
                return;

        gdev = gpiod_to_gpio_device(desc);
        gdev_data = gdev_get_data(gdev);
        if (!gdev_data)
                return;

        list_for_each_entry(tmp, &gdev_data->exported_lines, list) {
                if (gpiod_is_equal(desc, tmp->desc)) {
                        desc_data = tmp;
                        break;
                }
        }

        if (!desc_data)
                return;

        list_del(&desc_data->list);
        clear_bit(GPIOD_FLAG_EXPORT, &desc->flags);
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
        sysfs_put(desc_data->value_kn);
        device_unregister(desc_data->dev);

        /*
         * Release irq after deregistration to prevent race with
         * edge_store.
         */
        if (desc_data->irq_flags)
                gpio_sysfs_free_irq(desc_data);
#endif /* CONFIG_GPIO_SYSFS_LEGACY */

        sysfs_remove_groups(desc_data->parent,
                            desc_data->chip_attr_groups);

        mutex_destroy(&desc_data->mutex);
        kfree(desc_data);
}

/**
 * gpiod_unexport - reverse effect of gpiod_export()
 * @desc: GPIO to make unavailable
 *
 * This is implicit on gpiod_free().
 */
void gpiod_unexport(struct gpio_desc *desc)
{
        if (!desc) {
                pr_warn("%s: invalid GPIO\n", __func__);
                return;
        }

        guard(mutex)(&sysfs_lock);

        gpiod_unexport_unlocked(desc);
}
EXPORT_SYMBOL_GPL(gpiod_unexport);

int gpiochip_sysfs_register(struct gpio_device *gdev)
{
        struct gpiodev_data *data;
        struct gpio_chip *chip;
        struct device *parent;
        int err;

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

        guard(srcu)(&gdev->srcu);

        chip = srcu_dereference(gdev->chip, &gdev->srcu);
        if (!chip)
                return -ENODEV;

        /*
         * For sysfs backward compatibility we need to preserve this
         * preferred parenting to the gpio_chip parent field, if set.
         */
        if (chip->parent)
                parent = chip->parent;
        else
                parent = &gdev->dev;

        data = kmalloc_obj(*data);
        if (!data)
                return -ENOMEM;

        data->gdev = gdev;
        INIT_LIST_HEAD(&data->exported_lines);

        guard(mutex)(&sysfs_lock);

#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
        /* use chip->base for the ID; it's already known to be unique */
        data->cdev_base = device_create_with_groups(&gpio_class, parent,
                                                    MKDEV(0, 0), data,
                                                    gpiochip_groups,
                                                    GPIOCHIP_NAME "%d",
                                                    chip->base);
        if (IS_ERR(data->cdev_base)) {
                err = PTR_ERR(data->cdev_base);
                kfree(data);
                return err;
        }
#endif /* CONFIG_GPIO_SYSFS_LEGACY */

        data->cdev_id = device_create_with_groups(&gpio_class, parent,
                                                  MKDEV(0, 0), data,
                                                  gpiochip_ext_groups,
                                                  "chip%d", gdev->id);
        if (IS_ERR(data->cdev_id)) {
#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
                device_unregister(data->cdev_base);
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
                err = PTR_ERR(data->cdev_id);
                kfree(data);
                return err;
        }

        return 0;
}

void gpiochip_sysfs_unregister(struct gpio_device *gdev)
{
        struct gpiodev_data *data;
        struct gpio_desc *desc;
        struct gpio_chip *chip;

        guard(mutex)(&sysfs_lock);

        data = gdev_get_data(gdev);
        if (!data)
                return;

        guard(srcu)(&gdev->srcu);
        chip = srcu_dereference(gdev->chip, &gdev->srcu);
        if (!chip)
                return;

        /* unregister gpiod class devices owned by sysfs */
        for_each_gpio_desc_with_flag(chip, desc, GPIOD_FLAG_SYSFS) {
                gpiod_unexport_unlocked(desc);
                gpiod_free(desc);
        }

#if IS_ENABLED(CONFIG_GPIO_SYSFS_LEGACY)
        device_unregister(data->cdev_base);
#endif /* CONFIG_GPIO_SYSFS_LEGACY */
        device_unregister(data->cdev_id);
        kfree(data);
}

/*
 * We're not really looking for a device - we just want to iterate over the
 * list and call this callback for each GPIO device. This is why this function
 * always returns 0.
 */
static int gpiofind_sysfs_register(struct gpio_chip *gc, const void *data)
{
        struct gpio_device *gdev = gc->gpiodev;
        int ret;

        ret = gpiochip_sysfs_register(gdev);
        if (ret)
                gpiochip_err(gc, "failed to register the sysfs entry: %d\n", ret);

        return 0;
}

static int __init gpiolib_sysfs_init(void)
{
        int status;

        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 gpiod_export().
         */
        (void)gpio_device_find(NULL, gpiofind_sysfs_register);

        return 0;
}
postcore_initcall(gpiolib_sysfs_init);