v4.19.13 snapshot.
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
new file mode 100644
index 0000000..3dbaf48
--- /dev/null
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -0,0 +1,846 @@
+#include <linux/idr.h>
+#include <linux/mutex.h>
+#include <linux/device.h>
+#include <linux/sysfs.h>
+#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/interrupt.h>
+#include <linux/kdev_t.h>
+#include <linux/slab.h>
+#include <linux/ctype.h>
+
+#include "gpiolib.h"
+
+#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)
+
+struct gpiod_data {
+ struct gpio_desc *desc;
+
+ struct mutex mutex;
+ struct kernfs_node *value_kn;
+ int irq;
+ unsigned char irq_flags;
+
+ bool direction_can_change;
+};
+
+/*
+ * 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 = dev_get_drvdata(dev);
+ struct gpio_desc *desc = data->desc;
+ ssize_t status;
+
+ mutex_lock(&data->mutex);
+
+ gpiod_get_direction(desc);
+ status = sprintf(buf, "%s\n",
+ test_bit(FLAG_IS_OUT, &desc->flags)
+ ? "out" : "in");
+
+ mutex_unlock(&data->mutex);
+
+ return status;
+}
+
+static ssize_t direction_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t size)
+{
+ struct gpiod_data *data = dev_get_drvdata(dev);
+ struct gpio_desc *desc = data->desc;
+ ssize_t status;
+
+ mutex_lock(&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;
+
+ mutex_unlock(&data->mutex);
+
+ return status ? : size;
+}
+static DEVICE_ATTR_RW(direction);
+
+static ssize_t value_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct gpiod_data *data = dev_get_drvdata(dev);
+ struct gpio_desc *desc = data->desc;
+ ssize_t status;
+
+ mutex_lock(&data->mutex);
+
+ status = gpiod_get_value_cansleep(desc);
+ if (status < 0)
+ goto err;
+
+ buf[0] = '0' + status;
+ buf[1] = '\n';
+ status = 2;
+err:
+ mutex_unlock(&data->mutex);
+
+ return status;
+}
+
+static ssize_t value_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t size)
+{
+ struct gpiod_data *data = dev_get_drvdata(dev);
+ struct gpio_desc *desc = data->desc;
+ ssize_t status = 0;
+
+ mutex_lock(&data->mutex);
+
+ if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
+ status = -EPERM;
+ } else {
+ long value;
+
+ if (size <= 2 && isdigit(buf[0]) &&
+ (size == 1 || buf[1] == '\n'))
+ value = buf[0] - '0';
+ else
+ status = kstrtol(buf, 0, &value);
+ if (status == 0) {
+ gpiod_set_value_cansleep(desc, value);
+ status = size;
+ }
+ }
+
+ mutex_unlock(&data->mutex);
+
+ return status;
+}
+static DEVICE_ATTR_PREALLOC(value, S_IWUSR | S_IRUGO, value_show, value_store);
+
+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 device *dev, unsigned char flags)
+{
+ struct gpiod_data *data = dev_get_drvdata(dev);
+ struct gpio_desc *desc = data->desc;
+ unsigned long irq_flags;
+ int ret;
+
+ data->irq = gpiod_to_irq(desc);
+ if (data->irq < 0)
+ return -EIO;
+
+ data->value_kn = sysfs_get_dirent(dev->kobj.sd, "value");
+ if (!data->value_kn)
+ return -ENODEV;
+
+ irq_flags = IRQF_SHARED;
+ if (flags & GPIO_IRQF_TRIGGER_FALLING)
+ irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
+ IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
+ if (flags & GPIO_IRQF_TRIGGER_RISING)
+ irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
+ IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
+
+ /*
+ * 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(desc->gdev->chip, gpio_chip_hwgpio(desc));
+ if (ret < 0)
+ goto err_put_kn;
+
+ 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(desc->gdev->chip, gpio_chip_hwgpio(desc));
+err_put_kn:
+ sysfs_put(data->value_kn);
+
+ return ret;
+}
+
+/*
+ * Caller holds gpiod-data mutex (unless called after class-device
+ * deregistration).
+ */
+static void gpio_sysfs_free_irq(struct device *dev)
+{
+ struct gpiod_data *data = dev_get_drvdata(dev);
+ struct gpio_desc *desc = data->desc;
+
+ data->irq_flags = 0;
+ free_irq(data->irq, data);
+ gpiochip_unlock_as_irq(desc->gdev->chip, gpio_chip_hwgpio(desc));
+ sysfs_put(data->value_kn);
+}
+
+static const struct {
+ const char *name;
+ unsigned char flags;
+} trigger_types[] = {
+ { "none", 0 },
+ { "falling", GPIO_IRQF_TRIGGER_FALLING },
+ { "rising", GPIO_IRQF_TRIGGER_RISING },
+ { "both", GPIO_IRQF_TRIGGER_BOTH },
+};
+
+static ssize_t edge_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct gpiod_data *data = dev_get_drvdata(dev);
+ ssize_t status = 0;
+ int i;
+
+ mutex_lock(&data->mutex);
+
+ for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
+ if (data->irq_flags == trigger_types[i].flags) {
+ status = sprintf(buf, "%s\n", trigger_types[i].name);
+ break;
+ }
+ }
+
+ mutex_unlock(&data->mutex);
+
+ return status;
+}
+
+static ssize_t edge_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t size)
+{
+ struct gpiod_data *data = dev_get_drvdata(dev);
+ unsigned char flags;
+ ssize_t status = size;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(trigger_types); i++) {
+ if (sysfs_streq(trigger_types[i].name, buf))
+ break;
+ }
+
+ if (i == ARRAY_SIZE(trigger_types))
+ return -EINVAL;
+
+ flags = trigger_types[i].flags;
+
+ mutex_lock(&data->mutex);
+
+ if (flags == data->irq_flags) {
+ status = size;
+ goto out_unlock;
+ }
+
+ if (data->irq_flags)
+ gpio_sysfs_free_irq(dev);
+
+ if (flags) {
+ status = gpio_sysfs_request_irq(dev, flags);
+ if (!status)
+ status = size;
+ }
+
+out_unlock:
+ mutex_unlock(&data->mutex);
+
+ return status;
+}
+static DEVICE_ATTR_RW(edge);
+
+/* Caller holds gpiod-data mutex. */
+static int gpio_sysfs_set_active_low(struct device *dev, int value)
+{
+ struct gpiod_data *data = dev_get_drvdata(dev);
+ struct gpio_desc *desc = data->desc;
+ int status = 0;
+ unsigned int flags = data->irq_flags;
+
+ 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 (flags == GPIO_IRQF_TRIGGER_FALLING ||
+ flags == GPIO_IRQF_TRIGGER_RISING) {
+ gpio_sysfs_free_irq(dev);
+ status = gpio_sysfs_request_irq(dev, flags);
+ }
+
+ return status;
+}
+
+static ssize_t active_low_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct gpiod_data *data = dev_get_drvdata(dev);
+ struct gpio_desc *desc = data->desc;
+ ssize_t status;
+
+ mutex_lock(&data->mutex);
+
+ status = sprintf(buf, "%d\n",
+ !!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
+
+ mutex_unlock(&data->mutex);
+
+ return status;
+}
+
+static ssize_t active_low_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t size)
+{
+ struct gpiod_data *data = dev_get_drvdata(dev);
+ ssize_t status;
+ long value;
+
+ mutex_lock(&data->mutex);
+
+ status = kstrtol(buf, 0, &value);
+ if (status == 0)
+ status = gpio_sysfs_set_active_low(dev, value);
+
+ mutex_unlock(&data->mutex);
+
+ return status ? : size;
+}
+static DEVICE_ATTR_RW(active_low);
+
+static umode_t gpio_is_visible(struct kobject *kobj, struct attribute *attr,
+ int n)
+{
+ struct device *dev = container_of(kobj, struct device, kobj);
+ struct gpiod_data *data = dev_get_drvdata(dev);
+ struct gpio_desc *desc = data->desc;
+ umode_t mode = attr->mode;
+ bool show_direction = data->direction_can_change;
+
+ if (attr == &dev_attr_direction.attr) {
+ if (!show_direction)
+ mode = 0;
+ } else if (attr == &dev_attr_edge.attr) {
+ if (gpiod_to_irq(desc) < 0)
+ mode = 0;
+ if (!show_direction && test_bit(FLAG_IS_OUT, &desc->flags))
+ mode = 0;
+ }
+
+ return mode;
+}
+
+static struct attribute *gpio_attrs[] = {
+ &dev_attr_direction.attr,
+ &dev_attr_edge.attr,
+ &dev_attr_value.attr,
+ &dev_attr_active_low.attr,
+ NULL,
+};
+
+static const struct attribute_group gpio_group = {
+ .attrs = gpio_attrs,
+ .is_visible = gpio_is_visible,
+};
+
+static const struct attribute_group *gpio_groups[] = {
+ &gpio_group,
+ NULL
+};
+
+/*
+ * /sys/class/gpio/gpiochipN/
+ * /base ... matching gpio_chip.base (N)
+ * /label ... matching gpio_chip.label
+ * /ngpio ... matching gpio_chip.ngpio
+ */
+
+static ssize_t 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_RO(base);
+
+static ssize_t 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_RO(label);
+
+static ssize_t 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_RO(ngpio);
+
+static struct attribute *gpiochip_attrs[] = {
+ &dev_attr_base.attr,
+ &dev_attr_label.attr,
+ &dev_attr_ngpio.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(gpiochip);
+
+static struct gpio_desc *gpio_to_valid_desc(int gpio)
+{
+ return gpio_is_valid(gpio) ? gpio_to_desc(gpio) : NULL;
+}
+
+/*
+ * /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(struct class *class,
+ struct class_attribute *attr,
+ const char *buf, size_t len)
+{
+ long gpio;
+ struct gpio_desc *desc;
+ int status;
+
+ status = kstrtol(buf, 0, &gpio);
+ if (status < 0)
+ goto done;
+
+ desc = gpio_to_valid_desc(gpio);
+ /* reject invalid GPIOs */
+ if (!desc) {
+ pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
+ return -EINVAL;
+ }
+
+ /* 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 = gpiod_request(desc, "sysfs");
+ if (status < 0) {
+ if (status == -EPROBE_DEFER)
+ status = -ENODEV;
+ goto done;
+ }
+
+ status = gpiod_set_transitory(desc, false);
+ if (!status) {
+ status = gpiod_export(desc, true);
+ if (status < 0)
+ gpiod_free(desc);
+ else
+ set_bit(FLAG_SYSFS, &desc->flags);
+ }
+
+done:
+ if (status)
+ pr_debug("%s: status %d\n", __func__, status);
+ return status ? : len;
+}
+static CLASS_ATTR_WO(export);
+
+static ssize_t unexport_store(struct class *class,
+ struct class_attribute *attr,
+ const char *buf, size_t len)
+{
+ long gpio;
+ struct gpio_desc *desc;
+ int status;
+
+ status = kstrtol(buf, 0, &gpio);
+ if (status < 0)
+ goto done;
+
+ desc = gpio_to_valid_desc(gpio);
+ /* reject bogus commands (gpio_unexport ignores them) */
+ if (!desc) {
+ pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
+ return -EINVAL;
+ }
+
+ status = -EINVAL;
+
+ /* 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, &desc->flags)) {
+ status = 0;
+ gpiod_free(desc);
+ }
+done:
+ 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);
+
+static struct class gpio_class = {
+ .name = "gpio",
+ .owner = THIS_MODULE,
+
+ .class_groups = gpio_class_groups,
+};
+
+
+/**
+ * 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 zero on success, else an error.
+ */
+int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
+{
+ struct gpio_chip *chip;
+ struct gpio_device *gdev;
+ struct gpiod_data *data;
+ unsigned long flags;
+ int status;
+ const char *ioname = NULL;
+ struct device *dev;
+ int offset;
+
+ /* can't export until sysfs is available ... */
+ if (!gpio_class.p) {
+ pr_debug("%s: called too early!\n", __func__);
+ return -ENOENT;
+ }
+
+ if (!desc) {
+ pr_debug("%s: invalid gpio descriptor\n", __func__);
+ return -EINVAL;
+ }
+
+ gdev = desc->gdev;
+ chip = gdev->chip;
+
+ mutex_lock(&sysfs_lock);
+
+ /* check if chip is being removed */
+ if (!chip || !gdev->mockdev) {
+ status = -ENODEV;
+ goto err_unlock;
+ }
+
+ spin_lock_irqsave(&gpio_lock, flags);
+ if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
+ test_bit(FLAG_EXPORT, &desc->flags)) {
+ spin_unlock_irqrestore(&gpio_lock, flags);
+ gpiod_dbg(desc, "%s: unavailable (requested=%d, exported=%d)\n",
+ __func__,
+ test_bit(FLAG_REQUESTED, &desc->flags),
+ test_bit(FLAG_EXPORT, &desc->flags));
+ status = -EPERM;
+ goto err_unlock;
+ }
+ spin_unlock_irqrestore(&gpio_lock, flags);
+
+ data = kzalloc(sizeof(*data), GFP_KERNEL);
+ if (!data) {
+ status = -ENOMEM;
+ goto err_unlock;
+ }
+
+ data->desc = desc;
+ mutex_init(&data->mutex);
+ if (chip->direction_input && chip->direction_output)
+ data->direction_can_change = direction_may_change;
+ else
+ data->direction_can_change = false;
+
+ offset = gpio_chip_hwgpio(desc);
+ if (chip->names && chip->names[offset])
+ ioname = chip->names[offset];
+
+ dev = device_create_with_groups(&gpio_class, &gdev->dev,
+ MKDEV(0, 0), data, gpio_groups,
+ ioname ? ioname : "gpio%u",
+ desc_to_gpio(desc));
+ if (IS_ERR(dev)) {
+ status = PTR_ERR(dev);
+ goto err_free_data;
+ }
+
+ set_bit(FLAG_EXPORT, &desc->flags);
+ mutex_unlock(&sysfs_lock);
+ return 0;
+
+err_free_data:
+ kfree(data);
+err_unlock:
+ mutex_unlock(&sysfs_lock);
+ gpiod_dbg(desc, "%s: status %d\n", __func__, status);
+ return status;
+}
+EXPORT_SYMBOL_GPL(gpiod_export);
+
+static int match_export(struct device *dev, const void *desc)
+{
+ struct gpiod_data *data = dev_get_drvdata(dev);
+
+ return data->desc == desc;
+}
+
+/**
+ * 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 zero on success, else an error.
+ */
+int gpiod_export_link(struct device *dev, const char *name,
+ struct gpio_desc *desc)
+{
+ 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;
+}
+EXPORT_SYMBOL_GPL(gpiod_export_link);
+
+/**
+ * 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)
+{
+ struct gpiod_data *data;
+ struct device *dev;
+
+ if (!desc) {
+ pr_warn("%s: invalid GPIO\n", __func__);
+ return;
+ }
+
+ mutex_lock(&sysfs_lock);
+
+ if (!test_bit(FLAG_EXPORT, &desc->flags))
+ goto err_unlock;
+
+ dev = class_find_device(&gpio_class, NULL, desc, match_export);
+ if (!dev)
+ goto err_unlock;
+
+ data = dev_get_drvdata(dev);
+
+ clear_bit(FLAG_EXPORT, &desc->flags);
+
+ device_unregister(dev);
+
+ /*
+ * Release irq after deregistration to prevent race with edge_store.
+ */
+ if (data->irq_flags)
+ gpio_sysfs_free_irq(dev);
+
+ mutex_unlock(&sysfs_lock);
+
+ put_device(dev);
+ kfree(data);
+
+ return;
+
+err_unlock:
+ mutex_unlock(&sysfs_lock);
+}
+EXPORT_SYMBOL_GPL(gpiod_unexport);
+
+int gpiochip_sysfs_register(struct gpio_device *gdev)
+{
+ struct device *dev;
+ struct device *parent;
+ struct gpio_chip *chip = gdev->chip;
+
+ /*
+ * 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 (!gpio_class.p)
+ return 0;
+
+ /*
+ * 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;
+
+ /* use chip->base for the ID; it's already known to be unique */
+ dev = device_create_with_groups(&gpio_class, parent,
+ MKDEV(0, 0),
+ chip, gpiochip_groups,
+ "gpiochip%d", chip->base);
+ if (IS_ERR(dev))
+ return PTR_ERR(dev);
+
+ mutex_lock(&sysfs_lock);
+ gdev->mockdev = dev;
+ mutex_unlock(&sysfs_lock);
+
+ return 0;
+}
+
+void gpiochip_sysfs_unregister(struct gpio_device *gdev)
+{
+ struct gpio_desc *desc;
+ struct gpio_chip *chip = gdev->chip;
+ unsigned int i;
+
+ if (!gdev->mockdev)
+ return;
+
+ device_unregister(gdev->mockdev);
+
+ /* prevent further gpiod exports */
+ mutex_lock(&sysfs_lock);
+ gdev->mockdev = NULL;
+ mutex_unlock(&sysfs_lock);
+
+ /* unregister gpiod class devices owned by sysfs */
+ for (i = 0; i < chip->ngpio; i++) {
+ desc = &gdev->descs[i];
+ if (test_and_clear_bit(FLAG_SYSFS, &desc->flags))
+ gpiod_free(desc);
+ }
+}
+
+static int __init gpiolib_sysfs_init(void)
+{
+ int status;
+ unsigned long flags;
+ struct gpio_device *gdev;
+
+ 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);
+ list_for_each_entry(gdev, &gpio_devices, list) {
+ if (gdev->mockdev)
+ continue;
+
+ /*
+ * TODO we yield gpio_lock here because
+ * gpiochip_sysfs_register() acquires a mutex. This is unsafe
+ * and needs to be fixed.
+ *
+ * Also it would be nice to use gpiochip_find() here so we
+ * can keep gpio_chips local to gpiolib.c, but the yield of
+ * gpio_lock prevents us from doing this.
+ */
+ spin_unlock_irqrestore(&gpio_lock, flags);
+ status = gpiochip_sysfs_register(gdev);
+ spin_lock_irqsave(&gpio_lock, flags);
+ }
+ spin_unlock_irqrestore(&gpio_lock, flags);
+
+ return status;
+}
+postcore_initcall(gpiolib_sysfs_init);