// SPDX-License-Identifier: GPL-2.0
#include <linux/bitops.h>
#include <linux/cleanup.h>
#include <linux/device.h>
#include <linux/idr.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/spinlock.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 "gpiolib.h"
#include "gpiolib-sysfs.h"
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)
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;
int value;
mutex_lock(&data->mutex);
gpiod_get_direction(desc);
value = !!test_bit(FLAG_IS_OUT, &desc->flags);
mutex_unlock(&data->mutex);
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 = 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);
mutex_unlock(&data->mutex);
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 = dev_get_drvdata(dev);
struct gpio_desc *desc = data->desc;
ssize_t status;
long value;
status = kstrtol(buf, 0, &value);
mutex_lock(&data->mutex);
if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
status = -EPERM;
} else 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;
CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return -ENODEV;
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(guard.gc, 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(guard.gc, 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;
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, gpio_chip_hwgpio(desc));
sysfs_put(data->value_kn);
}
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 = dev_get_drvdata(dev);
int flags;
mutex_lock(&data->mutex);
flags = data->irq_flags;
mutex_unlock(&data->mutex);
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 = dev_get_drvdata(dev);
ssize_t status = size;
int flags;
flags = sysfs_match_string(trigger_names, buf);
if (flags < 0)
return 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);
unsigned int flags = data->irq_flags;
struct gpio_desc *desc = data->desc;
int status = 0;
if (!!test_bit(FLAG_ACTIVE_LOW, &desc->flags) == !!value)
return 0;
assign_bit(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(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;
int value;
mutex_lock(&data->mutex);
value = !!test_bit(FLAG_ACTIVE_LOW, &desc->flags);
mutex_unlock(&data->mutex);
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 = dev_get_drvdata(dev);
ssize_t status;
long value;
status = kstrtol(buf, 0, &value);
if (status)
return status;
mutex_lock(&data->mutex);
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 = kobj_to_dev(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_device *gdev = dev_get_drvdata(dev);
return sysfs_emit(buf, "%u\n", gdev->base);
}
static DEVICE_ATTR_RO(base);
static ssize_t label_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
const struct gpio_device *gdev = dev_get_drvdata(dev);
return sysfs_emit(buf, "%s\n", gdev->label);
}
static DEVICE_ATTR_RO(label);
static ssize_t ngpio_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
const struct gpio_device *gdev = dev_get_drvdata(dev);
return sysfs_emit(buf, "%u\n", gdev->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);
/*
* /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, offset;
long gpio;
status = kstrtol(buf, 0, &gpio);
if (status)
return status;
desc = gpio_to_desc(gpio);
/* reject invalid GPIOs */
if (!desc) {
pr_warn("%s: invalid GPIO %ld\n", __func__, gpio);
return -EINVAL;
}
CLASS(gpio_chip_guard, guard)(desc);
if (!guard.gc)
return -ENODEV;
offset = gpio_chip_hwgpio(desc);
if (!gpiochip_line_is_valid(guard.gc, offset)) {
pr_warn("%s: GPIO %ld masked\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_user(desc, "sysfs");
if (status)
goto done;
status = gpiod_set_transitory(desc, false);
if (status) {
gpiod_free(desc);
goto done;
}
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(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)
goto done;
desc = gpio_to_desc(gpio);
/* reject bogus commands (gpiod_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)) {
gpiod_unexport(desc);
gpiod_free(desc);
status = 0;
}
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",
.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:
* 0 on success, or negative errno on failure.
*/
int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
{
const char *ioname = NULL;
struct gpio_device *gdev;
struct gpiod_data *data;
struct device *dev;
int status, offset;
/* 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(FLAG_EXPORT, &desc->flags))
return -EPERM;
gdev = desc->gdev;
mutex_lock(&sysfs_lock);
/* check if chip is being removed */
if (!gdev->mockdev) {
status = -ENODEV;
goto err_unlock;
}
if (!test_bit(FLAG_REQUESTED, &desc->flags)) {
gpiod_dbg(desc, "%s: unavailable (not requested)\n", __func__);
status = -EPERM;
goto err_unlock;
}
data = kzalloc(sizeof(*data), GFP_KERNEL);
if (!data) {
status = -ENOMEM;
goto err_unlock;
}
data->desc = desc;
mutex_init(&data->mutex);
if (guard.gc->direction_input && guard.gc->direction_output)
data->direction_can_change = direction_may_change;
else
data->direction_can_change = false;
offset = gpio_chip_hwgpio(desc);
if (guard.gc->names && guard.gc->names[offset])
ioname = guard.gc->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;
}
mutex_unlock(&sysfs_lock);
return 0;
err_free_data:
kfree(data);
err_unlock:
mutex_unlock(&sysfs_lock);
clear_bit(FLAG_EXPORT, &desc->flags);
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:
* 0 on success, or negative errno on failure.
*/
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 gpio_chip *chip;
struct device *parent;
struct device *dev;
/*
* 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;
/* use chip->base for the ID; it's already known to be unique */
dev = device_create_with_groups(&gpio_class, parent, MKDEV(0, 0), gdev,
gpiochip_groups, GPIOCHIP_NAME "%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;
scoped_guard(mutex, &sysfs_lock) {
if (!gdev->mockdev)
return;
device_unregister(gdev->mockdev);
/* prevent further gpiod exports */
gdev->mockdev = NULL;
}
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, FLAG_SYSFS) {
gpiod_unexport(desc);
gpiod_free(desc);
}
}
/*
* 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;
if (gdev->mockdev)
return 0;
ret = gpiochip_sysfs_register(gdev);
if (ret)
chip_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);
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