linux/drivers/gpio/gpiolib-sysfs.c

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// SPDX-License-Identifier: GPL-2.0
#include <linux/idr.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/sysfs.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"
#include "gpiolib-sysfs.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.
*/
gpio: reflect base and ngpio into gpio_device Some information about the GPIO chip need to stay around also after the gpio_chip has been removed and only the gpio_device persist. The base and ngpio are such things, for example we don't want a new chip arriving to overlap the number space of a dangling gpio_device, and the chardev may still query the device for the number of lines etc. Note that the code that assigns base and insert gpio_device into the global list no longer check for a missing gpio_chip: we respect the number space allocated by any other gpio_device. As a consequence of the gdev being referenced directly from the gpio_desc, we need to verify it differently from all in-kernel API calls that fall through to direct queries to the gpio_chip vtable: we first check that desc is !NULL, then that desc->gdev is !NULL, then, if desc->gdev->chip is NULL, we *BAIL OUT* without any error, so as to manage the case where operations are requested on a device that is gone. These checks were non-uniform and partly missing in the past: so to simplify: create the macros VALIDATE_DESC() that will return -EINVAL if the desc or desc->gdev is missing and just 0 if the chip is gone, and conversely VALIDATE_DESC_VOID() for the case where the function does not return an error. By using these macros, we get warning messages about missing gdev with reference to the right function in the kernel log. Despite the macro business this simplifies the code and make it more readable than if we copy/paste the same descriptor checking code into all code ABI call sites (IMHO). Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-02-10 09:57:36 +00:00
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:
gpio: reflect base and ngpio into gpio_device Some information about the GPIO chip need to stay around also after the gpio_chip has been removed and only the gpio_device persist. The base and ngpio are such things, for example we don't want a new chip arriving to overlap the number space of a dangling gpio_device, and the chardev may still query the device for the number of lines etc. Note that the code that assigns base and insert gpio_device into the global list no longer check for a missing gpio_chip: we respect the number space allocated by any other gpio_device. As a consequence of the gdev being referenced directly from the gpio_desc, we need to verify it differently from all in-kernel API calls that fall through to direct queries to the gpio_chip vtable: we first check that desc is !NULL, then that desc->gdev is !NULL, then, if desc->gdev->chip is NULL, we *BAIL OUT* without any error, so as to manage the case where operations are requested on a device that is gone. These checks were non-uniform and partly missing in the past: so to simplify: create the macros VALIDATE_DESC() that will return -EINVAL if the desc or desc->gdev is missing and just 0 if the chip is gone, and conversely VALIDATE_DESC_VOID() for the case where the function does not return an error. By using these macros, we get warning messages about missing gdev with reference to the right function in the kernel log. Despite the macro business this simplifies the code and make it more readable than if we copy/paste the same descriptor checking code into all code ABI call sites (IMHO). Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-02-10 09:57:36 +00:00
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);
gpio: reflect base and ngpio into gpio_device Some information about the GPIO chip need to stay around also after the gpio_chip has been removed and only the gpio_device persist. The base and ngpio are such things, for example we don't want a new chip arriving to overlap the number space of a dangling gpio_device, and the chardev may still query the device for the number of lines etc. Note that the code that assigns base and insert gpio_device into the global list no longer check for a missing gpio_chip: we respect the number space allocated by any other gpio_device. As a consequence of the gdev being referenced directly from the gpio_desc, we need to verify it differently from all in-kernel API calls that fall through to direct queries to the gpio_chip vtable: we first check that desc is !NULL, then that desc->gdev is !NULL, then, if desc->gdev->chip is NULL, we *BAIL OUT* without any error, so as to manage the case where operations are requested on a device that is gone. These checks were non-uniform and partly missing in the past: so to simplify: create the macros VALIDATE_DESC() that will return -EINVAL if the desc or desc->gdev is missing and just 0 if the chip is gone, and conversely VALIDATE_DESC_VOID() for the case where the function does not return an error. By using these macros, we get warning messages about missing gdev with reference to the right function in the kernel log. Despite the macro business this simplifies the code and make it more readable than if we copy/paste the same descriptor checking code into all code ABI call sites (IMHO). Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-02-10 09:57:36 +00:00
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 = 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_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);
/*
* /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_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_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;
}
gpio: reflect base and ngpio into gpio_device Some information about the GPIO chip need to stay around also after the gpio_chip has been removed and only the gpio_device persist. The base and ngpio are such things, for example we don't want a new chip arriving to overlap the number space of a dangling gpio_device, and the chardev may still query the device for the number of lines etc. Note that the code that assigns base and insert gpio_device into the global list no longer check for a missing gpio_chip: we respect the number space allocated by any other gpio_device. As a consequence of the gdev being referenced directly from the gpio_desc, we need to verify it differently from all in-kernel API calls that fall through to direct queries to the gpio_chip vtable: we first check that desc is !NULL, then that desc->gdev is !NULL, then, if desc->gdev->chip is NULL, we *BAIL OUT* without any error, so as to manage the case where operations are requested on a device that is gone. These checks were non-uniform and partly missing in the past: so to simplify: create the macros VALIDATE_DESC() that will return -EINVAL if the desc or desc->gdev is missing and just 0 if the chip is gone, and conversely VALIDATE_DESC_VOID() for the case where the function does not return an error. By using these macros, we get warning messages about missing gdev with reference to the right function in the kernel log. Despite the macro business this simplifies the code and make it more readable than if we copy/paste the same descriptor checking code into all code ABI call sites (IMHO). Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-02-10 09:57:36 +00:00
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_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 = 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++) {
gpio: reflect base and ngpio into gpio_device Some information about the GPIO chip need to stay around also after the gpio_chip has been removed and only the gpio_device persist. The base and ngpio are such things, for example we don't want a new chip arriving to overlap the number space of a dangling gpio_device, and the chardev may still query the device for the number of lines etc. Note that the code that assigns base and insert gpio_device into the global list no longer check for a missing gpio_chip: we respect the number space allocated by any other gpio_device. As a consequence of the gdev being referenced directly from the gpio_desc, we need to verify it differently from all in-kernel API calls that fall through to direct queries to the gpio_chip vtable: we first check that desc is !NULL, then that desc->gdev is !NULL, then, if desc->gdev->chip is NULL, we *BAIL OUT* without any error, so as to manage the case where operations are requested on a device that is gone. These checks were non-uniform and partly missing in the past: so to simplify: create the macros VALIDATE_DESC() that will return -EINVAL if the desc or desc->gdev is missing and just 0 if the chip is gone, and conversely VALIDATE_DESC_VOID() for the case where the function does not return an error. By using these macros, we get warning messages about missing gdev with reference to the right function in the kernel log. Despite the macro business this simplifies the code and make it more readable than if we copy/paste the same descriptor checking code into all code ABI call sites (IMHO). Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-02-10 09:57:36 +00:00
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);