linux/drivers/gpio/gpiolib-sysfs.c
Linus Torvalds 70b8e9eb3b This is the bulk of the GPIO changes for the v4.14 cycle:
Core changes
 - Allow the GPIO irqchip to allocate IRQs dynamically. This is
   an important change on systems where only a restricted number
   of IRQs, lesser than the number of GPIO lines, can be utilized.
   Now we can allocate these on a first-come-first-served basis
   instead of hogging up valuable IRQ lines.
 - Serious fix-up of the kerneldoc documentation and inclusion
   into the kerneldoc builds.
 - Pulled in the IRQ simulator from the IRQ core tree and use
   this in the GPIO mockup driver for exhaustive testing of
   interrupt abilities.
 
 New drivers
 - New driver for ThunderX and OCTEON-TX. This is especially
   interesting as it picks up improvements from the IRQ core that
   allow us to handle fasteoi ACKs upwards in a hierarchy when
   there are IRQ flag latches on several levels in a hierarchy.
   Very interesting work here.
 - New subdriver for Renesas R-Car r8a7745 (RZ/G1E).
 
 Misc
 - Several fixes and improvements for Xilinx Zynq GPIO.
 - Support an enablement GPIO for the 74x164 GPIO.
 - Switch a bunch of chips to use devres to allocate irq
   descriptors.
 - A bunch of constification fixes.
 -----BEGIN PGP SIGNATURE-----
 
 iQIcBAABAgAGBQJZrmRvAAoJEEEQszewGV1zFd8P/0wwsPFfCY5tjqMwYcu2VIzA
 ZEPlN/Z14Xr/JC7X5N18qWaZSdqAP94do8fn1Utqr6mEOY71BAAmt1dRH3M651nz
 dyAnb5s8IlnFNrv2C3ksG4ArQP72y3uag7b/9fcDPSFBjQKHXP9zI5qhvxJI8XFY
 iesWkwkQayDzbKvm/bFWugclYjSNZCwtzGn2OD0zhh8vKchQBEdLYuiV06iEuvh4
 dkfpH5UhingJ0gMgMj3VLXvnaSPOQy321mnnF8cmHIwelZR8ij3JPQzirKB/cvTe
 fj/INc9/gXFOepFcEaQcWwspeXOXCjOajqfCyeLKLigj44E7pbv4HeTLJmQtCWv/
 fBlHnzjEJG7zZi8JOuKeMwMSc/6GPHBhlmZ4GjpMtIeNXQ8V2oosLbvSd5/whtPg
 u9QuDDeTJwjm1HY3kBNa50BKYrAAKIATHxnYAlGrDTf/9ea5Ld7AT/IfeGHS2AQR
 nV6I0byRYCxEVZUTPeYOMoHDNGgVgA9VPAhUUjLj6r6Kx2bS4Pn7KNvSNx24SQTU
 wP+rWDXRNJzIMr9+sWj3yAksYZPQSpV2+y/VizeHZA7ssv3ZzqKzfWPARhQy/ypF
 GN72LObdxaW01GjN9bJ8x4KxBj+tIo2lLXYIK5TdKZy+LRxnsbCK6JGa5gFxopQh
 325SOqkLlhaS2P6A2nHC
 =TYNw
 -----END PGP SIGNATURE-----

Merge tag 'gpio-v4.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio

Pull GPIO updates from Linus Walleij:
 "This is the bulk of the GPIO changes for the v4.14 cycle.

  Not so much changes this time, phew. David Daney and Bartosz
  Golaszewski did all the really interesting work in infrastructure
  improvement across GPIO and IRQ core, hats off for them and to tglx
  and Marc Z for general help with these patch sets.

  Core changes:

   - Allow the GPIO irqchip to allocate IRQs dynamically. This is an
     important change on systems where only a restricted number of IRQs,
     lesser than the number of GPIO lines, can be utilized. Now we can
     allocate these on a first-come-first-served basis instead of
     hogging up valuable IRQ lines.

   - Serious fix-up of the kerneldoc documentation and inclusion into
     the kerneldoc builds.

   - Pulled in the IRQ simulator from the IRQ core tree and use this in
     the GPIO mockup driver for exhaustive testing of interrupt
     abilities.

  New drivers:

   - New driver for ThunderX and OCTEON-TX. This is especially
     interesting as it picks up improvements from the IRQ core that
     allow us to handle fasteoi ACKs upwards in a hierarchy when there
     are IRQ flag latches on several levels in a hierarchy. Very
     interesting work here.

   - New subdriver for Renesas R-Car r8a7745 (RZ/G1E).

  Misc:

   - Several fixes and improvements for Xilinx Zynq GPIO.

   - Support an enablement GPIO for the 74x164 GPIO.

   - Switch a bunch of chips to use devres to allocate irq descriptors.

   - A bunch of constification fixes"

* tag 'gpio-v4.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio: (63 commits)
  gpio: mockup: remove unused variable gc
  gpio: pl061: constify amba_id
  Revert "gpiolib: request the gpio before querying its direction"
  gpio: twl6040: remove unneeded forward declaration
  gpio: zevio: make gpio_chip const
  gpio: add gpio_add_lookup_tables() to add several tables at once
  gpio: rcar: Add r8a7745 (RZ/G1E) support
  gpio: brcmstb: check return value of gpiochip_irqchip_add()
  MAINTAINERS: Add entry for THUNDERX GPIO Driver.
  gpio: Add gpio driver support for ThunderX and OCTEON-TX
  gpio: mockup: use irq_sim
  gpio: mxs: use devres for irq generic chip
  gpio: mxc: use devres for irq generic chip
  gpio: pch: use devres for irq generic chip
  gpio: ml-ioh: use devres for irq generic chip
  gpio: sta2x11: use devres for irq generic chip
  gpio: sta2x11: disallow unbinding the driver
  gpio: mxs: disallow unbinding the driver
  gpio: mxc: disallow unbinding the driver
  gpio: aspeed: Remove reference to clock name in debounce warning message
  ...
2017-09-05 11:49:48 -07:00

832 lines
19 KiB
C

#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 "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 = sprintf(buf, "%d\n", gpiod_get_value_cansleep(desc));
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;
mutex_lock(&data->mutex);
if (!test_bit(FLAG_IS_OUT, &desc->flags)) {
status = -EPERM;
} else {
long value;
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_RW(value);
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_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);