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gpiolib.c
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gpiolib.c
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#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/spinlock.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/gpio.h>
#include <linux/idr.h>
#include <linux/slab.h>
/* Optional implementation infrastructure for GPIO interfaces.
*
* Platforms may want to use this if they tend to use very many GPIOs
* that aren't part of a System-On-Chip core; or across I2C/SPI/etc.
*
* When kernel footprint or instruction count is an issue, simpler
* implementations may be preferred. The GPIO programming interface
* allows for inlining speed-critical get/set operations for common
* cases, so that access to SOC-integrated GPIOs can sometimes cost
* only an instruction or two per bit.
*/
/* When debugging, extend minimal trust to callers and platform code.
* Also emit diagnostic messages that may help initial bringup, when
* board setup or driver bugs are most common.
*
* Otherwise, minimize overhead in what may be bitbanging codepaths.
*/
#ifdef DEBUG
#define extra_checks 1
#else
#define extra_checks 0
#endif
/* gpio_lock prevents conflicts during gpio_desc[] table updates.
* While any GPIO is requested, its gpio_chip is not removable;
* each GPIO's "requested" flag serves as a lock and refcount.
*/
static DEFINE_SPINLOCK(gpio_lock);
struct gpio_desc {
struct gpio_chip *chip;
unsigned long flags;
/* flag symbols are bit numbers */
#define FLAG_REQUESTED 0
#define FLAG_IS_OUT 1
#define FLAG_RESERVED 2
#define FLAG_EXPORT 3 /* protected by sysfs_lock */
#define FLAG_SYSFS 4 /* exported via /sys/class/gpio/control */
#define FLAG_TRIG_FALL 5 /* trigger on falling edge */
#define FLAG_TRIG_RISE 6 /* trigger on rising edge */
#define FLAG_ACTIVE_LOW 7 /* sysfs value has active low */
#define PDESC_ID_SHIFT 16 /* add new flags before this one */
#define GPIO_FLAGS_MASK ((1 << PDESC_ID_SHIFT) - 1)
#define GPIO_TRIGGER_MASK (BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE))
#ifdef CONFIG_DEBUG_FS
const char *label;
#endif
};
static struct gpio_desc gpio_desc[ARCH_NR_GPIOS];
#ifdef CONFIG_GPIO_SYSFS
struct poll_desc {
struct work_struct work;
struct sysfs_dirent *value_sd;
};
static struct idr pdesc_idr;
#endif
static inline void desc_set_label(struct gpio_desc *d, const char *label)
{
#ifdef CONFIG_DEBUG_FS
d->label = label;
#endif
}
/* Warn when drivers omit gpio_request() calls -- legal but ill-advised
* when setting direction, and otherwise illegal. Until board setup code
* and drivers use explicit requests everywhere (which won't happen when
* those calls have no teeth) we can't avoid autorequesting. This nag
* message should motivate switching to explicit requests... so should
* the weaker cleanup after faults, compared to gpio_request().
*
* NOTE: the autorequest mechanism is going away; at this point it's
* only "legal" in the sense that (old) code using it won't break yet,
* but instead only triggers a WARN() stack dump.
*/
static int gpio_ensure_requested(struct gpio_desc *desc, unsigned offset)
{
const struct gpio_chip *chip = desc->chip;
const int gpio = chip->base + offset;
if (WARN(test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0,
"autorequest GPIO-%d\n", gpio)) {
if (!try_module_get(chip->owner)) {
pr_err("GPIO-%d: module can't be gotten \n", gpio);
clear_bit(FLAG_REQUESTED, &desc->flags);
/* lose */
return -EIO;
}
desc_set_label(desc, "[auto]");
/* caller must chip->request() w/o spinlock */
if (chip->request)
return 1;
}
return 0;
}
/* caller holds gpio_lock *OR* gpio is marked as requested */
static inline struct gpio_chip *gpio_to_chip(unsigned gpio)
{
return gpio_desc[gpio].chip;
}
/* dynamic allocation of GPIOs, e.g. on a hotplugged device */
static int gpiochip_find_base(int ngpio)
{
int i;
int spare = 0;
int base = -ENOSPC;
for (i = ARCH_NR_GPIOS - 1; i >= 0 ; i--) {
struct gpio_desc *desc = &gpio_desc[i];
struct gpio_chip *chip = desc->chip;
if (!chip && !test_bit(FLAG_RESERVED, &desc->flags)) {
spare++;
if (spare == ngpio) {
base = i;
break;
}
} else {
spare = 0;
if (chip)
i -= chip->ngpio - 1;
}
}
if (gpio_is_valid(base))
pr_debug("%s: found new base at %d\n", __func__, base);
return base;
}
/**
* gpiochip_reserve() - reserve range of gpios to use with platform code only
* @start: starting gpio number
* @ngpio: number of gpios to reserve
* Context: platform init, potentially before irqs or kmalloc will work
*
* Returns a negative errno if any gpio within the range is already reserved
* or registered, else returns zero as a success code. Use this function
* to mark a range of gpios as unavailable for dynamic gpio number allocation,
* for example because its driver support is not yet loaded.
*/
int __init gpiochip_reserve(int start, int ngpio)
{
int ret = 0;
unsigned long flags;
int i;
if (!gpio_is_valid(start) || !gpio_is_valid(start + ngpio - 1))
return -EINVAL;
spin_lock_irqsave(&gpio_lock, flags);
for (i = start; i < start + ngpio; i++) {
struct gpio_desc *desc = &gpio_desc[i];
if (desc->chip || test_bit(FLAG_RESERVED, &desc->flags)) {
ret = -EBUSY;
goto err;
}
set_bit(FLAG_RESERVED, &desc->flags);
}
pr_debug("%s: reserved gpios from %d to %d\n",
__func__, start, start + ngpio - 1);
err:
spin_unlock_irqrestore(&gpio_lock, flags);
return ret;
}
#ifdef CONFIG_GPIO_SYSFS
/* lock protects against unexport_gpio() being called while
* sysfs files are active.
*/
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 gpio_direction_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
const struct gpio_desc *desc = dev_get_drvdata(dev);
ssize_t status;
mutex_lock(&sysfs_lock);
if (!test_bit(FLAG_EXPORT, &desc->flags))
status = -EIO;
else
status = sprintf(buf, "%s\n",
test_bit(FLAG_IS_OUT, &desc->flags)
? "out" : "in");
mutex_unlock(&sysfs_lock);
return status;
}
static ssize_t gpio_direction_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t size)
{
const struct gpio_desc *desc = dev_get_drvdata(dev);
unsigned gpio = desc - gpio_desc;
ssize_t status;
mutex_lock(&sysfs_lock);
if (!test_bit(FLAG_EXPORT, &desc->flags))
status = -EIO;
else if (sysfs_streq(buf, "high"))
status = gpio_direction_output(gpio, 1);
else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
status = gpio_direction_output(gpio, 0);
else if (sysfs_streq(buf, "in"))
status = gpio_direction_input(gpio);
else
status = -EINVAL;
mutex_unlock(&sysfs_lock);
return status ? : size;
}
static /* const */ DEVICE_ATTR(direction, 0644,
gpio_direction_show, gpio_direction_store);
static ssize_t gpio_value_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
const struct gpio_desc *desc = dev_get_drvdata(dev);
unsigned gpio = desc - gpio_desc;
ssize_t status;
mutex_lock(&sysfs_lock);
if (!test_bit(FLAG_EXPORT, &desc->flags)) {
status = -EIO;
} else {
int value;
value = !!gpio_get_value_cansleep(gpio);
if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
value = !value;
status = sprintf(buf, "%d\n", value);
}
mutex_unlock(&sysfs_lock);
return status;
}
static ssize_t gpio_value_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t size)
{
const struct gpio_desc *desc = dev_get_drvdata(dev);
unsigned gpio = desc - gpio_desc;
ssize_t status;
mutex_lock(&sysfs_lock);
if (!test_bit(FLAG_EXPORT, &desc->flags))
status = -EIO;
else if (!test_bit(FLAG_IS_OUT, &desc->flags))
status = -EPERM;
else {
long value;
status = strict_strtol(buf, 0, &value);
if (status == 0) {
if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
value = !value;
gpio_set_value_cansleep(gpio, value != 0);
status = size;
}
}
mutex_unlock(&sysfs_lock);
return status;
}
static const DEVICE_ATTR(value, 0644,
gpio_value_show, gpio_value_store);
static irqreturn_t gpio_sysfs_irq(int irq, void *priv)
{
struct work_struct *work = priv;
schedule_work(work);
return IRQ_HANDLED;
}
static void gpio_notify_sysfs(struct work_struct *work)
{
struct poll_desc *pdesc;
pdesc = container_of(work, struct poll_desc, work);
sysfs_notify_dirent(pdesc->value_sd);
}
static int gpio_setup_irq(struct gpio_desc *desc, struct device *dev,
unsigned long gpio_flags)
{
struct poll_desc *pdesc;
unsigned long irq_flags;
int ret, irq, id;
if ((desc->flags & GPIO_TRIGGER_MASK) == gpio_flags)
return 0;
irq = gpio_to_irq(desc - gpio_desc);
if (irq < 0)
return -EIO;
id = desc->flags >> PDESC_ID_SHIFT;
pdesc = idr_find(&pdesc_idr, id);
if (pdesc) {
free_irq(irq, &pdesc->work);
cancel_work_sync(&pdesc->work);
}
desc->flags &= ~GPIO_TRIGGER_MASK;
if (!gpio_flags) {
ret = 0;
goto free_sd;
}
irq_flags = IRQF_SHARED;
if (test_bit(FLAG_TRIG_FALL, &gpio_flags))
irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING;
if (test_bit(FLAG_TRIG_RISE, &gpio_flags))
irq_flags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ?
IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING;
if (!pdesc) {
pdesc = kmalloc(sizeof(*pdesc), GFP_KERNEL);
if (!pdesc) {
ret = -ENOMEM;
goto err_out;
}
do {
ret = -ENOMEM;
if (idr_pre_get(&pdesc_idr, GFP_KERNEL))
ret = idr_get_new_above(&pdesc_idr,
pdesc, 1, &id);
} while (ret == -EAGAIN);
if (ret)
goto free_mem;
desc->flags &= GPIO_FLAGS_MASK;
desc->flags |= (unsigned long)id << PDESC_ID_SHIFT;
if (desc->flags >> PDESC_ID_SHIFT != id) {
ret = -ERANGE;
goto free_id;
}
pdesc->value_sd = sysfs_get_dirent(dev->kobj.sd, "value");
if (!pdesc->value_sd) {
ret = -ENODEV;
goto free_id;
}
INIT_WORK(&pdesc->work, gpio_notify_sysfs);
}
ret = request_irq(irq, gpio_sysfs_irq, irq_flags,
"gpiolib", &pdesc->work);
if (ret)
goto free_sd;
desc->flags |= gpio_flags;
return 0;
free_sd:
if (pdesc)
sysfs_put(pdesc->value_sd);
free_id:
idr_remove(&pdesc_idr, id);
desc->flags &= GPIO_FLAGS_MASK;
free_mem:
kfree(pdesc);
err_out:
return ret;
}
static const struct {
const char *name;
unsigned long flags;
} trigger_types[] = {
{ "none", 0 },
{ "falling", BIT(FLAG_TRIG_FALL) },
{ "rising", BIT(FLAG_TRIG_RISE) },
{ "both", BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE) },
};
static ssize_t gpio_edge_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
const struct gpio_desc *desc = dev_get_drvdata(dev);
ssize_t status;
mutex_lock(&sysfs_lock);
if (!test_bit(FLAG_EXPORT, &desc->flags))
status = -EIO;
else {
int i;
status = 0;
for (i = 0; i < ARRAY_SIZE(trigger_types); i++)
if ((desc->flags & GPIO_TRIGGER_MASK)
== trigger_types[i].flags) {
status = sprintf(buf, "%s\n",
trigger_types[i].name);
break;
}
}
mutex_unlock(&sysfs_lock);
return status;
}
static ssize_t gpio_edge_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t size)
{
struct gpio_desc *desc = dev_get_drvdata(dev);
ssize_t status;
int i;
for (i = 0; i < ARRAY_SIZE(trigger_types); i++)
if (sysfs_streq(trigger_types[i].name, buf))
goto found;
return -EINVAL;
found:
mutex_lock(&sysfs_lock);
if (!test_bit(FLAG_EXPORT, &desc->flags))
status = -EIO;
else {
status = gpio_setup_irq(desc, dev, trigger_types[i].flags);
if (!status)
status = size;
}
mutex_unlock(&sysfs_lock);
return status;
}
static DEVICE_ATTR(edge, 0644, gpio_edge_show, gpio_edge_store);
static int sysfs_set_active_low(struct gpio_desc *desc, struct device *dev,
int value)
{
int status = 0;
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 (dev != NULL && (!!test_bit(FLAG_TRIG_RISE, &desc->flags) ^
!!test_bit(FLAG_TRIG_FALL, &desc->flags))) {
unsigned long trigger_flags = desc->flags & GPIO_TRIGGER_MASK;
gpio_setup_irq(desc, dev, 0);
status = gpio_setup_irq(desc, dev, trigger_flags);
}
return status;
}
static ssize_t gpio_active_low_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
const struct gpio_desc *desc = dev_get_drvdata(dev);
ssize_t status;
mutex_lock(&sysfs_lock);
if (!test_bit(FLAG_EXPORT, &desc->flags))
status = -EIO;
else
status = sprintf(buf, "%d\n",
!!test_bit(FLAG_ACTIVE_LOW, &desc->flags));
mutex_unlock(&sysfs_lock);
return status;
}
static ssize_t gpio_active_low_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t size)
{
struct gpio_desc *desc = dev_get_drvdata(dev);
ssize_t status;
mutex_lock(&sysfs_lock);
if (!test_bit(FLAG_EXPORT, &desc->flags)) {
status = -EIO;
} else {
long value;
status = strict_strtol(buf, 0, &value);
if (status == 0)
status = sysfs_set_active_low(desc, dev, value != 0);
}
mutex_unlock(&sysfs_lock);
return status ? : size;
}
static const DEVICE_ATTR(active_low, 0644,
gpio_active_low_show, gpio_active_low_store);
static const struct attribute *gpio_attrs[] = {
&dev_attr_value.attr,
&dev_attr_active_low.attr,
NULL,
};
static const struct attribute_group gpio_attr_group = {
.attrs = (struct attribute **) gpio_attrs,
};
/*
* /sys/class/gpio/gpiochipN/
* /base ... matching gpio_chip.base (N)
* /label ... matching gpio_chip.label
* /ngpio ... matching gpio_chip.ngpio
*/
static ssize_t chip_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(base, 0444, chip_base_show, NULL);
static ssize_t chip_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(label, 0444, chip_label_show, NULL);
static ssize_t chip_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(ngpio, 0444, chip_ngpio_show, NULL);
static const struct attribute *gpiochip_attrs[] = {
&dev_attr_base.attr,
&dev_attr_label.attr,
&dev_attr_ngpio.attr,
NULL,
};
static const struct attribute_group gpiochip_attr_group = {
.attrs = (struct attribute **) gpiochip_attrs,
};
/*
* /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;
int status;
status = strict_strtol(buf, 0, &gpio);
if (status < 0)
goto done;
/* 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 = gpio_request(gpio, "sysfs");
if (status < 0)
goto done;
status = gpio_export(gpio, true);
if (status < 0)
gpio_free(gpio);
else
set_bit(FLAG_SYSFS, &gpio_desc[gpio].flags);
done:
if (status)
pr_debug("%s: status %d\n", __func__, status);
return status ? : len;
}
static ssize_t unexport_store(struct class *class,
struct class_attribute *attr,
const char *buf, size_t len)
{
long gpio;
int status;
status = strict_strtol(buf, 0, &gpio);
if (status < 0)
goto done;
status = -EINVAL;
/* reject bogus commands (gpio_unexport ignores them) */
if (!gpio_is_valid(gpio))
goto done;
/* 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, &gpio_desc[gpio].flags)) {
status = 0;
gpio_free(gpio);
}
done:
if (status)
pr_debug("%s: status %d\n", __func__, status);
return status ? : len;
}
static struct class_attribute gpio_class_attrs[] = {
__ATTR(export, 0200, NULL, export_store),
__ATTR(unexport, 0200, NULL, unexport_store),
__ATTR_NULL,
};
static struct class gpio_class = {
.name = "gpio",
.owner = THIS_MODULE,
.class_attrs = gpio_class_attrs,
};
/**
* gpio_export - export a GPIO through sysfs
* @gpio: 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 gpio_export(unsigned gpio, bool direction_may_change)
{
unsigned long flags;
struct gpio_desc *desc;
int status = -EINVAL;
char *ioname = NULL;
/* can't export until sysfs is available ... */
if (!gpio_class.p) {
pr_debug("%s: called too early!\n", __func__);
return -ENOENT;
}
if (!gpio_is_valid(gpio))
goto done;
mutex_lock(&sysfs_lock);
spin_lock_irqsave(&gpio_lock, flags);
desc = &gpio_desc[gpio];
if (test_bit(FLAG_REQUESTED, &desc->flags)
&& !test_bit(FLAG_EXPORT, &desc->flags)) {
status = 0;
if (!desc->chip->direction_input
|| !desc->chip->direction_output)
direction_may_change = false;
}
spin_unlock_irqrestore(&gpio_lock, flags);
if (desc->chip->names && desc->chip->names[gpio - desc->chip->base])
ioname = desc->chip->names[gpio - desc->chip->base];
if (status == 0) {
struct device *dev;
dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
desc, ioname ? ioname : "gpio%d", gpio);
if (!IS_ERR(dev)) {
status = sysfs_create_group(&dev->kobj,
&gpio_attr_group);
if (!status && direction_may_change)
status = device_create_file(dev,
&dev_attr_direction);
if (!status && gpio_to_irq(gpio) >= 0
&& (direction_may_change
|| !test_bit(FLAG_IS_OUT,
&desc->flags)))
status = device_create_file(dev,
&dev_attr_edge);
if (status != 0)
device_unregister(dev);
} else
status = PTR_ERR(dev);
if (status == 0)
set_bit(FLAG_EXPORT, &desc->flags);
}
mutex_unlock(&sysfs_lock);
done:
if (status)
pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
return status;
}
EXPORT_SYMBOL_GPL(gpio_export);
static int match_export(struct device *dev, void *data)
{
return dev_get_drvdata(dev) == data;
}
/**
* gpio_export_link - create a sysfs link to an exported GPIO node
* @dev: device under which to create symlink
* @name: name of the symlink
* @gpio: 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 gpio_export_link(struct device *dev, const char *name, unsigned gpio)
{
struct gpio_desc *desc;
int status = -EINVAL;
if (!gpio_is_valid(gpio))
goto done;
mutex_lock(&sysfs_lock);
desc = &gpio_desc[gpio];
if (test_bit(FLAG_EXPORT, &desc->flags)) {
struct device *tdev;
tdev = class_find_device(&gpio_class, NULL, desc, match_export);
if (tdev != NULL) {
status = sysfs_create_link(&dev->kobj, &tdev->kobj,
name);
} else {
status = -ENODEV;
}
}
mutex_unlock(&sysfs_lock);
done:
if (status)
pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
return status;
}
EXPORT_SYMBOL_GPL(gpio_export_link);
/**
* gpio_sysfs_set_active_low - set the polarity of gpio sysfs value
* @gpio: gpio to change
* @value: non-zero to use active low, i.e. inverted values
*
* Set the polarity of /sys/class/gpio/gpioN/value sysfs attribute.
* The GPIO does not have to be exported yet. If poll(2) support has
* been enabled for either rising or falling edge, it will be
* reconfigured to follow the new polarity.
*
* Returns zero on success, else an error.
*/
int gpio_sysfs_set_active_low(unsigned gpio, int value)
{
struct gpio_desc *desc;
struct device *dev = NULL;
int status = -EINVAL;
if (!gpio_is_valid(gpio))
goto done;
mutex_lock(&sysfs_lock);
desc = &gpio_desc[gpio];
if (test_bit(FLAG_EXPORT, &desc->flags)) {
dev = class_find_device(&gpio_class, NULL, desc, match_export);
if (dev == NULL) {
status = -ENODEV;
goto unlock;
}
}
status = sysfs_set_active_low(desc, dev, value);
unlock:
mutex_unlock(&sysfs_lock);
done:
if (status)
pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
return status;
}
EXPORT_SYMBOL_GPL(gpio_sysfs_set_active_low);
/**
* gpio_unexport - reverse effect of gpio_export()
* @gpio: gpio to make unavailable
*
* This is implicit on gpio_free().
*/
void gpio_unexport(unsigned gpio)
{
struct gpio_desc *desc;
int status = -EINVAL;
if (!gpio_is_valid(gpio))
goto done;
mutex_lock(&sysfs_lock);
desc = &gpio_desc[gpio];
if (test_bit(FLAG_EXPORT, &desc->flags)) {
struct device *dev = NULL;
dev = class_find_device(&gpio_class, NULL, desc, match_export);
if (dev) {
gpio_setup_irq(desc, dev, 0);
clear_bit(FLAG_EXPORT, &desc->flags);
put_device(dev);
device_unregister(dev);
status = 0;
} else
status = -ENODEV;
}
mutex_unlock(&sysfs_lock);
done:
if (status)
pr_debug("%s: gpio%d status %d\n", __func__, gpio, status);
}
EXPORT_SYMBOL_GPL(gpio_unexport);
static int gpiochip_export(struct gpio_chip *chip)
{
int status;
struct device *dev;
/* Many systems register gpio chips for SOC support very early,
* before driver model support is available. In those cases we
* export this later, in gpiolib_sysfs_init() ... here we just
* verify that _some_ field of gpio_class got initialized.
*/
if (!gpio_class.p)
return 0;
/* use chip->base for the ID; it's already known to be unique */
mutex_lock(&sysfs_lock);
dev = device_create(&gpio_class, chip->dev, MKDEV(0, 0), chip,
"gpiochip%d", chip->base);
if (!IS_ERR(dev)) {
status = sysfs_create_group(&dev->kobj,
&gpiochip_attr_group);
} else
status = PTR_ERR(dev);
chip->exported = (status == 0);
mutex_unlock(&sysfs_lock);
if (status) {
unsigned long flags;
unsigned gpio;
spin_lock_irqsave(&gpio_lock, flags);
gpio = chip->base;
while (gpio_desc[gpio].chip == chip)
gpio_desc[gpio++].chip = NULL;
spin_unlock_irqrestore(&gpio_lock, flags);
pr_debug("%s: chip %s status %d\n", __func__,
chip->label, status);
}
return status;
}
static void gpiochip_unexport(struct gpio_chip *chip)
{
int status;
struct device *dev;
mutex_lock(&sysfs_lock);
dev = class_find_device(&gpio_class, NULL, chip, match_export);
if (dev) {
put_device(dev);
device_unregister(dev);
chip->exported = 0;
status = 0;
} else
status = -ENODEV;
mutex_unlock(&sysfs_lock);
if (status)
pr_debug("%s: chip %s status %d\n", __func__,
chip->label, status);
}
static int __init gpiolib_sysfs_init(void)
{
int status;
unsigned long flags;
unsigned gpio;
idr_init(&pdesc_idr);
status = class_register(&gpio_class);
if (status < 0)
return status;