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linux-next/drivers/gpio/gpiolib.c
Heikki Krogerus 351cfe0fe8 gpiolib: change a warning to debug message when failing to get gpio 
It's the drivers responsibility to react on failure to get
the gpio descriptors and not the frameworks. Since there are
some common peripherals that may or may not have certain
pins connected to gpio lines, depending on the platform,
printing the warning there may end up generating useless bug
reports.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2013-12-03 13:10:48 +01:00

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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/list.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/gpio.h>
#include <linux/of_gpio.h>
#include <linux/acpi_gpio.h>
#include <linux/idr.h>
#include <linux/slab.h>
#include <linux/acpi.h>
#include <linux/gpio/driver.h>
#define CREATE_TRACE_POINTS
#include <trace/events/gpio.h>
/* Implementation infrastructure for GPIO interfaces.
*
* 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_EXPORT 2 /* protected by sysfs_lock */
#define FLAG_SYSFS 3 /* exported via /sys/class/gpio/control */
#define FLAG_TRIG_FALL 4 /* trigger on falling edge */
#define FLAG_TRIG_RISE 5 /* trigger on rising edge */
#define FLAG_ACTIVE_LOW 6 /* value has active low */
#define FLAG_OPEN_DRAIN 7 /* Gpio is open drain type */
#define FLAG_OPEN_SOURCE 8 /* Gpio is open source type */
#define FLAG_USED_AS_IRQ 9 /* GPIO is connected to an IRQ */
#define ID_SHIFT 16 /* add new flags before this one */
#define GPIO_FLAGS_MASK ((1 << 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];
#define GPIO_OFFSET_VALID(chip, offset) (offset >= 0 && offset < chip->ngpio)
static DEFINE_MUTEX(gpio_lookup_lock);
static LIST_HEAD(gpio_lookup_list);
static LIST_HEAD(gpio_chips);
#ifdef CONFIG_GPIO_SYSFS
static DEFINE_IDR(dirent_idr);
#endif
static int gpiod_request(struct gpio_desc *desc, const char *label);
static void gpiod_free(struct gpio_desc *desc);
#ifdef CONFIG_DEBUG_FS
#define gpiod_emerg(desc, fmt, ...) \
pr_emerg("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label, \
##__VA_ARGS__)
#define gpiod_crit(desc, fmt, ...) \
pr_crit("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label, \
##__VA_ARGS__)
#define gpiod_err(desc, fmt, ...) \
pr_err("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label, \
##__VA_ARGS__)
#define gpiod_warn(desc, fmt, ...) \
pr_warn("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label, \
##__VA_ARGS__)
#define gpiod_info(desc, fmt, ...) \
pr_info("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label, \
##__VA_ARGS__)
#define gpiod_dbg(desc, fmt, ...) \
pr_debug("gpio-%d (%s): " fmt, desc_to_gpio(desc), desc->label, \
##__VA_ARGS__)
#else
#define gpiod_emerg(desc, fmt, ...) \
pr_emerg("gpio-%d: " fmt, desc_to_gpio(desc), ##__VA_ARGS__)
#define gpiod_crit(desc, fmt, ...) \
pr_crit("gpio-%d: " fmt, desc_to_gpio(desc), ##__VA_ARGS__)
#define gpiod_err(desc, fmt, ...) \
pr_err("gpio-%d: " fmt, desc_to_gpio(desc), ##__VA_ARGS__)
#define gpiod_warn(desc, fmt, ...) \
pr_warn("gpio-%d: " fmt, desc_to_gpio(desc), ##__VA_ARGS__)
#define gpiod_info(desc, fmt, ...) \
pr_info("gpio-%d: " fmt, desc_to_gpio(desc), ##__VA_ARGS__)
#define gpiod_dbg(desc, fmt, ...) \
pr_debug("gpio-%d: " fmt, desc_to_gpio(desc), ##__VA_ARGS__)
#endif
static inline void desc_set_label(struct gpio_desc *d, const char *label)
{
#ifdef CONFIG_DEBUG_FS
d->label = label;
#endif
}
/*
* Return the GPIO number of the passed descriptor relative to its chip
*/
static int gpio_chip_hwgpio(const struct gpio_desc *desc)
{
return desc - &desc->chip->desc[0];
}
/**
* Convert a GPIO number to its descriptor
*/
struct gpio_desc *gpio_to_desc(unsigned gpio)
{
if (WARN(!gpio_is_valid(gpio), "invalid GPIO %d\n", gpio))
return NULL;
else
return &gpio_desc[gpio];
}
EXPORT_SYMBOL_GPL(gpio_to_desc);
/**
* Convert an offset on a certain chip to a corresponding descriptor
*/
static struct gpio_desc *gpiochip_offset_to_desc(struct gpio_chip *chip,
unsigned int offset)
{
unsigned int gpio = chip->base + offset;
return gpio_to_desc(gpio);
}
/**
* Convert a GPIO descriptor to the integer namespace.
* This should disappear in the future but is needed since we still
* use GPIO numbers for error messages and sysfs nodes
*/
int desc_to_gpio(const struct gpio_desc *desc)
{
return desc - &gpio_desc[0];
}
EXPORT_SYMBOL_GPL(desc_to_gpio);
/* 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)
{
const struct gpio_chip *chip = desc->chip;
const int gpio = desc_to_gpio(desc);
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;
}
/**
* gpiod_to_chip - Return the GPIO chip to which a GPIO descriptor belongs
* @desc: descriptor to return the chip of
*/
struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
{
return desc ? desc->chip : NULL;
}
EXPORT_SYMBOL_GPL(gpiod_to_chip);
/* dynamic allocation of GPIOs, e.g. on a hotplugged device */
static int gpiochip_find_base(int ngpio)
{
struct gpio_chip *chip;
int base = ARCH_NR_GPIOS - ngpio;
list_for_each_entry_reverse(chip, &gpio_chips, list) {
/* found a free space? */
if (chip->base + chip->ngpio <= base)
break;
else
/* nope, check the space right before the chip */
base = chip->base - ngpio;
}
if (gpio_is_valid(base)) {
pr_debug("%s: found new base at %d\n", __func__, base);
return base;
} else {
pr_err("%s: cannot find free range\n", __func__);
return -ENOSPC;
}
}
/**
* gpiod_get_direction - return the current direction of a GPIO
* @desc: GPIO to get the direction of
*
* Return GPIOF_DIR_IN or GPIOF_DIR_OUT, or an error code in case of error.
*
* This function may sleep if gpiod_cansleep() is true.
*/
int gpiod_get_direction(const struct gpio_desc *desc)
{
struct gpio_chip *chip;
unsigned offset;
int status = -EINVAL;
chip = gpiod_to_chip(desc);
offset = gpio_chip_hwgpio(desc);
if (!chip->get_direction)
return status;
status = chip->get_direction(chip, offset);
if (status > 0) {
/* GPIOF_DIR_IN, or other positive */
status = 1;
/* FLAG_IS_OUT is just a cache of the result of get_direction(),
* so it does not affect constness per se */
clear_bit(FLAG_IS_OUT, &((struct gpio_desc *)desc)->flags);
}
if (status == 0) {
/* GPIOF_DIR_OUT */
set_bit(FLAG_IS_OUT, &((struct gpio_desc *)desc)->flags);
}
return status;
}
EXPORT_SYMBOL_GPL(gpiod_get_direction);
#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 {
gpiod_get_direction(desc);
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)
{
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 if (sysfs_streq(buf, "high"))
status = gpiod_direction_output(desc, 1);
else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low"))
status = gpiod_direction_output(desc, 0);
else if (sysfs_streq(buf, "in"))
status = gpiod_direction_input(desc);
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)
{
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", gpiod_get_value_cansleep(desc));
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)
{
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 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(&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 sysfs_dirent *value_sd = priv;
sysfs_notify_dirent(value_sd);
return IRQ_HANDLED;
}
static int gpio_setup_irq(struct gpio_desc *desc, struct device *dev,
unsigned long gpio_flags)
{
struct sysfs_dirent *value_sd;
unsigned long irq_flags;
int ret, irq, id;
if ((desc->flags & GPIO_TRIGGER_MASK) == gpio_flags)
return 0;
irq = gpiod_to_irq(desc);
if (irq < 0)
return -EIO;
id = desc->flags >> ID_SHIFT;
value_sd = idr_find(&dirent_idr, id);
if (value_sd)
free_irq(irq, value_sd);
desc->flags &= ~GPIO_TRIGGER_MASK;
if (!gpio_flags) {
gpiod_unlock_as_irq(desc);
ret = 0;
goto free_id;
}
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 (!value_sd) {
value_sd = sysfs_get_dirent(dev->kobj.sd, "value");
if (!value_sd) {
ret = -ENODEV;
goto err_out;
}
ret = idr_alloc(&dirent_idr, value_sd, 1, 0, GFP_KERNEL);
if (ret < 0)
goto free_sd;
id = ret;
desc->flags &= GPIO_FLAGS_MASK;
desc->flags |= (unsigned long)id << ID_SHIFT;
if (desc->flags >> ID_SHIFT != id) {
ret = -ERANGE;
goto free_id;
}
}
ret = request_any_context_irq(irq, gpio_sysfs_irq, irq_flags,
"gpiolib", value_sd);
if (ret < 0)
goto free_id;
ret = gpiod_lock_as_irq(desc);
if (ret < 0) {
gpiod_warn(desc, "failed to flag the GPIO for IRQ\n");
goto free_id;
}
desc->flags |= gpio_flags;
return 0;
free_id:
idr_remove(&dirent_idr, id);
desc->flags &= GPIO_FLAGS_MASK;
free_sd:
if (value_sd)
sysfs_put(value_sd);
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 = kstrtol(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;
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_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 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 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,
};
/**
* gpiod_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 gpiod_export(struct gpio_desc *desc, bool direction_may_change)
{
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;
}
mutex_lock(&sysfs_lock);
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);
pr_debug("%s: gpio %d unavailable (requested=%d, exported=%d)\n",
__func__, desc_to_gpio(desc),
test_bit(FLAG_REQUESTED, &desc->flags),
test_bit(FLAG_EXPORT, &desc->flags));
status = -EPERM;
goto fail_unlock;
}
if (!desc->chip->direction_input || !desc->chip->direction_output)
direction_may_change = false;
spin_unlock_irqrestore(&gpio_lock, flags);
offset = gpio_chip_hwgpio(desc);
if (desc->chip->names && desc->chip->names[offset])
ioname = desc->chip->names[offset];
dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0),
desc, ioname ? ioname : "gpio%u",
desc_to_gpio(desc));
if (IS_ERR(dev)) {
status = PTR_ERR(dev);
goto fail_unlock;
}
status = sysfs_create_group(&dev->kobj, &gpio_attr_group);
if (status)
goto fail_unregister_device;
if (direction_may_change) {
status = device_create_file(dev, &dev_attr_direction);
if (status)
goto fail_unregister_device;
}
if (gpiod_to_irq(desc) >= 0 && (direction_may_change ||
!test_bit(FLAG_IS_OUT, &desc->flags))) {
status = device_create_file(dev, &dev_attr_edge);
if (status)
goto fail_unregister_device;
}
set_bit(FLAG_EXPORT, &desc->flags);
mutex_unlock(&sysfs_lock);
return 0;
fail_unregister_device:
device_unregister(dev);
fail_unlock:
mutex_unlock(&sysfs_lock);
pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
status);
return status;
}
EXPORT_SYMBOL_GPL(gpiod_export);
static int match_export(struct device *dev, const void *data)
{
return dev_get_drvdata(dev) == data;
}
/**
* gpiod_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 gpiod_export_link(struct device *dev, const char *name,
struct gpio_desc *desc)
{
int status = -EINVAL;
if (!desc) {
pr_warn("%s: invalid GPIO\n", __func__);
return -EINVAL;
}
mutex_lock(&sysfs_lock);
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);
if (status)
pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
status);
return status;
}
EXPORT_SYMBOL_GPL(gpiod_export_link);
/**
* gpiod_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 gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value)
{
struct device *dev = NULL;
int status = -EINVAL;
if (!desc) {
pr_warn("%s: invalid GPIO\n", __func__);
return -EINVAL;
}
mutex_lock(&sysfs_lock);
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);
if (status)
pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
status);
return status;
}
EXPORT_SYMBOL_GPL(gpiod_sysfs_set_active_low);
/**
* gpiod_unexport - reverse effect of gpio_export()
* @gpio: gpio to make unavailable
*
* This is implicit on gpio_free().
*/
void gpiod_unexport(struct gpio_desc *desc)
{
int status = 0;
struct device *dev = NULL;
if (!desc) {
pr_warn("%s: invalid GPIO\n", __func__);
return;
}
mutex_lock(&sysfs_lock);
if (test_bit(FLAG_EXPORT, &desc->flags)) {
dev = class_find_device(&gpio_class, NULL, desc, match_export);
if (dev) {
gpio_setup_irq(desc, dev, 0);
clear_bit(FLAG_EXPORT, &desc->flags);
} else
status = -ENODEV;
}
mutex_unlock(&sysfs_lock);
if (dev) {
device_unregister(dev);
put_device(dev);
}
if (status)
pr_debug("%s: gpio%d status %d\n", __func__, desc_to_gpio(desc),
status);
}
EXPORT_SYMBOL_GPL(gpiod_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 = 0;
while (gpio < chip->ngpio)
chip->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;
struct gpio_chip *chip;
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(chip, &gpio_chips, list) {
if (!chip || chip->exported)
continue;
spin_unlock_irqrestore(&gpio_lock, flags);
status = gpiochip_export(chip);
spin_lock_irqsave(&gpio_lock, flags);
}
spin_unlock_irqrestore(&gpio_lock, flags);
return status;
}
postcore_initcall(gpiolib_sysfs_init);
#else
static inline int gpiochip_export(struct gpio_chip *chip)
{
return 0;
}
static inline void gpiochip_unexport(struct gpio_chip *chip)
{
}
#endif /* CONFIG_GPIO_SYSFS */
/*
* Add a new chip to the global chips list, keeping the list of chips sorted
* by base order.
*
* Return -EBUSY if the new chip overlaps with some other chip's integer
* space.
*/
static int gpiochip_add_to_list(struct gpio_chip *chip)
{
struct list_head *pos = &gpio_chips;
struct gpio_chip *_chip;
int err = 0;
/* find where to insert our chip */
list_for_each(pos, &gpio_chips) {
_chip = list_entry(pos, struct gpio_chip, list);
/* shall we insert before _chip? */
if (_chip->base >= chip->base + chip->ngpio)
break;
}
/* are we stepping on the chip right before? */
if (pos != &gpio_chips && pos->prev != &gpio_chips) {
_chip = list_entry(pos->prev, struct gpio_chip, list);
if (_chip->base + _chip->ngpio > chip->base) {
dev_err(chip->dev,
"GPIO integer space overlap, cannot add chip\n");
err = -EBUSY;
}
}
if (!err)
list_add_tail(&chip->list, pos);
return err;
}
/**
* gpiochip_add() - register a gpio_chip
* @chip: the chip to register, with chip->base initialized
* Context: potentially before irqs or kmalloc will work
*
* Returns a negative errno if the chip can't be registered, such as
* because the chip->base is invalid or already associated with a
* different chip. Otherwise it returns zero as a success code.
*
* When gpiochip_add() is called very early during boot, so that GPIOs
* can be freely used, the chip->dev device must be registered before
* the gpio framework's arch_initcall(). Otherwise sysfs initialization
* for GPIOs will fail rudely.
*
* If chip->base is negative, this requests dynamic assignment of
* a range of valid GPIOs.
*/
int gpiochip_add(struct gpio_chip *chip)
{
unsigned long flags;
int status = 0;
unsigned id;
int base = chip->base;
if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1))
&& base >= 0) {
status = -EINVAL;
goto fail;
}
spin_lock_irqsave(&gpio_lock, flags);
if (base < 0) {
base = gpiochip_find_base(chip->ngpio);
if (base < 0) {
status = base;
goto unlock;
}
chip->base = base;
}
status = gpiochip_add_to_list(chip);
if (status == 0) {
chip->desc = &gpio_desc[chip->base];
for (id = 0; id < chip->ngpio; id++) {
struct gpio_desc *desc = &chip->desc[id];
desc->chip = chip;
/* REVISIT: most hardware initializes GPIOs as
* inputs (often with pullups enabled) so power
* usage is minimized. Linux code should set the
* gpio direction first thing; but until it does,
* and in case chip->get_direction is not set,
* we may expose the wrong direction in sysfs.
*/
desc->flags = !chip->direction_input
? (1 << FLAG_IS_OUT)
: 0;
}
}
spin_unlock_irqrestore(&gpio_lock, flags);
#ifdef CONFIG_PINCTRL
INIT_LIST_HEAD(&chip->pin_ranges);
#endif
of_gpiochip_add(chip);
if (status)
goto fail;
status = gpiochip_export(chip);
if (status)
goto fail;
pr_debug("gpiochip_add: registered GPIOs %d to %d on device: %s\n",
chip->base, chip->base + chip->ngpio - 1,
chip->label ? : "generic");
return 0;
unlock:
spin_unlock_irqrestore(&gpio_lock, flags);
fail:
/* failures here can mean systems won't boot... */
pr_err("gpiochip_add: gpios %d..%d (%s) failed to register\n",
chip->base, chip->base + chip->ngpio - 1,
chip->label ? : "generic");
return status;
}
EXPORT_SYMBOL_GPL(gpiochip_add);
/**
* gpiochip_remove() - unregister a gpio_chip
* @chip: the chip to unregister
*
* A gpio_chip with any GPIOs still requested may not be removed.
*/
int gpiochip_remove(struct gpio_chip *chip)
{
unsigned long flags;
int status = 0;
unsigned id;
spin_lock_irqsave(&gpio_lock, flags);
gpiochip_remove_pin_ranges(chip);
of_gpiochip_remove(chip);
for (id = 0; id < chip->ngpio; id++) {
if (test_bit(FLAG_REQUESTED, &chip->desc[id].flags)) {
status = -EBUSY;
break;
}
}
if (status == 0) {
for (id = 0; id < chip->ngpio; id++)
chip->desc[id].chip = NULL;
list_del(&chip->list);
}
spin_unlock_irqrestore(&gpio_lock, flags);
if (status == 0)
gpiochip_unexport(chip);
return status;
}
EXPORT_SYMBOL_GPL(gpiochip_remove);
/**
* gpiochip_find() - iterator for locating a specific gpio_chip
* @data: data to pass to match function
* @callback: Callback function to check gpio_chip
*
* Similar to bus_find_device. It returns a reference to a gpio_chip as
* determined by a user supplied @match callback. The callback should return
* 0 if the device doesn't match and non-zero if it does. If the callback is
* non-zero, this function will return to the caller and not iterate over any
* more gpio_chips.
*/
struct gpio_chip *gpiochip_find(void *data,
int (*match)(struct gpio_chip *chip,
void *data))
{
struct gpio_chip *chip;
unsigned long flags;
spin_lock_irqsave(&gpio_lock, flags);
list_for_each_entry(chip, &gpio_chips, list)
if (match(chip, data))
break;
/* No match? */
if (&chip->list == &gpio_chips)
chip = NULL;
spin_unlock_irqrestore(&gpio_lock, flags);
return chip;
}
EXPORT_SYMBOL_GPL(gpiochip_find);
static int gpiochip_match_name(struct gpio_chip *chip, void *data)
{
const char *name = data;
return !strcmp(chip->label, name);
}
static struct gpio_chip *find_chip_by_name(const char *name)
{
return gpiochip_find((void *)name, gpiochip_match_name);
}
#ifdef CONFIG_PINCTRL
/**
* gpiochip_add_pingroup_range() - add a range for GPIO <-> pin mapping
* @chip: the gpiochip to add the range for
* @pinctrl: the dev_name() of the pin controller to map to
* @gpio_offset: the start offset in the current gpio_chip number space
* @pin_group: name of the pin group inside the pin controller
*/
int gpiochip_add_pingroup_range(struct gpio_chip *chip,
struct pinctrl_dev *pctldev,
unsigned int gpio_offset, const char *pin_group)
{
struct gpio_pin_range *pin_range;
int ret;
pin_range = kzalloc(sizeof(*pin_range), GFP_KERNEL);
if (!pin_range) {
pr_err("%s: GPIO chip: failed to allocate pin ranges\n",
chip->label);
return -ENOMEM;
}
/* Use local offset as range ID */
pin_range->range.id = gpio_offset;
pin_range->range.gc = chip;
pin_range->range.name = chip->label;
pin_range->range.base = chip->base + gpio_offset;
pin_range->pctldev = pctldev;
ret = pinctrl_get_group_pins(pctldev, pin_group,
&pin_range->range.pins,
&pin_range->range.npins);
if (ret < 0) {
kfree(pin_range);
return ret;
}
pinctrl_add_gpio_range(pctldev, &pin_range->range);
pr_debug("GPIO chip %s: created GPIO range %d->%d ==> %s PINGRP %s\n",
chip->label, gpio_offset,
gpio_offset + pin_range->range.npins - 1,
pinctrl_dev_get_devname(pctldev), pin_group);
list_add_tail(&pin_range->node, &chip->pin_ranges);
return 0;
}
EXPORT_SYMBOL_GPL(gpiochip_add_pingroup_range);
/**
* gpiochip_add_pin_range() - add a range for GPIO <-> pin mapping
* @chip: the gpiochip to add the range for
* @pinctrl_name: the dev_name() of the pin controller to map to
* @gpio_offset: the start offset in the current gpio_chip number space
* @pin_offset: the start offset in the pin controller number space
* @npins: the number of pins from the offset of each pin space (GPIO and
* pin controller) to accumulate in this range
*/
int gpiochip_add_pin_range(struct gpio_chip *chip, const char *pinctl_name,
unsigned int gpio_offset, unsigned int pin_offset,
unsigned int npins)
{
struct gpio_pin_range *pin_range;
int ret;
pin_range = kzalloc(sizeof(*pin_range), GFP_KERNEL);
if (!pin_range) {
pr_err("%s: GPIO chip: failed to allocate pin ranges\n",
chip->label);
return -ENOMEM;
}
/* Use local offset as range ID */
pin_range->range.id = gpio_offset;
pin_range->range.gc = chip;
pin_range->range.name = chip->label;
pin_range->range.base = chip->base + gpio_offset;
pin_range->range.pin_base = pin_offset;
pin_range->range.npins = npins;
pin_range->pctldev = pinctrl_find_and_add_gpio_range(pinctl_name,
&pin_range->range);
if (IS_ERR(pin_range->pctldev)) {
ret = PTR_ERR(pin_range->pctldev);
pr_err("%s: GPIO chip: could not create pin range\n",
chip->label);
kfree(pin_range);
return ret;
}
pr_debug("GPIO chip %s: created GPIO range %d->%d ==> %s PIN %d->%d\n",
chip->label, gpio_offset, gpio_offset + npins - 1,
pinctl_name,
pin_offset, pin_offset + npins - 1);
list_add_tail(&pin_range->node, &chip->pin_ranges);
return 0;
}
EXPORT_SYMBOL_GPL(gpiochip_add_pin_range);
/**
* gpiochip_remove_pin_ranges() - remove all the GPIO <-> pin mappings
* @chip: the chip to remove all the mappings for
*/
void gpiochip_remove_pin_ranges(struct gpio_chip *chip)
{
struct gpio_pin_range *pin_range, *tmp;
list_for_each_entry_safe(pin_range, tmp, &chip->pin_ranges, node) {
list_del(&pin_range->node);
pinctrl_remove_gpio_range(pin_range->pctldev,
&pin_range->range);
kfree(pin_range);
}
}
EXPORT_SYMBOL_GPL(gpiochip_remove_pin_ranges);
#endif /* CONFIG_PINCTRL */
/* These "optional" allocation calls help prevent drivers from stomping
* on each other, and help provide better diagnostics in debugfs.
* They're called even less than the "set direction" calls.
*/
static int gpiod_request(struct gpio_desc *desc, const char *label)
{
struct gpio_chip *chip;
int status = -EPROBE_DEFER;
unsigned long flags;
if (!desc) {
pr_warn("%s: invalid GPIO\n", __func__);
return -EINVAL;
}
spin_lock_irqsave(&gpio_lock, flags);
chip = desc->chip;
if (chip == NULL)
goto done;
if (!try_module_get(chip->owner))
goto done;
/* NOTE: gpio_request() can be called in early boot,
* before IRQs are enabled, for non-sleeping (SOC) GPIOs.
*/
if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) {
desc_set_label(desc, label ? : "?");
status = 0;
} else {
status = -EBUSY;
module_put(chip->owner);
goto done;
}
if (chip->request) {
/* chip->request may sleep */
spin_unlock_irqrestore(&gpio_lock, flags);
status = chip->request(chip, gpio_chip_hwgpio(desc));
spin_lock_irqsave(&gpio_lock, flags);
if (status < 0) {
desc_set_label(desc, NULL);
module_put(chip->owner);
clear_bit(FLAG_REQUESTED, &desc->flags);
goto done;
}
}
if (chip->get_direction) {
/* chip->get_direction may sleep */
spin_unlock_irqrestore(&gpio_lock, flags);
gpiod_get_direction(desc);
spin_lock_irqsave(&gpio_lock, flags);
}
done:
if (status)
pr_debug("_gpio_request: gpio-%d (%s) status %d\n",
desc_to_gpio(desc), label ? : "?", status);
spin_unlock_irqrestore(&gpio_lock, flags);
return status;
}
int gpio_request(unsigned gpio, const char *label)
{
return gpiod_request(gpio_to_desc(gpio), label);
}
EXPORT_SYMBOL_GPL(gpio_request);
static void gpiod_free(struct gpio_desc *desc)
{
unsigned long flags;
struct gpio_chip *chip;
might_sleep();
if (!desc) {
WARN_ON(extra_checks);
return;
}
gpiod_unexport(desc);
spin_lock_irqsave(&gpio_lock, flags);
chip = desc->chip;
if (chip && test_bit(FLAG_REQUESTED, &desc->flags)) {
if (chip->free) {
spin_unlock_irqrestore(&gpio_lock, flags);
might_sleep_if(chip->can_sleep);
chip->free(chip, gpio_chip_hwgpio(desc));
spin_lock_irqsave(&gpio_lock, flags);
}
desc_set_label(desc, NULL);
module_put(desc->chip->owner);
clear_bit(FLAG_ACTIVE_LOW, &desc->flags);
clear_bit(FLAG_REQUESTED, &desc->flags);
clear_bit(FLAG_OPEN_DRAIN, &desc->flags);
clear_bit(FLAG_OPEN_SOURCE, &desc->flags);
} else
WARN_ON(extra_checks);
spin_unlock_irqrestore(&gpio_lock, flags);
}
void gpio_free(unsigned gpio)
{
gpiod_free(gpio_to_desc(gpio));
}
EXPORT_SYMBOL_GPL(gpio_free);
/**
* gpio_request_one - request a single GPIO with initial configuration
* @gpio: the GPIO number
* @flags: GPIO configuration as specified by GPIOF_*
* @label: a literal description string of this GPIO
*/
int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
{
struct gpio_desc *desc;
int err;
desc = gpio_to_desc(gpio);
err = gpiod_request(desc, label);
if (err)
return err;
if (flags & GPIOF_OPEN_DRAIN)
set_bit(FLAG_OPEN_DRAIN, &desc->flags);
if (flags & GPIOF_OPEN_SOURCE)
set_bit(FLAG_OPEN_SOURCE, &desc->flags);
if (flags & GPIOF_DIR_IN)
err = gpiod_direction_input(desc);
else
err = gpiod_direction_output(desc,
(flags & GPIOF_INIT_HIGH) ? 1 : 0);
if (err)
goto free_gpio;
if (flags & GPIOF_EXPORT) {
err = gpiod_export(desc, flags & GPIOF_EXPORT_CHANGEABLE);
if (err)
goto free_gpio;
}
return 0;
free_gpio:
gpiod_free(desc);
return err;
}
EXPORT_SYMBOL_GPL(gpio_request_one);
/**
* gpio_request_array - request multiple GPIOs in a single call
* @array: array of the 'struct gpio'
* @num: how many GPIOs in the array
*/
int gpio_request_array(const struct gpio *array, size_t num)
{
int i, err;
for (i = 0; i < num; i++, array++) {
err = gpio_request_one(array->gpio, array->flags, array->label);
if (err)
goto err_free;
}
return 0;
err_free:
while (i--)
gpio_free((--array)->gpio);
return err;
}
EXPORT_SYMBOL_GPL(gpio_request_array);
/**
* gpio_free_array - release multiple GPIOs in a single call
* @array: array of the 'struct gpio'
* @num: how many GPIOs in the array
*/
void gpio_free_array(const struct gpio *array, size_t num)
{
while (num--)
gpio_free((array++)->gpio);
}
EXPORT_SYMBOL_GPL(gpio_free_array);
/**
* gpiochip_is_requested - return string iff signal was requested
* @chip: controller managing the signal
* @offset: of signal within controller's 0..(ngpio - 1) range
*
* Returns NULL if the GPIO is not currently requested, else a string.
* If debugfs support is enabled, the string returned is the label passed
* to gpio_request(); otherwise it is a meaningless constant.
*
* This function is for use by GPIO controller drivers. The label can
* help with diagnostics, and knowing that the signal is used as a GPIO
* can help avoid accidentally multiplexing it to another controller.
*/
const char *gpiochip_is_requested(struct gpio_chip *chip, unsigned offset)
{
struct gpio_desc *desc;
if (!GPIO_OFFSET_VALID(chip, offset))
return NULL;
desc = &chip->desc[offset];
if (test_bit(FLAG_REQUESTED, &desc->flags) == 0)
return NULL;
#ifdef CONFIG_DEBUG_FS
return desc->label;
#else
return "?";
#endif
}
EXPORT_SYMBOL_GPL(gpiochip_is_requested);
/* Drivers MUST set GPIO direction before making get/set calls. In
* some cases this is done in early boot, before IRQs are enabled.
*
* As a rule these aren't called more than once (except for drivers
* using the open-drain emulation idiom) so these are natural places
* to accumulate extra debugging checks. Note that we can't (yet)
* rely on gpio_request() having been called beforehand.
*/
/**
* gpiod_direction_input - set the GPIO direction to input
* @desc: GPIO to set to input
*
* Set the direction of the passed GPIO to input, such as gpiod_get_value() can
* be called safely on it.
*
* Return 0 in case of success, else an error code.
*/
int gpiod_direction_input(struct gpio_desc *desc)
{
unsigned long flags;
struct gpio_chip *chip;
int status = -EINVAL;
int offset;
if (!desc || !desc->chip) {
pr_warn("%s: invalid GPIO\n", __func__);
return -EINVAL;
}
chip = desc->chip;
if (!chip->get || !chip->direction_input) {
gpiod_warn(desc,
"%s: missing get() or direction_input() operations\n",
__func__);
return -EIO;
}
spin_lock_irqsave(&gpio_lock, flags);
status = gpio_ensure_requested(desc);
if (status < 0)
goto fail;
/* now we know the gpio is valid and chip won't vanish */
spin_unlock_irqrestore(&gpio_lock, flags);
might_sleep_if(chip->can_sleep);
offset = gpio_chip_hwgpio(desc);
if (status) {
status = chip->request(chip, offset);
if (status < 0) {
gpiod_dbg(desc, "chip request fail, %d\n", status);
/* and it's not available to anyone else ...
* gpio_request() is the fully clean solution.
*/
goto lose;
}
}
status = chip->direction_input(chip, offset);
if (status == 0)
clear_bit(FLAG_IS_OUT, &desc->flags);
trace_gpio_direction(desc_to_gpio(desc), 1, status);
lose:
return status;
fail:
spin_unlock_irqrestore(&gpio_lock, flags);
if (status)
gpiod_dbg(desc, "%s status %d\n", __func__, status);
return status;
}
EXPORT_SYMBOL_GPL(gpiod_direction_input);
/**
* gpiod_direction_output - set the GPIO direction to input
* @desc: GPIO to set to output
* @value: initial output value of the GPIO
*
* Set the direction of the passed GPIO to output, such as gpiod_set_value() can
* be called safely on it. The initial value of the output must be specified.
*
* Return 0 in case of success, else an error code.
*/
int gpiod_direction_output(struct gpio_desc *desc, int value)
{
unsigned long flags;
struct gpio_chip *chip;
int status = -EINVAL;
int offset;
if (!desc || !desc->chip) {
pr_warn("%s: invalid GPIO\n", __func__);
return -EINVAL;
}
/* GPIOs used for IRQs shall not be set as output */
if (test_bit(FLAG_USED_AS_IRQ, &desc->flags)) {
gpiod_err(desc,
"%s: tried to set a GPIO tied to an IRQ as output\n",
__func__);
return -EIO;
}
/* Open drain pin should not be driven to 1 */
if (value && test_bit(FLAG_OPEN_DRAIN, &desc->flags))
return gpiod_direction_input(desc);
/* Open source pin should not be driven to 0 */
if (!value && test_bit(FLAG_OPEN_SOURCE, &desc->flags))
return gpiod_direction_input(desc);
chip = desc->chip;
if (!chip->set || !chip->direction_output) {
gpiod_warn(desc,
"%s: missing set() or direction_output() operations\n",
__func__);
return -EIO;
}
spin_lock_irqsave(&gpio_lock, flags);
status = gpio_ensure_requested(desc);
if (status < 0)
goto fail;
/* now we know the gpio is valid and chip won't vanish */
spin_unlock_irqrestore(&gpio_lock, flags);
might_sleep_if(chip->can_sleep);
offset = gpio_chip_hwgpio(desc);
if (status) {
status = chip->request(chip, offset);
if (status < 0) {
gpiod_dbg(desc, "chip request fail, %d\n", status);
/* and it's not available to anyone else ...
* gpio_request() is the fully clean solution.
*/
goto lose;
}
}
status = chip->direction_output(chip, offset, value);
if (status == 0)
set_bit(FLAG_IS_OUT, &desc->flags);
trace_gpio_value(desc_to_gpio(desc), 0, value);
trace_gpio_direction(desc_to_gpio(desc), 0, status);
lose:
return status;
fail:
spin_unlock_irqrestore(&gpio_lock, flags);
if (status)
gpiod_dbg(desc, "%s: gpio status %d\n", __func__, status);
return status;
}
EXPORT_SYMBOL_GPL(gpiod_direction_output);
/**
* gpiod_set_debounce - sets @debounce time for a @gpio
* @gpio: the gpio to set debounce time
* @debounce: debounce time is microseconds
*
* returns -ENOTSUPP if the controller does not support setting
* debounce.
*/
int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce)
{
unsigned long flags;
struct gpio_chip *chip;
int status = -EINVAL;
int offset;
if (!desc || !desc->chip) {
pr_warn("%s: invalid GPIO\n", __func__);
return -EINVAL;
}
chip = desc->chip;
if (!chip->set || !chip->set_debounce) {
gpiod_dbg(desc,
"%s: missing set() or set_debounce() operations\n",
__func__);
return -ENOTSUPP;
}
spin_lock_irqsave(&gpio_lock, flags);
status = gpio_ensure_requested(desc);
if (status < 0)
goto fail;
/* now we know the gpio is valid and chip won't vanish */
spin_unlock_irqrestore(&gpio_lock, flags);
might_sleep_if(chip->can_sleep);
offset = gpio_chip_hwgpio(desc);
return chip->set_debounce(chip, offset, debounce);
fail:
spin_unlock_irqrestore(&gpio_lock, flags);
if (status)
gpiod_dbg(desc, "%s: status %d\n", __func__, status);
return status;
}
EXPORT_SYMBOL_GPL(gpiod_set_debounce);
/**
* gpiod_is_active_low - test whether a GPIO is active-low or not
* @desc: the gpio descriptor to test
*
* Returns 1 if the GPIO is active-low, 0 otherwise.
*/
int gpiod_is_active_low(const struct gpio_desc *desc)
{
return test_bit(FLAG_ACTIVE_LOW, &desc->flags);
}
EXPORT_SYMBOL_GPL(gpiod_is_active_low);
/* I/O calls are only valid after configuration completed; the relevant
* "is this a valid GPIO" error checks should already have been done.
*
* "Get" operations are often inlinable as reading a pin value register,
* and masking the relevant bit in that register.
*
* When "set" operations are inlinable, they involve writing that mask to
* one register to set a low value, or a different register to set it high.
* Otherwise locking is needed, so there may be little value to inlining.
*
*------------------------------------------------------------------------
*
* IMPORTANT!!! The hot paths -- get/set value -- assume that callers
* have requested the GPIO. That can include implicit requesting by
* a direction setting call. Marking a gpio as requested locks its chip
* in memory, guaranteeing that these table lookups need no more locking
* and that gpiochip_remove() will fail.
*
* REVISIT when debugging, consider adding some instrumentation to ensure
* that the GPIO was actually requested.
*/
static int _gpiod_get_raw_value(const struct gpio_desc *desc)
{
struct gpio_chip *chip;
int value;
int offset;
chip = desc->chip;
offset = gpio_chip_hwgpio(desc);
value = chip->get ? chip->get(chip, offset) : 0;
trace_gpio_value(desc_to_gpio(desc), 1, value);
return value;
}
/**
* gpiod_get_raw_value() - return a gpio's raw value
* @desc: gpio whose value will be returned
*
* Return the GPIO's raw value, i.e. the value of the physical line disregarding
* its ACTIVE_LOW status.
*
* This function should be called from contexts where we cannot sleep, and will
* complain if the GPIO chip functions potentially sleep.
*/
int gpiod_get_raw_value(const struct gpio_desc *desc)
{
if (!desc)
return 0;
/* Should be using gpio_get_value_cansleep() */
WARN_ON(desc->chip->can_sleep);
return _gpiod_get_raw_value(desc);
}
EXPORT_SYMBOL_GPL(gpiod_get_raw_value);
/**
* gpiod_get_value() - return a gpio's value
* @desc: gpio whose value will be returned
*
* Return the GPIO's logical value, i.e. taking the ACTIVE_LOW status into
* account.
*
* This function should be called from contexts where we cannot sleep, and will
* complain if the GPIO chip functions potentially sleep.
*/
int gpiod_get_value(const struct gpio_desc *desc)
{
int value;
if (!desc)
return 0;
/* Should be using gpio_get_value_cansleep() */
WARN_ON(desc->chip->can_sleep);
value = _gpiod_get_raw_value(desc);
if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
value = !value;
return value;
}
EXPORT_SYMBOL_GPL(gpiod_get_value);
/*
* _gpio_set_open_drain_value() - Set the open drain gpio's value.
* @desc: gpio descriptor whose state need to be set.
* @value: Non-zero for setting it HIGH otherise it will set to LOW.
*/
static void _gpio_set_open_drain_value(struct gpio_desc *desc, int value)
{
int err = 0;
struct gpio_chip *chip = desc->chip;
int offset = gpio_chip_hwgpio(desc);
if (value) {
err = chip->direction_input(chip, offset);
if (!err)
clear_bit(FLAG_IS_OUT, &desc->flags);
} else {
err = chip->direction_output(chip, offset, 0);
if (!err)
set_bit(FLAG_IS_OUT, &desc->flags);
}
trace_gpio_direction(desc_to_gpio(desc), value, err);
if (err < 0)
gpiod_err(desc,
"%s: Error in set_value for open drain err %d\n",
__func__, err);
}
/*
* _gpio_set_open_source_value() - Set the open source gpio's value.
* @desc: gpio descriptor whose state need to be set.
* @value: Non-zero for setting it HIGH otherise it will set to LOW.
*/
static void _gpio_set_open_source_value(struct gpio_desc *desc, int value)
{
int err = 0;
struct gpio_chip *chip = desc->chip;
int offset = gpio_chip_hwgpio(desc);
if (value) {
err = chip->direction_output(chip, offset, 1);
if (!err)
set_bit(FLAG_IS_OUT, &desc->flags);
} else {
err = chip->direction_input(chip, offset);
if (!err)
clear_bit(FLAG_IS_OUT, &desc->flags);
}
trace_gpio_direction(desc_to_gpio(desc), !value, err);
if (err < 0)
gpiod_err(desc,
"%s: Error in set_value for open source err %d\n",
__func__, err);
}
static void _gpiod_set_raw_value(struct gpio_desc *desc, int value)
{
struct gpio_chip *chip;
chip = desc->chip;
trace_gpio_value(desc_to_gpio(desc), 0, value);
if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
_gpio_set_open_drain_value(desc, value);
else if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
_gpio_set_open_source_value(desc, value);
else
chip->set(chip, gpio_chip_hwgpio(desc), value);
}
/**
* gpiod_set_raw_value() - assign a gpio's raw value
* @desc: gpio whose value will be assigned
* @value: value to assign
*
* Set the raw value of the GPIO, i.e. the value of its physical line without
* regard for its ACTIVE_LOW status.
*
* This function should be called from contexts where we cannot sleep, and will
* complain if the GPIO chip functions potentially sleep.
*/
void gpiod_set_raw_value(struct gpio_desc *desc, int value)
{
if (!desc)
return;
/* Should be using gpio_set_value_cansleep() */
WARN_ON(desc->chip->can_sleep);
_gpiod_set_raw_value(desc, value);
}
EXPORT_SYMBOL_GPL(gpiod_set_raw_value);
/**
* gpiod_set_value() - assign a gpio's value
* @desc: gpio whose value will be assigned
* @value: value to assign
*
* Set the logical value of the GPIO, i.e. taking its ACTIVE_LOW status into
* account
*
* This function should be called from contexts where we cannot sleep, and will
* complain if the GPIO chip functions potentially sleep.
*/
void gpiod_set_value(struct gpio_desc *desc, int value)
{
if (!desc)
return;
/* Should be using gpio_set_value_cansleep() */
WARN_ON(desc->chip->can_sleep);
if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
value = !value;
_gpiod_set_raw_value(desc, value);
}
EXPORT_SYMBOL_GPL(gpiod_set_value);
/**
* gpiod_cansleep() - report whether gpio value access may sleep
* @desc: gpio to check
*
*/
int gpiod_cansleep(const struct gpio_desc *desc)
{
if (!desc)
return 0;
return desc->chip->can_sleep;
}
EXPORT_SYMBOL_GPL(gpiod_cansleep);
/**
* gpiod_to_irq() - return the IRQ corresponding to a GPIO
* @desc: gpio whose IRQ will be returned (already requested)
*
* Return the IRQ corresponding to the passed GPIO, or an error code in case of
* error.
*/
int gpiod_to_irq(const struct gpio_desc *desc)
{
struct gpio_chip *chip;
int offset;
if (!desc)
return -EINVAL;
chip = desc->chip;
offset = gpio_chip_hwgpio(desc);
return chip->to_irq ? chip->to_irq(chip, offset) : -ENXIO;
}
EXPORT_SYMBOL_GPL(gpiod_to_irq);
/**
* gpiod_lock_as_irq() - lock a GPIO to be used as IRQ
* @gpio: the GPIO line to lock as used for IRQ
*
* This is used directly by GPIO drivers that want to lock down
* a certain GPIO line to be used as IRQs, for example in the
* .to_irq() callback of their gpio_chip, or in the .irq_enable()
* of its irq_chip implementation if the GPIO is known from that
* code.
*/
int gpiod_lock_as_irq(struct gpio_desc *desc)
{
if (!desc)
return -EINVAL;
if (test_bit(FLAG_IS_OUT, &desc->flags)) {
gpiod_err(desc,
"%s: tried to flag a GPIO set as output for IRQ\n",
__func__);
return -EIO;
}
set_bit(FLAG_USED_AS_IRQ, &desc->flags);
return 0;
}
EXPORT_SYMBOL_GPL(gpiod_lock_as_irq);
int gpio_lock_as_irq(struct gpio_chip *chip, unsigned int offset)
{
return gpiod_lock_as_irq(gpiochip_offset_to_desc(chip, offset));
}
EXPORT_SYMBOL_GPL(gpio_lock_as_irq);
/**
* gpiod_unlock_as_irq() - unlock a GPIO used as IRQ
* @gpio: the GPIO line to unlock from IRQ usage
*
* This is used directly by GPIO drivers that want to indicate
* that a certain GPIO is no longer used exclusively for IRQ.
*/
void gpiod_unlock_as_irq(struct gpio_desc *desc)
{
if (!desc)
return;
clear_bit(FLAG_USED_AS_IRQ, &desc->flags);
}
EXPORT_SYMBOL_GPL(gpiod_unlock_as_irq);
void gpio_unlock_as_irq(struct gpio_chip *chip, unsigned int offset)
{
return gpiod_unlock_as_irq(gpiochip_offset_to_desc(chip, offset));
}
EXPORT_SYMBOL_GPL(gpio_unlock_as_irq);
/**
* gpiod_get_raw_value_cansleep() - return a gpio's raw value
* @desc: gpio whose value will be returned
*
* Return the GPIO's raw value, i.e. the value of the physical line disregarding
* its ACTIVE_LOW status.
*
* This function is to be called from contexts that can sleep.
*/
int gpiod_get_raw_value_cansleep(const struct gpio_desc *desc)
{
might_sleep_if(extra_checks);
if (!desc)
return 0;
return _gpiod_get_raw_value(desc);
}
EXPORT_SYMBOL_GPL(gpiod_get_raw_value_cansleep);
/**
* gpiod_get_value_cansleep() - return a gpio's value
* @desc: gpio whose value will be returned
*
* Return the GPIO's logical value, i.e. taking the ACTIVE_LOW status into
* account.
*
* This function is to be called from contexts that can sleep.
*/
int gpiod_get_value_cansleep(const struct gpio_desc *desc)
{
int value;
might_sleep_if(extra_checks);
if (!desc)
return 0;
value = _gpiod_get_raw_value(desc);
if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
value = !value;
return value;
}
EXPORT_SYMBOL_GPL(gpiod_get_value_cansleep);
/**
* gpiod_set_raw_value_cansleep() - assign a gpio's raw value
* @desc: gpio whose value will be assigned
* @value: value to assign
*
* Set the raw value of the GPIO, i.e. the value of its physical line without
* regard for its ACTIVE_LOW status.
*
* This function is to be called from contexts that can sleep.
*/
void gpiod_set_raw_value_cansleep(struct gpio_desc *desc, int value)
{
might_sleep_if(extra_checks);
if (!desc)
return;
_gpiod_set_raw_value(desc, value);
}
EXPORT_SYMBOL_GPL(gpiod_set_raw_value_cansleep);
/**
* gpiod_set_value_cansleep() - assign a gpio's value
* @desc: gpio whose value will be assigned
* @value: value to assign
*
* Set the logical value of the GPIO, i.e. taking its ACTIVE_LOW status into
* account
*
* This function is to be called from contexts that can sleep.
*/
void gpiod_set_value_cansleep(struct gpio_desc *desc, int value)
{
might_sleep_if(extra_checks);
if (!desc)
return;
if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
value = !value;
_gpiod_set_raw_value(desc, value);
}
EXPORT_SYMBOL_GPL(gpiod_set_value_cansleep);
/**
* gpiod_add_table() - register GPIO device consumers
* @table: array of consumers to register
* @num: number of consumers in table
*/
void gpiod_add_table(struct gpiod_lookup *table, size_t size)
{
mutex_lock(&gpio_lookup_lock);
while (size--) {
list_add_tail(&table->list, &gpio_lookup_list);
table++;
}
mutex_unlock(&gpio_lookup_lock);
}
#ifdef CONFIG_OF
static struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,
unsigned int idx,
enum gpio_lookup_flags *flags)
{
char prop_name[32]; /* 32 is max size of property name */
enum of_gpio_flags of_flags;
struct gpio_desc *desc;
if (con_id)
snprintf(prop_name, 32, "%s-gpios", con_id);
else
snprintf(prop_name, 32, "gpios");
desc = of_get_named_gpiod_flags(dev->of_node, prop_name, idx,
&of_flags);
if (IS_ERR(desc))
return desc;
if (of_flags & OF_GPIO_ACTIVE_LOW)
*flags |= GPIO_ACTIVE_LOW;
return desc;
}
#else
static struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,
unsigned int idx,
enum gpio_lookup_flags *flags)
{
return ERR_PTR(-ENODEV);
}
#endif
static struct gpio_desc *acpi_find_gpio(struct device *dev, const char *con_id,
unsigned int idx,
enum gpio_lookup_flags *flags)
{
struct acpi_gpio_info info;
struct gpio_desc *desc;
desc = acpi_get_gpiod_by_index(dev, idx, &info);
if (IS_ERR(desc))
return desc;
if (info.gpioint && info.active_low)
*flags |= GPIO_ACTIVE_LOW;
return desc;
}
static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
unsigned int idx,
enum gpio_lookup_flags *flags)
{
const char *dev_id = dev ? dev_name(dev) : NULL;
struct gpio_desc *desc = ERR_PTR(-ENODEV);
unsigned int match, best = 0;
struct gpiod_lookup *p;
mutex_lock(&gpio_lookup_lock);
list_for_each_entry(p, &gpio_lookup_list, list) {
match = 0;
if (p->dev_id) {
if (!dev_id || strcmp(p->dev_id, dev_id))
continue;
match += 2;
}
if (p->con_id) {
if (!con_id || strcmp(p->con_id, con_id))
continue;
match += 1;
}
if (p->idx != idx)
continue;
if (match > best) {
struct gpio_chip *chip;
chip = find_chip_by_name(p->chip_label);
if (!chip) {
dev_warn(dev, "cannot find GPIO chip %s\n",
p->chip_label);
continue;
}
if (chip->ngpio <= p->chip_hwnum) {
dev_warn(dev, "GPIO chip %s has %d GPIOs\n",
chip->label, chip->ngpio);
continue;
}
desc = gpio_to_desc(chip->base + p->chip_hwnum);
*flags = p->flags;
if (match != 3)
best = match;
else
break;
}
}
mutex_unlock(&gpio_lookup_lock);
return desc;
}
/**
* gpio_get - obtain a GPIO for a given GPIO function
* @dev: GPIO consumer
* @con_id: function within the GPIO consumer
*
* Return the GPIO descriptor corresponding to the function con_id of device
* dev, or an IS_ERR() condition if an error occured.
*/
struct gpio_desc *__must_check gpiod_get(struct device *dev, const char *con_id)
{
return gpiod_get_index(dev, con_id, 0);
}
EXPORT_SYMBOL_GPL(gpiod_get);
/**
* gpiod_get_index - obtain a GPIO from a multi-index GPIO function
* @dev: GPIO consumer
* @con_id: function within the GPIO consumer
* @idx: index of the GPIO to obtain in the consumer
*
* This variant of gpiod_get() allows to access GPIOs other than the first
* defined one for functions that define several GPIOs.
*
* Return a valid GPIO descriptor, or an IS_ERR() condition in case of error.
*/
struct gpio_desc *__must_check gpiod_get_index(struct device *dev,
const char *con_id,
unsigned int idx)
{
struct gpio_desc *desc = NULL;
int status;
enum gpio_lookup_flags flags = 0;
dev_dbg(dev, "GPIO lookup for consumer %s\n", con_id);
/* Using device tree? */
if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node) {
dev_dbg(dev, "using device tree for GPIO lookup\n");
desc = of_find_gpio(dev, con_id, idx, &flags);
} else if (IS_ENABLED(CONFIG_ACPI) && dev && ACPI_HANDLE(dev)) {
dev_dbg(dev, "using ACPI for GPIO lookup\n");
desc = acpi_find_gpio(dev, con_id, idx, &flags);
}
/*
* Either we are not using DT or ACPI, or their lookup did not return
* a result. In that case, use platform lookup as a fallback.
*/
if (!desc || IS_ERR(desc)) {
struct gpio_desc *pdesc;
dev_dbg(dev, "using lookup tables for GPIO lookup");
pdesc = gpiod_find(dev, con_id, idx, &flags);
/* If used as fallback, do not replace the previous error */
if (!IS_ERR(pdesc) || !desc)
desc = pdesc;
}
if (IS_ERR(desc)) {
dev_dbg(dev, "lookup for GPIO %s failed\n", con_id);
return desc;
}
status = gpiod_request(desc, con_id);
if (status < 0)
return ERR_PTR(status);
if (flags & GPIO_ACTIVE_LOW)
set_bit(FLAG_ACTIVE_LOW, &desc->flags);
if (flags & GPIO_OPEN_DRAIN)
set_bit(FLAG_OPEN_DRAIN, &desc->flags);
if (flags & GPIO_OPEN_SOURCE)
set_bit(FLAG_OPEN_SOURCE, &desc->flags);
return desc;
}
EXPORT_SYMBOL_GPL(gpiod_get_index);
/**
* gpiod_put - dispose of a GPIO descriptor
* @desc: GPIO descriptor to dispose of
*
* No descriptor can be used after gpiod_put() has been called on it.
*/
void gpiod_put(struct gpio_desc *desc)
{
gpiod_free(desc);
}
EXPORT_SYMBOL_GPL(gpiod_put);
#ifdef CONFIG_DEBUG_FS
static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip)
{
unsigned i;
unsigned gpio = chip->base;
struct gpio_desc *gdesc = &chip->desc[0];
int is_out;
int is_irq;
for (i = 0; i < chip->ngpio; i++, gpio++, gdesc++) {
if (!test_bit(FLAG_REQUESTED, &gdesc->flags))
continue;
gpiod_get_direction(gdesc);
is_out = test_bit(FLAG_IS_OUT, &gdesc->flags);
is_irq = test_bit(FLAG_USED_AS_IRQ, &gdesc->flags);
seq_printf(s, " gpio-%-3d (%-20.20s) %s %s %s",
gpio, gdesc->label,
is_out ? "out" : "in ",
chip->get
? (chip->get(chip, i) ? "hi" : "lo")
: "? ",
is_irq ? "IRQ" : " ");
seq_printf(s, "\n");
}
}
static void *gpiolib_seq_start(struct seq_file *s, loff_t *pos)
{
unsigned long flags;
struct gpio_chip *chip = NULL;
loff_t index = *pos;
s->private = "";
spin_lock_irqsave(&gpio_lock, flags);
list_for_each_entry(chip, &gpio_chips, list)
if (index-- == 0) {
spin_unlock_irqrestore(&gpio_lock, flags);
return chip;
}
spin_unlock_irqrestore(&gpio_lock, flags);
return NULL;
}
static void *gpiolib_seq_next(struct seq_file *s, void *v, loff_t *pos)
{
unsigned long flags;
struct gpio_chip *chip = v;
void *ret = NULL;
spin_lock_irqsave(&gpio_lock, flags);
if (list_is_last(&chip->list, &gpio_chips))
ret = NULL;
else
ret = list_entry(chip->list.next, struct gpio_chip, list);
spin_unlock_irqrestore(&gpio_lock, flags);
s->private = "\n";
++*pos;
return ret;
}
static void gpiolib_seq_stop(struct seq_file *s, void *v)
{
}
static int gpiolib_seq_show(struct seq_file *s, void *v)
{
struct gpio_chip *chip = v;
struct device *dev;
seq_printf(s, "%sGPIOs %d-%d", (char *)s->private,
chip->base, chip->base + chip->ngpio - 1);
dev = chip->dev;
if (dev)
seq_printf(s, ", %s/%s", dev->bus ? dev->bus->name : "no-bus",
dev_name(dev));
if (chip->label)
seq_printf(s, ", %s", chip->label);
if (chip->can_sleep)
seq_printf(s, ", can sleep");
seq_printf(s, ":\n");
if (chip->dbg_show)
chip->dbg_show(s, chip);
else
gpiolib_dbg_show(s, chip);
return 0;
}
static const struct seq_operations gpiolib_seq_ops = {
.start = gpiolib_seq_start,
.next = gpiolib_seq_next,
.stop = gpiolib_seq_stop,
.show = gpiolib_seq_show,
};
static int gpiolib_open(struct inode *inode, struct file *file)
{
return seq_open(file, &gpiolib_seq_ops);
}
static const struct file_operations gpiolib_operations = {
.owner = THIS_MODULE,
.open = gpiolib_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
static int __init gpiolib_debugfs_init(void)
{
/* /sys/kernel/debug/gpio */
(void) debugfs_create_file("gpio", S_IFREG | S_IRUGO,
NULL, NULL, &gpiolib_operations);
return 0;
}
subsys_initcall(gpiolib_debugfs_init);
#endif /* DEBUG_FS */
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