diff options
Diffstat (limited to 'drivers/gpio/gpiolib.c')
| -rw-r--r-- | drivers/gpio/gpiolib.c | 1739 |
1 files changed, 1739 insertions, 0 deletions
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c new file mode 100644 index 00000000..a971e3d0 --- /dev/null +++ b/drivers/gpio/gpiolib.c @@ -0,0 +1,1739 @@ +#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/of_gpio.h> +#include <linux/idr.h> +#include <linux/slab.h> + +#define CREATE_TRACE_POINTS +#include <trace/events/gpio.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 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]; + +#ifdef CONFIG_GPIO_SYSFS +static DEFINE_IDR(dirent_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 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 = gpio_to_irq(desc - gpio_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) { + 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, NULL, "value"); + if (!value_sd) { + ret = -ENODEV; + goto err_out; + } + + do { + ret = -ENOMEM; + if (idr_pre_get(&dirent_idr, GFP_KERNEL)) + ret = idr_get_new_above(&dirent_idr, value_sd, + 1, &id); + } while (ret == -EAGAIN); + + if (ret) + goto free_sd; + + 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; + + 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 = 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; + const 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%u", 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 = 0; + + if (!gpio_is_valid(gpio)) { + status = -EINVAL; + 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); + } 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; + + 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); + for (gpio = 0; gpio < ARCH_NR_GPIOS; gpio++) { + struct gpio_chip *chip; + + chip = gpio_desc[gpio].chip; + 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 */ + +/** + * 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; + } + + /* these GPIO numbers must not be managed by another gpio_chip */ + for (id = base; id < base + chip->ngpio; id++) { + if (gpio_desc[id].chip != NULL) { + status = -EBUSY; + break; + } + } + if (status == 0) { + for (id = base; id < base + chip->ngpio; id++) { + gpio_desc[id].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, + * we may expose the wrong direction in sysfs. + */ + gpio_desc[id].flags = !chip->direction_input + ? (1 << FLAG_IS_OUT) + : 0; + } + } + + of_gpiochip_add(chip); + +unlock: + spin_unlock_irqrestore(&gpio_lock, flags); + + if (status) + goto fail; + + status = gpiochip_export(chip); + if (status) + goto fail; + + return 0; +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); + + of_gpiochip_remove(chip); + + for (id = chip->base; id < chip->base + chip->ngpio; id++) { + if (test_bit(FLAG_REQUESTED, &gpio_desc[id].flags)) { + status = -EBUSY; + break; + } + } + if (status == 0) { + for (id = chip->base; id < chip->base + chip->ngpio; id++) + gpio_desc[id].chip = NULL; + } + + 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 = NULL; + unsigned long flags; + int i; + + spin_lock_irqsave(&gpio_lock, flags); + for (i = 0; i < ARCH_NR_GPIOS; i++) { + if (!gpio_desc[i].chip) + continue; + + if (match(gpio_desc[i].chip, data)) { + chip = gpio_desc[i].chip; + break; + } + } + spin_unlock_irqrestore(&gpio_lock, flags); + + return chip; +} +EXPORT_SYMBOL_GPL(gpiochip_find); + +/* 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. + */ +int gpio_request(unsigned gpio, const char *label) +{ + struct gpio_desc *desc; + struct gpio_chip *chip; + int status = -EINVAL; + unsigned long flags; + + spin_lock_irqsave(&gpio_lock, flags); + + if (!gpio_is_valid(gpio)) + goto done; + desc = &gpio_desc[gpio]; + 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->base); + spin_lock_irqsave(&gpio_lock, flags); + + if (status < 0) { + desc_set_label(desc, NULL); + module_put(chip->owner); + clear_bit(FLAG_REQUESTED, &desc->flags); + } + } + +done: + if (status) + pr_debug("gpio_request: gpio-%d (%s) status %d\n", + gpio, label ? : "?", status); + spin_unlock_irqrestore(&gpio_lock, flags); + return status; +} +EXPORT_SYMBOL_GPL(gpio_request); + +void gpio_free(unsigned gpio) +{ + unsigned long flags; + struct gpio_desc *desc; + struct gpio_chip *chip; + + might_sleep(); + + if (!gpio_is_valid(gpio)) { + WARN_ON(extra_checks); + return; + } + + gpio_unexport(gpio); + + spin_lock_irqsave(&gpio_lock, flags); + + desc = &gpio_desc[gpio]; + 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->base); + 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); + } else + WARN_ON(extra_checks); + + spin_unlock_irqrestore(&gpio_lock, flags); +} +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) +{ + int err; + + err = gpio_request(gpio, label); + if (err) + return err; + + if (flags & GPIOF_DIR_IN) + err = gpio_direction_input(gpio); + else + err = gpio_direction_output(gpio, + (flags & GPIOF_INIT_HIGH) ? 1 : 0); + + if (err) + gpio_free(gpio); + + 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) +{ + unsigned gpio = chip->base + offset; + + if (!gpio_is_valid(gpio) || gpio_desc[gpio].chip != chip) + return NULL; + if (test_bit(FLAG_REQUESTED, &gpio_desc[gpio].flags) == 0) + return NULL; +#ifdef CONFIG_DEBUG_FS + return gpio_desc[gpio].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. + */ + +int gpio_direction_input(unsigned gpio) +{ + unsigned long flags; + struct gpio_chip *chip; + struct gpio_desc *desc = &gpio_desc[gpio]; + int status = -EINVAL; + + spin_lock_irqsave(&gpio_lock, flags); + + if (!gpio_is_valid(gpio)) + goto fail; + chip = desc->chip; + if (!chip || !chip->get || !chip->direction_input) + goto fail; + gpio -= chip->base; + if (gpio >= chip->ngpio) + goto fail; + status = gpio_ensure_requested(desc, gpio); + 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); + + if (status) { + status = chip->request(chip, gpio); + if (status < 0) { + pr_debug("GPIO-%d: chip request fail, %d\n", + chip->base + gpio, status); + /* and it's not available to anyone else ... + * gpio_request() is the fully clean solution. + */ + goto lose; + } + } + + status = chip->direction_input(chip, gpio); + if (status == 0) + clear_bit(FLAG_IS_OUT, &desc->flags); + + trace_gpio_direction(chip->base + gpio, 1, status); +lose: + return status; +fail: + spin_unlock_irqrestore(&gpio_lock, flags); + if (status) + pr_debug("%s: gpio-%d status %d\n", + __func__, gpio, status); + return status; +} +EXPORT_SYMBOL_GPL(gpio_direction_input); + +int gpio_direction_output(unsigned gpio, int value) +{ + unsigned long flags; + struct gpio_chip *chip; + struct gpio_desc *desc = &gpio_desc[gpio]; + int status = -EINVAL; + + spin_lock_irqsave(&gpio_lock, flags); + + if (!gpio_is_valid(gpio)) + goto fail; + chip = desc->chip; + if (!chip || !chip->set || !chip->direction_output) + goto fail; + gpio -= chip->base; + if (gpio >= chip->ngpio) + goto fail; + status = gpio_ensure_requested(desc, gpio); + 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); + + if (status) { + status = chip->request(chip, gpio); + if (status < 0) { + pr_debug("GPIO-%d: chip request fail, %d\n", + chip->base + gpio, status); + /* and it's not available to anyone else ... + * gpio_request() is the fully clean solution. + */ + goto lose; + } + } + + status = chip->direction_output(chip, gpio, value); + if (status == 0) + set_bit(FLAG_IS_OUT, &desc->flags); + trace_gpio_value(chip->base + gpio, 0, value); + trace_gpio_direction(chip->base + gpio, 0, status); +lose: + return status; +fail: + spin_unlock_irqrestore(&gpio_lock, flags); + if (status) + pr_debug("%s: gpio-%d status %d\n", + __func__, gpio, status); + return status; +} +EXPORT_SYMBOL_GPL(gpio_direction_output); + +/** + * gpio_set_debounce - sets @debounce time for a @gpio + * @gpio: the gpio to set debounce time + * @debounce: debounce time is microseconds + */ +int gpio_set_debounce(unsigned gpio, unsigned debounce) +{ + unsigned long flags; + struct gpio_chip *chip; + struct gpio_desc *desc = &gpio_desc[gpio]; + int status = -EINVAL; + + spin_lock_irqsave(&gpio_lock, flags); + + if (!gpio_is_valid(gpio)) + goto fail; + chip = desc->chip; + if (!chip || !chip->set || !chip->set_debounce) + goto fail; + gpio -= chip->base; + if (gpio >= chip->ngpio) + goto fail; + status = gpio_ensure_requested(desc, gpio); + 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); + + return chip->set_debounce(chip, gpio, debounce); + +fail: + spin_unlock_irqrestore(&gpio_lock, flags); + if (status) + pr_debug("%s: gpio-%d status %d\n", + __func__, gpio, status); + + return status; +} +EXPORT_SYMBOL_GPL(gpio_set_debounce); + +/* 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. + */ + +/** + * __gpio_get_value() - return a gpio's value + * @gpio: gpio whose value will be returned + * Context: any + * + * This is used directly or indirectly to implement gpio_get_value(). + * It returns the zero or nonzero value provided by the associated + * gpio_chip.get() method; or zero if no such method is provided. + */ +int __gpio_get_value(unsigned gpio) +{ + struct gpio_chip *chip; + int value; + + chip = gpio_to_chip(gpio); + WARN_ON(chip->can_sleep); + value = chip->get ? chip->get(chip, gpio - chip->base) : 0; + trace_gpio_value(gpio, 1, value); + return value; +} +EXPORT_SYMBOL_GPL(__gpio_get_value); + +/** + * __gpio_set_value() - assign a gpio's value + * @gpio: gpio whose value will be assigned + * @value: value to assign + * Context: any + * + * This is used directly or indirectly to implement gpio_set_value(). + * It invokes the associated gpio_chip.set() method. + */ +void __gpio_set_value(unsigned gpio, int value) +{ + struct gpio_chip *chip; + + chip = gpio_to_chip(gpio); + WARN_ON(chip->can_sleep); + trace_gpio_value(gpio, 0, value); + chip->set(chip, gpio - chip->base, value); +} +EXPORT_SYMBOL_GPL(__gpio_set_value); + +/** + * __gpio_cansleep() - report whether gpio value access will sleep + * @gpio: gpio in question + * Context: any + * + * This is used directly or indirectly to implement gpio_cansleep(). It + * returns nonzero if access reading or writing the GPIO value can sleep. + */ +int __gpio_cansleep(unsigned gpio) +{ + struct gpio_chip *chip; + + /* only call this on GPIOs that are valid! */ + chip = gpio_to_chip(gpio); + + return chip->can_sleep; +} +EXPORT_SYMBOL_GPL(__gpio_cansleep); + +/** + * __gpio_to_irq() - return the IRQ corresponding to a GPIO + * @gpio: gpio whose IRQ will be returned (already requested) + * Context: any + * + * This is used directly or indirectly to implement gpio_to_irq(). + * It returns the number of the IRQ signaled by this (input) GPIO, + * or a negative errno. + */ +int __gpio_to_irq(unsigned gpio) +{ + struct gpio_chip *chip; + + chip = gpio_to_chip(gpio); + return chip->to_irq ? chip->to_irq(chip, gpio - chip->base) : -ENXIO; +} +EXPORT_SYMBOL_GPL(__gpio_to_irq); + + + +/* There's no value in making it easy to inline GPIO calls that may sleep. + * Common examples include ones connected to I2C or SPI chips. + */ + +int gpio_get_value_cansleep(unsigned gpio) +{ + struct gpio_chip *chip; + int value; + + might_sleep_if(extra_checks); + chip = gpio_to_chip(gpio); + value = chip->get ? chip->get(chip, gpio - chip->base) : 0; + trace_gpio_value(gpio, 1, value); + return value; +} +EXPORT_SYMBOL_GPL(gpio_get_value_cansleep); + +void gpio_set_value_cansleep(unsigned gpio, int value) +{ + struct gpio_chip *chip; + + might_sleep_if(extra_checks); + chip = gpio_to_chip(gpio); + trace_gpio_value(gpio, 0, value); + chip->set(chip, gpio - chip->base, value); +} +EXPORT_SYMBOL_GPL(gpio_set_value_cansleep); + + +#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 = &gpio_desc[gpio]; + int is_out; + + for (i = 0; i < chip->ngpio; i++, gpio++, gdesc++) { + if (!test_bit(FLAG_REQUESTED, &gdesc->flags)) + continue; + + is_out = test_bit(FLAG_IS_OUT, &gdesc->flags); + seq_printf(s, " gpio-%-3d (%-20.20s) %s %s", + gpio, gdesc->label, + is_out ? "out" : "in ", + chip->get + ? (chip->get(chip, i) ? "hi" : "lo") + : "? "); + seq_printf(s, "\n"); + } +} + +static int gpiolib_show(struct seq_file *s, void *unused) +{ + struct gpio_chip *chip = NULL; + unsigned gpio; + int started = 0; + + /* REVISIT this isn't locked against gpio_chip removal ... */ + + for (gpio = 0; gpio_is_valid(gpio); gpio++) { + struct device *dev; + + if (chip == gpio_desc[gpio].chip) + continue; + chip = gpio_desc[gpio].chip; + if (!chip) + continue; + + seq_printf(s, "%sGPIOs %d-%d", + started ? "\n" : "", + 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"); + + started = 1; + if (chip->dbg_show) + chip->dbg_show(s, chip); + else + gpiolib_dbg_show(s, chip); + } + return 0; +} + +static int gpiolib_open(struct inode *inode, struct file *file) +{ + return single_open(file, gpiolib_show, NULL); +} + +static const struct file_operations gpiolib_operations = { + .open = gpiolib_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_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 */ |