diff --git a/Documentation/ABI/testing/sysfs-gpio b/Documentation/ABI/testing/sysfs-gpio index 8aab8092ad35dd4bfc55188e22999651b572b24a..80f4c94c7befdc67e9ecfec2753238ee7811bc1b 100644 --- a/Documentation/ABI/testing/sysfs-gpio +++ b/Documentation/ABI/testing/sysfs-gpio @@ -19,6 +19,7 @@ Description: /gpioN ... for each exported GPIO #N /value ... always readable, writes fail for input GPIOs /direction ... r/w as: in, out (default low); write: high, low + /edge ... r/w as: none, falling, rising, both /gpiochipN ... for each gpiochip; #N is its first GPIO /base ... (r/o) same as N /label ... (r/o) descriptive, not necessarily unique diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt index 566edaa56a530899fecb85ca67b8815089661b20..fa4dc077ae0eed46adf4a7312f5d033fec717fdf 100644 --- a/Documentation/gpio.txt +++ b/Documentation/gpio.txt @@ -524,6 +524,13 @@ and have the following read/write attributes: is configured as an output, this value may be written; any nonzero value is treated as high. + "edge" ... reads as either "none", "rising", "falling", or + "both". Write these strings to select the signal edge(s) + that will make poll(2) on the "value" file return. + + This file exists only if the pin can be configured as an + interrupt generating input pin. + GPIO controllers have paths like /sys/class/gpio/chipchip42/ (for the controller implementing GPIOs starting at #42) and have the following read-only attributes: diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index aef6b3d8e2cf32f637cbdaeb2d4557f73e976361..bb11a429394ab865f7e07cfc289d8a32330bd320 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1,5 +1,6 @@ #include #include +#include #include #include #include @@ -7,6 +8,7 @@ #include #include #include +#include /* Optional implementation infrastructure for GPIO interfaces. @@ -49,6 +51,13 @@ struct gpio_desc { #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 PDESC_ID_SHIFT 16 /* add new flags before this one */ + +#define GPIO_FLAGS_MASK ((1 << PDESC_ID_SHIFT) - 1) +#define GPIO_TRIGGER_MASK (BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE)) #ifdef CONFIG_DEBUG_FS const char *label; @@ -56,6 +65,15 @@ struct gpio_desc { }; static struct gpio_desc gpio_desc[ARCH_NR_GPIOS]; +#ifdef CONFIG_GPIO_SYSFS +struct poll_desc { + struct work_struct work; + struct sysfs_dirent *value_sd; +}; + +static struct idr pdesc_idr; +#endif + static inline void desc_set_label(struct gpio_desc *d, const char *label) { #ifdef CONFIG_DEBUG_FS @@ -188,10 +206,10 @@ static DEFINE_MUTEX(sysfs_lock); * /value * * always readable, subject to hardware behavior * * may be writable, as zero/nonzero - * - * REVISIT there will likely be an attribute for configuring async - * notifications, e.g. to specify polling interval or IRQ trigger type - * that would for example trigger a poll() on the "value". + * /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" */ static ssize_t gpio_direction_show(struct device *dev, @@ -288,6 +306,175 @@ static ssize_t gpio_value_store(struct device *dev, static /*const*/ DEVICE_ATTR(value, 0644, gpio_value_show, gpio_value_store); +static irqreturn_t gpio_sysfs_irq(int irq, void *priv) +{ + struct work_struct *work = priv; + + schedule_work(work); + return IRQ_HANDLED; +} + +static void gpio_notify_sysfs(struct work_struct *work) +{ + struct poll_desc *pdesc; + + pdesc = container_of(work, struct poll_desc, work); + sysfs_notify_dirent(pdesc->value_sd); +} + +static int gpio_setup_irq(struct gpio_desc *desc, struct device *dev, + unsigned long gpio_flags) +{ + struct poll_desc *pdesc; + unsigned long irq_flags; + int ret, irq, id; + + if ((desc->flags & GPIO_TRIGGER_MASK) == gpio_flags) + return 0; + + irq = gpio_to_irq(desc - gpio_desc); + if (irq < 0) + return -EIO; + + id = desc->flags >> PDESC_ID_SHIFT; + pdesc = idr_find(&pdesc_idr, id); + if (pdesc) { + free_irq(irq, &pdesc->work); + cancel_work_sync(&pdesc->work); + } + + desc->flags &= ~GPIO_TRIGGER_MASK; + + if (!gpio_flags) { + ret = 0; + goto free_sd; + } + + irq_flags = IRQF_SHARED; + if (test_bit(FLAG_TRIG_FALL, &gpio_flags)) + irq_flags |= IRQF_TRIGGER_FALLING; + if (test_bit(FLAG_TRIG_RISE, &gpio_flags)) + irq_flags |= IRQF_TRIGGER_RISING; + + if (!pdesc) { + pdesc = kmalloc(sizeof(*pdesc), GFP_KERNEL); + if (!pdesc) { + ret = -ENOMEM; + goto err_out; + } + + do { + ret = -ENOMEM; + if (idr_pre_get(&pdesc_idr, GFP_KERNEL)) + ret = idr_get_new_above(&pdesc_idr, + pdesc, 1, &id); + } while (ret == -EAGAIN); + + if (ret) + goto free_mem; + + desc->flags &= GPIO_FLAGS_MASK; + desc->flags |= (unsigned long)id << PDESC_ID_SHIFT; + + if (desc->flags >> PDESC_ID_SHIFT != id) { + ret = -ERANGE; + goto free_id; + } + + pdesc->value_sd = sysfs_get_dirent(dev->kobj.sd, "value"); + if (!pdesc->value_sd) { + ret = -ENODEV; + goto free_id; + } + INIT_WORK(&pdesc->work, gpio_notify_sysfs); + } + + ret = request_irq(irq, gpio_sysfs_irq, irq_flags, + "gpiolib", &pdesc->work); + if (ret) + goto free_sd; + + desc->flags |= gpio_flags; + return 0; + +free_sd: + sysfs_put(pdesc->value_sd); +free_id: + idr_remove(&pdesc_idr, id); + desc->flags &= GPIO_FLAGS_MASK; +free_mem: + kfree(pdesc); +err_out: + return ret; +} + +static const struct { + const char *name; + unsigned long flags; +} trigger_types[] = { + { "none", 0 }, + { "falling", BIT(FLAG_TRIG_FALL) }, + { "rising", BIT(FLAG_TRIG_RISE) }, + { "both", BIT(FLAG_TRIG_FALL) | BIT(FLAG_TRIG_RISE) }, +}; + +static ssize_t gpio_edge_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + const struct gpio_desc *desc = dev_get_drvdata(dev); + ssize_t status; + + mutex_lock(&sysfs_lock); + + if (!test_bit(FLAG_EXPORT, &desc->flags)) + status = -EIO; + else { + int i; + + status = 0; + for (i = 0; i < ARRAY_SIZE(trigger_types); i++) + if ((desc->flags & GPIO_TRIGGER_MASK) + == trigger_types[i].flags) { + status = sprintf(buf, "%s\n", + trigger_types[i].name); + break; + } + } + + mutex_unlock(&sysfs_lock); + return status; +} + +static ssize_t gpio_edge_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t size) +{ + struct gpio_desc *desc = dev_get_drvdata(dev); + ssize_t status; + int i; + + for (i = 0; i < ARRAY_SIZE(trigger_types); i++) + if (sysfs_streq(trigger_types[i].name, buf)) + goto found; + return -EINVAL; + +found: + mutex_lock(&sysfs_lock); + + if (!test_bit(FLAG_EXPORT, &desc->flags)) + status = -EIO; + else { + status = gpio_setup_irq(desc, dev, trigger_types[i].flags); + if (!status) + status = size; + } + + mutex_unlock(&sysfs_lock); + + return status; +} + +static DEVICE_ATTR(edge, 0644, gpio_edge_show, gpio_edge_store); + static const struct attribute *gpio_attrs[] = { &dev_attr_direction.attr, &dev_attr_value.attr, @@ -473,7 +660,7 @@ int gpio_export(unsigned gpio, bool direction_may_change) struct device *dev; dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0), - desc, ioname ? ioname : "gpio%d", gpio); + desc, ioname ? ioname : "gpio%d", gpio); if (dev) { if (direction_may_change) status = sysfs_create_group(&dev->kobj, @@ -481,6 +668,14 @@ int gpio_export(unsigned gpio, bool direction_may_change) else status = device_create_file(dev, &dev_attr_value); + + 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 @@ -572,6 +767,7 @@ void gpio_unexport(unsigned gpio) 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); @@ -656,6 +852,8 @@ static int __init gpiolib_sysfs_init(void) unsigned long flags; unsigned gpio; + idr_init(&pdesc_idr); + status = class_register(&gpio_class); if (status < 0) return status;