---

yaml
---
r: 164820
b: refs/heads/master
c: ff77c35
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: d120c17faeb391f5b4b99af8b1e190619934ecdd
+refs/heads/master: ff77c352ae17768c61cfc36357f0a3904552f11c

trunk/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

trunk/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:

trunk/drivers/gpio/gpiolib.c

@@ -1,12 +1,14 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/spinlock.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
 #include <linux/gpio.h>
+#include <linux/idr.h>
 
 
 /* Optional implementation infrastructure for GPIO interfaces.
@@ -49,13 +51,29 @@ 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;
 #endif
 };
 static struct gpio_desc gpio_desc[ARCH_NR_GPIOS];
 
+#ifdef CONFIG_GPIO_SYSFS
+struct poll_desc {
+	struct work_struct	work;
+	struct sysfs_dirent	*value_sd;
+};
+
+static struct idr pdesc_idr;
+#endif
+
 static inline void desc_set_label(struct gpio_desc *d, const char *label)
 {
 #ifdef CONFIG_DEBUG_FS
@@ -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,
@@ -473,14 +660,22 @@ 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,
 						&gpio_attr_group);
 			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;