[PATCH RESEND v3] gpio: lib-sysfs: Add 'wakeup' attribute

@@ -20,6 +20,7 @@ Description:
 	    /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
+	    /wakeup ... r/w as: enabled, disabled
 	/gpiochipN ... for each gpiochip; #N is its first GPIO
 	    /base ... (r/o) same as N
 	    /label ... (r/o) descriptive, not necessarily unique

@@ -97,6 +97,14 @@ and have the following read/write attributes:
 		for "rising" and "falling" edges will follow this
 		setting.
 
+	"wakeup" ... reads as either "enabled" or "disabled". Write these
+		strings to set/clear the 'wakeup' flag of the IRQ associated
+		with this GPIO. If the IRQ has the 'wakeup' flag set, it can
+		wake the system from sleep states.
+
+		This file exists only if the pin can generate interrupts and
+		the driver implements the required infrastructure.
+
 GPIO controllers have paths like /sys/class/gpio/gpiochip42/ (for the
 controller implementing GPIOs starting at #42) and have the following
 read-only attributes:

@@ -286,6 +286,58 @@ found:
 
 static DEVICE_ATTR(edge, 0644, gpio_edge_show, gpio_edge_store);
 
+static ssize_t gpio_wakeup_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	ssize_t			status;
+	const struct gpio_desc	*desc = dev_get_drvdata(dev);
+	int			irq = gpiod_to_irq(desc);
+	struct irq_desc		*irq_desc = irq_to_desc(irq);
+
+	mutex_lock(&sysfs_lock);
+
+	if (irqd_is_wakeup_set(&irq_desc->irq_data))
+		status = sprintf(buf, "enabled\n");
+	else
+		status = sprintf(buf, "disabled\n");
+
+	mutex_unlock(&sysfs_lock);
+
+	return status;
+}
+
+static ssize_t gpio_wakeup_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	int			ret;
+	unsigned int		on;
+	struct gpio_desc	*desc = dev_get_drvdata(dev);
+	int			irq = gpiod_to_irq(desc);
+
+	mutex_lock(&sysfs_lock);
+
+	if (sysfs_streq("enabled", buf)) {
+		on = true;
+	} else if (sysfs_streq("disabled", buf)) {
+		on = false;
+	} else {
+		mutex_unlock(&sysfs_lock);
+		return -EINVAL;
+	}
+
+	ret = irq_set_irq_wake(irq, on);
+
+	mutex_unlock(&sysfs_lock);
+
+	if (ret)
+		pr_warn("%s: failed to %s wake\n", __func__,
+				on ? "enable" : "disable");
+
+	return size;
+}
+
+static DEVICE_ATTR(wakeup, 0644, gpio_wakeup_show, gpio_wakeup_store);
+
 static int sysfs_set_active_low(struct gpio_desc *desc, struct device *dev,
 				int value)
 {

@@ -526,7 +578,7 @@ static struct class gpio_class = {
 int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 {
 	unsigned long		flags;
-	int			status;
+	int			status, irq;
 	const char		*ioname = NULL;
 	struct device		*dev;
 	int			offset;

@@ -582,11 +634,24 @@ int gpiod_export(struct gpio_desc *desc, bool direction_may_change)
 			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;
+	irq = gpiod_to_irq(desc);
+	if (irq >= 0) {
+		struct irq_desc *irq_desc = irq_to_desc(irq);
+		struct irq_chip	*irqchip = irq_desc_get_chip(irq_desc);
+
+		if (direction_may_change ||
+				!test_bit(FLAG_IS_OUT, &desc->flags)) {
+			status = device_create_file(dev, &dev_attr_edge);
+			if (status)
+				goto fail_unregister_device;
+		}
+
+		if (irqchip->flags & IRQCHIP_SKIP_SET_WAKE ||
+				irqchip->irq_set_wake) {
+			status = device_create_file(dev, &dev_attr_wakeup);
+			if (status)
+				goto fail_unregister_device;
+		}
 	}
 
 	set_bit(FLAG_EXPORT, &desc->flags);