[PATCH v2] gpio: lib-sysfs: Add 'wakeup' attribute

[PATCH v2] gpio: lib-sysfs: Add 'wakeup' attribute

[Soren Brinkmann]

Add an attribute 'wakeup' to the GPIO sysfs interface which allows
marking/unmarking a GPIO as wake IRQ.
The file 'wakeup' is created in each exported GPIOs directory, if an IRQ
is associated with that GPIO and the irqchip implements set_wake().
Writing 'enabled' to that file will enable wake for that GPIO, while
writing 'disabled' will disable wake.
Reading that file will return either 'disabled' or 'enabled' depening on
the currently set flag for the GPIO's IRQ.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
---
v2:
 - fix error path to unlock mutex before return
---
 drivers/gpio/gpiolib-sysfs.c | 77 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 71 insertions(+), 6 deletions(-)

diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 5f2150b619a7..7588b6d5ba94 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -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);
-- 
2.1.2.1.g5e69ed6

Re: [PATCH v2] gpio: lib-sysfs: Add 'wakeup' attribute

[Linus Walleij]

On Tue, Oct 14, 2014 at 1:50 AM, Soren Brinkmann
<soren.brinkmann@xilinx.com> wrote:

> Add an attribute 'wakeup' to the GPIO sysfs interface which allows
> marking/unmarking a GPIO as wake IRQ.
> The file 'wakeup' is created in each exported GPIOs directory, if an IRQ
> is associated with that GPIO and the irqchip implements set_wake().
> Writing 'enabled' to that file will enable wake for that GPIO, while
> writing 'disabled' will disable wake.
> Reading that file will return either 'disabled' or 'enabled' depening on
> the currently set flag for the GPIO's IRQ.
>
> Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
> ---
> v2:
>  - fix error path to unlock mutex before return

As you're adding an ABI, you should be patching
Documentation/ABI/testing/sysfs-gpio and
Documentation/gpio/sysfs.txt in this patch.

While I *HATE* the idea of adding IRQ support to userspace
for GPIOs, this "just" adds the wakeup capacity, so I guess I'm
OK with it.

Provided you add it to the ABI doc...

Yours,
Linus Walleij

Re: [PATCH v2] gpio: lib-sysfs: Add 'wakeup' attribute

[Sören Brinkmann]

On Mon, 2014-10-27 at 05:52PM +0100, Linus Walleij wrote:
> On Tue, Oct 14, 2014 at 1:50 AM, Soren Brinkmann
> <soren.brinkmann@xilinx.com> wrote:
> 
> > Add an attribute 'wakeup' to the GPIO sysfs interface which allows
> > marking/unmarking a GPIO as wake IRQ.
> > The file 'wakeup' is created in each exported GPIOs directory, if an IRQ
> > is associated with that GPIO and the irqchip implements set_wake().
> > Writing 'enabled' to that file will enable wake for that GPIO, while
> > writing 'disabled' will disable wake.
> > Reading that file will return either 'disabled' or 'enabled' depening on
> > the currently set flag for the GPIO's IRQ.
> >
> > Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
> > Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
> > ---
> > v2:
> >  - fix error path to unlock mutex before return
> 
> As you're adding an ABI, you should be patching
> Documentation/ABI/testing/sysfs-gpio and
> Documentation/gpio/sysfs.txt in this patch.
> 
> While I *HATE* the idea of adding IRQ support to userspace
> for GPIOs, this "just" adds the wakeup capacity, so I guess I'm
> OK with it.
> 
> Provided you add it to the ABI doc...

Thanks. I will add some documentation and sent a new patch.

	Thanks,
	Sören