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

[PATCH v3] 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>
---
v3:
 - add documentation
v2:
 - fix error path to unlock mutex before return

As additional reference, these are the email threads of the v2 and v1
submission:
https://lkml.org/lkml/2014/10/13/481
https://lkml.org/lkml/2014/9/4/496
---
 Documentation/ABI/testing/sysfs-gpio |  1 +
 Documentation/gpio/sysfs.txt         |  8 ++++
 drivers/gpio/gpiolib-sysfs.c         | 77 +++++++++++++++++++++++++++++++++---
 3 files changed, 80 insertions(+), 6 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-gpio b/Documentation/ABI/testing/sysfs-gpio
index 80f4c94c7bef..4cc7f4b3f724 100644
--- a/Documentation/ABI/testing/sysfs-gpio
+++ b/Documentation/ABI/testing/sysfs-gpio
@@ -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
diff --git a/Documentation/gpio/sysfs.txt b/Documentation/gpio/sysfs.txt
index c2c3a97f8ff7..f703377d528f 100644
--- a/Documentation/gpio/sysfs.txt
+++ b/Documentation/gpio/sysfs.txt
@@ -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:
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 v3] gpio: lib-sysfs: Add 'wakeup' attribute

[Linus Walleij]

On Mon, Oct 27, 2014 at 7:30 PM, 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>
> ---
> v3:
>  - add documentation
> v2:
>  - fix error path to unlock mutex before return
(...)

Looking better!

> +       "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.

Should this not be 0/1 rather than the string "enabled"/"disabled"?

I think that is the common pattern in sysfs?

Not sure, but want an indication from the ABI people.

Yours,
Linus Walleij

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

[Sören Brinkmann]

On Fri, 2014-10-31 at 08:03AM +0100, Linus Walleij wrote:
> On Mon, Oct 27, 2014 at 7:30 PM, 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>
> > ---
> > v3:
> >  - add documentation
> > v2:
> >  - fix error path to unlock mutex before return
> (...)
> 
> Looking better!
> 
> > +       "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.
> 
> Should this not be 0/1 rather than the string "enabled"/"disabled"?
> 
> I think that is the common pattern in sysfs?
> 
> Not sure, but want an indication from the ABI people.

So, as I told Alexandre, 'wakeup' including the values 'enabled' &
'disabled' is how devices that support wake expose this functionality. I
think this is more in line with what already exists. As reference, have
a look at https://www.kernel.org/doc/Documentation/power/devices.txt. It
has a section '/sys/devices/.../power/wakeup files'.

	Thanks,
	Sören

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

[Sören Brinkmann]

Another month past. Any updates on this?

	Thanks,
	Sören

On Mon, 2014-10-27 at 11:30AM -0700, Soren Brinkmann 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>
> ---
> v3:
>  - add documentation
> v2:
>  - fix error path to unlock mutex before return
> 
> As additional reference, these are the email threads of the v2 and v1
> submission:
> https://lkml.org/lkml/2014/10/13/481
> https://lkml.org/lkml/2014/9/4/496
> ---
>  Documentation/ABI/testing/sysfs-gpio |  1 +
>  Documentation/gpio/sysfs.txt         |  8 ++++
>  drivers/gpio/gpiolib-sysfs.c         | 77 +++++++++++++++++++++++++++++++++---
>  3 files changed, 80 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-gpio b/Documentation/ABI/testing/sysfs-gpio
> index 80f4c94c7bef..4cc7f4b3f724 100644
> --- a/Documentation/ABI/testing/sysfs-gpio
> +++ b/Documentation/ABI/testing/sysfs-gpio
> @@ -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
> diff --git a/Documentation/gpio/sysfs.txt b/Documentation/gpio/sysfs.txt
> index c2c3a97f8ff7..f703377d528f 100644
> --- a/Documentation/gpio/sysfs.txt
> +++ b/Documentation/gpio/sysfs.txt
> @@ -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:
> 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 v3] gpio: lib-sysfs: Add 'wakeup' attribute

[Alexandre Courbot]

On Tue, Dec 2, 2014 at 3:21 AM, Sören Brinkmann
<soren.brinkmann-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org> wrote:
> Another month past. Any updates on this?

Thanks for pinging. We are just waiting for Linus' call on this - as
far as I am concerned, this looks good.