[PATCH V3 0/2] watchdog: Sysfs status read support

[PATCH V3 0/2] watchdog: Sysfs status read support

[Pratyush Anand]

These patches provide support to read different watchdog device status
through sysfs interface.

Changes since V2:
* Used static struct class watchdog_class in stead of pointer. It helped in
 keep using device_create().
* Above logic was moved to a separate patch.
* Changed subject line of other patch to look more relevant

Changes since V1(RFC):
* Removed keepalive and start ABI
* timeout is read only now
* state returns text
* only supported ABI visible
* ABI contact changed to MAINTAINER
* unnecessary mutex removed
* aligned continuation with '('
* unnecessary initialization of status (= 0) corrected
* unnecessary else removed
* used __ATTRIBUTE_GROUPS
* removed watchdog_device_create and added functionality in watchdog_dev_register.
* optimized nowayout_show
* Now no -EOPNOTSUPP return for timeout read in case of wdd->timeout = 0.

Pratyush Anand (2):
  watchdog: Use static struct class watchdog_class in stead of pointer
  watchdog: Read device status through sysfs attributes

 Documentation/ABI/testing/sysfs-class-watchdog |  51 ++++++++++
 drivers/watchdog/watchdog_core.c               |  17 +---
 drivers/watchdog/watchdog_core.h               |   2 +-
 drivers/watchdog/watchdog_dev.c                | 136 ++++++++++++++++++++++++-
 4 files changed, 187 insertions(+), 19 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-class-watchdog

-- 
2.4.3

[PATCH V3 1/2] watchdog: Use static struct class watchdog_class in stead of pointer

[Pratyush Anand]

We need few sysfs attributes to know different status of a watchdog device.
To do that, we need to associate .dev_groups with watchdog_class. So
convert it from pointer to static.
Putting this static struct in watchdog_dev.c, so that static device
attributes defined in that file can be attached to it.

Signed-off-by: Pratyush Anand <panand@redhat.com>
Suggested-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/watchdog/watchdog_core.c | 15 ++-------------
 drivers/watchdog/watchdog_core.h |  2 +-
 drivers/watchdog/watchdog_dev.c  | 26 ++++++++++++++++++++++----
 3 files changed, 25 insertions(+), 18 deletions(-)

diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index 1a8059455413..47d38c5c3f9a 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -274,19 +274,9 @@ static int __init watchdog_deferred_registration(void)
 
 static int __init watchdog_init(void)
 {
-	int err;
-
-	watchdog_class = class_create(THIS_MODULE, "watchdog");
-	if (IS_ERR(watchdog_class)) {
-		pr_err("couldn't create class\n");
+	watchdog_class = watchdog_dev_init();
+	if (IS_ERR(watchdog_class))
 		return PTR_ERR(watchdog_class);
-	}
-
-	err = watchdog_dev_init();
-	if (err < 0) {
-		class_destroy(watchdog_class);
-		return err;
-	}
 
 	watchdog_deferred_registration();
 	return 0;
@@ -295,7 +285,6 @@ static int __init watchdog_init(void)
 static void __exit watchdog_exit(void)
 {
 	watchdog_dev_exit();
-	class_destroy(watchdog_class);
 	ida_destroy(&watchdog_ida);
 }
 
diff --git a/drivers/watchdog/watchdog_core.h b/drivers/watchdog/watchdog_core.h
index 6c951418fca7..1c8d6b0e68c7 100644
--- a/drivers/watchdog/watchdog_core.h
+++ b/drivers/watchdog/watchdog_core.h
@@ -33,5 +33,5 @@
  */
 extern int watchdog_dev_register(struct watchdog_device *);
 extern int watchdog_dev_unregister(struct watchdog_device *);
-extern int __init watchdog_dev_init(void);
+extern struct class * __init watchdog_dev_init(void);
 extern void __exit watchdog_dev_exit(void);
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 6aaefbad303e..986282d44b90 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -578,18 +578,35 @@ int watchdog_dev_unregister(struct watchdog_device *watchdog)
 	return 0;
 }
 
+static struct class watchdog_class = {
+	.name =		"watchdog",
+	.owner =	THIS_MODULE,
+};
+
 /*
  *	watchdog_dev_init: init dev part of watchdog core
  *
  *	Allocate a range of chardev nodes to use for watchdog devices
  */
 
-int __init watchdog_dev_init(void)
+struct class * __init watchdog_dev_init(void)
 {
-	int err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
-	if (err < 0)
+	int err;
+
+	err = class_register(&watchdog_class);
+	if (err < 0) {
+		pr_err("couldn't register class\n");
+		return ERR_PTR(err);
+	}
+
+	err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
+	if (err < 0) {
 		pr_err("watchdog: unable to allocate char dev region\n");
-	return err;
+		class_unregister(&watchdog_class);
+		return ERR_PTR(err);
+	}
+
+	return &watchdog_class;
 }
 
 /*
@@ -601,4 +618,5 @@ int __init watchdog_dev_init(void)
 void __exit watchdog_dev_exit(void)
 {
 	unregister_chrdev_region(watchdog_devt, MAX_DOGS);
+	class_unregister(&watchdog_class);
 }
-- 
2.4.3

[PATCH V3 2/2] watchdog: Read device status through sysfs attributes

[Pratyush Anand]

This patch adds following attributes to watchdog device's sysfs interface
to read its different status.

* state - reads whether device is active or not
* identity - reads Watchdog device's identity string.
* timeout - reads current timeout.
* timeleft - reads timeleft before watchdog generates a reset
* bootstatus - reads status of the watchdog device at boot
* status - reads watchdog device's  internal status bits
* nowayout - reads whether nowayout feature was set or not

Testing with iTCO_wdt:
 # cd /sys/class/watchdog/watchdog1/
 # ls
bootstatus  dev  device  identity  nowayout  power  state
subsystem  timeleft  timeout  uevent
 # cat identity
iTCO_wdt
 # cat timeout
30
 # cat state
inactive
 # echo > /dev/watchdog1
 # cat timeleft
26
 # cat state
active
 # cat bootstatus
0
 # cat nowayout
0

Signed-off-by: Pratyush Anand <panand@redhat.com>
---
 Documentation/ABI/testing/sysfs-class-watchdog |  51 ++++++++++++
 drivers/watchdog/watchdog_core.c               |   2 +-
 drivers/watchdog/watchdog_dev.c                | 110 +++++++++++++++++++++++++
 3 files changed, 162 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/ABI/testing/sysfs-class-watchdog

diff --git a/Documentation/ABI/testing/sysfs-class-watchdog b/Documentation/ABI/testing/sysfs-class-watchdog
new file mode 100644
index 000000000000..736046b33040
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-watchdog
@@ -0,0 +1,51 @@
+What:		/sys/class/watchdog/watchdogn/bootstatus
+Date:		August 2015
+Contact:	Wim Van Sebroeck <wim@iguana.be>
+Description:
+		It is a read only file. It contains status of the watchdog
+		device at boot. It is equivalent to WDIOC_GETBOOTSTATUS of
+		ioctl interface.
+
+What:		/sys/class/watchdog/watchdogn/identity
+Date:		August 2015
+Contact:	Wim Van Sebroeck <wim@iguana.be>
+Description:
+		It is a read only file. It contains identity string of
+		watchdog device.
+
+What:		/sys/class/watchdog/watchdogn/nowayout
+Date:		August 2015
+Contact:	Wim Van Sebroeck <wim@iguana.be>
+Description:
+		It is a read only file. While reading, it gives '1' if that
+		device supports nowayout feature else, it gives '0'.
+
+What:		/sys/class/watchdog/watchdogn/state
+Date:		August 2015
+Contact:	Wim Van Sebroeck <wim@iguana.be>
+Description:
+		It is a read only file. It gives active/inactive status of
+		watchdog device.
+
+What:		/sys/class/watchdog/watchdogn/status
+Date:		August 2015
+Contact:	Wim Van Sebroeck <wim@iguana.be>
+Description:
+		It is a read only file. It contains watchdog device's
+		internal status bits. It is equivalent to WDIOC_GETSTATUS
+		of ioctl interface.
+
+What:		/sys/class/watchdog/watchdogn/timeleft
+Date:		August 2015
+Contact:	Wim Van Sebroeck <wim@iguana.be>
+Description:
+		It is a read only file. It contains value of time left for
+		reset generation. It is equivalent to WDIOC_GETTIMELEFT of
+		ioctl interface.
+
+What:		/sys/class/watchdog/watchdogn/timeout
+Date:		August 2015
+Contact:	Wim Van Sebroeck <wim@iguana.be>
+Description:
+		It is a read only file. It is read to know about current
+		value of timeout programmed.
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index 47d38c5c3f9a..62666f021762 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -183,7 +183,7 @@ static int __watchdog_register_device(struct watchdog_device *wdd)
 
 	devno = wdd->cdev.dev;
 	wdd->dev = device_create(watchdog_class, wdd->parent, devno,
-					NULL, "watchdog%d", wdd->id);
+					wdd, "watchdog%d", wdd->id);
 	if (IS_ERR(wdd->dev)) {
 		watchdog_dev_unregister(wdd);
 		ida_simple_remove(&watchdog_ida, id);
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 986282d44b90..cbac8f88f390 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -248,6 +248,115 @@ out_timeleft:
 	return err;
 }
 
+static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
+				char *buf)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status));
+}
+static DEVICE_ATTR_RO(nowayout);
+
+static ssize_t status_show(struct device *dev, struct device_attribute *attr,
+				char *buf)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+	ssize_t status;
+	unsigned int val;
+
+	status = watchdog_get_status(wdd, &val);
+	if (!status)
+		status = sprintf(buf, "%u\n", val);
+
+	return status;
+}
+static DEVICE_ATTR_RO(status);
+
+static ssize_t bootstatus_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%u\n", wdd->bootstatus);
+}
+static DEVICE_ATTR_RO(bootstatus);
+
+static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
+				char *buf)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+	ssize_t status;
+	unsigned int val;
+
+	status = watchdog_get_timeleft(wdd, &val);
+	if (!status)
+		status = sprintf(buf, "%u\n", val);
+
+	return status;
+}
+static DEVICE_ATTR_RO(timeleft);
+
+static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
+				char *buf)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%u\n", wdd->timeout);
+}
+static DEVICE_ATTR_RO(timeout);
+
+static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
+				char *buf)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%s\n", wdd->info->identity);
+}
+static DEVICE_ATTR_RO(identity);
+
+static ssize_t state_show(struct device *dev, struct device_attribute *attr,
+				char *buf)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+
+	if (watchdog_active(wdd))
+		return sprintf(buf, "active\n");
+
+	return sprintf(buf, "inactive\n");
+}
+static DEVICE_ATTR_RO(state);
+
+static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
+				int n)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+	umode_t mode = attr->mode;
+
+	if (attr == &dev_attr_status.attr && !wdd->ops->status)
+		mode = 0;
+	else if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
+		mode = 0;
+
+	return mode;
+}
+static struct attribute *wdt_attrs[] = {
+	&dev_attr_state.attr,
+	&dev_attr_identity.attr,
+	&dev_attr_timeout.attr,
+	&dev_attr_timeleft.attr,
+	&dev_attr_bootstatus.attr,
+	&dev_attr_status.attr,
+	&dev_attr_nowayout.attr,
+	NULL,
+};
+
+static const struct attribute_group wdt_group = {
+	.attrs = wdt_attrs,
+	.is_visible = wdt_is_visible,
+};
+__ATTRIBUTE_GROUPS(wdt);
+
 /*
  *	watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
  *	@wddev: the watchdog device to do the ioctl on
@@ -581,6 +690,7 @@ int watchdog_dev_unregister(struct watchdog_device *watchdog)
 static struct class watchdog_class = {
 	.name =		"watchdog",
 	.owner =	THIS_MODULE,
+	.dev_groups = 	wdt_groups,
 };
 
 /*
-- 
2.4.3

[PATCH V3 2/2] watchdog: Read device status through sysfs attributes

[Pratyush Anand]

This patch adds following attributes to watchdog device's sysfs interface
to read its different status.

* state - reads whether device is active or not
* identity - reads Watchdog device's identity string.
* timeout - reads current timeout.
* timeleft - reads timeleft before watchdog generates a reset
* bootstatus - reads status of the watchdog device at boot
* status - reads watchdog device's  internal status bits
* nowayout - reads whether nowayout feature was set or not

Testing with iTCO_wdt:
 # cd /sys/class/watchdog/watchdog1/
 # ls
bootstatus  dev  device  identity  nowayout  power  state
subsystem  timeleft  timeout  uevent
 # cat identity
iTCO_wdt
 # cat timeout
30
 # cat state
inactive
 # echo > /dev/watchdog1
 # cat timeleft
26
 # cat state
active
 # cat bootstatus
0
 # cat nowayout
0

Signed-off-by: Pratyush Anand <panand-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 Documentation/ABI/testing/sysfs-class-watchdog |  51 ++++++++++++
 drivers/watchdog/watchdog_core.c               |   2 +-
 drivers/watchdog/watchdog_dev.c                | 110 +++++++++++++++++++++++++
 3 files changed, 162 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/ABI/testing/sysfs-class-watchdog

diff --git a/Documentation/ABI/testing/sysfs-class-watchdog b/Documentation/ABI/testing/sysfs-class-watchdog
new file mode 100644
index 000000000000..736046b33040
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-watchdog
@@ -0,0 +1,51 @@
+What:		/sys/class/watchdog/watchdogn/bootstatus
+Date:		August 2015
+Contact:	Wim Van Sebroeck <wim-IQzOog9fTRqzQB+pC5nmwQ@public.gmane.org>
+Description:
+		It is a read only file. It contains status of the watchdog
+		device at boot. It is equivalent to WDIOC_GETBOOTSTATUS of
+		ioctl interface.
+
+What:		/sys/class/watchdog/watchdogn/identity
+Date:		August 2015
+Contact:	Wim Van Sebroeck <wim-IQzOog9fTRqzQB+pC5nmwQ@public.gmane.org>
+Description:
+		It is a read only file. It contains identity string of
+		watchdog device.
+
+What:		/sys/class/watchdog/watchdogn/nowayout
+Date:		August 2015
+Contact:	Wim Van Sebroeck <wim-IQzOog9fTRqzQB+pC5nmwQ@public.gmane.org>
+Description:
+		It is a read only file. While reading, it gives '1' if that
+		device supports nowayout feature else, it gives '0'.
+
+What:		/sys/class/watchdog/watchdogn/state
+Date:		August 2015
+Contact:	Wim Van Sebroeck <wim-IQzOog9fTRqzQB+pC5nmwQ@public.gmane.org>
+Description:
+		It is a read only file. It gives active/inactive status of
+		watchdog device.
+
+What:		/sys/class/watchdog/watchdogn/status
+Date:		August 2015
+Contact:	Wim Van Sebroeck <wim-IQzOog9fTRqzQB+pC5nmwQ@public.gmane.org>
+Description:
+		It is a read only file. It contains watchdog device's
+		internal status bits. It is equivalent to WDIOC_GETSTATUS
+		of ioctl interface.
+
+What:		/sys/class/watchdog/watchdogn/timeleft
+Date:		August 2015
+Contact:	Wim Van Sebroeck <wim-IQzOog9fTRqzQB+pC5nmwQ@public.gmane.org>
+Description:
+		It is a read only file. It contains value of time left for
+		reset generation. It is equivalent to WDIOC_GETTIMELEFT of
+		ioctl interface.
+
+What:		/sys/class/watchdog/watchdogn/timeout
+Date:		August 2015
+Contact:	Wim Van Sebroeck <wim-IQzOog9fTRqzQB+pC5nmwQ@public.gmane.org>
+Description:
+		It is a read only file. It is read to know about current
+		value of timeout programmed.
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index 47d38c5c3f9a..62666f021762 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -183,7 +183,7 @@ static int __watchdog_register_device(struct watchdog_device *wdd)
 
 	devno = wdd->cdev.dev;
 	wdd->dev = device_create(watchdog_class, wdd->parent, devno,
-					NULL, "watchdog%d", wdd->id);
+					wdd, "watchdog%d", wdd->id);
 	if (IS_ERR(wdd->dev)) {
 		watchdog_dev_unregister(wdd);
 		ida_simple_remove(&watchdog_ida, id);
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 986282d44b90..cbac8f88f390 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -248,6 +248,115 @@ out_timeleft:
 	return err;
 }
 
+static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
+				char *buf)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status));
+}
+static DEVICE_ATTR_RO(nowayout);
+
+static ssize_t status_show(struct device *dev, struct device_attribute *attr,
+				char *buf)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+	ssize_t status;
+	unsigned int val;
+
+	status = watchdog_get_status(wdd, &val);
+	if (!status)
+		status = sprintf(buf, "%u\n", val);
+
+	return status;
+}
+static DEVICE_ATTR_RO(status);
+
+static ssize_t bootstatus_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%u\n", wdd->bootstatus);
+}
+static DEVICE_ATTR_RO(bootstatus);
+
+static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
+				char *buf)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+	ssize_t status;
+	unsigned int val;
+
+	status = watchdog_get_timeleft(wdd, &val);
+	if (!status)
+		status = sprintf(buf, "%u\n", val);
+
+	return status;
+}
+static DEVICE_ATTR_RO(timeleft);
+
+static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
+				char *buf)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%u\n", wdd->timeout);
+}
+static DEVICE_ATTR_RO(timeout);
+
+static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
+				char *buf)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+
+	return sprintf(buf, "%s\n", wdd->info->identity);
+}
+static DEVICE_ATTR_RO(identity);
+
+static ssize_t state_show(struct device *dev, struct device_attribute *attr,
+				char *buf)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+
+	if (watchdog_active(wdd))
+		return sprintf(buf, "active\n");
+
+	return sprintf(buf, "inactive\n");
+}
+static DEVICE_ATTR_RO(state);
+
+static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
+				int n)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+	umode_t mode = attr->mode;
+
+	if (attr == &dev_attr_status.attr && !wdd->ops->status)
+		mode = 0;
+	else if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
+		mode = 0;
+
+	return mode;
+}
+static struct attribute *wdt_attrs[] = {
+	&dev_attr_state.attr,
+	&dev_attr_identity.attr,
+	&dev_attr_timeout.attr,
+	&dev_attr_timeleft.attr,
+	&dev_attr_bootstatus.attr,
+	&dev_attr_status.attr,
+	&dev_attr_nowayout.attr,
+	NULL,
+};
+
+static const struct attribute_group wdt_group = {
+	.attrs = wdt_attrs,
+	.is_visible = wdt_is_visible,
+};
+__ATTRIBUTE_GROUPS(wdt);
+
 /*
  *	watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
  *	@wddev: the watchdog device to do the ioctl on
@@ -581,6 +690,7 @@ int watchdog_dev_unregister(struct watchdog_device *watchdog)
 static struct class watchdog_class = {
 	.name =		"watchdog",
 	.owner =	THIS_MODULE,
+	.dev_groups = 	wdt_groups,
 };
 
 /*
-- 
2.4.3

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Re: [PATCH V3 1/2] watchdog: Use static struct class watchdog_class in stead of pointer

[Guenter Roeck]

On 09/02/2015 08:21 PM, Pratyush Anand wrote:
> We need few sysfs attributes to know different status of a watchdog device.
> To do that, we need to associate .dev_groups with watchdog_class. So
> convert it from pointer to static.
> Putting this static struct in watchdog_dev.c, so that static device
> attributes defined in that file can be attached to it.
>
> Signed-off-by: Pratyush Anand <panand@redhat.com>
> Suggested-by: Guenter Roeck <linux@roeck-us.net>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
>   drivers/watchdog/watchdog_core.c | 15 ++-------------
>   drivers/watchdog/watchdog_core.h |  2 +-
>   drivers/watchdog/watchdog_dev.c  | 26 ++++++++++++++++++++++----
>   3 files changed, 25 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
> index 1a8059455413..47d38c5c3f9a 100644
> --- a/drivers/watchdog/watchdog_core.c
> +++ b/drivers/watchdog/watchdog_core.c
> @@ -274,19 +274,9 @@ static int __init watchdog_deferred_registration(void)
>
>   static int __init watchdog_init(void)
>   {
> -	int err;
> -
> -	watchdog_class = class_create(THIS_MODULE, "watchdog");
> -	if (IS_ERR(watchdog_class)) {
> -		pr_err("couldn't create class\n");
> +	watchdog_class = watchdog_dev_init();
> +	if (IS_ERR(watchdog_class))
>   		return PTR_ERR(watchdog_class);
> -	}
> -
> -	err = watchdog_dev_init();
> -	if (err < 0) {
> -		class_destroy(watchdog_class);
> -		return err;
> -	}
>
>   	watchdog_deferred_registration();
>   	return 0;
> @@ -295,7 +285,6 @@ static int __init watchdog_init(void)
>   static void __exit watchdog_exit(void)
>   {
>   	watchdog_dev_exit();
> -	class_destroy(watchdog_class);
>   	ida_destroy(&watchdog_ida);
>   }
>
> diff --git a/drivers/watchdog/watchdog_core.h b/drivers/watchdog/watchdog_core.h
> index 6c951418fca7..1c8d6b0e68c7 100644
> --- a/drivers/watchdog/watchdog_core.h
> +++ b/drivers/watchdog/watchdog_core.h
> @@ -33,5 +33,5 @@
>    */
>   extern int watchdog_dev_register(struct watchdog_device *);
>   extern int watchdog_dev_unregister(struct watchdog_device *);
> -extern int __init watchdog_dev_init(void);
> +extern struct class * __init watchdog_dev_init(void);
>   extern void __exit watchdog_dev_exit(void);
> diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
> index 6aaefbad303e..986282d44b90 100644
> --- a/drivers/watchdog/watchdog_dev.c
> +++ b/drivers/watchdog/watchdog_dev.c
> @@ -578,18 +578,35 @@ int watchdog_dev_unregister(struct watchdog_device *watchdog)
>   	return 0;
>   }
>
> +static struct class watchdog_class = {
> +	.name =		"watchdog",
> +	.owner =	THIS_MODULE,
> +};
> +
>   /*
>    *	watchdog_dev_init: init dev part of watchdog core
>    *
>    *	Allocate a range of chardev nodes to use for watchdog devices
>    */
>
> -int __init watchdog_dev_init(void)
> +struct class * __init watchdog_dev_init(void)
>   {
> -	int err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
> -	if (err < 0)
> +	int err;
> +
> +	err = class_register(&watchdog_class);
> +	if (err < 0) {
> +		pr_err("couldn't register class\n");
> +		return ERR_PTR(err);
> +	}
> +
> +	err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
> +	if (err < 0) {
>   		pr_err("watchdog: unable to allocate char dev region\n");
> -	return err;
> +		class_unregister(&watchdog_class);
> +		return ERR_PTR(err);
> +	}
> +
> +	return &watchdog_class;
>   }
>
>   /*
> @@ -601,4 +618,5 @@ int __init watchdog_dev_init(void)
>   void __exit watchdog_dev_exit(void)
>   {
>   	unregister_chrdev_region(watchdog_devt, MAX_DOGS);
> +	class_unregister(&watchdog_class);
>   }
>

Re: [PATCH V3 2/2] watchdog: Read device status through sysfs attributes

[Pratyush Anand]

On 03/09/2015:03:52:32 AM, Guenter Roeck wrote:
> On 09/02/2015 08:22 PM, Pratyush Anand wrote:
> >This patch adds following attributes to watchdog device's sysfs interface
> >to read its different status.
> >
> >* state - reads whether device is active or not
> >* identity - reads Watchdog device's identity string.
> >* timeout - reads current timeout.
> >* timeleft - reads timeleft before watchdog generates a reset
> >* bootstatus - reads status of the watchdog device at boot
> >* status - reads watchdog device's  internal status bits
> >* nowayout - reads whether nowayout feature was set or not
> >
> >Testing with iTCO_wdt:
> >  # cd /sys/class/watchdog/watchdog1/
> >  # ls
> >bootstatus  dev  device  identity  nowayout  power  state
> >subsystem  timeleft  timeout  uevent
> >  # cat identity
> >iTCO_wdt
> >  # cat timeout
> >30
> >  # cat state
> >inactive
> >  # echo > /dev/watchdog1
> >  # cat timeleft
> >26
> >  # cat state
> >active
> >  # cat bootstatus
> >0
> >  # cat nowayout
> >0
> >
> >Signed-off-by: Pratyush Anand <panand@redhat.com>
> 
> Looks good, except for
> 
> WARNING: please, no space before tabs
> #250: FILE: drivers/watchdog/watchdog_dev.c:693:
> +^I.dev_groups = ^Iwdt_groups,$
> 
> [ there is a space after '=' ]
> 
> Assuming you fix that,
> 
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>
> 

Thanks a lot for the review.
I will fix it and will send it again.

~Pratyush