[PATCH V2] watchdog: Add watchdog device control through sysfs attributes

[Pratyush Anand]

This patch adds following attributes to watchdog device's sysfs interface.

* 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 
---
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.

 Documentation/ABI/testing/sysfs-class-watchdog |  51 ++
 drivers/watchdog/watchdog_core.c   |  16 +--
 drivers/watchdog/watchdog_core.h   |   3 +-
 drivers/watchdog/watchdog_dev.c| 132 -
 4 files changed, 183 insertions(+), 19 deletions(-)
 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 ..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 
+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 
+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 
+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 
+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 
+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 
+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 
+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 1a8059455413..3f9eb13b2023 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -139,7 +139,7 @@ EXPORT_SYMBOL_GPL(watchdog_init_timeout);
 
 static int __watchdog_register_device(struct watchdog_device *wdd)
 {
-   int ret, id, devno;
+   int ret, id;
 
if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
return -EINVAL;
@@ -162,7 +162,7 @@ static int __watchdog_register_device(struct 
watchdog_device *wdd)
return id;
wdd->id = id;
 
-   ret = watchdog_dev_register(wdd);
+   ret = watchdog_dev_register(wdd, watchdog_class);
if (ret) {
ida_simple_remove(_ida, id);
if (!(id == 0 && ret == -EBUSY))
@@ -174,23 +174,13 @@ static int __watchdog_register_device(struct 
watchdog_device *wdd)
return id;
wdd->id = id;
 
-   ret = watchdog_dev_register(wdd);
+   ret = 

[PATCH V2] watchdog: Add watchdog device control through sysfs attributes

[Pratyush Anand]

This patch adds following attributes to watchdog device's sysfs interface.

* 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 
---
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.

 Documentation/ABI/testing/sysfs-class-watchdog |  51 ++
 drivers/watchdog/watchdog_core.c   |  16 +--
 drivers/watchdog/watchdog_core.h   |   3 +-
 drivers/watchdog/watchdog_dev.c| 132 -
 4 files changed, 183 insertions(+), 19 deletions(-)
 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 ..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 
+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 
+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 
+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 
+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 
+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 
+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 
+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 1a8059455413..3f9eb13b2023 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -139,7 +139,7 @@ EXPORT_SYMBOL_GPL(watchdog_init_timeout);
 
 static int __watchdog_register_device(struct watchdog_device *wdd)
 {
-   int ret, id, devno;
+   int ret, id;
 
if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
return -EINVAL;
@@ -162,7 +162,7 @@ static int __watchdog_register_device(struct 
watchdog_device *wdd)
return id;
wdd->id = id;
 
-   ret = watchdog_dev_register(wdd);
+   ret = watchdog_dev_register(wdd, watchdog_class);
if (ret) {
ida_simple_remove(_ida, id);
if (!(id == 0 && ret == -EBUSY))
@@ -174,23 +174,13 @@ static int __watchdog_register_device(struct 
watchdog_device *wdd)
return