[PATCH V5 2/2] watchdog: Read device status through sysfs attributes

Pratyush Anand
2015-12-17T12:24:46Z

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>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
---
Documentation/ABI/testing/sysfs-class-watchdog | 51 +++++++++++
drivers/watchdog/Kconfig | 7 ++
drivers/watchdog/watchdog_core.c | 2 +-
drivers/watchdog/watchdog_dev.c | 114 +++++++++++++++++++++++++
4 files changed, 173 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/Kconfig b/drivers/watchdog/Kconfig
index 1c427beffadd..71e47dde7d4a 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -46,6 +46,13 @@ config WATCHDOG_NOWAYOUT
get killed. If you say Y here, the watchdog cannot be stopped once
it has been started.

+config WATCHDOG_SYSFS
+ bool "Read different watchdog information through sysfs"
+ default n
+ help
+ Say Y here if you want to enable watchdog device status read through
+ sysfs attributes.
+
#
# General Watchdog drivers
#
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index a55e846eec79..62f4496b7975 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -194,7 +194,7 @@ 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 055a4e1b4c13..d93118e97d11 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -247,6 +247,117 @@ out_timeleft:
return err;
}

+#ifdef CONFIG_WATCHDOG_SYSFS
+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);
+#endif
+
/*
* watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
* @wdd: the watchdog device to do the ioctl on
@@ -584,6 +695,9 @@ int watchdog_dev_unregister(struct watchdog_device *wdd)
static struct class watchdog_class = {
.name = "watchdog",
.owner = THIS_MODULE,
+#ifdef CONFIG_WATCHDOG_SYSFS
+ .dev_groups = wdt_groups,
+#endif
};

/*
--
2.5.0