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

[Pratyush Anand]

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

* start - writes non zero value to start and zero to stop
* state - reads whether device is active or not(1 for active and 0 for
inactive)
* identity - reads Watchdog device's identity string.
* keepalive - writes to ping a watchdog device
* timeout - reads current timeout and writes to program a new 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  keepalive  nowayout  power  start  state
status  subsystem  timeleft  timeout  uevent
 # cat identity
iTCO_wdt
 # cat timeout
30
 # echo 1 > start
 # cat timeleft
26
 # echo 120 > timeout
 # cat timeleft
116
 # echo > keepalive
 # cat timeleft
118
 # cat state
1
 # echo 0 > start
 # cat state
0
 # cat bootstatus
0
 # cat nowayout
0
 # cat status
cat: status: Operation not supported

Signed-off-by: Pratyush Anand <panand@xxxxxxxxxx>
---
 Documentation/ABI/testing/sysfs-class-watchdog |  74 +++++++++
 drivers/watchdog/watchdog_core.c               |   6 +-
 drivers/watchdog/watchdog_core.h               |   2 +
 drivers/watchdog/watchdog_dev.c                | 206 +++++++++++++++++++++++++
 4 files changed, 284 insertions(+), 4 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 000000000000..31e7be53edf8
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-watchdog
@@ -0,0 +1,74 @@
+What:		/sys/class/watchdog/watchdogn/bootstatus
+Date:		August 2015
+Contact:	Pratyush Anand <panand@xxxxxxxxxx>
+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:	Pratyush Anand <panand@xxxxxxxxxx>
+Description:
+		It is a read only file. It contains identity string of
+		watchdog device.
+
+What:		/sys/class/watchdog/watchdogn/keepalive
+Date:		August 2015
+Contact:	Pratyush Anand <panand@xxxxxxxxxx>
+Description:
+		It is a write only file. It is written to ping a watchdog
+		device to keep it alive. It is equivalent to
+		WDIOC_KEEPALIVE of ioctl interface.
+
+What:		/sys/class/watchdog/watchdogn/nowayout
+Date:		August 2015
+Contact:	Pratyush Anand <panand@xxxxxxxxxx>
+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/start
+Date:		August 2015
+Contact:	Pratyush Anand <panand@xxxxxxxxxx>
+Description:
+		It is a write only file. Writing '1' will trigger that
+		watchdog device and writing '0' will stop it. These are
+		equivalent to WDIOS_ENABLECARD and WDIOS_DISABLECARD of ioctl
+		interface. If a device has nowayout programmed, then that
+		can not be stopped. Therefore, it is recommended to read
+		state file to insure that whether watchdog device was
+		stopped or not after writing '0'.
+
+What:		/sys/class/watchdog/watchdogn/state
+Date:		August 2015
+Contact:	Pratyush Anand <panand@xxxxxxxxxx>
+Description:
+		It is a read only file. If it is read as '1' then a watchdog
+		device is active. If it is read as '0' then a watchdog
+		device is inactive.
+
+What:		/sys/class/watchdog/watchdogn/status
+Date:		August 2015
+Contact:	Pratyush Anand <panand@xxxxxxxxxx>
+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:	Pratyush Anand <panand@xxxxxxxxxx>
+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:	Pratyush Anand <panand@xxxxxxxxxx>
+Description:
+		It is a read/write file. It is read to know about current
+		timeout and written to program a new timeout value. These
+		are equivalent to WDIOC_SETTIMEOUT and WDIOC_GETTIMEOUT of
+		ioctl interface.
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index 1a8059455413..703ff7b23f31 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;
@@ -181,9 +181,7 @@ 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->dev = watchdog_device_create(watchdog_class, wdd);
 	if (IS_ERR(wdd->dev)) {
 		watchdog_dev_unregister(wdd);
 		ida_simple_remove(&watchdog_ida, id);
diff --git a/drivers/watchdog/watchdog_core.h b/drivers/watchdog/watchdog_core.h
index 6c951418fca7..36abd15ffcea 100644
--- a/drivers/watchdog/watchdog_core.h
+++ b/drivers/watchdog/watchdog_core.h
@@ -31,6 +31,8 @@
 /*
  *	Functions/procedures to be called by the core
  */
+struct device * watchdog_device_create(struct class *,
+				struct watchdog_device *);
 extern int watchdog_dev_register(struct watchdog_device *);
 extern int watchdog_dev_unregister(struct watchdog_device *);
 extern int __init watchdog_dev_init(void);
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 6aaefbad303e..1186b5a918e9 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -248,6 +248,212 @@ 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);
+	bool nowayout = false;
+
+	mutex_lock(&wdd->lock);
+	if (test_bit(WDOG_NO_WAY_OUT, &wdd->status))
+		nowayout = true;
+	mutex_unlock(&wdd->lock);
+
+	return sprintf(buf, "%d\n", nowayout);
+}
+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);
+	ssize_t status;
+
+	mutex_lock(&wdd->lock);
+	status = sprintf(buf, "%u\n", wdd->bootstatus);
+	mutex_unlock(&wdd->lock);
+
+	return status;
+}
+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_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+	unsigned int val;
+	ssize_t status = 0;
+
+	status = kstrtouint(buf, 0, &val);
+	if (!status) {
+		status = watchdog_set_timeout(wdd, val);
+		if (status >= 0)
+			status = watchdog_ping(wdd);
+	}
+
+	if (status < 0)
+		return status;
+	else
+		return size;
+}
+
+static ssize_t timeout_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+	ssize_t status;
+
+	mutex_lock(&wdd->lock);
+	if (wdd->timeout == 0)
+		status = -EOPNOTSUPP;
+	else
+		status = sprintf(buf, "%u\n", wdd->timeout);
+	mutex_unlock(&wdd->lock);
+
+	return status;
+}
+static DEVICE_ATTR_RW(timeout);
+
+static ssize_t keepalive_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+	ssize_t status = 0;
+
+	mutex_lock(&wdd->lock);
+	if (!(wdd->info->options & WDIOF_KEEPALIVEPING))
+		status = -EOPNOTSUPP;
+	mutex_unlock(&wdd->lock);
+
+	if (!status)
+		status = watchdog_ping(wdd);
+
+	if (status < 0)
+		return status;
+	else
+		return size;
+}
+static DEVICE_ATTR_WO(keepalive);
+
+static ssize_t identity_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+	ssize_t status;
+
+	mutex_lock(&wdd->lock);
+	status = sprintf(buf, "%s\n", wdd->info->identity);
+	mutex_unlock(&wdd->lock);
+
+	return status;
+}
+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);
+	bool active;
+
+	mutex_lock(&wdd->lock);
+	active = watchdog_active(wdd);
+	mutex_unlock(&wdd->lock);
+
+	return sprintf(buf, "%d\n", active);
+}
+static DEVICE_ATTR_RO(state);
+
+static ssize_t start_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+	ssize_t status = 0;
+	unsigned int val;
+
+	status = kstrtouint(buf, 0, &val);
+	if (status)
+		return status;
+	if (val)
+		status = watchdog_start(wdd);
+	else
+		status = watchdog_stop(wdd);
+
+	if (status < 0)
+		return status;
+	else
+		return size;
+}
+static DEVICE_ATTR_WO(start);
+
+static struct attribute *wdt_attrs[] = {
+	&dev_attr_start.attr,
+	&dev_attr_state.attr,
+	&dev_attr_identity.attr,
+	&dev_attr_keepalive.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,
+};
+
+static const struct attribute_group *wdt_groups[] = {
+	&wdt_group,
+	NULL
+};
+
+/*
+ *	watchdog_device_create: create a struct device for a given watchdog
+ *	device
+ *	@wdc: watchdog class with which created device is associated
+ *	@wdd: watchdog device
+ *
+ *	Creates a struct device corresponding to given watchdog device and
+ *	associates a device attribute_group with it.
+ */
+struct device * watchdog_device_create(struct class *wdc,
+					struct watchdog_device *wdd)
+{
+	return device_create_with_groups(wdc, wdd->parent, wdd->cdev.dev,
+			wdd, wdt_groups, "watchdog%d", wdd->id);
+}
+
 /*
  *	watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
  *	@wddev: the watchdog device to do the ioctl on
-- 
2.4.3

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