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

[Guenter Roeck <linux@roeck-us.net>]

On 12/17/2015 04:23 AM, 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>
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>

Almost. See below.

> ---
>   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);

#else

#define wdt_groups	NULL

Then you don't need the second #ifdef below.

> +#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
>   };
>
>   /*
>