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

Guenter Roeck
2015-12-17T14:53:32Z

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
> };
>
> /*
>