From: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
Since the watchdog framework centrializes the IOCTL interfaces of device
drivers now, SETPRETIMEOUT and GETPRETIMEOUT need to be added in the
common code.
Signed-off-by: Robin Gong <b38343@xxxxxxxxxxxxx>
Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
---
Changes since Robin's last version:
* rebased
* 0 is valid and means disable pretimeout
add code and docs for that
* add docs that drivers must update pretimeout when a new timeout is set
* reworded some documentation
* core handles wdd->pretimeout if set_pretimeout() is not populated
* add pretimeout to sysfs
Documentation/watchdog/watchdog-kernel-api.txt | 20 ++++++++++
drivers/watchdog/watchdog_dev.c | 53 +++++++++++++++++++++++++-
include/linux/watchdog.h | 11 ++++++
3 files changed, 82 insertions(+), 2 deletions(-)
diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index a9a65f8c0de9f0..4d4e0db6750c5f 100644
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -50,6 +50,7 @@ struct watchdog_device {
const struct watchdog_ops *ops;
unsigned int bootstatus;
unsigned int timeout;
+ unsigned int pretimeout;
unsigned int min_timeout;
unsigned int max_timeout;
unsigned int min_hw_heartbeat_ms;
@@ -77,6 +78,7 @@ It contains following fields:
* timeout: the watchdog timer's timeout value (in seconds).
This is the time after which the system will reboot if user space does
not send a heartbeat request if WDOG_ACTIVE is set.
+* pretimeout: the watchdog timer's pretimeout value (in seconds).
* min_timeout: the watchdog timer's minimum timeout value (in seconds).
If set, the minimum configurable value for 'timeout'.
* max_timeout: the watchdog timer's maximum timeout value (in seconds),
@@ -120,6 +122,7 @@ struct watchdog_ops {
int (*ping)(struct watchdog_device *);
unsigned int (*status)(struct watchdog_device *);
int (*set_timeout)(struct watchdog_device *, unsigned int);
+ int (*set_pretimeout)(struct watchdog_device *, unsigned int);
unsigned int (*get_timeleft)(struct watchdog_device *);
int (*restart)(struct watchdog_device *);
void (*ref)(struct watchdog_device *) __deprecated;
@@ -183,6 +186,23 @@ they are supported. These optional routines/operations are:
set_timeout is not provided but WDIOF_SETTIMEOUT is set, the watchdog
infrastructure updates the timeout value of the watchdog_device internally
to the requested value.
+ If the pretimeout feature is used (WDIOF_PRETIMEOUT), then set_timeout must
+ also take care of checking if pretimeout is still valid and set up the timer
+ accordingly. This can't be done in the core without races, so it is the
+ duty of the driver.
+* set_pretimeout: this routine checks and changes the pretimeout value of
+ the watchdog. It is optional because not all watchdogs support pretimeout
+ notification. The timeout value is not an absolute time, but the number of
+ seconds before the actual timeout would happen. It returns 0 on success,
+ -EINVAL for "parameter out of range" and -EIO for "could not write value to
+ the watchdog". A value of 0 disables pretimeout notification.
+ (Note: the WDIOF_PRETIMEOUT needs to be set in the options field of the
+ watchdog's info structure).
+ If the watchdog driver does not have to perform any action but setting the
+ watchdog_device.pretimeout, this callback can be omitted. That means if
+ set_pretimeout is not provided but WDIOF_PRETIMEOUT is set, the watchdog
+ infrastructure updates the pretimeout value of the watchdog_device internally
+ to the requested value.
* get_timeleft: this routines returns the time that's left before a reset.
* restart: this routine restarts the machine. It returns 0 on success or a
negative errno code for failure.
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 5d028f94a90743..ad9f4032f02d18 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -308,10 +308,14 @@ static int watchdog_set_timeout(struct watchdog_device *wdd,
if (watchdog_timeout_invalid(wdd, timeout))
return -EINVAL;
- if (wdd->ops->set_timeout)
+ if (wdd->ops->set_timeout) {
err = wdd->ops->set_timeout(wdd, timeout);
- else
+ } else {
wdd->timeout = timeout;
+ /* Disable pretimeout if it doesn't fit the new timeout */
+ if (wdd->pretimeout > wdd->timeout)
+ wdd->pretimeout = 0;
+ }
watchdog_update_worker(wdd);
@@ -319,6 +323,31 @@ static int watchdog_set_timeout(struct watchdog_device *wdd,
}
/*
+ * watchdog_set_pretimeout: set the watchdog timer pretimeout
+ * @wdd: the watchdog device to set the timeout for
+ * @timeout: pretimeout to set in seconds
+ */
+
+static int watchdog_set_pretimeout(struct watchdog_device *wdd,
+ unsigned int timeout)
+{
+ int err = 0;
+
+ if (!(wdd->info->options & WDIOF_PRETIMEOUT))
+ return -EOPNOTSUPP;
+
+ if (watchdog_pretimeout_invalid(wdd, timeout))
+ return -EINVAL;
+
+ if (wdd->ops->set_pretimeout)
+ err = wdd->ops->set_pretimeout(wdd, timeout);
+ else
+ wdd->pretimeout = timeout;
+
+ return err;
+}
+
+/*
* watchdog_get_timeleft: wrapper to get the time left before a reboot
* @wdd: the watchdog device to get the remaining time from
* @timeleft: the time that's left
@@ -402,6 +431,15 @@ static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
}
static DEVICE_ATTR_RO(timeout);
+static ssize_t pretimeout_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct watchdog_device *wdd = dev_get_drvdata(dev);
+
+ return sprintf(buf, "%u\n", wdd->pretimeout);
+}
+static DEVICE_ATTR_RO(pretimeout);
+
static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
@@ -441,6 +479,7 @@ static struct attribute *wdt_attrs[] = {
&dev_attr_state.attr,
&dev_attr_identity.attr,
&dev_attr_timeout.attr,
+ &dev_attr_pretimeout.attr,
&dev_attr_timeleft.attr,
&dev_attr_bootstatus.attr,
&dev_attr_status.attr,
@@ -621,6 +660,16 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
break;
err = put_user(val, p);
break;
+ case WDIOC_SETPRETIMEOUT:
+ if (get_user(val, p)) {
+ err = -EFAULT;
+ break;
+ }
+ err = watchdog_set_pretimeout(wdd, val);
+ break;
+ case WDIOC_GETPRETIMEOUT:
+ err = put_user(wdd->pretimeout, p);
+ break;
default:
err = -ENOTTY;
break;
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index 4b2fa45370fceb..496e52e5b91fc7 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -29,6 +29,7 @@ struct watchdog_governor;
* @ping: The routine that sends a keepalive ping to the watchdog device.
* @status: The routine that shows the status of the watchdog device.
* @set_timeout:The routine for setting the watchdog devices timeout value (in seconds).
+ * @set_pretimeout:The routine for setting the watchdog devices pretimeout.
* @get_timeleft:The routine that gets the time left before a reset (in seconds).
* @restart: The routine for restarting the machine.
* @ioctl: The routines that handles extra ioctl calls.
@@ -47,6 +48,7 @@ struct watchdog_ops {
int (*ping)(struct watchdog_device *);
unsigned int (*status)(struct watchdog_device *);
int (*set_timeout)(struct watchdog_device *, unsigned int);
+ int (*set_pretimeout)(struct watchdog_device *, unsigned int);
unsigned int (*get_timeleft)(struct watchdog_device *);
int (*restart)(struct watchdog_device *, unsigned long, void *);
long (*ioctl)(struct watchdog_device *, unsigned int, unsigned long);
@@ -63,6 +65,7 @@ struct watchdog_ops {
* @gov: Pointer to watchdog pretimeout governor.
* @bootstatus: Status of the watchdog device at boot.
* @timeout: The watchdog devices timeout value (in seconds).
+ * @pretimeout: The watchdog devices pre_timeout value.
* @min_timeout:The watchdog devices minimum timeout value (in seconds).
* @max_timeout:The watchdog devices maximum timeout value (in seconds)
* as configurable from user space. Only relevant if
@@ -98,6 +101,7 @@ struct watchdog_device {
struct watchdog_governor *gov;
unsigned int bootstatus;
unsigned int timeout;
+ unsigned int pretimeout;
unsigned int min_timeout;
unsigned int max_timeout;
unsigned int min_hw_heartbeat_ms;
@@ -165,6 +169,13 @@ static inline bool watchdog_timeout_invalid(struct watchdog_device *wdd, unsigne
t > wdd->max_timeout);
}
+/* Use the following function to check if a pretimeout value is invalid */
+static inline bool watchdog_pretimeout_invalid(struct watchdog_device *wdd,
+ unsigned int t)
+{
+ return t && wdd->timeout && t >= wdd->timeout;
+}
+
/* Use the following functions to manipulate watchdog driver specific data */
static inline void watchdog_set_drvdata(struct watchdog_device *wdd, void *data)
{
--
2.8.1
