[PATCH v4 4/7] Watchdog: introdouce "pretimeout" into framework

From: fu . wei
Date: Tue Jun 02 2015 - 00:06:54 EST

From: Fu Wei <fu.wei@xxxxxxxxxx>

Also update Documentation/watchdog/watchdog-kernel-api.txt to
introduce:
(1)the new elements in the watchdog_device and watchdog_ops struct;
(2)the new API "watchdog_init_timeouts"

Reasons:
(1)kernel already has two watchdog drivers are using "pretimeout":
drivers/char/ipmi/ipmi_watchdog.c
drivers/watchdog/kempld_wdt.c(but the definition is different)
(2)some other drivers are going to use this: ARM SBSA Generic Watchdog

Signed-off-by: Fu Wei <fu.wei@xxxxxxxxxx>
---
Documentation/watchdog/watchdog-kernel-api.txt | 47 ++++++++--
drivers/watchdog/watchdog_core.c | 115 +++++++++++++++++++------
drivers/watchdog/watchdog_dev.c | 53 ++++++++++++
include/linux/watchdog.h | 33 ++++++-
4 files changed, 212 insertions(+), 36 deletions(-)

diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index a0438f3..95b355d 100644
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -49,6 +49,9 @@ struct watchdog_device {
unsigned int timeout;
unsigned int min_timeout;
unsigned int max_timeout;
+ unsigned int pretimeout;
+ unsigned int min_pretimeout;
+ unsigned int max_pretimeout;
void *driver_data;
struct mutex lock;
unsigned long status;
@@ -70,6 +73,9 @@ It contains following fields:
* timeout: the watchdog timer's timeout value (in seconds).
* min_timeout: the watchdog timer's minimum timeout value (in seconds).
* max_timeout: the watchdog timer's maximum timeout value (in seconds).
+* pretimeout: the watchdog timer's pretimeout value (in seconds).
+* min_pretimeout: the watchdog timer's minimum pretimeout value (in seconds).
+* max_pretimeout: the watchdog timer's maximum pretimeout value (in seconds).
* bootstatus: status of the device after booting (reported with watchdog
WDIOF_* status bits).
* driver_data: a pointer to the drivers private data of a watchdog device.
@@ -92,6 +98,7 @@ 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 *);
void (*ref)(struct watchdog_device *);
void (*unref)(struct watchdog_device *);
@@ -153,9 +160,19 @@ they are supported. These optional routines/operations are:
and -EIO for "could not write value to the watchdog". On success this
routine should set the timeout value of the watchdog_device to the
achieved timeout value (which may be different from the requested one
- because the watchdog does not necessarily has a 1 second resolution).
+ because the watchdog does not necessarily has a 1 second resolution;
+ If the driver supports pretimeout, then the timeout value must be greater
+ than that).
(Note: the WDIOF_SETTIMEOUT needs to be set in the options field of the
watchdog's info structure).
+* set_pretimeout: this routine checks and changes the pretimeout of the
+ watchdog timer device. It returns 0 on success, -EINVAL for "parameter out of
+ range" and -EIO for "could not write value to the watchdog". On success this
+ routine should set the pretimeout value of the watchdog_device to the
+ achieved pretimeout value (which may be different from the requested one
+ because the watchdog does not necessarily has a 1 second resolution).
+ (Note: the WDIOF_PRETIMEOUT needs to be set in the options field of the
+ watchdog's info structure).
* get_timeleft: this routines returns the time that's left before a reset.
* ref: the operation that calls kref_get on the kref of a dynamically
allocated watchdog_device struct.
@@ -219,8 +236,28 @@ extern int watchdog_init_timeout(struct watchdog_device *wdd,
unsigned int timeout_parm, struct device *dev);

The watchdog_init_timeout function allows you to initialize the timeout field
-using the module timeout parameter or by retrieving the timeout-sec property from
-the device tree (if the module timeout parameter is invalid). Best practice is
-to set the default timeout value as timeout value in the watchdog_device and
-then use this function to set the user "preferred" timeout value.
+using the module timeout parameter or by retrieving the first element of
+the timeout-sec property from the device tree (if the module timeout parameter
+is invalid). Best practice is to set the default timeout value as timeout value
+in the watchdog_device and then use this function to set the user "preferred"
+timeout value.
+This routine returns zero on success and a negative errno code for failure.
+
+Some watchdog timers have two stage of timeouts(timeout and pretimeout),
+to initialize the timeout and pretimeout fields at the same time, the following
+function can be used:
+
+extern int watchdog_init_timeouts(struct watchdog_device *wdd,
+ unsigned int pretimeout_parm,
+ unsigned int timeout_parm,
+ struct device *dev);
+
+The watchdog_init_timeouts function allows you to initialize the pretimeout and
+timeout fields using the module pretimeout and timeout parameter or by
+retrieving the elements in the timeout-sec property(the first element is for
+timeout, the second one is for pretimeout) from the device tree(if the module
+pretimeout and timeout parameter are invalid).
+Best practice is to set the default pretimeout and timeout value as pretimeout
+and timeout value in the watchdog_device and then use this function to set the
+user "preferred" pretimeout value.
This routine returns zero on success and a negative errno code for failure.
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index cec9b55..ff18db3 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -43,60 +43,119 @@
static DEFINE_IDA(watchdog_ida);
static struct class *watchdog_class;

-static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
+static void watchdog_check_min_max_timeouts(struct watchdog_device *wdd)
{
/*
- * Check that we have valid min and max timeout values, if
- * not reset them both to 0 (=not used or unknown)
+ * Check that we have valid min and max pretimeout and timeout values,
+ * if not reset them both to 0 (=not used or unknown)
*/
+ if (wdd->min_pretimeout > wdd->max_pretimeout) {
+ pr_info("Invalid min and max pretimeout, resetting to 0\n");
+ wdd->min_pretimeout = 0;
+ wdd->max_pretimeout = 0;
+ }
if (wdd->min_timeout > wdd->max_timeout) {
pr_info("Invalid min and max timeout values, resetting to 0!\n");
wdd->min_timeout = 0;
wdd->max_timeout = 0;
}
+ /*
+ * Check that we have valid min timeout and max pretimeout values,
+ * if not reset them.
+ */
+ if (wdd->min_pretimeout && wdd->min_timeout < wdd->min_pretimeout) {
+ pr_info("Invalid min_timeout, resetting to min_pretimeout+1\n");
+ wdd->min_timeout = wdd->min_pretimeout + 1;
+ }
+ if (wdd->max_pretimeout && wdd->max_timeout < wdd->max_pretimeout) {
+ pr_info("Invalid max_pretimeout, resetting to max_timeout-1\n");
+ wdd->max_pretimeout = wdd->max_timeout - 1;
+ }
}

/**
- * watchdog_init_timeout() - initialize the timeout field
+ * watchdog_init_timeouts() - initialize the pretimeout and timeout field
+ * @pretimeout_parm: pretimeout module parameter
* @timeout_parm: timeout module parameter
* @dev: Device that stores the timeout-sec property
*
- * Initialize the timeout field of the watchdog_device struct with either the
- * timeout module parameter (if it is valid value) or the timeout-sec property
- * (only if it is a valid value and the timeout_parm is out of bounds).
- * If none of them are valid then we keep the old value (which should normally
- * be the default timeout value.
+ * Initialize the pretimeout and timeout field of the watchdog_device struct
+ * with either the pretimeout and timeout module parameter (if it is valid
+ * value) or the timeout-sec property (only if it is a valid value and the
+ * pretimeout_parm and timeout_parm is out of bounds). If none of them are
+ * valid, then we keep the old value (which should normally be the default
+ * timeout value).
*
* A zero is returned on success and -EINVAL for failure.
*/
-int watchdog_init_timeout(struct watchdog_device *wdd,
- unsigned int timeout_parm, struct device *dev)
+int watchdog_init_timeouts(struct watchdog_device *wdd,
+ unsigned int pretimeout_parm,
+ unsigned int timeout_parm,
+ struct device *dev)
{
- unsigned int t = 0;
- int ret = 0;
+ int ret = 0, length = 0;
+ u32 timeouts[2] = {0};

- watchdog_check_min_max_timeout(wdd);
+ watchdog_check_min_max_timeouts(wdd);

- /* try to get the timeout module parameter first */
- if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) {
- wdd->timeout = timeout_parm;
- return ret;
+ /*
+ * Try to get the pretimeout module parameter first,
+ * but it can be "0", that means we don't use pretimeout.
+ */
+ if (pretimeout_parm) {
+ if (!watchdog_pretimeout_invalid(wdd, pretimeout_parm))
+ timeouts[1] = pretimeout_parm;
+ ret = -EINVAL; /* pretimeout_parm is not "0", and invalid */
}
- if (timeout_parm)
+
+ /*
+ * Try to get the timeout module parameter,
+ * if it's valid and pretimeout is ont invalid(ret == 0),
+ * assignment and return zero. Otherwise, try dtb.
+ */
+ if (timeout_parm) {
+ if (!watchdog_timeout_invalid(wdd, timeout_parm) && !ret) {
+ wdd->timeout = timeout_parm;
+ wdd->pretimeout = timeouts[1];
+ return 0;
+ }
ret = -EINVAL;
+ }

- /* try to get the timeout_sec property */
+ /*
+ * We get here, the situation is one of them:
+ * (1)at least one of parameters is invalid(ret = -EINVAL);
+ * (2)both of them are 0.(ret = 0)
+ * So give up the module parameter(at least drop the invalid one),
+ * try to get the timeout_sec property from dtb.
+ */
if (dev == NULL || dev->of_node == NULL)
return ret;
- of_property_read_u32(dev->of_node, "timeout-sec", &t);
- if (!watchdog_timeout_invalid(wdd, t) && t)
- wdd->timeout = t;
- else
- ret = -EINVAL;

- return ret;
+ /*
+ * We get here, that means maybe we can get timeouts from dtb,
+ * if "timeout-sec" is available and the data is valid.
+ */
+ of_find_property(dev->of_node, "timeout-sec", &length);
+ if (length > 0 && length <= sizeof(u32) * 2) {
+ of_property_read_u32_array(dev->of_node,
+ "timeout-sec", timeouts,
+ length / sizeof(u32));
+ if (length == sizeof(u32) * 2 && timeouts[1] &&
+ watchdog_pretimeout_invalid(wdd, timeouts[1]))
+ return -EINVAL; /* pretimeout is invalid */
+
+ if (!watchdog_timeout_invalid(wdd, timeouts[0]) &&
+ timeouts[0]) {
+ wdd->timeout = timeouts[0];
+ wdd->pretimeout = timeouts[1];
+ return 0;
+ }
+ }
+
+ return -EINVAL;
}
-EXPORT_SYMBOL_GPL(watchdog_init_timeout);
+EXPORT_SYMBOL_GPL(watchdog_init_timeouts);

/**
* watchdog_register_device() - register a watchdog device
@@ -119,7 +178,7 @@ int watchdog_register_device(struct watchdog_device *wdd)
if (wdd->ops->start == NULL || wdd->ops->stop == NULL)
return -EINVAL;

- watchdog_check_min_max_timeout(wdd);
+ watchdog_check_min_max_timeouts(wdd);

/*
* Note: now that all watchdog_device data has been verified, we
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 6aaefba..af0777e 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -218,6 +218,38 @@ out_timeout:
}

/*
+ * watchdog_set_pretimeout: set the watchdog timer pretimeout
+ * @wddev: the watchdog device to set the timeout for
+ * @pretimeout: pretimeout to set in seconds
+ */
+
+static int watchdog_set_pretimeout(struct watchdog_device *wddev,
+ unsigned int pretimeout)
+{
+ int err;
+
+ if (!wddev->ops->set_pretimeout ||
+ !(wddev->info->options & WDIOF_PRETIMEOUT))
+ return -EOPNOTSUPP;
+
+ if (watchdog_pretimeout_invalid(wddev, pretimeout))
+ return -EINVAL;
+
+ mutex_lock(&wddev->lock);
+
+ if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
+ err = -ENODEV;
+ goto out_pretimeout;
+ }
+
+ err = wddev->ops->set_pretimeout(wddev, pretimeout);
+
+out_pretimeout:
+ mutex_unlock(&wddev->lock);
+ return err;
+}
+
+/*
* watchdog_get_timeleft: wrapper to get the time left before a reboot
* @wddev: the watchdog device to get the remaining time from
* @timeleft: the time that's left
@@ -388,6 +420,27 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
if (wdd->timeout == 0)
return -EOPNOTSUPP;
return put_user(wdd->timeout, p);
+ case WDIOC_SETPRETIMEOUT:
+ /* check if we support the pretimeout */
+ if (!(wdd->info->options & WDIOF_PRETIMEOUT))
+ return -EOPNOTSUPP;
+ if (get_user(val, p))
+ return -EFAULT;
+ err = watchdog_set_pretimeout(wdd, val);
+ if (err < 0)
+ return err;
+ /*
+ * If the watchdog is active then we send a keepalive ping
+ * to make sure that the watchdog keeps running (and if
+ * possible that it takes the new pretimeout)
+ */
+ watchdog_ping(wdd);
+ /* Fall */
+ case WDIOC_GETPRETIMEOUT:
+ /* check if we support the pretimeout */
+ if (wdd->info->options & WDIOF_PRETIMEOUT)
+ return put_user(wdd->pretimeout, p);
+ return -EOPNOTSUPP;
case WDIOC_GETTIMELEFT:
err = watchdog_get_timeleft(wdd, &val);
if (err)
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index a746bf5..b1e325d 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -25,6 +25,7 @@ struct watchdog_device;
* @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.
+ * @set_pretimeout:The routine for setting the watchdog devices pretimeout value
* @get_timeleft:The routine that get's the time that's left before a reset.
* @ref: The ref operation for dyn. allocated watchdog_device structs
* @unref: The unref operation for dyn. allocated watchdog_device structs
@@ -44,6 +45,7 @@ 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 *);
void (*ref)(struct watchdog_device *);
void (*unref)(struct watchdog_device *);
@@ -62,6 +64,9 @@ struct watchdog_ops {
* @timeout: The watchdog devices timeout value.
* @min_timeout:The watchdog devices minimum timeout value.
* @max_timeout:The watchdog devices maximum timeout value.
+ * @pretimeout: The watchdog devices pretimeout value.
+ * @min_pretimeout:The watchdog devices minimum pretimeout value.
+ * @max_pretimeout:The watchdog devices maximum pretimeout value.
* @driver-data:Pointer to the drivers private data.
* @lock: Lock for watchdog core internal use only.
* @status: Field that contains the devices internal status bits.
@@ -86,6 +91,9 @@ struct watchdog_device {
unsigned int timeout;
unsigned int min_timeout;
unsigned int max_timeout;
+ unsigned int pretimeout;
+ unsigned int min_pretimeout;
+ unsigned int max_pretimeout;
void *driver_data;
struct mutex lock;
unsigned long status;
@@ -117,7 +125,17 @@ static inline void watchdog_set_nowayout(struct watchdog_device *wdd, bool noway
static inline bool watchdog_timeout_invalid(struct watchdog_device *wdd, unsigned int t)
{
return ((wdd->max_timeout != 0) &&
- (t < wdd->min_timeout || t > wdd->max_timeout));
+ (t < wdd->min_timeout || t > wdd->max_timeout ||
+ t <= wdd->pretimeout));
+}
+
+/* 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 (wdd->max_pretimeout != 0 &&
+ (t < wdd->min_pretimeout || t > wdd->max_pretimeout ||
+ (wdd->timeout != 0 && t >= wdd->timeout)));
}

/* Use the following functions to manipulate watchdog driver specific data */
@@ -132,11 +150,20 @@ static inline void *watchdog_get_drvdata(struct watchdog_device *wdd)
}

/* drivers/watchdog/watchdog_core.c */
-extern int watchdog_init_timeout(struct watchdog_device *wdd,
- unsigned int timeout_parm, struct device *dev);
+extern int watchdog_init_timeouts(struct watchdog_device *wdd,
+ unsigned int pretimeout_parm,
+ unsigned int timeout_parm,
+ struct device *dev);
extern int watchdog_register_device(struct watchdog_device *);
extern void watchdog_unregister_device(struct watchdog_device *);

+static inline int watchdog_init_timeout(struct watchdog_device *wdd,
+ unsigned int timeout_parm,
+ struct device *dev)
+{
+ return watchdog_init_timeouts(wdd, 0, timeout_parm, dev);
+}
+
#ifdef CONFIG_HARDLOCKUP_DETECTOR
void watchdog_nmi_disable_all(void);
void watchdog_nmi_enable_all(void);
--
1.9.1

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