[PATCH v8 4/5] Watchdog: introdouce "pretimeout" into framework

From: fu . wei
Date: Tue Oct 27 2015 - 12:08:07 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>
Tested-by: Pratyush Anand <panand@xxxxxxxxxx>
---
Documentation/watchdog/watchdog-kernel-api.txt | 55 +++++++++--
drivers/watchdog/watchdog_core.c | 127 +++++++++++++++++++------
drivers/watchdog/watchdog_dev.c | 53 +++++++++++
include/linux/watchdog.h | 39 +++++++-
4 files changed, 232 insertions(+), 42 deletions(-)

diff --git a/Documentation/watchdog/watchdog-kernel-api.txt b/Documentation/watchdog/watchdog-kernel-api.txt
index d8b0d33..9be942c 100644
--- a/Documentation/watchdog/watchdog-kernel-api.txt
+++ b/Documentation/watchdog/watchdog-kernel-api.txt
@@ -53,6 +53,9 @@ 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;
@@ -75,6 +78,9 @@ 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.
@@ -99,6 +105,7 @@ 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 *);
@@ -156,13 +163,24 @@ they are supported. These optional routines/operations are:
* status: this routine checks the status of the watchdog timer device. The
status of the device is reported with watchdog WDIOF_* status flags/bits.
* set_timeout: this routine checks and changes the timeout 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 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).
+ timer device. It returns 0 on success, -EINVAL for "parameter out of
+ range" (e.g., if the driver supports pretimeout, then the requested
+ timeout value must be greater than the pretimeout value) and -EIO for
+ "could not write value to the watchdog". On success this routine will
+ set the timeout value of the watchdog_device to an actual timeout value
+ (which may be different from the requested one because the watchdog does
+ not necessarily have a 1 second resolution).
(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 will set the pretimeout value of the
+ watchdog_device to an actual pretimeout value (which may be different
+ from the requested one because the watchdog does not necessarily have 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.
@@ -226,8 +244,27 @@ 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 the 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 stages of timeout (timeout and pretimeout).
+To initialize the timeout and pretimeout fields at the same time, the
+following function can be used:
+
+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 from
+the device tree (if the module pretimeout and timeout parameter are
+invalid). Best practice is to set the default pretimeout and timeout
+values as pretimeout and timeout values 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 1a80594..44918d5 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c
@@ -85,57 +85,126 @@ static void watchdog_deferred_registration_del(struct watchdog_device *wdd)
static void watchdog_check_min_max_timeout(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 all to 0 (=not used or unknown)
*/
- if (wdd->min_timeout > wdd->max_timeout) {
- pr_info("Invalid min and max timeout values, resetting to 0!\n");
+ if (wdd->min_pretimeout > wdd->max_pretimeout ||
+ wdd->min_timeout > wdd->max_timeout ||
+ wdd->min_timeout < wdd->min_pretimeout ||
+ wdd->max_timeout < wdd->max_pretimeout) {
+ pr_info("Invalid min or max timeouts, resetting to 0\n");
+ wdd->min_pretimeout = 0;
+ wdd->max_pretimeout = 0;
wdd->min_timeout = 0;
wdd->max_timeout = 0;
}
}

/**
- * 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 both the pretimeout and timeout module parameters (if they are valid) or
+ * the timeout-sec property (only if they are valid and the pretimeout_parm or
+ * timeout_parm is out of bounds). If one of them is invalid, 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};
+ struct property *prop;

watchdog_check_min_max_timeout(wdd);

- /* try to get the timeout module parameter first */
- if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) {
- wdd->timeout = timeout_parm;
- return ret;
- }
- if (timeout_parm)
+ /*
+ * Backup the timeouts of wdd, and set them to the parameters,
+ * because watchdog_pretimeout_invalid uses wdd->timeout to validate
+ * the pretimeout_parm, and watchdog_timeout_invalid uses
+ * wdd->pretimeout to validate timeout_parm.
+ * if any of parameters is wrong, restore the default values before
+ * return.
+ */
+ timeouts[0] = wdd->timeout;
+ timeouts[1] = wdd->pretimeout;
+ wdd->timeout = timeout_parm;
+ wdd->pretimeout = pretimeout_parm;
+
+ /*
+ * Try to get the pretimeout module parameter first.
+ * Note: zero is a valid value for pretimeout.
+ */
+ if (watchdog_pretimeout_invalid(wdd, pretimeout_parm))
ret = -EINVAL;

- /* try to get the timeout_sec property */
- 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
+ /*
+ * Try to get the timeout module parameter,
+ * if it's valid and pretimeout is valid(ret == 0),
+ * assignment and return zero. Otherwise, try dtb.
+ */
+ if (timeout_parm && !ret) {
+ if (!watchdog_timeout_invalid(wdd, timeout_parm))
+ return 0;
ret = -EINVAL;
+ }

- return ret;
+ /*
+ * Either at least one of the module parameters is invalid,
+ * or timeout_parm is 0. Try to get the timeout_sec property.
+ */
+ if (!dev || !dev->of_node) {
+ wdd->timeout = timeouts[0];
+ wdd->pretimeout = timeouts[1];
+ return ret;
+ }
+
+ /*
+ * Backup default values to *_parms,
+ * timeouts[] will be used by of_property_read_u32_array.
+ */
+ timeout_parm = timeouts[0];
+ pretimeout_parm = timeouts[1];
+
+ prop = of_find_property(dev->of_node, "timeout-sec", &length);
+ if (prop && length > 0 && length <= sizeof(u32) * 2) {
+ of_property_read_u32_array(dev->of_node,
+ "timeout-sec", timeouts,
+ length / sizeof(u32));
+ wdd->timeout = timeouts[0];
+ wdd->pretimeout = timeouts[1];
+
+ if (length == sizeof(u32) * 2) {
+ if (watchdog_pretimeout_invalid(wdd, timeouts[1]))
+ goto error;
+ ret = 0;
+ } else {
+ ret = -EINVAL;
+ }
+
+ if (!watchdog_timeout_invalid(wdd, timeouts[0]) &&
+ timeouts[0]) {
+ if (ret) /* Only one value in "timeout-sec" */
+ wdd->pretimeout = pretimeout_parm;
+ return 0;
+ }
+ }
+
+error:
+ /* restore default values */
+ wdd->timeout = timeout_parm;
+ wdd->pretimeout = pretimeout_parm;
+
+ return -EINVAL;
}
-EXPORT_SYMBOL_GPL(watchdog_init_timeout);
+EXPORT_SYMBOL_GPL(watchdog_init_timeouts);

static int __watchdog_register_device(struct watchdog_device *wdd)
{
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 d74a0e9..eaea7b0 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.
@@ -88,6 +93,9 @@ 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;
@@ -119,8 +127,22 @@ static inline void watchdog_set_nowayout(struct watchdog_device *wdd, bool noway
/* Use the following function to check if a timeout value is invalid */
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));
+ return (wdd->max_timeout &&
+ (t < wdd->min_timeout || t > wdd->max_timeout)) ||
+ (wdd->pretimeout && t <= wdd->pretimeout);
+}
+
+/*
+ * Use the following function to check if a pretimeout value is invalid.
+ * It can be "0", that means we don't use pretimeout.
+ * This function returns false, when pretimeout is 0.
+ */
+static inline bool watchdog_pretimeout_invalid(struct watchdog_device *wdd,
+ unsigned int t)
+{
+ return t && ((wdd->max_pretimeout &&
+ (t < wdd->min_pretimeout || t > wdd->max_pretimeout)) ||
+ (wdd->timeout && t >= wdd->timeout));
}

/* Use the following functions to manipulate watchdog driver specific data */
@@ -135,8 +157,17 @@ 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);
+int watchdog_init_timeouts(struct watchdog_device *wdd,
+ unsigned int pretimeout_parm,
+ unsigned int timeout_parm,
+ struct device *dev);
+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);
+}
+
extern int watchdog_register_device(struct watchdog_device *);
extern void watchdog_unregister_device(struct watchdog_device *);

--
2.4.3

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