[PATCH v4 1/6] watchdog: Add API to trigger reboots
From: linux@roeck-us.net (Guenter Roeck)
Date: 2014-05-16 01:22:51
Also in:
linux-watchdog, lkml
Subsystem:
the rest, watchdog device drivers · Maintainers:
Linus Torvalds, Wim Van Sebroeck, Guenter Roeck
Some hardware implements reboot through its watchdog hardware,
for example by triggering a watchdog timeout. Platform specific
code starts to spread into watchdog drivers, typically by setting
pointers to a callback functions which is then called from the
platform reset handler.
To simplify code and provide a unified API to trigger reboots by
watchdog drivers, provide a single API to trigger such reboots
through the watchdog subsystem.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v4: Protect accesses to wdd_reboot_dev with spinlock to avoid potential
race conditions.
Drop Acked-by and Tested-by tags because changes are too significant
and warrant re-evaluation and re-testing.
v3: Drop reboot mode and cmd string parameters from API
v2: Remove unnecessary check for ops in reboot function
drivers/watchdog/watchdog_core.c | 27 +++++++++++++++++++++++++++
include/linux/watchdog.h | 8 ++++++++
2 files changed, 35 insertions(+)
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
index cec9b55..e61f4ed 100644
--- a/drivers/watchdog/watchdog_core.c
+++ b/drivers/watchdog/watchdog_core.c@@ -37,12 +37,27 @@ #include <linux/idr.h> /* For ida_* macros */ #include <linux/err.h> /* For IS_ERR macros */ #include <linux/of.h> /* For of_get_timeout_sec */ +#include <linux/spinlock.h> /* For spinlock */ #include "watchdog_core.h" /* For watchdog_dev_register/... */ static DEFINE_IDA(watchdog_ida); static struct class *watchdog_class; +static DEFINE_SPINLOCK(wdd_reboot_lock); +static struct watchdog_device *wdd_reboot_dev; + +void watchdog_do_reboot(void) +{ + unsigned long flags; + + spin_lock_irqsave(&wdd_reboot_lock, flags); + if (wdd_reboot_dev) + wdd_reboot_dev->ops->reboot(wdd_reboot_dev); + spin_unlock_irqrestore(&wdd_reboot_lock, flags); +} +EXPORT_SYMBOL(watchdog_do_reboot); + static void watchdog_check_min_max_timeout(struct watchdog_device *wdd) { /*
@@ -111,6 +126,7 @@ EXPORT_SYMBOL_GPL(watchdog_init_timeout); int watchdog_register_device(struct watchdog_device *wdd) { int ret, id, devno; + unsigned long flags; if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL) return -EINVAL;
@@ -162,6 +178,11 @@ int watchdog_register_device(struct watchdog_device *wdd) return ret; } + spin_lock_irqsave(&wdd_reboot_lock, flags); + if (wdd->ops->reboot && !wdd_reboot_dev) + wdd_reboot_dev = wdd; + spin_unlock_irqrestore(&wdd_reboot_lock, flags); + return 0; } EXPORT_SYMBOL_GPL(watchdog_register_device);
@@ -177,10 +198,16 @@ void watchdog_unregister_device(struct watchdog_device *wdd) { int ret; int devno; + unsigned long flags; if (wdd == NULL) return; + spin_lock_irqsave(&wdd_reboot_lock, flags); + if (wdd == wdd_reboot_dev) + wdd_reboot_dev = NULL; + spin_unlock_irqrestore(&wdd_reboot_lock, flags); + devno = wdd->cdev.dev; ret = watchdog_dev_unregister(wdd); if (ret)
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index 2a3038e..1e9da0a 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h@@ -23,6 +23,7 @@ struct watchdog_device; * @start: The routine for starting the watchdog device. * @stop: The routine for stopping the watchdog device. * @ping: The routine that sends a keepalive ping to the watchdog device. + * @reboot: The routine for rebooting the system * @status: The routine that shows the status of the watchdog device. * @set_timeout:The routine for setting the watchdog devices timeout value. * @get_timeleft:The routine that get's the time that's left before a reset.
@@ -42,6 +43,7 @@ struct watchdog_ops { int (*stop)(struct watchdog_device *); /* optional operations */ int (*ping)(struct watchdog_device *); + void (*reboot)(struct watchdog_device *); unsigned int (*status)(struct watchdog_device *); int (*set_timeout)(struct watchdog_device *, unsigned int); unsigned int (*get_timeleft)(struct watchdog_device *);
@@ -142,4 +144,10 @@ extern int watchdog_init_timeout(struct watchdog_device *wdd, extern int watchdog_register_device(struct watchdog_device *); extern void watchdog_unregister_device(struct watchdog_device *); +#ifdef CONFIG_WATCHDOG_CORE +extern void watchdog_do_reboot(void); +#else +static inline void watchdog_do_reboot(void) { } +#endif + #endif /* ifndef _LINUX_WATCHDOG_H */
--
1.9.1