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Message-ID: <20140516012234.GA16592@roeck-us.net>
Date: Thu, 15 May 2014 18:22:34 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: linux-watchdog@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org
Cc: Wim Van Sebroeck <wim@...ana.be>,
Catalin Marinas <catalin.marinas@....com>,
Maxime Ripard <maxime.ripard@...e-electrons.com>,
Will Deacon <will.deacon@....com>,
Arnd Bergmann <arnd@...db.de>,
Heiko Stuebner <heiko@...ech.de>,
Russell King <linux@....linux.org.uk>,
Jonas Jensen <jonas.jensen@...il.com>,
Randy Dunlap <rdunlap@...radead.org>,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v4 1/6] watchdog: Add API to trigger reboots
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@...ck-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
--
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