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authorVladimir Zapolskiy <vladimir_zapolskiy@mentor.com>2016-10-07 15:39:54 +0300
committerWim Van Sebroeck <wim@iguana.be>2016-10-08 10:27:10 +0200
commitff84136cb6a4943f489ad037fe93f43be0573c23 (patch)
treebde99dc52bf4066e666681d280011d37d17d269a /drivers/watchdog/watchdog_pretimeout.c
parentfc113d54e9d7ef3296cdf2eff49c8ca0a3e5a482 (diff)
watchdog: add watchdog pretimeout governor framework
The change adds a simple watchdog pretimeout framework infrastructure, its purpose is to allow users to select a desired handling of watchdog pretimeout events, which may be generated by some watchdog devices. A user selects a default watchdog pretimeout governor during compilation stage. Watchdogs with WDIOF_PRETIMEOUT capability now have one more device attribute in sysfs, pretimeout_governor attribute is intended to display the selected watchdog pretimeout governor. The framework has no impact at runtime on watchdog devices with no WDIOF_PRETIMEOUT capability set. Signed-off-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Diffstat (limited to 'drivers/watchdog/watchdog_pretimeout.c')
-rw-r--r--drivers/watchdog/watchdog_pretimeout.c131
1 files changed, 131 insertions, 0 deletions
diff --git a/drivers/watchdog/watchdog_pretimeout.c b/drivers/watchdog/watchdog_pretimeout.c
new file mode 100644
index 000000000000..72612255fb55
--- /dev/null
+++ b/drivers/watchdog/watchdog_pretimeout.c
@@ -0,0 +1,131 @@
+/*
+ * Copyright (C) 2015-2016 Mentor Graphics
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ */
+
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/watchdog.h>
+
+#include "watchdog_pretimeout.h"
+
+/* Default watchdog pretimeout governor */
+static struct watchdog_governor *default_gov;
+
+/* The spinlock protects default_gov, wdd->gov and pretimeout_list */
+static DEFINE_SPINLOCK(pretimeout_lock);
+
+/* List of watchdog devices, which can generate a pretimeout event */
+static LIST_HEAD(pretimeout_list);
+
+struct watchdog_pretimeout {
+ struct watchdog_device *wdd;
+ struct list_head entry;
+};
+
+int watchdog_pretimeout_governor_get(struct watchdog_device *wdd, char *buf)
+{
+ int count = 0;
+
+ spin_lock_irq(&pretimeout_lock);
+ if (wdd->gov)
+ count = sprintf(buf, "%s\n", wdd->gov->name);
+ spin_unlock_irq(&pretimeout_lock);
+
+ return count;
+}
+
+void watchdog_notify_pretimeout(struct watchdog_device *wdd)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&pretimeout_lock, flags);
+ if (!wdd->gov) {
+ spin_unlock_irqrestore(&pretimeout_lock, flags);
+ return;
+ }
+
+ wdd->gov->pretimeout(wdd);
+ spin_unlock_irqrestore(&pretimeout_lock, flags);
+}
+EXPORT_SYMBOL_GPL(watchdog_notify_pretimeout);
+
+int watchdog_register_governor(struct watchdog_governor *gov)
+{
+ struct watchdog_pretimeout *p;
+
+ if (!default_gov) {
+ spin_lock_irq(&pretimeout_lock);
+ default_gov = gov;
+
+ list_for_each_entry(p, &pretimeout_list, entry)
+ if (!p->wdd->gov)
+ p->wdd->gov = default_gov;
+ spin_unlock_irq(&pretimeout_lock);
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL(watchdog_register_governor);
+
+void watchdog_unregister_governor(struct watchdog_governor *gov)
+{
+ struct watchdog_pretimeout *p;
+
+ spin_lock_irq(&pretimeout_lock);
+ if (gov == default_gov)
+ default_gov = NULL;
+
+ list_for_each_entry(p, &pretimeout_list, entry)
+ if (p->wdd->gov == gov)
+ p->wdd->gov = default_gov;
+ spin_unlock_irq(&pretimeout_lock);
+}
+EXPORT_SYMBOL(watchdog_unregister_governor);
+
+int watchdog_register_pretimeout(struct watchdog_device *wdd)
+{
+ struct watchdog_pretimeout *p;
+
+ if (!(wdd->info->options & WDIOF_PRETIMEOUT))
+ return 0;
+
+ p = kzalloc(sizeof(*p), GFP_KERNEL);
+ if (!p)
+ return -ENOMEM;
+
+ spin_lock_irq(&pretimeout_lock);
+ list_add(&p->entry, &pretimeout_list);
+ p->wdd = wdd;
+ wdd->gov = default_gov;
+ spin_unlock_irq(&pretimeout_lock);
+
+ return 0;
+}
+
+void watchdog_unregister_pretimeout(struct watchdog_device *wdd)
+{
+ struct watchdog_pretimeout *p, *t;
+
+ if (!(wdd->info->options & WDIOF_PRETIMEOUT))
+ return;
+
+ spin_lock_irq(&pretimeout_lock);
+ wdd->gov = NULL;
+
+ list_for_each_entry_safe(p, t, &pretimeout_list, entry) {
+ if (p->wdd == wdd) {
+ list_del(&p->entry);
+ break;
+ }
+ }
+ spin_unlock_irq(&pretimeout_lock);
+
+ kfree(p);
+}