watchdog: add watchdog pretimeout governor framework

[cascardo/linux.git] / drivers / watchdog / watchdog_pretimeout.c

diff --git a/drivers/watchdog/watchdog_pretimeout.c b/drivers/watchdog/watchdog_pretimeout.c
new file mode 100644 (file)
index 0000000..7261225
--- /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);
+}