From ff84136cb6a4943f489ad037fe93f43be0573c23 Mon Sep 17 00:00:00 2001 From: Vladimir Zapolskiy Date: Fri, 7 Oct 2016 15:39:54 +0300 Subject: 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 Reviewed-by: Guenter Roeck Reviewed-by: Wolfram Sang Tested-by: Wolfram Sang Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck --- drivers/watchdog/watchdog_pretimeout.c | 131 +++++++++++++++++++++++++++++++++ 1 file changed, 131 insertions(+) create mode 100644 drivers/watchdog/watchdog_pretimeout.c (limited to 'drivers/watchdog/watchdog_pretimeout.c') 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 +#include +#include +#include + +#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); +} -- cgit v1.2.3-59-g8ed1b