![Wolfram Sang](/assets/img/avatar_default.png)
This not only removes boilerplate code from watchdog drivers, it can also be more specific which of the supplied value actually fails. Also, the loglevel becomes now consistent across drivers. Reviewed-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
390 lines
11 KiB
C
390 lines
11 KiB
C
/*
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* watchdog_core.c
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*
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* (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
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* All Rights Reserved.
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*
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* (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
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*
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* This source code is part of the generic code that can be used
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* by all the watchdog timer drivers.
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*
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* Based on source code of the following authors:
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* Matt Domsch <Matt_Domsch@dell.com>,
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* Rob Radez <rob@osinvestor.com>,
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* Rusty Lynch <rusty@linux.co.intel.com>
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* Satyam Sharma <satyam@infradead.org>
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* Randy Dunlap <randy.dunlap@oracle.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
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* admit liability nor provide warranty for any of this software.
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* This material is provided "AS-IS" and at no charge.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h> /* For EXPORT_SYMBOL/module stuff/... */
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#include <linux/types.h> /* For standard types */
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#include <linux/errno.h> /* For the -ENODEV/... values */
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#include <linux/kernel.h> /* For printk/panic/... */
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#include <linux/reboot.h> /* For restart handler */
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#include <linux/watchdog.h> /* For watchdog specific items */
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#include <linux/init.h> /* For __init/__exit/... */
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#include <linux/idr.h> /* For ida_* macros */
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#include <linux/err.h> /* For IS_ERR macros */
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#include <linux/of.h> /* For of_get_timeout_sec */
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#include "watchdog_core.h" /* For watchdog_dev_register/... */
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static DEFINE_IDA(watchdog_ida);
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/*
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* Deferred Registration infrastructure.
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*
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* Sometimes watchdog drivers needs to be loaded as soon as possible,
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* for example when it's impossible to disable it. To do so,
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* raising the initcall level of the watchdog driver is a solution.
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* But in such case, the miscdev is maybe not ready (subsys_initcall), and
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* watchdog_core need miscdev to register the watchdog as a char device.
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*
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* The deferred registration infrastructure offer a way for the watchdog
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* subsystem to register a watchdog properly, even before miscdev is ready.
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*/
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static DEFINE_MUTEX(wtd_deferred_reg_mutex);
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static LIST_HEAD(wtd_deferred_reg_list);
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static bool wtd_deferred_reg_done;
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static int watchdog_deferred_registration_add(struct watchdog_device *wdd)
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{
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list_add_tail(&wdd->deferred,
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&wtd_deferred_reg_list);
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return 0;
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}
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static void watchdog_deferred_registration_del(struct watchdog_device *wdd)
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{
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struct list_head *p, *n;
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struct watchdog_device *wdd_tmp;
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list_for_each_safe(p, n, &wtd_deferred_reg_list) {
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wdd_tmp = list_entry(p, struct watchdog_device,
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deferred);
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if (wdd_tmp == wdd) {
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list_del(&wdd_tmp->deferred);
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break;
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}
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}
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}
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static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
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{
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/*
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* Check that we have valid min and max timeout values, if
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* not reset them both to 0 (=not used or unknown)
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*/
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if (!wdd->max_hw_heartbeat_ms && wdd->min_timeout > wdd->max_timeout) {
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pr_info("Invalid min and max timeout values, resetting to 0!\n");
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wdd->min_timeout = 0;
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wdd->max_timeout = 0;
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}
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}
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/**
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* watchdog_init_timeout() - initialize the timeout field
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* @wdd: watchdog device
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* @timeout_parm: timeout module parameter
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* @dev: Device that stores the timeout-sec property
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*
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* Initialize the timeout field of the watchdog_device struct with either the
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* timeout module parameter (if it is valid value) or the timeout-sec property
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* (only if it is a valid value and the timeout_parm is out of bounds).
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* If none of them are valid then we keep the old value (which should normally
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* be the default timeout value). Note that for the module parameter, '0' means
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* 'use default' while it is an invalid value for the timeout-sec property.
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* It should simply be dropped if you want to use the default value then.
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*
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* A zero is returned on success or -EINVAL if all provided values are out of
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* bounds.
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*/
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int watchdog_init_timeout(struct watchdog_device *wdd,
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unsigned int timeout_parm, struct device *dev)
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{
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const char *dev_str = wdd->parent ? dev_name(wdd->parent) :
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(const char *)wdd->info->identity;
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unsigned int t = 0;
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int ret = 0;
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watchdog_check_min_max_timeout(wdd);
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/* check the driver supplied value (likely a module parameter) first */
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if (timeout_parm) {
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if (!watchdog_timeout_invalid(wdd, timeout_parm)) {
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wdd->timeout = timeout_parm;
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return 0;
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}
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pr_err("%s: driver supplied timeout (%u) out of range\n",
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dev_str, timeout_parm);
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ret = -EINVAL;
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}
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/* try to get the timeout_sec property */
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if (dev && dev->of_node &&
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of_property_read_u32(dev->of_node, "timeout-sec", &t) == 0) {
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if (t && !watchdog_timeout_invalid(wdd, t)) {
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wdd->timeout = t;
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return 0;
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}
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pr_err("%s: DT supplied timeout (%u) out of range\n", dev_str, t);
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ret = -EINVAL;
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}
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if (ret < 0 && wdd->timeout)
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pr_warn("%s: falling back to default timeout (%u)\n", dev_str,
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wdd->timeout);
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return ret;
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}
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EXPORT_SYMBOL_GPL(watchdog_init_timeout);
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static int watchdog_restart_notifier(struct notifier_block *nb,
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unsigned long action, void *data)
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{
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struct watchdog_device *wdd = container_of(nb, struct watchdog_device,
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restart_nb);
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int ret;
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ret = wdd->ops->restart(wdd, action, data);
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if (ret)
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return NOTIFY_BAD;
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return NOTIFY_DONE;
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}
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/**
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* watchdog_set_restart_priority - Change priority of restart handler
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* @wdd: watchdog device
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* @priority: priority of the restart handler, should follow these guidelines:
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* 0: use watchdog's restart function as last resort, has limited restart
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* capabilies
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* 128: default restart handler, use if no other handler is expected to be
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* available and/or if restart is sufficient to restart the entire system
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* 255: preempt all other handlers
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*
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* If a wdd->ops->restart function is provided when watchdog_register_device is
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* called, it will be registered as a restart handler with the priority given
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* here.
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*/
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void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority)
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{
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wdd->restart_nb.priority = priority;
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}
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EXPORT_SYMBOL_GPL(watchdog_set_restart_priority);
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static int __watchdog_register_device(struct watchdog_device *wdd)
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{
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int ret, id = -1;
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if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
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return -EINVAL;
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/* Mandatory operations need to be supported */
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if (!wdd->ops->start || (!wdd->ops->stop && !wdd->max_hw_heartbeat_ms))
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return -EINVAL;
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watchdog_check_min_max_timeout(wdd);
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/*
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* Note: now that all watchdog_device data has been verified, we
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* will not check this anymore in other functions. If data gets
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* corrupted in a later stage then we expect a kernel panic!
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*/
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/* Use alias for watchdog id if possible */
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if (wdd->parent) {
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ret = of_alias_get_id(wdd->parent->of_node, "watchdog");
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if (ret >= 0)
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id = ida_simple_get(&watchdog_ida, ret,
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ret + 1, GFP_KERNEL);
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}
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if (id < 0)
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id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
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if (id < 0)
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return id;
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wdd->id = id;
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ret = watchdog_dev_register(wdd);
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if (ret) {
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ida_simple_remove(&watchdog_ida, id);
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if (!(id == 0 && ret == -EBUSY))
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return ret;
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/* Retry in case a legacy watchdog module exists */
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id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
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if (id < 0)
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return id;
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wdd->id = id;
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ret = watchdog_dev_register(wdd);
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if (ret) {
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ida_simple_remove(&watchdog_ida, id);
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return ret;
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}
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}
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if (wdd->ops->restart) {
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wdd->restart_nb.notifier_call = watchdog_restart_notifier;
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ret = register_restart_handler(&wdd->restart_nb);
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if (ret)
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pr_warn("watchdog%d: Cannot register restart handler (%d)\n",
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wdd->id, ret);
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}
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return 0;
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}
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/**
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* watchdog_register_device() - register a watchdog device
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* @wdd: watchdog device
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*
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* Register a watchdog device with the kernel so that the
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* watchdog timer can be accessed from userspace.
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*
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* A zero is returned on success and a negative errno code for
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* failure.
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*/
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int watchdog_register_device(struct watchdog_device *wdd)
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{
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int ret;
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mutex_lock(&wtd_deferred_reg_mutex);
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if (wtd_deferred_reg_done)
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ret = __watchdog_register_device(wdd);
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else
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ret = watchdog_deferred_registration_add(wdd);
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mutex_unlock(&wtd_deferred_reg_mutex);
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return ret;
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}
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EXPORT_SYMBOL_GPL(watchdog_register_device);
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static void __watchdog_unregister_device(struct watchdog_device *wdd)
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{
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if (wdd == NULL)
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return;
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if (wdd->ops->restart)
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unregister_restart_handler(&wdd->restart_nb);
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watchdog_dev_unregister(wdd);
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ida_simple_remove(&watchdog_ida, wdd->id);
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}
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/**
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* watchdog_unregister_device() - unregister a watchdog device
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* @wdd: watchdog device to unregister
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*
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* Unregister a watchdog device that was previously successfully
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* registered with watchdog_register_device().
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*/
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void watchdog_unregister_device(struct watchdog_device *wdd)
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{
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mutex_lock(&wtd_deferred_reg_mutex);
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if (wtd_deferred_reg_done)
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__watchdog_unregister_device(wdd);
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else
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watchdog_deferred_registration_del(wdd);
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mutex_unlock(&wtd_deferred_reg_mutex);
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}
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EXPORT_SYMBOL_GPL(watchdog_unregister_device);
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static void devm_watchdog_unregister_device(struct device *dev, void *res)
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{
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watchdog_unregister_device(*(struct watchdog_device **)res);
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}
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/**
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* devm_watchdog_register_device() - resource managed watchdog_register_device()
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* @dev: device that is registering this watchdog device
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* @wdd: watchdog device
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*
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* Managed watchdog_register_device(). For watchdog device registered by this
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* function, watchdog_unregister_device() is automatically called on driver
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* detach. See watchdog_register_device() for more information.
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*/
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int devm_watchdog_register_device(struct device *dev,
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struct watchdog_device *wdd)
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{
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struct watchdog_device **rcwdd;
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int ret;
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rcwdd = devres_alloc(devm_watchdog_unregister_device, sizeof(*rcwdd),
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GFP_KERNEL);
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if (!rcwdd)
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return -ENOMEM;
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ret = watchdog_register_device(wdd);
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if (!ret) {
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*rcwdd = wdd;
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devres_add(dev, rcwdd);
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} else {
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devres_free(rcwdd);
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(devm_watchdog_register_device);
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static int __init watchdog_deferred_registration(void)
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{
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mutex_lock(&wtd_deferred_reg_mutex);
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wtd_deferred_reg_done = true;
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while (!list_empty(&wtd_deferred_reg_list)) {
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struct watchdog_device *wdd;
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wdd = list_first_entry(&wtd_deferred_reg_list,
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struct watchdog_device, deferred);
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list_del(&wdd->deferred);
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__watchdog_register_device(wdd);
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}
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mutex_unlock(&wtd_deferred_reg_mutex);
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return 0;
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}
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static int __init watchdog_init(void)
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{
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int err;
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err = watchdog_dev_init();
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if (err < 0)
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return err;
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watchdog_deferred_registration();
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return 0;
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}
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static void __exit watchdog_exit(void)
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{
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watchdog_dev_exit();
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ida_destroy(&watchdog_ida);
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}
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subsys_initcall_sync(watchdog_init);
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module_exit(watchdog_exit);
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MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
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MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
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MODULE_DESCRIPTION("WatchDog Timer Driver Core");
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MODULE_LICENSE("GPL");
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