diff options
Diffstat (limited to 'drivers/watchdog/watchdog_core.c')
| -rw-r--r-- | drivers/watchdog/watchdog_core.c | 485 |
1 files changed, 485 insertions, 0 deletions
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c new file mode 100644 index 000000000..c777a612d --- /dev/null +++ b/drivers/watchdog/watchdog_core.c @@ -0,0 +1,485 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * watchdog_core.c + * + * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>, + * All Rights Reserved. + * + * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>. + * + * This source code is part of the generic code that can be used + * by all the watchdog timer drivers. + * + * Based on source code of the following authors: + * Matt Domsch <Matt_Domsch@dell.com>, + * Rob Radez <rob@osinvestor.com>, + * Rusty Lynch <rusty@linux.co.intel.com> + * Satyam Sharma <satyam@infradead.org> + * Randy Dunlap <randy.dunlap@oracle.com> + * + * Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw. + * admit liability nor provide warranty for any of this software. + * This material is provided "AS-IS" and at no charge. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> /* For EXPORT_SYMBOL/module stuff/... */ +#include <linux/types.h> /* For standard types */ +#include <linux/errno.h> /* For the -ENODEV/... values */ +#include <linux/kernel.h> /* For printk/panic/... */ +#include <linux/reboot.h> /* For restart handler */ +#include <linux/watchdog.h> /* For watchdog specific items */ +#include <linux/init.h> /* For __init/__exit/... */ +#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/suspend.h> + +#include "watchdog_core.h" /* For watchdog_dev_register/... */ + +#define CREATE_TRACE_POINTS +#include <trace/events/watchdog.h> + +static DEFINE_IDA(watchdog_ida); + +static int stop_on_reboot = -1; +module_param(stop_on_reboot, int, 0444); +MODULE_PARM_DESC(stop_on_reboot, "Stop watchdogs on reboot (0=keep watching, 1=stop)"); + +/* + * Deferred Registration infrastructure. + * + * Sometimes watchdog drivers needs to be loaded as soon as possible, + * for example when it's impossible to disable it. To do so, + * raising the initcall level of the watchdog driver is a solution. + * But in such case, the miscdev is maybe not ready (subsys_initcall), and + * watchdog_core need miscdev to register the watchdog as a char device. + * + * The deferred registration infrastructure offer a way for the watchdog + * subsystem to register a watchdog properly, even before miscdev is ready. + */ + +static DEFINE_MUTEX(wtd_deferred_reg_mutex); +static LIST_HEAD(wtd_deferred_reg_list); +static bool wtd_deferred_reg_done; + +static void watchdog_deferred_registration_add(struct watchdog_device *wdd) +{ + list_add_tail(&wdd->deferred, + &wtd_deferred_reg_list); +} + +static void watchdog_deferred_registration_del(struct watchdog_device *wdd) +{ + struct list_head *p, *n; + struct watchdog_device *wdd_tmp; + + list_for_each_safe(p, n, &wtd_deferred_reg_list) { + wdd_tmp = list_entry(p, struct watchdog_device, + deferred); + if (wdd_tmp == wdd) { + list_del(&wdd_tmp->deferred); + break; + } + } +} + +static void watchdog_check_min_max_timeout(struct watchdog_device *wdd) +{ + /* + * Check that we have valid min and max timeout values, if + * not reset them both to 0 (=not used or unknown) + */ + if (!wdd->max_hw_heartbeat_ms && wdd->min_timeout > wdd->max_timeout) { + pr_info("Invalid min and max timeout values, resetting to 0!\n"); + wdd->min_timeout = 0; + wdd->max_timeout = 0; + } +} + +/** + * watchdog_init_timeout() - initialize the timeout field + * @wdd: watchdog device + * @timeout_parm: timeout module parameter + * @dev: Device that stores the timeout-sec property + * + * Initialize the timeout field of the watchdog_device struct with either the + * timeout module parameter (if it is valid value) or the timeout-sec property + * (only if it is a valid value and the timeout_parm is out of bounds). + * If none of them are valid then we keep the old value (which should normally + * be the default timeout value). Note that for the module parameter, '0' means + * 'use default' while it is an invalid value for the timeout-sec property. + * It should simply be dropped if you want to use the default value then. + * + * A zero is returned on success or -EINVAL if all provided values are out of + * bounds. + */ +int watchdog_init_timeout(struct watchdog_device *wdd, + unsigned int timeout_parm, struct device *dev) +{ + const char *dev_str = wdd->parent ? dev_name(wdd->parent) : + (const char *)wdd->info->identity; + unsigned int t = 0; + int ret = 0; + + watchdog_check_min_max_timeout(wdd); + + /* check the driver supplied value (likely a module parameter) first */ + if (timeout_parm) { + if (!watchdog_timeout_invalid(wdd, timeout_parm)) { + wdd->timeout = timeout_parm; + return 0; + } + pr_err("%s: driver supplied timeout (%u) out of range\n", + dev_str, timeout_parm); + ret = -EINVAL; + } + + /* try to get the timeout_sec property */ + if (dev && dev->of_node && + of_property_read_u32(dev->of_node, "timeout-sec", &t) == 0) { + if (t && !watchdog_timeout_invalid(wdd, t)) { + wdd->timeout = t; + return 0; + } + pr_err("%s: DT supplied timeout (%u) out of range\n", dev_str, t); + ret = -EINVAL; + } + + if (ret < 0 && wdd->timeout) + pr_warn("%s: falling back to default timeout (%u)\n", dev_str, + wdd->timeout); + + return ret; +} +EXPORT_SYMBOL_GPL(watchdog_init_timeout); + +static int watchdog_reboot_notifier(struct notifier_block *nb, + unsigned long code, void *data) +{ + struct watchdog_device *wdd; + + wdd = container_of(nb, struct watchdog_device, reboot_nb); + if (code == SYS_DOWN || code == SYS_HALT) { + if (watchdog_active(wdd) || watchdog_hw_running(wdd)) { + int ret; + + ret = wdd->ops->stop(wdd); + trace_watchdog_stop(wdd, ret); + if (ret) + return NOTIFY_BAD; + } + } + + return NOTIFY_DONE; +} + +static int watchdog_restart_notifier(struct notifier_block *nb, + unsigned long action, void *data) +{ + struct watchdog_device *wdd = container_of(nb, struct watchdog_device, + restart_nb); + + int ret; + + ret = wdd->ops->restart(wdd, action, data); + if (ret) + return NOTIFY_BAD; + + return NOTIFY_DONE; +} + +static int watchdog_pm_notifier(struct notifier_block *nb, unsigned long mode, + void *data) +{ + struct watchdog_device *wdd; + int ret = 0; + + wdd = container_of(nb, struct watchdog_device, pm_nb); + + switch (mode) { + case PM_HIBERNATION_PREPARE: + case PM_RESTORE_PREPARE: + case PM_SUSPEND_PREPARE: + ret = watchdog_dev_suspend(wdd); + break; + case PM_POST_HIBERNATION: + case PM_POST_RESTORE: + case PM_POST_SUSPEND: + ret = watchdog_dev_resume(wdd); + break; + } + + if (ret) + return NOTIFY_BAD; + + return NOTIFY_DONE; +} + +/** + * watchdog_set_restart_priority - Change priority of restart handler + * @wdd: watchdog device + * @priority: priority of the restart handler, should follow these guidelines: + * 0: use watchdog's restart function as last resort, has limited restart + * capabilies + * 128: default restart handler, use if no other handler is expected to be + * available and/or if restart is sufficient to restart the entire system + * 255: preempt all other handlers + * + * If a wdd->ops->restart function is provided when watchdog_register_device is + * called, it will be registered as a restart handler with the priority given + * here. + */ +void watchdog_set_restart_priority(struct watchdog_device *wdd, int priority) +{ + wdd->restart_nb.priority = priority; +} +EXPORT_SYMBOL_GPL(watchdog_set_restart_priority); + +static int __watchdog_register_device(struct watchdog_device *wdd) +{ + int ret, id = -1; + + if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL) + return -EINVAL; + + /* Mandatory operations need to be supported */ + if (!wdd->ops->start || (!wdd->ops->stop && !wdd->max_hw_heartbeat_ms)) + return -EINVAL; + + watchdog_check_min_max_timeout(wdd); + + /* + * Note: now that all watchdog_device data has been verified, we + * will not check this anymore in other functions. If data gets + * corrupted in a later stage then we expect a kernel panic! + */ + + /* Use alias for watchdog id if possible */ + if (wdd->parent) { + ret = of_alias_get_id(wdd->parent->of_node, "watchdog"); + if (ret >= 0) + id = ida_simple_get(&watchdog_ida, ret, + ret + 1, GFP_KERNEL); + } + + if (id < 0) + id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL); + + if (id < 0) + return id; + wdd->id = id; + + ret = watchdog_dev_register(wdd); + if (ret) { + ida_simple_remove(&watchdog_ida, id); + if (!(id == 0 && ret == -EBUSY)) + return ret; + + /* Retry in case a legacy watchdog module exists */ + id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL); + if (id < 0) + return id; + wdd->id = id; + + ret = watchdog_dev_register(wdd); + if (ret) { + ida_simple_remove(&watchdog_ida, id); + return ret; + } + } + + /* Module parameter to force watchdog policy on reboot. */ + if (stop_on_reboot != -1) { + if (stop_on_reboot) + set_bit(WDOG_STOP_ON_REBOOT, &wdd->status); + else + clear_bit(WDOG_STOP_ON_REBOOT, &wdd->status); + } + + if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) { + if (!wdd->ops->stop) + pr_warn("watchdog%d: stop_on_reboot not supported\n", wdd->id); + else { + wdd->reboot_nb.notifier_call = watchdog_reboot_notifier; + + ret = register_reboot_notifier(&wdd->reboot_nb); + if (ret) { + pr_err("watchdog%d: Cannot register reboot notifier (%d)\n", + wdd->id, ret); + watchdog_dev_unregister(wdd); + ida_simple_remove(&watchdog_ida, id); + return ret; + } + } + } + + if (wdd->ops->restart) { + wdd->restart_nb.notifier_call = watchdog_restart_notifier; + + ret = register_restart_handler(&wdd->restart_nb); + if (ret) + pr_warn("watchdog%d: Cannot register restart handler (%d)\n", + wdd->id, ret); + } + + if (test_bit(WDOG_NO_PING_ON_SUSPEND, &wdd->status)) { + wdd->pm_nb.notifier_call = watchdog_pm_notifier; + + ret = register_pm_notifier(&wdd->pm_nb); + if (ret) + pr_warn("watchdog%d: Cannot register pm handler (%d)\n", + wdd->id, ret); + } + + return 0; +} + +/** + * watchdog_register_device() - register a watchdog device + * @wdd: watchdog device + * + * Register a watchdog device with the kernel so that the + * watchdog timer can be accessed from userspace. + * + * A zero is returned on success and a negative errno code for + * failure. + */ + +int watchdog_register_device(struct watchdog_device *wdd) +{ + const char *dev_str; + int ret = 0; + + mutex_lock(&wtd_deferred_reg_mutex); + if (wtd_deferred_reg_done) + ret = __watchdog_register_device(wdd); + else + watchdog_deferred_registration_add(wdd); + mutex_unlock(&wtd_deferred_reg_mutex); + + if (ret) { + dev_str = wdd->parent ? dev_name(wdd->parent) : + (const char *)wdd->info->identity; + pr_err("%s: failed to register watchdog device (err = %d)\n", + dev_str, ret); + } + + return ret; +} +EXPORT_SYMBOL_GPL(watchdog_register_device); + +static void __watchdog_unregister_device(struct watchdog_device *wdd) +{ + if (wdd == NULL) + return; + + if (wdd->ops->restart) + unregister_restart_handler(&wdd->restart_nb); + + if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) + unregister_reboot_notifier(&wdd->reboot_nb); + + watchdog_dev_unregister(wdd); + ida_simple_remove(&watchdog_ida, wdd->id); +} + +/** + * watchdog_unregister_device() - unregister a watchdog device + * @wdd: watchdog device to unregister + * + * Unregister a watchdog device that was previously successfully + * registered with watchdog_register_device(). + */ + +void watchdog_unregister_device(struct watchdog_device *wdd) +{ + mutex_lock(&wtd_deferred_reg_mutex); + if (wtd_deferred_reg_done) + __watchdog_unregister_device(wdd); + else + watchdog_deferred_registration_del(wdd); + mutex_unlock(&wtd_deferred_reg_mutex); +} + +EXPORT_SYMBOL_GPL(watchdog_unregister_device); + +static void devm_watchdog_unregister_device(struct device *dev, void *res) +{ + watchdog_unregister_device(*(struct watchdog_device **)res); +} + +/** + * devm_watchdog_register_device() - resource managed watchdog_register_device() + * @dev: device that is registering this watchdog device + * @wdd: watchdog device + * + * Managed watchdog_register_device(). For watchdog device registered by this + * function, watchdog_unregister_device() is automatically called on driver + * detach. See watchdog_register_device() for more information. + */ +int devm_watchdog_register_device(struct device *dev, + struct watchdog_device *wdd) +{ + struct watchdog_device **rcwdd; + int ret; + + rcwdd = devres_alloc(devm_watchdog_unregister_device, sizeof(*rcwdd), + GFP_KERNEL); + if (!rcwdd) + return -ENOMEM; + + ret = watchdog_register_device(wdd); + if (!ret) { + *rcwdd = wdd; + devres_add(dev, rcwdd); + } else { + devres_free(rcwdd); + } + + return ret; +} +EXPORT_SYMBOL_GPL(devm_watchdog_register_device); + +static int __init watchdog_deferred_registration(void) +{ + mutex_lock(&wtd_deferred_reg_mutex); + wtd_deferred_reg_done = true; + while (!list_empty(&wtd_deferred_reg_list)) { + struct watchdog_device *wdd; + + wdd = list_first_entry(&wtd_deferred_reg_list, + struct watchdog_device, deferred); + list_del(&wdd->deferred); + __watchdog_register_device(wdd); + } + mutex_unlock(&wtd_deferred_reg_mutex); + return 0; +} + +static int __init watchdog_init(void) +{ + int err; + + err = watchdog_dev_init(); + if (err < 0) + return err; + + watchdog_deferred_registration(); + return 0; +} + +static void __exit watchdog_exit(void) +{ + watchdog_dev_exit(); + ida_destroy(&watchdog_ida); +} + +subsys_initcall_sync(watchdog_init); +module_exit(watchdog_exit); + +MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>"); +MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>"); +MODULE_DESCRIPTION("WatchDog Timer Driver Core"); +MODULE_LICENSE("GPL"); |