1 files changed, 444 insertions, 0 deletions
diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
new file mode 100644
index 000000000..0e9a99559
--- /dev/null
+++ b/drivers/watchdog/watchdog_core.c
@@ -0,0 +1,444 @@
+// 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 "watchdog_core.h"	/* For watchdog_dev_register/... */
+
+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)) {
+			int ret;
+
+			ret = wdd->ops->stop(wdd);
+			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;
+}
+
+/**
+ * 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);
+	}
+
+	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");