--- /dev/null
+/*
+ * Driver for watchdog device controlled through GPIO-line
+ *
+ * Author: 2013, Alexander Shiyan <shc_work@mail.ru>
+ *
+ * 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/err.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/of_gpio.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/watchdog.h>
+
+#define SOFT_TIMEOUT_MIN 1
+#define SOFT_TIMEOUT_DEF 60
+#define SOFT_TIMEOUT_MAX 0xffff
+
+enum {
+ HW_ALGO_TOGGLE,
+ HW_ALGO_LEVEL,
+};
+
+struct gpio_wdt_priv {
+ int gpio;
+ bool active_low;
+ bool state;
+ bool always_running;
+ bool armed;
+ unsigned int hw_algo;
+ unsigned int hw_margin;
+ unsigned long last_jiffies;
+ struct notifier_block notifier;
+ struct timer_list timer;
+ struct watchdog_device wdd;
+};
+
+static void gpio_wdt_disable(struct gpio_wdt_priv *priv)
+{
+ gpio_set_value_cansleep(priv->gpio, !priv->active_low);
+
+ /* Put GPIO back to tristate */
+ if (priv->hw_algo == HW_ALGO_TOGGLE)
+ gpio_direction_input(priv->gpio);
+}
+
+static void gpio_wdt_start_impl(struct gpio_wdt_priv *priv)
+{
+ priv->state = priv->active_low;
+ gpio_direction_output(priv->gpio, priv->state);
+ priv->last_jiffies = jiffies;
+ mod_timer(&priv->timer, priv->last_jiffies + priv->hw_margin);
+}
+
+static int gpio_wdt_start(struct watchdog_device *wdd)
+{
+ struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
+
+ gpio_wdt_start_impl(priv);
+ priv->armed = true;
+
+ return 0;
+}
+
+static int gpio_wdt_stop(struct watchdog_device *wdd)
+{
+ struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
+
+ priv->armed = false;
+ if (!priv->always_running) {
+ mod_timer(&priv->timer, 0);
+ gpio_wdt_disable(priv);
+ }
+
+ return 0;
+}
+
+static int gpio_wdt_ping(struct watchdog_device *wdd)
+{
+ struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
+
+ priv->last_jiffies = jiffies;
+
+ return 0;
+}
+
+static int gpio_wdt_set_timeout(struct watchdog_device *wdd, unsigned int t)
+{
+ wdd->timeout = t;
+
+ return gpio_wdt_ping(wdd);
+}
+
+static void gpio_wdt_hwping(unsigned long data)
+{
+ struct watchdog_device *wdd = (struct watchdog_device *)data;
+ struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
+
+ if (priv->armed && time_after(jiffies, priv->last_jiffies +
+ msecs_to_jiffies(wdd->timeout * 1000))) {
+ dev_crit(wdd->dev, "Timer expired. System will reboot soon!\n");
+ return;
+ }
+
+ /* Restart timer */
+ mod_timer(&priv->timer, jiffies + priv->hw_margin);
+
+ switch (priv->hw_algo) {
+ case HW_ALGO_TOGGLE:
+ /* Toggle output pin */
+ priv->state = !priv->state;
+ gpio_set_value_cansleep(priv->gpio, priv->state);
+ break;
+ case HW_ALGO_LEVEL:
+ /* Pulse */
+ gpio_set_value_cansleep(priv->gpio, !priv->active_low);
+ udelay(1);
+ gpio_set_value_cansleep(priv->gpio, priv->active_low);
+ break;
+ }
+}
+
+static int gpio_wdt_notify_sys(struct notifier_block *nb, unsigned long code,
+ void *unused)
+{
+ struct gpio_wdt_priv *priv = container_of(nb, struct gpio_wdt_priv,
+ notifier);
+
+ mod_timer(&priv->timer, 0);
+
+ switch (code) {
+ case SYS_HALT:
+ case SYS_POWER_OFF:
+ gpio_wdt_disable(priv);
+ break;
+ default:
+ break;
+ }
+
+ return NOTIFY_DONE;
+}
+
+static const struct watchdog_info gpio_wdt_ident = {
+ .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
+ WDIOF_SETTIMEOUT,
+ .identity = "GPIO Watchdog",
+};
+
+static const struct watchdog_ops gpio_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = gpio_wdt_start,
+ .stop = gpio_wdt_stop,
+ .ping = gpio_wdt_ping,
+ .set_timeout = gpio_wdt_set_timeout,
+};
+
+static int gpio_wdt_probe(struct platform_device *pdev)
+{
+ struct gpio_wdt_priv *priv;
+ enum of_gpio_flags flags;
+ unsigned int hw_margin;
+ unsigned long f = 0;
+ const char *algo;
+ int ret;
+
+ priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->gpio = of_get_gpio_flags(pdev->dev.of_node, 0, &flags);
+ if (!gpio_is_valid(priv->gpio))
+ return priv->gpio;
+
+ priv->active_low = flags & OF_GPIO_ACTIVE_LOW;
+
+ ret = of_property_read_string(pdev->dev.of_node, "hw_algo", &algo);
+ if (ret)
+ return ret;
+ if (!strncmp(algo, "toggle", 6)) {
+ priv->hw_algo = HW_ALGO_TOGGLE;
+ f = GPIOF_IN;
+ } else if (!strncmp(algo, "level", 5)) {
+ priv->hw_algo = HW_ALGO_LEVEL;
+ f = priv->active_low ? GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW;
+ } else {
+ return -EINVAL;
+ }
+
+ ret = devm_gpio_request_one(&pdev->dev, priv->gpio, f,
+ dev_name(&pdev->dev));
+ if (ret)
+ return ret;
+
+ ret = of_property_read_u32(pdev->dev.of_node,
+ "hw_margin_ms", &hw_margin);
+ if (ret)
+ return ret;
+ /* Disallow values lower than 2 and higher than 65535 ms */
+ if (hw_margin < 2 || hw_margin > 65535)
+ return -EINVAL;
+
+ /* Use safe value (1/2 of real timeout) */
+ priv->hw_margin = msecs_to_jiffies(hw_margin / 2);
+
+ priv->always_running = of_property_read_bool(pdev->dev.of_node,
+ "always-running");
+
+ watchdog_set_drvdata(&priv->wdd, priv);
+
+ priv->wdd.info = &gpio_wdt_ident;
+ priv->wdd.ops = &gpio_wdt_ops;
+ priv->wdd.min_timeout = SOFT_TIMEOUT_MIN;
+ priv->wdd.max_timeout = SOFT_TIMEOUT_MAX;
+
+ if (watchdog_init_timeout(&priv->wdd, 0, &pdev->dev) < 0)
+ priv->wdd.timeout = SOFT_TIMEOUT_DEF;
+
+ setup_timer(&priv->timer, gpio_wdt_hwping, (unsigned long)&priv->wdd);
+
+ ret = watchdog_register_device(&priv->wdd);
+ if (ret)
+ return ret;
+
+ priv->notifier.notifier_call = gpio_wdt_notify_sys;
+ ret = register_reboot_notifier(&priv->notifier);
+ if (ret)
+ goto error_unregister;
+
+ if (priv->always_running)
+ gpio_wdt_start_impl(priv);
+
+ return 0;
+
+error_unregister:
+ watchdog_unregister_device(&priv->wdd);
+ return ret;
+}
+
+static int gpio_wdt_remove(struct platform_device *pdev)
+{
+ struct gpio_wdt_priv *priv = platform_get_drvdata(pdev);
+
+ del_timer_sync(&priv->timer);
+ unregister_reboot_notifier(&priv->notifier);
+ watchdog_unregister_device(&priv->wdd);
+
+ return 0;
+}
+
+static const struct of_device_id gpio_wdt_dt_ids[] = {
+ { .compatible = "linux,wdt-gpio", },
+ { }
+};
+MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids);
+
+static struct platform_driver gpio_wdt_driver = {
+ .driver = {
+ .name = "gpio-wdt",
+ .of_match_table = gpio_wdt_dt_ids,
+ },
+ .probe = gpio_wdt_probe,
+ .remove = gpio_wdt_remove,
+};
+module_platform_driver(gpio_wdt_driver);
+
+MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
+MODULE_DESCRIPTION("GPIO Watchdog");
+MODULE_LICENSE("GPL");
Code Review / kvmfornfv.git / blobdiff