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- // SPDX-License-Identifier: GPL-2.0-or-later
- /*
- * Driver for watchdog device controlled through GPIO-line
- *
- * Author: 2013, Alexander Shiyan <shc_work@mail.ru>
- */
- #include <linux/err.h>
- #include <linux/delay.h>
- #include <linux/module.h>
- #include <linux/gpio/consumer.h>
- #include <linux/of.h>
- #include <linux/platform_device.h>
- #include <linux/watchdog.h>
- static bool nowayout = WATCHDOG_NOWAYOUT;
- module_param(nowayout, bool, 0);
- MODULE_PARM_DESC(nowayout,
- "Watchdog cannot be stopped once started (default="
- __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
- #define SOFT_TIMEOUT_MIN 1
- #define SOFT_TIMEOUT_DEF 60
- enum {
- HW_ALGO_TOGGLE,
- HW_ALGO_LEVEL,
- };
- struct gpio_wdt_priv {
- struct gpio_desc *gpiod;
- bool state;
- bool always_running;
- unsigned int hw_algo;
- struct watchdog_device wdd;
- };
- static void gpio_wdt_disable(struct gpio_wdt_priv *priv)
- {
- /* Eternal ping */
- gpiod_set_value_cansleep(priv->gpiod, 1);
- /* Put GPIO back to tristate */
- if (priv->hw_algo == HW_ALGO_TOGGLE)
- gpiod_direction_input(priv->gpiod);
- }
- static int gpio_wdt_ping(struct watchdog_device *wdd)
- {
- struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
- switch (priv->hw_algo) {
- case HW_ALGO_TOGGLE:
- /* Toggle output pin */
- priv->state = !priv->state;
- gpiod_set_value_cansleep(priv->gpiod, priv->state);
- break;
- case HW_ALGO_LEVEL:
- /* Pulse */
- gpiod_set_value_cansleep(priv->gpiod, 1);
- udelay(1);
- gpiod_set_value_cansleep(priv->gpiod, 0);
- break;
- }
- return 0;
- }
- static int gpio_wdt_start(struct watchdog_device *wdd)
- {
- struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
- priv->state = 0;
- gpiod_direction_output(priv->gpiod, priv->state);
- set_bit(WDOG_HW_RUNNING, &wdd->status);
- return gpio_wdt_ping(wdd);
- }
- static int gpio_wdt_stop(struct watchdog_device *wdd)
- {
- struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
- if (!priv->always_running) {
- gpio_wdt_disable(priv);
- } else {
- set_bit(WDOG_HW_RUNNING, &wdd->status);
- }
- return 0;
- }
- 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,
- };
- static int gpio_wdt_probe(struct platform_device *pdev)
- {
- struct device *dev = &pdev->dev;
- struct device_node *np = dev->of_node;
- struct gpio_wdt_priv *priv;
- enum gpiod_flags gflags;
- unsigned int hw_margin;
- const char *algo;
- int ret;
- priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
- if (!priv)
- return -ENOMEM;
- platform_set_drvdata(pdev, priv);
- ret = of_property_read_string(np, "hw_algo", &algo);
- if (ret)
- return ret;
- if (!strcmp(algo, "toggle")) {
- priv->hw_algo = HW_ALGO_TOGGLE;
- gflags = GPIOD_IN;
- } else if (!strcmp(algo, "level")) {
- priv->hw_algo = HW_ALGO_LEVEL;
- gflags = GPIOD_OUT_LOW;
- } else {
- return -EINVAL;
- }
- priv->gpiod = devm_gpiod_get(dev, NULL, gflags);
- if (IS_ERR(priv->gpiod))
- return PTR_ERR(priv->gpiod);
- ret = of_property_read_u32(np,
- "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;
- priv->always_running = of_property_read_bool(np,
- "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_hw_heartbeat_ms = hw_margin;
- priv->wdd.parent = dev;
- priv->wdd.timeout = SOFT_TIMEOUT_DEF;
- watchdog_init_timeout(&priv->wdd, 0, dev);
- watchdog_set_nowayout(&priv->wdd, nowayout);
- watchdog_stop_on_reboot(&priv->wdd);
- if (priv->always_running)
- gpio_wdt_start(&priv->wdd);
- return devm_watchdog_register_device(dev, &priv->wdd);
- }
- 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,
- };
- #ifdef CONFIG_GPIO_WATCHDOG_ARCH_INITCALL
- static int __init gpio_wdt_init(void)
- {
- return platform_driver_register(&gpio_wdt_driver);
- }
- arch_initcall(gpio_wdt_init);
- #else
- module_platform_driver(gpio_wdt_driver);
- #endif
- MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");
- MODULE_DESCRIPTION("GPIO Watchdog");
- MODULE_LICENSE("GPL");
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