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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Driver for watchdog device controlled through GPIO-line4 *5 * Author: 2013, Alexander Shiyan <shc_work@mail.ru>6 */7 8#include <linux/delay.h>9#include <linux/err.h>10#include <linux/gpio/consumer.h>11#include <linux/mod_devicetable.h>12#include <linux/module.h>13#include <linux/platform_device.h>14#include <linux/property.h>15#include <linux/watchdog.h>16 17static bool nowayout = WATCHDOG_NOWAYOUT;18module_param(nowayout, bool, 0);19MODULE_PARM_DESC(nowayout,20 "Watchdog cannot be stopped once started (default="21 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");22 23#define SOFT_TIMEOUT_MIN 124#define SOFT_TIMEOUT_DEF 6025 26enum {27 HW_ALGO_TOGGLE,28 HW_ALGO_LEVEL,29};30 31struct gpio_wdt_priv {32 struct gpio_desc *gpiod;33 bool state;34 bool always_running;35 unsigned int hw_algo;36 struct watchdog_device wdd;37};38 39static void gpio_wdt_disable(struct gpio_wdt_priv *priv)40{41 /* Eternal ping */42 gpiod_set_value_cansleep(priv->gpiod, 1);43 44 /* Put GPIO back to tristate */45 if (priv->hw_algo == HW_ALGO_TOGGLE)46 gpiod_direction_input(priv->gpiod);47}48 49static int gpio_wdt_ping(struct watchdog_device *wdd)50{51 struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);52 53 switch (priv->hw_algo) {54 case HW_ALGO_TOGGLE:55 /* Toggle output pin */56 priv->state = !priv->state;57 gpiod_set_value_cansleep(priv->gpiod, priv->state);58 break;59 case HW_ALGO_LEVEL:60 /* Pulse */61 gpiod_set_value_cansleep(priv->gpiod, 1);62 udelay(1);63 gpiod_set_value_cansleep(priv->gpiod, 0);64 break;65 }66 return 0;67}68 69static int gpio_wdt_start(struct watchdog_device *wdd)70{71 struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);72 73 priv->state = 0;74 gpiod_direction_output(priv->gpiod, priv->state);75 76 set_bit(WDOG_HW_RUNNING, &wdd->status);77 78 return gpio_wdt_ping(wdd);79}80 81static int gpio_wdt_stop(struct watchdog_device *wdd)82{83 struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);84 85 if (!priv->always_running) {86 gpio_wdt_disable(priv);87 } else {88 set_bit(WDOG_HW_RUNNING, &wdd->status);89 }90 91 return 0;92}93 94static const struct watchdog_info gpio_wdt_ident = {95 .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |96 WDIOF_SETTIMEOUT,97 .identity = "GPIO Watchdog",98};99 100static const struct watchdog_ops gpio_wdt_ops = {101 .owner = THIS_MODULE,102 .start = gpio_wdt_start,103 .stop = gpio_wdt_stop,104 .ping = gpio_wdt_ping,105};106 107static int gpio_wdt_probe(struct platform_device *pdev)108{109 struct device *dev = &pdev->dev;110 struct gpio_wdt_priv *priv;111 enum gpiod_flags gflags;112 unsigned int hw_margin;113 const char *algo;114 int ret;115 116 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);117 if (!priv)118 return -ENOMEM;119 120 platform_set_drvdata(pdev, priv);121 122 ret = device_property_read_string(dev, "hw_algo", &algo);123 if (ret)124 return ret;125 if (!strcmp(algo, "toggle")) {126 priv->hw_algo = HW_ALGO_TOGGLE;127 gflags = GPIOD_IN;128 } else if (!strcmp(algo, "level")) {129 priv->hw_algo = HW_ALGO_LEVEL;130 gflags = GPIOD_OUT_LOW;131 } else {132 return -EINVAL;133 }134 135 priv->gpiod = devm_gpiod_get(dev, NULL, gflags);136 if (IS_ERR(priv->gpiod))137 return PTR_ERR(priv->gpiod);138 139 ret = device_property_read_u32(dev, "hw_margin_ms", &hw_margin);140 if (ret)141 return ret;142 /* Disallow values lower than 2 and higher than 65535 ms */143 if (hw_margin < 2 || hw_margin > 65535)144 return -EINVAL;145 146 priv->always_running = device_property_read_bool(dev, "always-running");147 148 watchdog_set_drvdata(&priv->wdd, priv);149 150 priv->wdd.info = &gpio_wdt_ident;151 priv->wdd.ops = &gpio_wdt_ops;152 priv->wdd.min_timeout = SOFT_TIMEOUT_MIN;153 priv->wdd.max_hw_heartbeat_ms = hw_margin;154 priv->wdd.parent = dev;155 priv->wdd.timeout = SOFT_TIMEOUT_DEF;156 157 watchdog_init_timeout(&priv->wdd, 0, dev);158 watchdog_set_nowayout(&priv->wdd, nowayout);159 160 watchdog_stop_on_reboot(&priv->wdd);161 162 if (priv->always_running)163 gpio_wdt_start(&priv->wdd);164 165 return devm_watchdog_register_device(dev, &priv->wdd);166}167 168static const struct of_device_id gpio_wdt_dt_ids[] = {169 { .compatible = "linux,wdt-gpio", },170 { }171};172MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids);173 174static struct platform_driver gpio_wdt_driver = {175 .driver = {176 .name = "gpio-wdt",177 .of_match_table = gpio_wdt_dt_ids,178 },179 .probe = gpio_wdt_probe,180};181 182#ifdef CONFIG_GPIO_WATCHDOG_ARCH_INITCALL183static int __init gpio_wdt_init(void)184{185 return platform_driver_register(&gpio_wdt_driver);186}187arch_initcall(gpio_wdt_init);188#else189module_platform_driver(gpio_wdt_driver);190#endif191 192MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>");193MODULE_DESCRIPTION("GPIO Watchdog");194MODULE_LICENSE("GPL");195