1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * Driver for watchdog device controlled through GPIO-line |
4 | * |
5 | * Author: 2013, Alexander Shiyan <shc_work@mail.ru> |
6 | */ |
7 | |
8 | #include <linux/err.h> |
9 | #include <linux/delay.h> |
10 | #include <linux/module.h> |
11 | #include <linux/gpio/consumer.h> |
12 | #include <linux/of.h> |
13 | #include <linux/platform_device.h> |
14 | #include <linux/watchdog.h> |
15 | |
16 | static bool nowayout = WATCHDOG_NOWAYOUT; |
17 | module_param(nowayout, bool, 0); |
18 | MODULE_PARM_DESC(nowayout, |
19 | "Watchdog cannot be stopped once started (default=" |
20 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")" ); |
21 | |
22 | #define SOFT_TIMEOUT_MIN 1 |
23 | #define SOFT_TIMEOUT_DEF 60 |
24 | |
25 | enum { |
26 | HW_ALGO_TOGGLE, |
27 | HW_ALGO_LEVEL, |
28 | }; |
29 | |
30 | struct gpio_wdt_priv { |
31 | struct gpio_desc *gpiod; |
32 | bool state; |
33 | bool always_running; |
34 | unsigned int hw_algo; |
35 | struct watchdog_device wdd; |
36 | }; |
37 | |
38 | static void gpio_wdt_disable(struct gpio_wdt_priv *priv) |
39 | { |
40 | /* Eternal ping */ |
41 | gpiod_set_value_cansleep(desc: priv->gpiod, value: 1); |
42 | |
43 | /* Put GPIO back to tristate */ |
44 | if (priv->hw_algo == HW_ALGO_TOGGLE) |
45 | gpiod_direction_input(desc: priv->gpiod); |
46 | } |
47 | |
48 | static int gpio_wdt_ping(struct watchdog_device *wdd) |
49 | { |
50 | struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); |
51 | |
52 | switch (priv->hw_algo) { |
53 | case HW_ALGO_TOGGLE: |
54 | /* Toggle output pin */ |
55 | priv->state = !priv->state; |
56 | gpiod_set_value_cansleep(desc: priv->gpiod, value: priv->state); |
57 | break; |
58 | case HW_ALGO_LEVEL: |
59 | /* Pulse */ |
60 | gpiod_set_value_cansleep(desc: priv->gpiod, value: 1); |
61 | udelay(1); |
62 | gpiod_set_value_cansleep(desc: priv->gpiod, value: 0); |
63 | break; |
64 | } |
65 | return 0; |
66 | } |
67 | |
68 | static int gpio_wdt_start(struct watchdog_device *wdd) |
69 | { |
70 | struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); |
71 | |
72 | priv->state = 0; |
73 | gpiod_direction_output(desc: priv->gpiod, value: priv->state); |
74 | |
75 | set_bit(WDOG_HW_RUNNING, addr: &wdd->status); |
76 | |
77 | return gpio_wdt_ping(wdd); |
78 | } |
79 | |
80 | static int gpio_wdt_stop(struct watchdog_device *wdd) |
81 | { |
82 | struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); |
83 | |
84 | if (!priv->always_running) { |
85 | gpio_wdt_disable(priv); |
86 | } else { |
87 | set_bit(WDOG_HW_RUNNING, addr: &wdd->status); |
88 | } |
89 | |
90 | return 0; |
91 | } |
92 | |
93 | static const struct watchdog_info gpio_wdt_ident = { |
94 | .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | |
95 | WDIOF_SETTIMEOUT, |
96 | .identity = "GPIO Watchdog" , |
97 | }; |
98 | |
99 | static const struct watchdog_ops gpio_wdt_ops = { |
100 | .owner = THIS_MODULE, |
101 | .start = gpio_wdt_start, |
102 | .stop = gpio_wdt_stop, |
103 | .ping = gpio_wdt_ping, |
104 | }; |
105 | |
106 | static int gpio_wdt_probe(struct platform_device *pdev) |
107 | { |
108 | struct device *dev = &pdev->dev; |
109 | struct device_node *np = dev->of_node; |
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, size: sizeof(*priv), GFP_KERNEL); |
117 | if (!priv) |
118 | return -ENOMEM; |
119 | |
120 | platform_set_drvdata(pdev, data: priv); |
121 | |
122 | ret = of_property_read_string(np, propname: "hw_algo" , out_string: &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, flags: gflags); |
136 | if (IS_ERR(ptr: priv->gpiod)) |
137 | return PTR_ERR(ptr: priv->gpiod); |
138 | |
139 | ret = of_property_read_u32(np, |
140 | propname: "hw_margin_ms" , out_value: &hw_margin); |
141 | if (ret) |
142 | return ret; |
143 | /* Disallow values lower than 2 and higher than 65535 ms */ |
144 | if (hw_margin < 2 || hw_margin > 65535) |
145 | return -EINVAL; |
146 | |
147 | priv->always_running = of_property_read_bool(np, |
148 | propname: "always-running" ); |
149 | |
150 | watchdog_set_drvdata(wdd: &priv->wdd, data: priv); |
151 | |
152 | priv->wdd.info = &gpio_wdt_ident; |
153 | priv->wdd.ops = &gpio_wdt_ops; |
154 | priv->wdd.min_timeout = SOFT_TIMEOUT_MIN; |
155 | priv->wdd.max_hw_heartbeat_ms = hw_margin; |
156 | priv->wdd.parent = dev; |
157 | priv->wdd.timeout = SOFT_TIMEOUT_DEF; |
158 | |
159 | watchdog_init_timeout(wdd: &priv->wdd, timeout_parm: 0, dev); |
160 | watchdog_set_nowayout(wdd: &priv->wdd, nowayout); |
161 | |
162 | watchdog_stop_on_reboot(wdd: &priv->wdd); |
163 | |
164 | if (priv->always_running) |
165 | gpio_wdt_start(wdd: &priv->wdd); |
166 | |
167 | return devm_watchdog_register_device(dev, &priv->wdd); |
168 | } |
169 | |
170 | static const struct of_device_id gpio_wdt_dt_ids[] = { |
171 | { .compatible = "linux,wdt-gpio" , }, |
172 | { } |
173 | }; |
174 | MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids); |
175 | |
176 | static struct platform_driver gpio_wdt_driver = { |
177 | .driver = { |
178 | .name = "gpio-wdt" , |
179 | .of_match_table = gpio_wdt_dt_ids, |
180 | }, |
181 | .probe = gpio_wdt_probe, |
182 | }; |
183 | |
184 | #ifdef CONFIG_GPIO_WATCHDOG_ARCH_INITCALL |
185 | static int __init gpio_wdt_init(void) |
186 | { |
187 | return platform_driver_register(&gpio_wdt_driver); |
188 | } |
189 | arch_initcall(gpio_wdt_init); |
190 | #else |
191 | module_platform_driver(gpio_wdt_driver); |
192 | #endif |
193 | |
194 | MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>" ); |
195 | MODULE_DESCRIPTION("GPIO Watchdog" ); |
196 | MODULE_LICENSE("GPL" ); |
197 | |