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25134eaf AS |
1 | /* |
2 | * Driver for watchdog device controlled through GPIO-line | |
3 | * | |
4 | * Author: 2013, Alexander Shiyan <shc_work@mail.ru> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation; either version 2 of the License, or | |
9 | * (at your option) any later version. | |
10 | */ | |
11 | ||
12 | #include <linux/err.h> | |
13 | #include <linux/delay.h> | |
14 | #include <linux/module.h> | |
25134eaf AS |
15 | #include <linux/of_gpio.h> |
16 | #include <linux/platform_device.h> | |
25134eaf AS |
17 | #include <linux/watchdog.h> |
18 | ||
19 | #define SOFT_TIMEOUT_MIN 1 | |
20 | #define SOFT_TIMEOUT_DEF 60 | |
25134eaf AS |
21 | |
22 | enum { | |
23 | HW_ALGO_TOGGLE, | |
24 | HW_ALGO_LEVEL, | |
25 | }; | |
26 | ||
27 | struct gpio_wdt_priv { | |
28 | int gpio; | |
29 | bool active_low; | |
30 | bool state; | |
ba804a95 | 31 | bool always_running; |
25134eaf | 32 | unsigned int hw_algo; |
25134eaf AS |
33 | struct watchdog_device wdd; |
34 | }; | |
35 | ||
36 | static void gpio_wdt_disable(struct gpio_wdt_priv *priv) | |
37 | { | |
38 | gpio_set_value_cansleep(priv->gpio, !priv->active_low); | |
39 | ||
40 | /* Put GPIO back to tristate */ | |
41 | if (priv->hw_algo == HW_ALGO_TOGGLE) | |
42 | gpio_direction_input(priv->gpio); | |
43 | } | |
44 | ||
03bca158 | 45 | static int gpio_wdt_ping(struct watchdog_device *wdd) |
4f2d0b2d | 46 | { |
4f2d0b2d UKK |
47 | struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); |
48 | ||
4f2d0b2d UKK |
49 | switch (priv->hw_algo) { |
50 | case HW_ALGO_TOGGLE: | |
51 | /* Toggle output pin */ | |
52 | priv->state = !priv->state; | |
53 | gpio_set_value_cansleep(priv->gpio, priv->state); | |
54 | break; | |
55 | case HW_ALGO_LEVEL: | |
56 | /* Pulse */ | |
57 | gpio_set_value_cansleep(priv->gpio, !priv->active_low); | |
58 | udelay(1); | |
59 | gpio_set_value_cansleep(priv->gpio, priv->active_low); | |
60 | break; | |
61 | } | |
03bca158 | 62 | return 0; |
ba804a95 ML |
63 | } |
64 | ||
65 | static int gpio_wdt_start(struct watchdog_device *wdd) | |
66 | { | |
67 | struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); | |
68 | ||
03bca158 GR |
69 | priv->state = priv->active_low; |
70 | gpio_direction_output(priv->gpio, priv->state); | |
25134eaf | 71 | |
03bca158 GR |
72 | set_bit(WDOG_HW_RUNNING, &wdd->status); |
73 | ||
74 | return gpio_wdt_ping(wdd); | |
25134eaf AS |
75 | } |
76 | ||
77 | static int gpio_wdt_stop(struct watchdog_device *wdd) | |
78 | { | |
79 | struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd); | |
80 | ||
ba804a95 | 81 | if (!priv->always_running) { |
ba804a95 | 82 | gpio_wdt_disable(priv); |
03bca158 | 83 | clear_bit(WDOG_HW_RUNNING, &wdd->status); |
ba804a95 | 84 | } |
25134eaf AS |
85 | |
86 | return 0; | |
87 | } | |
88 | ||
25134eaf AS |
89 | static const struct watchdog_info gpio_wdt_ident = { |
90 | .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING | | |
91 | WDIOF_SETTIMEOUT, | |
92 | .identity = "GPIO Watchdog", | |
93 | }; | |
94 | ||
95 | static const struct watchdog_ops gpio_wdt_ops = { | |
96 | .owner = THIS_MODULE, | |
97 | .start = gpio_wdt_start, | |
98 | .stop = gpio_wdt_stop, | |
99 | .ping = gpio_wdt_ping, | |
25134eaf AS |
100 | }; |
101 | ||
102 | static int gpio_wdt_probe(struct platform_device *pdev) | |
103 | { | |
104 | struct gpio_wdt_priv *priv; | |
105 | enum of_gpio_flags flags; | |
106 | unsigned int hw_margin; | |
107 | unsigned long f = 0; | |
108 | const char *algo; | |
109 | int ret; | |
110 | ||
111 | priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); | |
112 | if (!priv) | |
113 | return -ENOMEM; | |
114 | ||
1ac06563 WY |
115 | platform_set_drvdata(pdev, priv); |
116 | ||
25134eaf AS |
117 | priv->gpio = of_get_gpio_flags(pdev->dev.of_node, 0, &flags); |
118 | if (!gpio_is_valid(priv->gpio)) | |
119 | return priv->gpio; | |
120 | ||
121 | priv->active_low = flags & OF_GPIO_ACTIVE_LOW; | |
122 | ||
123 | ret = of_property_read_string(pdev->dev.of_node, "hw_algo", &algo); | |
124 | if (ret) | |
125 | return ret; | |
0a0a542f | 126 | if (!strcmp(algo, "toggle")) { |
25134eaf AS |
127 | priv->hw_algo = HW_ALGO_TOGGLE; |
128 | f = GPIOF_IN; | |
0a0a542f | 129 | } else if (!strcmp(algo, "level")) { |
25134eaf AS |
130 | priv->hw_algo = HW_ALGO_LEVEL; |
131 | f = priv->active_low ? GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW; | |
132 | } else { | |
133 | return -EINVAL; | |
134 | } | |
135 | ||
136 | ret = devm_gpio_request_one(&pdev->dev, priv->gpio, f, | |
137 | dev_name(&pdev->dev)); | |
138 | if (ret) | |
139 | return ret; | |
140 | ||
141 | ret = of_property_read_u32(pdev->dev.of_node, | |
142 | "hw_margin_ms", &hw_margin); | |
143 | if (ret) | |
144 | return ret; | |
145 | /* Disallow values lower than 2 and higher than 65535 ms */ | |
146 | if (hw_margin < 2 || hw_margin > 65535) | |
147 | return -EINVAL; | |
148 | ||
ba804a95 ML |
149 | priv->always_running = of_property_read_bool(pdev->dev.of_node, |
150 | "always-running"); | |
151 | ||
25134eaf AS |
152 | watchdog_set_drvdata(&priv->wdd, priv); |
153 | ||
154 | priv->wdd.info = &gpio_wdt_ident; | |
155 | priv->wdd.ops = &gpio_wdt_ops; | |
156 | priv->wdd.min_timeout = SOFT_TIMEOUT_MIN; | |
03bca158 | 157 | priv->wdd.max_hw_heartbeat_ms = hw_margin; |
6551881c | 158 | priv->wdd.parent = &pdev->dev; |
25134eaf AS |
159 | |
160 | if (watchdog_init_timeout(&priv->wdd, 0, &pdev->dev) < 0) | |
161 | priv->wdd.timeout = SOFT_TIMEOUT_DEF; | |
162 | ||
28e805b4 DR |
163 | watchdog_stop_on_reboot(&priv->wdd); |
164 | ||
ba804a95 | 165 | if (priv->always_running) |
03bca158 | 166 | gpio_wdt_start(&priv->wdd); |
ba804a95 | 167 | |
03bca158 GR |
168 | ret = watchdog_register_device(&priv->wdd); |
169 | ||
170 | return ret; | |
25134eaf AS |
171 | } |
172 | ||
173 | static int gpio_wdt_remove(struct platform_device *pdev) | |
174 | { | |
175 | struct gpio_wdt_priv *priv = platform_get_drvdata(pdev); | |
176 | ||
25134eaf AS |
177 | watchdog_unregister_device(&priv->wdd); |
178 | ||
179 | return 0; | |
180 | } | |
181 | ||
182 | static const struct of_device_id gpio_wdt_dt_ids[] = { | |
183 | { .compatible = "linux,wdt-gpio", }, | |
184 | { } | |
185 | }; | |
186 | MODULE_DEVICE_TABLE(of, gpio_wdt_dt_ids); | |
187 | ||
188 | static struct platform_driver gpio_wdt_driver = { | |
189 | .driver = { | |
190 | .name = "gpio-wdt", | |
25134eaf AS |
191 | .of_match_table = gpio_wdt_dt_ids, |
192 | }, | |
193 | .probe = gpio_wdt_probe, | |
194 | .remove = gpio_wdt_remove, | |
195 | }; | |
5e53c8ed JBT |
196 | |
197 | #ifdef CONFIG_GPIO_WATCHDOG_ARCH_INITCALL | |
198 | static int __init gpio_wdt_init(void) | |
199 | { | |
200 | return platform_driver_register(&gpio_wdt_driver); | |
201 | } | |
202 | arch_initcall(gpio_wdt_init); | |
203 | #else | |
25134eaf | 204 | module_platform_driver(gpio_wdt_driver); |
5e53c8ed | 205 | #endif |
25134eaf AS |
206 | |
207 | MODULE_AUTHOR("Alexander Shiyan <shc_work@mail.ru>"); | |
208 | MODULE_DESCRIPTION("GPIO Watchdog"); | |
209 | MODULE_LICENSE("GPL"); |