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1 | /* |
2 | * Watchdog driver for Atmel AT91RM9200 (Thunder) |
3 | * |
4 | * Copyright (C) 2003 SAN People (Pty) Ltd |
5 | * |
6 | * This program is free software; you can redistribute it and/or |
7 | * modify it under the terms of the GNU General Public License |
8 | * as published by the Free Software Foundation; either version |
9 | * 2 of the License, or (at your option) any later version. |
10 | */ |
11 | |
12 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
13 | |
14 | #include <linux/bitops.h> |
15 | #include <linux/errno.h> |
16 | #include <linux/fs.h> |
17 | #include <linux/init.h> |
18 | #include <linux/io.h> |
19 | #include <linux/kernel.h> |
20 | #include <linux/miscdevice.h> |
21 | #include <linux/module.h> |
22 | #include <linux/moduleparam.h> |
23 | #include <linux/platform_device.h> |
24 | #include <linux/types.h> |
25 | #include <linux/watchdog.h> |
26 | #include <linux/uaccess.h> |
27 | #include <linux/of.h> |
28 | #include <linux/of_device.h> |
29 | #include <mach/at91_st.h> |
30 | |
31 | #define WDT_DEFAULT_TIME 5 /* seconds */ |
32 | #define WDT_MAX_TIME 256 /* seconds */ |
33 | |
34 | static int wdt_time = WDT_DEFAULT_TIME; |
35 | static bool nowayout = WATCHDOG_NOWAYOUT; |
36 | |
37 | module_param(wdt_time, int, 0); |
38 | MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default=" |
39 | __MODULE_STRING(WDT_DEFAULT_TIME) ")"); |
40 | |
41 | #ifdef CONFIG_WATCHDOG_NOWAYOUT |
42 | module_param(nowayout, bool, 0); |
43 | MODULE_PARM_DESC(nowayout, |
44 | "Watchdog cannot be stopped once started (default=" |
45 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
46 | #endif |
47 | |
48 | |
49 | static unsigned long at91wdt_busy; |
50 | |
51 | /* ......................................................................... */ |
52 | |
53 | /* |
54 | * Disable the watchdog. |
55 | */ |
56 | static inline void at91_wdt_stop(void) |
57 | { |
58 | at91_st_write(AT91_ST_WDMR, AT91_ST_EXTEN); |
59 | } |
60 | |
61 | /* |
62 | * Enable and reset the watchdog. |
63 | */ |
64 | static inline void at91_wdt_start(void) |
65 | { |
66 | at91_st_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN | |
67 | (((65536 * wdt_time) >> 8) & AT91_ST_WDV)); |
68 | at91_st_write(AT91_ST_CR, AT91_ST_WDRST); |
69 | } |
70 | |
71 | /* |
72 | * Reload the watchdog timer. (ie, pat the watchdog) |
73 | */ |
74 | static inline void at91_wdt_reload(void) |
75 | { |
76 | at91_st_write(AT91_ST_CR, AT91_ST_WDRST); |
77 | } |
78 | |
79 | /* ......................................................................... */ |
80 | |
81 | /* |
82 | * Watchdog device is opened, and watchdog starts running. |
83 | */ |
84 | static int at91_wdt_open(struct inode *inode, struct file *file) |
85 | { |
86 | if (test_and_set_bit(0, &at91wdt_busy)) |
87 | return -EBUSY; |
88 | |
89 | at91_wdt_start(); |
90 | return nonseekable_open(inode, file); |
91 | } |
92 | |
93 | /* |
94 | * Close the watchdog device. |
95 | * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also |
96 | * disabled. |
97 | */ |
98 | static int at91_wdt_close(struct inode *inode, struct file *file) |
99 | { |
100 | /* Disable the watchdog when file is closed */ |
101 | if (!nowayout) |
102 | at91_wdt_stop(); |
103 | |
104 | clear_bit(0, &at91wdt_busy); |
105 | return 0; |
106 | } |
107 | |
108 | /* |
109 | * Change the watchdog time interval. |
110 | */ |
111 | static int at91_wdt_settimeout(int new_time) |
112 | { |
113 | /* |
114 | * All counting occurs at SLOW_CLOCK / 128 = 256 Hz |
115 | * |
116 | * Since WDV is a 16-bit counter, the maximum period is |
117 | * 65536 / 256 = 256 seconds. |
118 | */ |
119 | if ((new_time <= 0) || (new_time > WDT_MAX_TIME)) |
120 | return -EINVAL; |
121 | |
122 | /* Set new watchdog time. It will be used when |
123 | at91_wdt_start() is called. */ |
124 | wdt_time = new_time; |
125 | return 0; |
126 | } |
127 | |
128 | static const struct watchdog_info at91_wdt_info = { |
129 | .identity = "at91 watchdog", |
130 | .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, |
131 | }; |
132 | |
133 | /* |
134 | * Handle commands from user-space. |
135 | */ |
136 | static long at91_wdt_ioctl(struct file *file, |
137 | unsigned int cmd, unsigned long arg) |
138 | { |
139 | void __user *argp = (void __user *)arg; |
140 | int __user *p = argp; |
141 | int new_value; |
142 | |
143 | switch (cmd) { |
144 | case WDIOC_GETSUPPORT: |
145 | return copy_to_user(argp, &at91_wdt_info, |
146 | sizeof(at91_wdt_info)) ? -EFAULT : 0; |
147 | case WDIOC_GETSTATUS: |
148 | case WDIOC_GETBOOTSTATUS: |
149 | return put_user(0, p); |
150 | case WDIOC_SETOPTIONS: |
151 | if (get_user(new_value, p)) |
152 | return -EFAULT; |
153 | if (new_value & WDIOS_DISABLECARD) |
154 | at91_wdt_stop(); |
155 | if (new_value & WDIOS_ENABLECARD) |
156 | at91_wdt_start(); |
157 | return 0; |
158 | case WDIOC_KEEPALIVE: |
159 | at91_wdt_reload(); /* pat the watchdog */ |
160 | return 0; |
161 | case WDIOC_SETTIMEOUT: |
162 | if (get_user(new_value, p)) |
163 | return -EFAULT; |
164 | if (at91_wdt_settimeout(new_value)) |
165 | return -EINVAL; |
166 | /* Enable new time value */ |
167 | at91_wdt_start(); |
168 | /* Return current value */ |
169 | return put_user(wdt_time, p); |
170 | case WDIOC_GETTIMEOUT: |
171 | return put_user(wdt_time, p); |
172 | default: |
173 | return -ENOTTY; |
174 | } |
175 | } |
176 | |
177 | /* |
178 | * Pat the watchdog whenever device is written to. |
179 | */ |
180 | static ssize_t at91_wdt_write(struct file *file, const char *data, |
181 | size_t len, loff_t *ppos) |
182 | { |
183 | at91_wdt_reload(); /* pat the watchdog */ |
184 | return len; |
185 | } |
186 | |
187 | /* ......................................................................... */ |
188 | |
189 | static const struct file_operations at91wdt_fops = { |
190 | .owner = THIS_MODULE, |
191 | .llseek = no_llseek, |
192 | .unlocked_ioctl = at91_wdt_ioctl, |
193 | .open = at91_wdt_open, |
194 | .release = at91_wdt_close, |
195 | .write = at91_wdt_write, |
196 | }; |
197 | |
198 | static struct miscdevice at91wdt_miscdev = { |
199 | .minor = WATCHDOG_MINOR, |
200 | .name = "watchdog", |
201 | .fops = &at91wdt_fops, |
202 | }; |
203 | |
204 | static int at91wdt_probe(struct platform_device *pdev) |
205 | { |
206 | int res; |
207 | |
208 | if (at91wdt_miscdev.parent) |
209 | return -EBUSY; |
210 | at91wdt_miscdev.parent = &pdev->dev; |
211 | |
212 | res = misc_register(&at91wdt_miscdev); |
213 | if (res) |
214 | return res; |
215 | |
216 | pr_info("AT91 Watchdog Timer enabled (%d seconds%s)\n", |
217 | wdt_time, nowayout ? ", nowayout" : ""); |
218 | return 0; |
219 | } |
220 | |
221 | static int at91wdt_remove(struct platform_device *pdev) |
222 | { |
223 | int res; |
224 | |
225 | res = misc_deregister(&at91wdt_miscdev); |
226 | if (!res) |
227 | at91wdt_miscdev.parent = NULL; |
228 | |
229 | return res; |
230 | } |
231 | |
232 | static void at91wdt_shutdown(struct platform_device *pdev) |
233 | { |
234 | at91_wdt_stop(); |
235 | } |
236 | |
237 | #ifdef CONFIG_PM |
238 | |
239 | static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message) |
240 | { |
241 | at91_wdt_stop(); |
242 | return 0; |
243 | } |
244 | |
245 | static int at91wdt_resume(struct platform_device *pdev) |
246 | { |
247 | if (at91wdt_busy) |
248 | at91_wdt_start(); |
249 | return 0; |
250 | } |
251 | |
252 | #else |
253 | #define at91wdt_suspend NULL |
254 | #define at91wdt_resume NULL |
255 | #endif |
256 | |
257 | static const struct of_device_id at91_wdt_dt_ids[] = { |
258 | { .compatible = "atmel,at91rm9200-wdt" }, |
259 | { /* sentinel */ } |
260 | }; |
261 | MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids); |
262 | |
263 | static struct platform_driver at91wdt_driver = { |
264 | .probe = at91wdt_probe, |
265 | .remove = at91wdt_remove, |
266 | .shutdown = at91wdt_shutdown, |
267 | .suspend = at91wdt_suspend, |
268 | .resume = at91wdt_resume, |
269 | .driver = { |
270 | .name = "at91_wdt", |
271 | .owner = THIS_MODULE, |
272 | .of_match_table = of_match_ptr(at91_wdt_dt_ids), |
273 | }, |
274 | }; |
275 | |
276 | static int __init at91_wdt_init(void) |
277 | { |
278 | /* Check that the heartbeat value is within range; |
279 | if not reset to the default */ |
280 | if (at91_wdt_settimeout(wdt_time)) { |
281 | at91_wdt_settimeout(WDT_DEFAULT_TIME); |
282 | pr_info("wdt_time value must be 1 <= wdt_time <= 256, using %d\n", |
283 | wdt_time); |
284 | } |
285 | |
286 | return platform_driver_register(&at91wdt_driver); |
287 | } |
288 | |
289 | static void __exit at91_wdt_exit(void) |
290 | { |
291 | platform_driver_unregister(&at91wdt_driver); |
292 | } |
293 | |
294 | module_init(at91_wdt_init); |
295 | module_exit(at91_wdt_exit); |
296 | |
297 | MODULE_AUTHOR("Andrew Victor"); |
298 | MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200"); |
299 | MODULE_LICENSE("GPL"); |
300 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |
301 | MODULE_ALIAS("platform:at91_wdt"); |
302 |
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