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1 | /* |
2 | * Watchdog driver for Atmel AT91SAM9x processors. |
3 | * |
4 | * Copyright (C) 2008 Renaud CERRATO r.cerrato@til-technologies.fr |
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 | /* |
13 | * The Watchdog Timer Mode Register can be only written to once. If the |
14 | * timeout need to be set from Linux, be sure that the bootstrap or the |
15 | * bootloader doesn't write to this register. |
16 | */ |
17 | |
18 | #include <linux/errno.h> |
19 | #include <linux/fs.h> |
20 | #include <linux/init.h> |
21 | #include <linux/io.h> |
22 | #include <linux/kernel.h> |
23 | #include <linux/miscdevice.h> |
24 | #include <linux/module.h> |
25 | #include <linux/moduleparam.h> |
26 | #include <linux/platform_device.h> |
27 | #include <linux/types.h> |
28 | #include <linux/watchdog.h> |
29 | #include <linux/jiffies.h> |
30 | #include <linux/timer.h> |
31 | #include <linux/bitops.h> |
32 | #include <linux/uaccess.h> |
33 | |
34 | #include <mach/at91_wdt.h> |
35 | |
36 | #define DRV_NAME "AT91SAM9 Watchdog" |
37 | |
38 | /* AT91SAM9 watchdog runs a 12bit counter @ 256Hz, |
39 | * use this to convert a watchdog |
40 | * value from/to milliseconds. |
41 | */ |
42 | #define ms_to_ticks(t) (((t << 8) / 1000) - 1) |
43 | #define ticks_to_ms(t) (((t + 1) * 1000) >> 8) |
44 | |
45 | /* Hardware timeout in seconds */ |
46 | #define WDT_HW_TIMEOUT 2 |
47 | |
48 | /* Timer heartbeat (500ms) */ |
49 | #define WDT_TIMEOUT (HZ/2) |
50 | |
51 | /* User land timeout */ |
52 | #define WDT_HEARTBEAT 15 |
53 | static int heartbeat = WDT_HEARTBEAT; |
54 | module_param(heartbeat, int, 0); |
55 | MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. " |
56 | "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")"); |
57 | |
58 | static int nowayout = WATCHDOG_NOWAYOUT; |
59 | module_param(nowayout, int, 0); |
60 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " |
61 | "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
62 | |
63 | static void at91_ping(unsigned long data); |
64 | |
65 | static struct { |
66 | unsigned long next_heartbeat; /* the next_heartbeat for the timer */ |
67 | unsigned long open; |
68 | char expect_close; |
69 | struct timer_list timer; /* The timer that pings the watchdog */ |
70 | } at91wdt_private; |
71 | |
72 | /* ......................................................................... */ |
73 | |
74 | |
75 | /* |
76 | * Reload the watchdog timer. (ie, pat the watchdog) |
77 | */ |
78 | static inline void at91_wdt_reset(void) |
79 | { |
80 | at91_sys_write(AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT); |
81 | } |
82 | |
83 | /* |
84 | * Timer tick |
85 | */ |
86 | static void at91_ping(unsigned long data) |
87 | { |
88 | if (time_before(jiffies, at91wdt_private.next_heartbeat) || |
89 | (!nowayout && !at91wdt_private.open)) { |
90 | at91_wdt_reset(); |
91 | mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT); |
92 | } else |
93 | printk(KERN_CRIT DRV_NAME": I will reset your machine !\n"); |
94 | } |
95 | |
96 | /* |
97 | * Watchdog device is opened, and watchdog starts running. |
98 | */ |
99 | static int at91_wdt_open(struct inode *inode, struct file *file) |
100 | { |
101 | if (test_and_set_bit(0, &at91wdt_private.open)) |
102 | return -EBUSY; |
103 | |
104 | at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ; |
105 | mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT); |
106 | |
107 | return nonseekable_open(inode, file); |
108 | } |
109 | |
110 | /* |
111 | * Close the watchdog device. |
112 | */ |
113 | static int at91_wdt_close(struct inode *inode, struct file *file) |
114 | { |
115 | clear_bit(0, &at91wdt_private.open); |
116 | |
117 | /* stop internal ping */ |
118 | if (!at91wdt_private.expect_close) |
119 | del_timer(&at91wdt_private.timer); |
120 | |
121 | at91wdt_private.expect_close = 0; |
122 | return 0; |
123 | } |
124 | |
125 | /* |
126 | * Set the watchdog time interval in 1/256Hz (write-once) |
127 | * Counter is 12 bit. |
128 | */ |
129 | static int at91_wdt_settimeout(unsigned int timeout) |
130 | { |
131 | unsigned int reg; |
132 | unsigned int mr; |
133 | |
134 | /* Check if disabled */ |
135 | mr = at91_sys_read(AT91_WDT_MR); |
136 | if (mr & AT91_WDT_WDDIS) { |
137 | printk(KERN_ERR DRV_NAME": sorry, watchdog is disabled\n"); |
138 | return -EIO; |
139 | } |
140 | |
141 | /* |
142 | * All counting occurs at SLOW_CLOCK / 128 = 256 Hz |
143 | * |
144 | * Since WDV is a 12-bit counter, the maximum period is |
145 | * 4096 / 256 = 16 seconds. |
146 | */ |
147 | reg = AT91_WDT_WDRSTEN /* causes watchdog reset */ |
148 | /* | AT91_WDT_WDRPROC causes processor reset only */ |
149 | | AT91_WDT_WDDBGHLT /* disabled in debug mode */ |
150 | | AT91_WDT_WDD /* restart at any time */ |
151 | | (timeout & AT91_WDT_WDV); /* timer value */ |
152 | at91_sys_write(AT91_WDT_MR, reg); |
153 | |
154 | return 0; |
155 | } |
156 | |
157 | static const struct watchdog_info at91_wdt_info = { |
158 | .identity = DRV_NAME, |
159 | .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | |
160 | WDIOF_MAGICCLOSE, |
161 | }; |
162 | |
163 | /* |
164 | * Handle commands from user-space. |
165 | */ |
166 | static long at91_wdt_ioctl(struct file *file, |
167 | unsigned int cmd, unsigned long arg) |
168 | { |
169 | void __user *argp = (void __user *)arg; |
170 | int __user *p = argp; |
171 | int new_value; |
172 | |
173 | switch (cmd) { |
174 | case WDIOC_GETSUPPORT: |
175 | return copy_to_user(argp, &at91_wdt_info, |
176 | sizeof(at91_wdt_info)) ? -EFAULT : 0; |
177 | |
178 | case WDIOC_GETSTATUS: |
179 | case WDIOC_GETBOOTSTATUS: |
180 | return put_user(0, p); |
181 | |
182 | case WDIOC_KEEPALIVE: |
183 | at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ; |
184 | return 0; |
185 | |
186 | case WDIOC_SETTIMEOUT: |
187 | if (get_user(new_value, p)) |
188 | return -EFAULT; |
189 | |
190 | heartbeat = new_value; |
191 | at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ; |
192 | |
193 | return put_user(new_value, p); /* return current value */ |
194 | |
195 | case WDIOC_GETTIMEOUT: |
196 | return put_user(heartbeat, p); |
197 | } |
198 | return -ENOTTY; |
199 | } |
200 | |
201 | /* |
202 | * Pat the watchdog whenever device is written to. |
203 | */ |
204 | static ssize_t at91_wdt_write(struct file *file, const char *data, size_t len, |
205 | loff_t *ppos) |
206 | { |
207 | if (!len) |
208 | return 0; |
209 | |
210 | /* Scan for magic character */ |
211 | if (!nowayout) { |
212 | size_t i; |
213 | |
214 | at91wdt_private.expect_close = 0; |
215 | |
216 | for (i = 0; i < len; i++) { |
217 | char c; |
218 | if (get_user(c, data + i)) |
219 | return -EFAULT; |
220 | if (c == 'V') { |
221 | at91wdt_private.expect_close = 42; |
222 | break; |
223 | } |
224 | } |
225 | } |
226 | |
227 | at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ; |
228 | |
229 | return len; |
230 | } |
231 | |
232 | /* ......................................................................... */ |
233 | |
234 | static const struct file_operations at91wdt_fops = { |
235 | .owner = THIS_MODULE, |
236 | .llseek = no_llseek, |
237 | .unlocked_ioctl = at91_wdt_ioctl, |
238 | .open = at91_wdt_open, |
239 | .release = at91_wdt_close, |
240 | .write = at91_wdt_write, |
241 | }; |
242 | |
243 | static struct miscdevice at91wdt_miscdev = { |
244 | .minor = WATCHDOG_MINOR, |
245 | .name = "watchdog", |
246 | .fops = &at91wdt_fops, |
247 | }; |
248 | |
249 | static int __init at91wdt_probe(struct platform_device *pdev) |
250 | { |
251 | int res; |
252 | |
253 | if (at91wdt_miscdev.parent) |
254 | return -EBUSY; |
255 | at91wdt_miscdev.parent = &pdev->dev; |
256 | |
257 | /* Set watchdog */ |
258 | res = at91_wdt_settimeout(ms_to_ticks(WDT_HW_TIMEOUT * 1000)); |
259 | if (res) |
260 | return res; |
261 | |
262 | res = misc_register(&at91wdt_miscdev); |
263 | if (res) |
264 | return res; |
265 | |
266 | at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ; |
267 | setup_timer(&at91wdt_private.timer, at91_ping, 0); |
268 | mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT); |
269 | |
270 | printk(KERN_INFO DRV_NAME " enabled (heartbeat=%d sec, nowayout=%d)\n", |
271 | heartbeat, nowayout); |
272 | |
273 | return 0; |
274 | } |
275 | |
276 | static int __exit at91wdt_remove(struct platform_device *pdev) |
277 | { |
278 | int res; |
279 | |
280 | res = misc_deregister(&at91wdt_miscdev); |
281 | if (!res) |
282 | at91wdt_miscdev.parent = NULL; |
283 | |
284 | return res; |
285 | } |
286 | |
287 | #ifdef CONFIG_PM |
288 | |
289 | static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message) |
290 | { |
291 | return 0; |
292 | } |
293 | |
294 | static int at91wdt_resume(struct platform_device *pdev) |
295 | { |
296 | return 0; |
297 | } |
298 | |
299 | #else |
300 | #define at91wdt_suspend NULL |
301 | #define at91wdt_resume NULL |
302 | #endif |
303 | |
304 | static struct platform_driver at91wdt_driver = { |
305 | .remove = __exit_p(at91wdt_remove), |
306 | .suspend = at91wdt_suspend, |
307 | .resume = at91wdt_resume, |
308 | .driver = { |
309 | .name = "at91_wdt", |
310 | .owner = THIS_MODULE, |
311 | }, |
312 | }; |
313 | |
314 | static int __init at91sam_wdt_init(void) |
315 | { |
316 | return platform_driver_probe(&at91wdt_driver, at91wdt_probe); |
317 | } |
318 | |
319 | static void __exit at91sam_wdt_exit(void) |
320 | { |
321 | platform_driver_unregister(&at91wdt_driver); |
322 | } |
323 | |
324 | module_init(at91sam_wdt_init); |
325 | module_exit(at91sam_wdt_exit); |
326 | |
327 | MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>"); |
328 | MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors"); |
329 | MODULE_LICENSE("GPL"); |
330 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |
331 |
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