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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/kernel.h> | |
22 | #include <linux/miscdevice.h> | |
23 | #include <linux/module.h> | |
24 | #include <linux/moduleparam.h> | |
25 | #include <linux/platform_device.h> | |
26 | #include <linux/types.h> | |
27 | #include <linux/watchdog.h> | |
28 | #include <linux/jiffies.h> | |
29 | #include <linux/timer.h> | |
30 | #include <linux/bitops.h> | |
31 | #include <linux/uaccess.h> | |
32 | ||
c1dfda39 | 33 | #include <mach/at91_wdt.h> |
e6bb42e3 RC |
34 | |
35 | #define DRV_NAME "AT91SAM9 Watchdog" | |
36 | ||
37 | /* AT91SAM9 watchdog runs a 12bit counter @ 256Hz, | |
38 | * use this to convert a watchdog | |
39 | * value from/to milliseconds. | |
40 | */ | |
41 | #define ms_to_ticks(t) (((t << 8) / 1000) - 1) | |
42 | #define ticks_to_ms(t) (((t + 1) * 1000) >> 8) | |
43 | ||
44 | /* Hardware timeout in seconds */ | |
45 | #define WDT_HW_TIMEOUT 2 | |
46 | ||
47 | /* Timer heartbeat (500ms) */ | |
48 | #define WDT_TIMEOUT (HZ/2) | |
49 | ||
50 | /* User land timeout */ | |
51 | #define WDT_HEARTBEAT 15 | |
52 | static int heartbeat = WDT_HEARTBEAT; | |
53 | module_param(heartbeat, int, 0); | |
54 | MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. " | |
55 | "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")"); | |
56 | ||
57 | static int nowayout = WATCHDOG_NOWAYOUT; | |
58 | module_param(nowayout, int, 0); | |
59 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " | |
60 | "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); | |
61 | ||
62 | static void at91_ping(unsigned long data); | |
63 | ||
64 | static struct { | |
65 | unsigned long next_heartbeat; /* the next_heartbeat for the timer */ | |
66 | unsigned long open; | |
67 | char expect_close; | |
68 | struct timer_list timer; /* The timer that pings the watchdog */ | |
69 | } at91wdt_private; | |
70 | ||
71 | /* ......................................................................... */ | |
72 | ||
73 | ||
74 | /* | |
75 | * Reload the watchdog timer. (ie, pat the watchdog) | |
76 | */ | |
77 | static inline void at91_wdt_reset(void) | |
78 | { | |
79 | at91_sys_write(AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT); | |
80 | } | |
81 | ||
82 | /* | |
83 | * Timer tick | |
84 | */ | |
85 | static void at91_ping(unsigned long data) | |
86 | { | |
87 | if (time_before(jiffies, at91wdt_private.next_heartbeat) || | |
88 | (!nowayout && !at91wdt_private.open)) { | |
89 | at91_wdt_reset(); | |
90 | mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT); | |
91 | } else | |
92 | printk(KERN_CRIT DRV_NAME": I will reset your machine !\n"); | |
93 | } | |
94 | ||
95 | /* | |
96 | * Watchdog device is opened, and watchdog starts running. | |
97 | */ | |
98 | static int at91_wdt_open(struct inode *inode, struct file *file) | |
99 | { | |
100 | if (test_and_set_bit(0, &at91wdt_private.open)) | |
101 | return -EBUSY; | |
102 | ||
103 | at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ; | |
104 | mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT); | |
105 | ||
106 | return nonseekable_open(inode, file); | |
107 | } | |
108 | ||
109 | /* | |
110 | * Close the watchdog device. | |
111 | */ | |
112 | static int at91_wdt_close(struct inode *inode, struct file *file) | |
113 | { | |
114 | clear_bit(0, &at91wdt_private.open); | |
115 | ||
116 | /* stop internal ping */ | |
117 | if (!at91wdt_private.expect_close) | |
118 | del_timer(&at91wdt_private.timer); | |
119 | ||
120 | at91wdt_private.expect_close = 0; | |
121 | return 0; | |
122 | } | |
123 | ||
124 | /* | |
125 | * Set the watchdog time interval in 1/256Hz (write-once) | |
126 | * Counter is 12 bit. | |
127 | */ | |
128 | static int at91_wdt_settimeout(unsigned int timeout) | |
129 | { | |
130 | unsigned int reg; | |
131 | unsigned int mr; | |
132 | ||
133 | /* Check if disabled */ | |
134 | mr = at91_sys_read(AT91_WDT_MR); | |
135 | if (mr & AT91_WDT_WDDIS) { | |
136 | printk(KERN_ERR DRV_NAME": sorry, watchdog is disabled\n"); | |
137 | return -EIO; | |
138 | } | |
139 | ||
140 | /* | |
141 | * All counting occurs at SLOW_CLOCK / 128 = 256 Hz | |
142 | * | |
143 | * Since WDV is a 12-bit counter, the maximum period is | |
144 | * 4096 / 256 = 16 seconds. | |
145 | */ | |
146 | reg = AT91_WDT_WDRSTEN /* causes watchdog reset */ | |
147 | /* | AT91_WDT_WDRPROC causes processor reset only */ | |
148 | | AT91_WDT_WDDBGHLT /* disabled in debug mode */ | |
149 | | AT91_WDT_WDD /* restart at any time */ | |
150 | | (timeout & AT91_WDT_WDV); /* timer value */ | |
151 | at91_sys_write(AT91_WDT_MR, reg); | |
152 | ||
153 | return 0; | |
154 | } | |
155 | ||
156 | static const struct watchdog_info at91_wdt_info = { | |
157 | .identity = DRV_NAME, | |
158 | .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING, | |
159 | }; | |
160 | ||
161 | /* | |
162 | * Handle commands from user-space. | |
163 | */ | |
164 | static long at91_wdt_ioctl(struct file *file, | |
165 | unsigned int cmd, unsigned long arg) | |
166 | { | |
167 | void __user *argp = (void __user *)arg; | |
168 | int __user *p = argp; | |
169 | int new_value; | |
170 | ||
171 | switch (cmd) { | |
172 | case WDIOC_GETSUPPORT: | |
173 | return copy_to_user(argp, &at91_wdt_info, | |
174 | sizeof(at91_wdt_info)) ? -EFAULT : 0; | |
175 | ||
176 | case WDIOC_GETSTATUS: | |
177 | case WDIOC_GETBOOTSTATUS: | |
178 | return put_user(0, p); | |
179 | ||
180 | case WDIOC_KEEPALIVE: | |
181 | at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ; | |
182 | return 0; | |
183 | ||
184 | case WDIOC_SETTIMEOUT: | |
185 | if (get_user(new_value, p)) | |
186 | return -EFAULT; | |
187 | ||
188 | heartbeat = new_value; | |
189 | at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ; | |
190 | ||
191 | return put_user(new_value, p); /* return current value */ | |
192 | ||
193 | case WDIOC_GETTIMEOUT: | |
194 | return put_user(heartbeat, p); | |
195 | } | |
196 | return -ENOTTY; | |
197 | } | |
198 | ||
199 | /* | |
200 | * Pat the watchdog whenever device is written to. | |
201 | */ | |
202 | static ssize_t at91_wdt_write(struct file *file, const char *data, size_t len, | |
203 | loff_t *ppos) | |
204 | { | |
205 | if (!len) | |
206 | return 0; | |
207 | ||
208 | /* Scan for magic character */ | |
209 | if (!nowayout) { | |
210 | size_t i; | |
211 | ||
212 | at91wdt_private.expect_close = 0; | |
213 | ||
214 | for (i = 0; i < len; i++) { | |
215 | char c; | |
216 | if (get_user(c, data + i)) | |
217 | return -EFAULT; | |
218 | if (c == 'V') { | |
219 | at91wdt_private.expect_close = 42; | |
220 | break; | |
221 | } | |
222 | } | |
223 | } | |
224 | ||
225 | at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ; | |
226 | ||
227 | return len; | |
228 | } | |
229 | ||
230 | /* ......................................................................... */ | |
231 | ||
232 | static const struct file_operations at91wdt_fops = { | |
233 | .owner = THIS_MODULE, | |
234 | .llseek = no_llseek, | |
235 | .unlocked_ioctl = at91_wdt_ioctl, | |
236 | .open = at91_wdt_open, | |
237 | .release = at91_wdt_close, | |
238 | .write = at91_wdt_write, | |
239 | }; | |
240 | ||
241 | static struct miscdevice at91wdt_miscdev = { | |
242 | .minor = WATCHDOG_MINOR, | |
243 | .name = "watchdog", | |
244 | .fops = &at91wdt_fops, | |
245 | }; | |
246 | ||
247 | static int __init at91wdt_probe(struct platform_device *pdev) | |
248 | { | |
249 | int res; | |
250 | ||
251 | if (at91wdt_miscdev.parent) | |
252 | return -EBUSY; | |
253 | at91wdt_miscdev.parent = &pdev->dev; | |
254 | ||
255 | /* Set watchdog */ | |
256 | res = at91_wdt_settimeout(ms_to_ticks(WDT_HW_TIMEOUT * 1000)); | |
257 | if (res) | |
258 | return res; | |
259 | ||
260 | res = misc_register(&at91wdt_miscdev); | |
261 | if (res) | |
262 | return res; | |
263 | ||
264 | at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ; | |
265 | setup_timer(&at91wdt_private.timer, at91_ping, 0); | |
266 | mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT); | |
267 | ||
268 | printk(KERN_INFO DRV_NAME " enabled (heartbeat=%d sec, nowayout=%d)\n", | |
269 | heartbeat, nowayout); | |
270 | ||
271 | return 0; | |
272 | } | |
273 | ||
274 | static int __exit at91wdt_remove(struct platform_device *pdev) | |
275 | { | |
276 | int res; | |
277 | ||
278 | res = misc_deregister(&at91wdt_miscdev); | |
279 | if (!res) | |
280 | at91wdt_miscdev.parent = NULL; | |
281 | ||
282 | return res; | |
283 | } | |
284 | ||
285 | #ifdef CONFIG_PM | |
286 | ||
287 | static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message) | |
288 | { | |
289 | return 0; | |
290 | } | |
291 | ||
292 | static int at91wdt_resume(struct platform_device *pdev) | |
293 | { | |
294 | return 0; | |
295 | } | |
296 | ||
297 | #else | |
298 | #define at91wdt_suspend NULL | |
299 | #define at91wdt_resume NULL | |
300 | #endif | |
301 | ||
302 | static struct platform_driver at91wdt_driver = { | |
303 | .remove = __exit_p(at91wdt_remove), | |
304 | .suspend = at91wdt_suspend, | |
305 | .resume = at91wdt_resume, | |
306 | .driver = { | |
307 | .name = "at91_wdt", | |
308 | .owner = THIS_MODULE, | |
309 | }, | |
310 | }; | |
311 | ||
312 | static int __init at91sam_wdt_init(void) | |
313 | { | |
314 | return platform_driver_probe(&at91wdt_driver, at91wdt_probe); | |
315 | } | |
316 | ||
317 | static void __exit at91sam_wdt_exit(void) | |
318 | { | |
319 | platform_driver_unregister(&at91wdt_driver); | |
320 | } | |
321 | ||
322 | module_init(at91sam_wdt_init); | |
323 | module_exit(at91sam_wdt_exit); | |
324 | ||
325 | MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>"); | |
326 | MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors"); | |
327 | MODULE_LICENSE("GPL"); | |
328 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |