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e6bb42e3 RC |
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> | |
2af29b78 | 21 | #include <linux/io.h> |
e6bb42e3 RC |
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 | ||
c1dfda39 | 34 | #include <mach/at91_wdt.h> |
e6bb42e3 RC |
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, | |
e73a7802 WVS |
159 | .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | |
160 | WDIOF_MAGICCLOSE, | |
e6bb42e3 RC |
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, | |
143a2e54 | 205 | loff_t *ppos) |
e6bb42e3 RC |
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); |