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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