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1 | /* |
2 | * 60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x |
3 | * |
4 | * Based on acquirewdt.c by Alan Cox. |
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 | * The author does NOT admit liability nor provide warranty for |
12 | * any of this software. This material is provided "AS-IS" in |
13 | * the hope that it may be useful for others. |
14 | * |
15 | * (c) Copyright 2000 Jakob Oestergaard <jakob@unthought.net> |
16 | * |
17 | * 12/4 - 2000 [Initial revision] |
18 | * 25/4 - 2000 Added /dev/watchdog support |
19 | * 09/5 - 2001 [smj@oro.net] fixed fop_write to "return 1" |
20 | * on success |
21 | * 12/4 - 2002 [rob@osinvestor.com] eliminate fop_read |
22 | * fix possible wdt_is_open race |
23 | * add CONFIG_WATCHDOG_NOWAYOUT support |
24 | * remove lock_kernel/unlock_kernel pairs |
25 | * added KERN_* to printk's |
26 | * got rid of extraneous comments |
27 | * changed watchdog_info to correctly reflect what |
28 | * the driver offers |
29 | * added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS, |
30 | * WDIOC_SETTIMEOUT, WDIOC_GETTIMEOUT, and |
31 | * WDIOC_SETOPTIONS ioctls |
32 | * 09/8 - 2003 [wim@iguana.be] cleanup of trailing spaces |
33 | * use module_param |
34 | * made timeout (the emulated heartbeat) a |
35 | * module_param |
36 | * made the keepalive ping an internal subroutine |
37 | * made wdt_stop and wdt_start module params |
38 | * added extra printk's for startup problems |
39 | * added MODULE_AUTHOR and MODULE_DESCRIPTION info |
40 | * |
41 | * |
42 | * This WDT driver is different from the other Linux WDT |
43 | * drivers in the following ways: |
44 | * *) The driver will ping the watchdog by itself, because this |
45 | * particular WDT has a very short timeout (one second) and it |
46 | * would be insane to count on any userspace daemon always |
47 | * getting scheduled within that time frame. |
48 | * |
49 | */ |
50 | |
51 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
52 | |
53 | #include <linux/module.h> |
54 | #include <linux/moduleparam.h> |
55 | #include <linux/types.h> |
56 | #include <linux/timer.h> |
57 | #include <linux/jiffies.h> |
58 | #include <linux/miscdevice.h> |
59 | #include <linux/watchdog.h> |
60 | #include <linux/fs.h> |
61 | #include <linux/ioport.h> |
62 | #include <linux/notifier.h> |
63 | #include <linux/reboot.h> |
64 | #include <linux/init.h> |
65 | #include <linux/io.h> |
66 | #include <linux/uaccess.h> |
67 | |
68 | |
69 | #define OUR_NAME "sbc60xxwdt" |
70 | #define PFX OUR_NAME ": " |
71 | |
72 | /* |
73 | * You must set these - The driver cannot probe for the settings |
74 | */ |
75 | |
76 | static int wdt_stop = 0x45; |
77 | module_param(wdt_stop, int, 0); |
78 | MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)"); |
79 | |
80 | static int wdt_start = 0x443; |
81 | module_param(wdt_start, int, 0); |
82 | MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)"); |
83 | |
84 | /* |
85 | * The 60xx board can use watchdog timeout values from one second |
86 | * to several minutes. The default is one second, so if we reset |
87 | * the watchdog every ~250ms we should be safe. |
88 | */ |
89 | |
90 | #define WDT_INTERVAL (HZ/4+1) |
91 | |
92 | /* |
93 | * We must not require too good response from the userspace daemon. |
94 | * Here we require the userspace daemon to send us a heartbeat |
95 | * char to /dev/watchdog every 30 seconds. |
96 | * If the daemon pulses us every 25 seconds, we can still afford |
97 | * a 5 second scheduling delay on the (high priority) daemon. That |
98 | * should be sufficient for a box under any load. |
99 | */ |
100 | |
101 | #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */ |
102 | static int timeout = WATCHDOG_TIMEOUT; /* in seconds, multiplied by HZ to |
103 | get seconds to wait for a ping */ |
104 | module_param(timeout, int, 0); |
105 | MODULE_PARM_DESC(timeout, |
106 | "Watchdog timeout in seconds. (1<=timeout<=3600, default=" |
107 | __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); |
108 | |
109 | static bool nowayout = WATCHDOG_NOWAYOUT; |
110 | module_param(nowayout, bool, 0); |
111 | MODULE_PARM_DESC(nowayout, |
112 | "Watchdog cannot be stopped once started (default=" |
113 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
114 | |
115 | static void wdt_timer_ping(unsigned long); |
116 | static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0); |
117 | static unsigned long next_heartbeat; |
118 | static unsigned long wdt_is_open; |
119 | static char wdt_expect_close; |
120 | |
121 | /* |
122 | * Whack the dog |
123 | */ |
124 | |
125 | static void wdt_timer_ping(unsigned long data) |
126 | { |
127 | /* If we got a heartbeat pulse within the WDT_US_INTERVAL |
128 | * we agree to ping the WDT |
129 | */ |
130 | if (time_before(jiffies, next_heartbeat)) { |
131 | /* Ping the WDT by reading from wdt_start */ |
132 | inb_p(wdt_start); |
133 | /* Re-set the timer interval */ |
134 | mod_timer(&timer, jiffies + WDT_INTERVAL); |
135 | } else |
136 | pr_warn("Heartbeat lost! Will not ping the watchdog\n"); |
137 | } |
138 | |
139 | /* |
140 | * Utility routines |
141 | */ |
142 | |
143 | static void wdt_startup(void) |
144 | { |
145 | next_heartbeat = jiffies + (timeout * HZ); |
146 | |
147 | /* Start the timer */ |
148 | mod_timer(&timer, jiffies + WDT_INTERVAL); |
149 | pr_info("Watchdog timer is now enabled\n"); |
150 | } |
151 | |
152 | static void wdt_turnoff(void) |
153 | { |
154 | /* Stop the timer */ |
155 | del_timer(&timer); |
156 | inb_p(wdt_stop); |
157 | pr_info("Watchdog timer is now disabled...\n"); |
158 | } |
159 | |
160 | static void wdt_keepalive(void) |
161 | { |
162 | /* user land ping */ |
163 | next_heartbeat = jiffies + (timeout * HZ); |
164 | } |
165 | |
166 | /* |
167 | * /dev/watchdog handling |
168 | */ |
169 | |
170 | static ssize_t fop_write(struct file *file, const char __user *buf, |
171 | size_t count, loff_t *ppos) |
172 | { |
173 | /* See if we got the magic character 'V' and reload the timer */ |
174 | if (count) { |
175 | if (!nowayout) { |
176 | size_t ofs; |
177 | |
178 | /* note: just in case someone wrote the |
179 | magic character five months ago... */ |
180 | wdt_expect_close = 0; |
181 | |
182 | /* scan to see whether or not we got the |
183 | magic character */ |
184 | for (ofs = 0; ofs != count; ofs++) { |
185 | char c; |
186 | if (get_user(c, buf + ofs)) |
187 | return -EFAULT; |
188 | if (c == 'V') |
189 | wdt_expect_close = 42; |
190 | } |
191 | } |
192 | |
193 | /* Well, anyhow someone wrote to us, we should |
194 | return that favour */ |
195 | wdt_keepalive(); |
196 | } |
197 | return count; |
198 | } |
199 | |
200 | static int fop_open(struct inode *inode, struct file *file) |
201 | { |
202 | /* Just in case we're already talking to someone... */ |
203 | if (test_and_set_bit(0, &wdt_is_open)) |
204 | return -EBUSY; |
205 | |
206 | if (nowayout) |
207 | __module_get(THIS_MODULE); |
208 | |
209 | /* Good, fire up the show */ |
210 | wdt_startup(); |
211 | return nonseekable_open(inode, file); |
212 | } |
213 | |
214 | static int fop_close(struct inode *inode, struct file *file) |
215 | { |
216 | if (wdt_expect_close == 42) |
217 | wdt_turnoff(); |
218 | else { |
219 | del_timer(&timer); |
220 | pr_crit("device file closed unexpectedly. Will not stop the WDT!\n"); |
221 | } |
222 | clear_bit(0, &wdt_is_open); |
223 | wdt_expect_close = 0; |
224 | return 0; |
225 | } |
226 | |
227 | static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg) |
228 | { |
229 | void __user *argp = (void __user *)arg; |
230 | int __user *p = argp; |
231 | static const struct watchdog_info ident = { |
232 | .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | |
233 | WDIOF_MAGICCLOSE, |
234 | .firmware_version = 1, |
235 | .identity = "SBC60xx", |
236 | }; |
237 | |
238 | switch (cmd) { |
239 | case WDIOC_GETSUPPORT: |
240 | return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; |
241 | case WDIOC_GETSTATUS: |
242 | case WDIOC_GETBOOTSTATUS: |
243 | return put_user(0, p); |
244 | case WDIOC_SETOPTIONS: |
245 | { |
246 | int new_options, retval = -EINVAL; |
247 | if (get_user(new_options, p)) |
248 | return -EFAULT; |
249 | if (new_options & WDIOS_DISABLECARD) { |
250 | wdt_turnoff(); |
251 | retval = 0; |
252 | } |
253 | if (new_options & WDIOS_ENABLECARD) { |
254 | wdt_startup(); |
255 | retval = 0; |
256 | } |
257 | return retval; |
258 | } |
259 | case WDIOC_KEEPALIVE: |
260 | wdt_keepalive(); |
261 | return 0; |
262 | case WDIOC_SETTIMEOUT: |
263 | { |
264 | int new_timeout; |
265 | if (get_user(new_timeout, p)) |
266 | return -EFAULT; |
267 | /* arbitrary upper limit */ |
268 | if (new_timeout < 1 || new_timeout > 3600) |
269 | return -EINVAL; |
270 | |
271 | timeout = new_timeout; |
272 | wdt_keepalive(); |
273 | /* Fall through */ |
274 | } |
275 | case WDIOC_GETTIMEOUT: |
276 | return put_user(timeout, p); |
277 | default: |
278 | return -ENOTTY; |
279 | } |
280 | } |
281 | |
282 | static const struct file_operations wdt_fops = { |
283 | .owner = THIS_MODULE, |
284 | .llseek = no_llseek, |
285 | .write = fop_write, |
286 | .open = fop_open, |
287 | .release = fop_close, |
288 | .unlocked_ioctl = fop_ioctl, |
289 | }; |
290 | |
291 | static struct miscdevice wdt_miscdev = { |
292 | .minor = WATCHDOG_MINOR, |
293 | .name = "watchdog", |
294 | .fops = &wdt_fops, |
295 | }; |
296 | |
297 | /* |
298 | * Notifier for system down |
299 | */ |
300 | |
301 | static int wdt_notify_sys(struct notifier_block *this, unsigned long code, |
302 | void *unused) |
303 | { |
304 | if (code == SYS_DOWN || code == SYS_HALT) |
305 | wdt_turnoff(); |
306 | return NOTIFY_DONE; |
307 | } |
308 | |
309 | /* |
310 | * The WDT needs to learn about soft shutdowns in order to |
311 | * turn the timebomb registers off. |
312 | */ |
313 | |
314 | static struct notifier_block wdt_notifier = { |
315 | .notifier_call = wdt_notify_sys, |
316 | }; |
317 | |
318 | static void __exit sbc60xxwdt_unload(void) |
319 | { |
320 | wdt_turnoff(); |
321 | |
322 | /* Deregister */ |
323 | misc_deregister(&wdt_miscdev); |
324 | |
325 | unregister_reboot_notifier(&wdt_notifier); |
326 | if ((wdt_stop != 0x45) && (wdt_stop != wdt_start)) |
327 | release_region(wdt_stop, 1); |
328 | release_region(wdt_start, 1); |
329 | } |
330 | |
331 | static int __init sbc60xxwdt_init(void) |
332 | { |
333 | int rc = -EBUSY; |
334 | |
335 | if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */ |
336 | timeout = WATCHDOG_TIMEOUT; |
337 | pr_info("timeout value must be 1 <= x <= 3600, using %d\n", |
338 | timeout); |
339 | } |
340 | |
341 | if (!request_region(wdt_start, 1, "SBC 60XX WDT")) { |
342 | pr_err("I/O address 0x%04x already in use\n", wdt_start); |
343 | rc = -EIO; |
344 | goto err_out; |
345 | } |
346 | |
347 | /* We cannot reserve 0x45 - the kernel already has! */ |
348 | if (wdt_stop != 0x45 && wdt_stop != wdt_start) { |
349 | if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) { |
350 | pr_err("I/O address 0x%04x already in use\n", wdt_stop); |
351 | rc = -EIO; |
352 | goto err_out_region1; |
353 | } |
354 | } |
355 | |
356 | rc = register_reboot_notifier(&wdt_notifier); |
357 | if (rc) { |
358 | pr_err("cannot register reboot notifier (err=%d)\n", rc); |
359 | goto err_out_region2; |
360 | } |
361 | |
362 | rc = misc_register(&wdt_miscdev); |
363 | if (rc) { |
364 | pr_err("cannot register miscdev on minor=%d (err=%d)\n", |
365 | wdt_miscdev.minor, rc); |
366 | goto err_out_reboot; |
367 | } |
368 | pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n", |
369 | timeout, nowayout); |
370 | |
371 | return 0; |
372 | |
373 | err_out_reboot: |
374 | unregister_reboot_notifier(&wdt_notifier); |
375 | err_out_region2: |
376 | if (wdt_stop != 0x45 && wdt_stop != wdt_start) |
377 | release_region(wdt_stop, 1); |
378 | err_out_region1: |
379 | release_region(wdt_start, 1); |
380 | err_out: |
381 | return rc; |
382 | } |
383 | |
384 | module_init(sbc60xxwdt_init); |
385 | module_exit(sbc60xxwdt_unload); |
386 | |
387 | MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>"); |
388 | MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver"); |
389 | MODULE_LICENSE("GPL"); |
390 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |
391 |
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