1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | /* |
3 | * SBC8360 Watchdog driver |
4 | * |
5 | * (c) Copyright 2005 Webcon, Inc. |
6 | * |
7 | * Based on ib700wdt.c, which is based on advantechwdt.c which is based |
8 | * on acquirewdt.c which is based on wdt.c. |
9 | * |
10 | * (c) Copyright 2001 Charles Howes <chowes@vsol.net> |
11 | * |
12 | * Based on advantechwdt.c which is based on acquirewdt.c which |
13 | * is based on wdt.c. |
14 | * |
15 | * (c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl> |
16 | * |
17 | * Based on acquirewdt.c which is based on wdt.c. |
18 | * Original copyright messages: |
19 | * |
20 | * (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>, |
21 | * All Rights Reserved. |
22 | * |
23 | * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide |
24 | * warranty for any of this software. This material is provided |
25 | * "AS-IS" and at no charge. |
26 | * |
27 | * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk> |
28 | * |
29 | * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com> |
30 | * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT |
31 | * Added timeout module option to override default |
32 | * |
33 | */ |
34 | |
35 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
36 | |
37 | #include <linux/module.h> |
38 | #include <linux/types.h> |
39 | #include <linux/miscdevice.h> |
40 | #include <linux/watchdog.h> |
41 | #include <linux/ioport.h> |
42 | #include <linux/delay.h> |
43 | #include <linux/notifier.h> |
44 | #include <linux/fs.h> |
45 | #include <linux/reboot.h> |
46 | #include <linux/init.h> |
47 | #include <linux/spinlock.h> |
48 | #include <linux/moduleparam.h> |
49 | #include <linux/io.h> |
50 | #include <linux/uaccess.h> |
51 | |
52 | |
53 | static unsigned long sbc8360_is_open; |
54 | static char expect_close; |
55 | |
56 | /* |
57 | * |
58 | * Watchdog Timer Configuration |
59 | * |
60 | * The function of the watchdog timer is to reset the system automatically |
61 | * and is defined at I/O port 0120H and 0121H. To enable the watchdog timer |
62 | * and allow the system to reset, write appropriate values from the table |
63 | * below to I/O port 0120H and 0121H. To disable the timer, write a zero |
64 | * value to I/O port 0121H for the system to stop the watchdog function. |
65 | * |
66 | * The following describes how the timer should be programmed (according to |
67 | * the vendor documentation) |
68 | * |
69 | * Enabling Watchdog: |
70 | * MOV AX,000AH (enable, phase I) |
71 | * MOV DX,0120H |
72 | * OUT DX,AX |
73 | * MOV AX,000BH (enable, phase II) |
74 | * MOV DX,0120H |
75 | * OUT DX,AX |
76 | * MOV AX,000nH (set multiplier n, from 1-4) |
77 | * MOV DX,0120H |
78 | * OUT DX,AX |
79 | * MOV AX,000mH (set base timer m, from 0-F) |
80 | * MOV DX,0121H |
81 | * OUT DX,AX |
82 | * |
83 | * Reset timer: |
84 | * MOV AX,000mH (same as set base timer, above) |
85 | * MOV DX,0121H |
86 | * OUT DX,AX |
87 | * |
88 | * Disabling Watchdog: |
89 | * MOV AX,0000H (a zero value) |
90 | * MOV DX,0120H |
91 | * OUT DX,AX |
92 | * |
93 | * Watchdog timeout configuration values: |
94 | * N |
95 | * M | 1 2 3 4 |
96 | * --|---------------------------------- |
97 | * 0 | 0.5s 5s 50s 100s |
98 | * 1 | 1s 10s 100s 200s |
99 | * 2 | 1.5s 15s 150s 300s |
100 | * 3 | 2s 20s 200s 400s |
101 | * 4 | 2.5s 25s 250s 500s |
102 | * 5 | 3s 30s 300s 600s |
103 | * 6 | 3.5s 35s 350s 700s |
104 | * 7 | 4s 40s 400s 800s |
105 | * 8 | 4.5s 45s 450s 900s |
106 | * 9 | 5s 50s 500s 1000s |
107 | * A | 5.5s 55s 550s 1100s |
108 | * B | 6s 60s 600s 1200s |
109 | * C | 6.5s 65s 650s 1300s |
110 | * D | 7s 70s 700s 1400s |
111 | * E | 7.5s 75s 750s 1500s |
112 | * F | 8s 80s 800s 1600s |
113 | * |
114 | * Another way to say the same things is: |
115 | * For N=1, Timeout = (M+1) * 0.5s |
116 | * For N=2, Timeout = (M+1) * 5s |
117 | * For N=3, Timeout = (M+1) * 50s |
118 | * For N=4, Timeout = (M+1) * 100s |
119 | * |
120 | */ |
121 | |
122 | static int wd_times[64][2] = { |
123 | {0, 1}, /* 0 = 0.5s */ |
124 | {1, 1}, /* 1 = 1s */ |
125 | {2, 1}, /* 2 = 1.5s */ |
126 | {3, 1}, /* 3 = 2s */ |
127 | {4, 1}, /* 4 = 2.5s */ |
128 | {5, 1}, /* 5 = 3s */ |
129 | {6, 1}, /* 6 = 3.5s */ |
130 | {7, 1}, /* 7 = 4s */ |
131 | {8, 1}, /* 8 = 4.5s */ |
132 | {9, 1}, /* 9 = 5s */ |
133 | {0xA, 1}, /* 10 = 5.5s */ |
134 | {0xB, 1}, /* 11 = 6s */ |
135 | {0xC, 1}, /* 12 = 6.5s */ |
136 | {0xD, 1}, /* 13 = 7s */ |
137 | {0xE, 1}, /* 14 = 7.5s */ |
138 | {0xF, 1}, /* 15 = 8s */ |
139 | {0, 2}, /* 16 = 5s */ |
140 | {1, 2}, /* 17 = 10s */ |
141 | {2, 2}, /* 18 = 15s */ |
142 | {3, 2}, /* 19 = 20s */ |
143 | {4, 2}, /* 20 = 25s */ |
144 | {5, 2}, /* 21 = 30s */ |
145 | {6, 2}, /* 22 = 35s */ |
146 | {7, 2}, /* 23 = 40s */ |
147 | {8, 2}, /* 24 = 45s */ |
148 | {9, 2}, /* 25 = 50s */ |
149 | {0xA, 2}, /* 26 = 55s */ |
150 | {0xB, 2}, /* 27 = 60s */ |
151 | {0xC, 2}, /* 28 = 65s */ |
152 | {0xD, 2}, /* 29 = 70s */ |
153 | {0xE, 2}, /* 30 = 75s */ |
154 | {0xF, 2}, /* 31 = 80s */ |
155 | {0, 3}, /* 32 = 50s */ |
156 | {1, 3}, /* 33 = 100s */ |
157 | {2, 3}, /* 34 = 150s */ |
158 | {3, 3}, /* 35 = 200s */ |
159 | {4, 3}, /* 36 = 250s */ |
160 | {5, 3}, /* 37 = 300s */ |
161 | {6, 3}, /* 38 = 350s */ |
162 | {7, 3}, /* 39 = 400s */ |
163 | {8, 3}, /* 40 = 450s */ |
164 | {9, 3}, /* 41 = 500s */ |
165 | {0xA, 3}, /* 42 = 550s */ |
166 | {0xB, 3}, /* 43 = 600s */ |
167 | {0xC, 3}, /* 44 = 650s */ |
168 | {0xD, 3}, /* 45 = 700s */ |
169 | {0xE, 3}, /* 46 = 750s */ |
170 | {0xF, 3}, /* 47 = 800s */ |
171 | {0, 4}, /* 48 = 100s */ |
172 | {1, 4}, /* 49 = 200s */ |
173 | {2, 4}, /* 50 = 300s */ |
174 | {3, 4}, /* 51 = 400s */ |
175 | {4, 4}, /* 52 = 500s */ |
176 | {5, 4}, /* 53 = 600s */ |
177 | {6, 4}, /* 54 = 700s */ |
178 | {7, 4}, /* 55 = 800s */ |
179 | {8, 4}, /* 56 = 900s */ |
180 | {9, 4}, /* 57 = 1000s */ |
181 | {0xA, 4}, /* 58 = 1100s */ |
182 | {0xB, 4}, /* 59 = 1200s */ |
183 | {0xC, 4}, /* 60 = 1300s */ |
184 | {0xD, 4}, /* 61 = 1400s */ |
185 | {0xE, 4}, /* 62 = 1500s */ |
186 | {0xF, 4} /* 63 = 1600s */ |
187 | }; |
188 | |
189 | #define SBC8360_ENABLE 0x120 |
190 | #define SBC8360_BASETIME 0x121 |
191 | |
192 | static int timeout = 27; |
193 | static int wd_margin = 0xB; |
194 | static int wd_multiplier = 2; |
195 | static bool nowayout = WATCHDOG_NOWAYOUT; |
196 | |
197 | module_param(timeout, int, 0); |
198 | MODULE_PARM_DESC(timeout, "Index into timeout table (0-63) (default=27 (60s))" ); |
199 | module_param(nowayout, bool, 0); |
200 | MODULE_PARM_DESC(nowayout, |
201 | "Watchdog cannot be stopped once started (default=" |
202 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")" ); |
203 | |
204 | /* |
205 | * Kernel methods. |
206 | */ |
207 | |
208 | /* Activate and pre-configure watchdog */ |
209 | static void sbc8360_activate(void) |
210 | { |
211 | /* Enable the watchdog */ |
212 | outb(value: 0x0A, SBC8360_ENABLE); |
213 | msleep_interruptible(msecs: 100); |
214 | outb(value: 0x0B, SBC8360_ENABLE); |
215 | msleep_interruptible(msecs: 100); |
216 | /* Set timeout multiplier */ |
217 | outb(value: wd_multiplier, SBC8360_ENABLE); |
218 | msleep_interruptible(msecs: 100); |
219 | /* Nothing happens until first sbc8360_ping() */ |
220 | } |
221 | |
222 | /* Kernel pings watchdog */ |
223 | static void sbc8360_ping(void) |
224 | { |
225 | /* Write the base timer register */ |
226 | outb(value: wd_margin, SBC8360_BASETIME); |
227 | } |
228 | |
229 | /* stop watchdog */ |
230 | static void sbc8360_stop(void) |
231 | { |
232 | /* De-activate the watchdog */ |
233 | outb(value: 0, SBC8360_ENABLE); |
234 | } |
235 | |
236 | /* Userspace pings kernel driver, or requests clean close */ |
237 | static ssize_t sbc8360_write(struct file *file, const char __user *buf, |
238 | size_t count, loff_t *ppos) |
239 | { |
240 | if (count) { |
241 | if (!nowayout) { |
242 | size_t i; |
243 | |
244 | /* In case it was set long ago */ |
245 | expect_close = 0; |
246 | |
247 | for (i = 0; i != count; i++) { |
248 | char c; |
249 | if (get_user(c, buf + i)) |
250 | return -EFAULT; |
251 | if (c == 'V') |
252 | expect_close = 42; |
253 | } |
254 | } |
255 | sbc8360_ping(); |
256 | } |
257 | return count; |
258 | } |
259 | |
260 | static int sbc8360_open(struct inode *inode, struct file *file) |
261 | { |
262 | if (test_and_set_bit(nr: 0, addr: &sbc8360_is_open)) |
263 | return -EBUSY; |
264 | if (nowayout) |
265 | __module_get(THIS_MODULE); |
266 | |
267 | /* Activate and ping once to start the countdown */ |
268 | sbc8360_activate(); |
269 | sbc8360_ping(); |
270 | return stream_open(inode, filp: file); |
271 | } |
272 | |
273 | static int sbc8360_close(struct inode *inode, struct file *file) |
274 | { |
275 | if (expect_close == 42) |
276 | sbc8360_stop(); |
277 | else |
278 | pr_crit("SBC8360 device closed unexpectedly. SBC8360 will not stop!\n" ); |
279 | |
280 | clear_bit(nr: 0, addr: &sbc8360_is_open); |
281 | expect_close = 0; |
282 | return 0; |
283 | } |
284 | |
285 | /* |
286 | * Notifier for system down |
287 | */ |
288 | |
289 | static int sbc8360_notify_sys(struct notifier_block *this, unsigned long code, |
290 | void *unused) |
291 | { |
292 | if (code == SYS_DOWN || code == SYS_HALT) |
293 | sbc8360_stop(); /* Disable the SBC8360 Watchdog */ |
294 | |
295 | return NOTIFY_DONE; |
296 | } |
297 | |
298 | /* |
299 | * Kernel Interfaces |
300 | */ |
301 | |
302 | static const struct file_operations sbc8360_fops = { |
303 | .owner = THIS_MODULE, |
304 | .llseek = no_llseek, |
305 | .write = sbc8360_write, |
306 | .open = sbc8360_open, |
307 | .release = sbc8360_close, |
308 | }; |
309 | |
310 | static struct miscdevice sbc8360_miscdev = { |
311 | .minor = WATCHDOG_MINOR, |
312 | .name = "watchdog" , |
313 | .fops = &sbc8360_fops, |
314 | }; |
315 | |
316 | /* |
317 | * The SBC8360 needs to learn about soft shutdowns in order to |
318 | * turn the timebomb registers off. |
319 | */ |
320 | |
321 | static struct notifier_block sbc8360_notifier = { |
322 | .notifier_call = sbc8360_notify_sys, |
323 | }; |
324 | |
325 | static int __init sbc8360_init(void) |
326 | { |
327 | int res; |
328 | unsigned long int mseconds = 60000; |
329 | |
330 | if (timeout < 0 || timeout > 63) { |
331 | pr_err("Invalid timeout index (must be 0-63)\n" ); |
332 | res = -EINVAL; |
333 | goto out; |
334 | } |
335 | |
336 | if (!request_region(SBC8360_ENABLE, 1, "SBC8360" )) { |
337 | pr_err("ENABLE method I/O %X is not available\n" , |
338 | SBC8360_ENABLE); |
339 | res = -EIO; |
340 | goto out; |
341 | } |
342 | if (!request_region(SBC8360_BASETIME, 1, "SBC8360" )) { |
343 | pr_err("BASETIME method I/O %X is not available\n" , |
344 | SBC8360_BASETIME); |
345 | res = -EIO; |
346 | goto out_nobasetimereg; |
347 | } |
348 | |
349 | res = register_reboot_notifier(&sbc8360_notifier); |
350 | if (res) { |
351 | pr_err("Failed to register reboot notifier\n" ); |
352 | goto out_noreboot; |
353 | } |
354 | |
355 | res = misc_register(misc: &sbc8360_miscdev); |
356 | if (res) { |
357 | pr_err("failed to register misc device\n" ); |
358 | goto out_nomisc; |
359 | } |
360 | |
361 | wd_margin = wd_times[timeout][0]; |
362 | wd_multiplier = wd_times[timeout][1]; |
363 | |
364 | if (wd_multiplier == 1) |
365 | mseconds = (wd_margin + 1) * 500; |
366 | else if (wd_multiplier == 2) |
367 | mseconds = (wd_margin + 1) * 5000; |
368 | else if (wd_multiplier == 3) |
369 | mseconds = (wd_margin + 1) * 50000; |
370 | else if (wd_multiplier == 4) |
371 | mseconds = (wd_margin + 1) * 100000; |
372 | |
373 | /* My kingdom for the ability to print "0.5 seconds" in the kernel! */ |
374 | pr_info("Timeout set at %ld ms\n" , mseconds); |
375 | |
376 | return 0; |
377 | |
378 | out_nomisc: |
379 | unregister_reboot_notifier(&sbc8360_notifier); |
380 | out_noreboot: |
381 | release_region(SBC8360_BASETIME, 1); |
382 | out_nobasetimereg: |
383 | release_region(SBC8360_ENABLE, 1); |
384 | out: |
385 | return res; |
386 | } |
387 | |
388 | static void __exit sbc8360_exit(void) |
389 | { |
390 | misc_deregister(misc: &sbc8360_miscdev); |
391 | unregister_reboot_notifier(&sbc8360_notifier); |
392 | release_region(SBC8360_ENABLE, 1); |
393 | release_region(SBC8360_BASETIME, 1); |
394 | } |
395 | |
396 | module_init(sbc8360_init); |
397 | module_exit(sbc8360_exit); |
398 | |
399 | MODULE_AUTHOR("Ian E. Morgan <imorgan@webcon.ca>" ); |
400 | MODULE_DESCRIPTION("SBC8360 watchdog driver" ); |
401 | MODULE_LICENSE("GPL" ); |
402 | MODULE_VERSION("1.01" ); |
403 | |
404 | /* end of sbc8360.c */ |
405 | |