1 /*
2 * MachZ ZF-Logic Watchdog Timer driver for Linux
3 *
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
9 *
10 * The author does NOT admit liability nor provide warranty for
11 * any of this software. This material is provided "AS-IS" in
12 * the hope that it may be useful for others.
13 *
14 * Author: Fernando Fuganti <fuganti@conectiva.com.br>
15 *
16 * Based on sbc60xxwdt.c by Jakob Oestergaard
17 *
18 *
19 * We have two timers (wd#1, wd#2) driven by a 32 KHz clock with the
20 * following periods:
21 * wd#1 - 2 seconds;
22 * wd#2 - 7.2 ms;
23 * After the expiration of wd#1, it can generate a NMI, SCI, SMI, or
24 * a system RESET and it starts wd#2 that unconditionally will RESET
25 * the system when the counter reaches zero.
26 *
27 * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
28 * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
29 */
30
31 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
32
33 #include <linux/module.h>
34 #include <linux/moduleparam.h>
35 #include <linux/types.h>
36 #include <linux/timer.h>
37 #include <linux/jiffies.h>
38 #include <linux/miscdevice.h>
39 #include <linux/watchdog.h>
40 #include <linux/fs.h>
41 #include <linux/ioport.h>
42 #include <linux/notifier.h>
43 #include <linux/reboot.h>
44 #include <linux/init.h>
45 #include <linux/io.h>
46 #include <linux/uaccess.h>
47
48
49 /* ports */
50 #define ZF_IOBASE 0x218
51 #define INDEX 0x218
52 #define DATA_B 0x219
53 #define DATA_W 0x21A
54 #define DATA_D 0x21A
55
56 /* indexes */ /* size */
57 #define ZFL_VERSION 0x02 /* 16 */
58 #define CONTROL 0x10 /* 16 */
59 #define STATUS 0x12 /* 8 */
60 #define COUNTER_1 0x0C /* 16 */
61 #define COUNTER_2 0x0E /* 8 */
62 #define PULSE_LEN 0x0F /* 8 */
63
64 /* controls */
65 #define ENABLE_WD1 0x0001
66 #define ENABLE_WD2 0x0002
67 #define RESET_WD1 0x0010
68 #define RESET_WD2 0x0020
69 #define GEN_SCI 0x0100
70 #define GEN_NMI 0x0200
71 #define GEN_SMI 0x0400
72 #define GEN_RESET 0x0800
73
74
75 /* utilities */
76
77 #define WD1 0
78 #define WD2 1
79
80 #define zf_writew(port, data) { outb(port, INDEX); outw(data, DATA_W); }
81 #define zf_writeb(port, data) { outb(port, INDEX); outb(data, DATA_B); }
82 #define zf_get_ZFL_version() zf_readw(ZFL_VERSION)
83
84
zf_readw(unsigned char port)85 static unsigned short zf_readw(unsigned char port)
86 {
87 outb(port, INDEX);
88 return inw(DATA_W);
89 }
90
91
92 MODULE_AUTHOR("Fernando Fuganti <fuganti@conectiva.com.br>");
93 MODULE_DESCRIPTION("MachZ ZF-Logic Watchdog driver");
94 MODULE_LICENSE("GPL");
95 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
96
97 static bool nowayout = WATCHDOG_NOWAYOUT;
98 module_param(nowayout, bool, 0);
99 MODULE_PARM_DESC(nowayout,
100 "Watchdog cannot be stopped once started (default="
101 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
102
103 #define PFX "machzwd"
104
105 static const struct watchdog_info zf_info = {
106 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
107 .firmware_version = 1,
108 .identity = "ZF-Logic watchdog",
109 };
110
111
112 /*
113 * action refers to action taken when watchdog resets
114 * 0 = GEN_RESET
115 * 1 = GEN_SMI
116 * 2 = GEN_NMI
117 * 3 = GEN_SCI
118 * defaults to GEN_RESET (0)
119 */
120 static int action;
121 module_param(action, int, 0);
122 MODULE_PARM_DESC(action, "after watchdog resets, generate: "
123 "0 = RESET(*) 1 = SMI 2 = NMI 3 = SCI");
124
125 static void zf_ping(unsigned long data);
126
127 static int zf_action = GEN_RESET;
128 static unsigned long zf_is_open;
129 static char zf_expect_close;
130 static DEFINE_SPINLOCK(zf_port_lock);
131 static DEFINE_TIMER(zf_timer, zf_ping, 0, 0);
132 static unsigned long next_heartbeat;
133
134
135 /* timeout for user land heart beat (10 seconds) */
136 #define ZF_USER_TIMEO (HZ*10)
137
138 /* timeout for hardware watchdog (~500ms) */
139 #define ZF_HW_TIMEO (HZ/2)
140
141 /* number of ticks on WD#1 (driven by a 32KHz clock, 2s) */
142 #define ZF_CTIMEOUT 0xffff
143
144 #ifndef ZF_DEBUG
145 #define dprintk(format, args...)
146 #else
147 #define dprintk(format, args...) \
148 pr_debug(":%s:%d: " format, __func__, __LINE__ , ## args)
149 #endif
150
151
zf_set_status(unsigned char new)152 static inline void zf_set_status(unsigned char new)
153 {
154 zf_writeb(STATUS, new);
155 }
156
157
158 /* CONTROL register functions */
159
zf_get_control(void)160 static inline unsigned short zf_get_control(void)
161 {
162 return zf_readw(CONTROL);
163 }
164
zf_set_control(unsigned short new)165 static inline void zf_set_control(unsigned short new)
166 {
167 zf_writew(CONTROL, new);
168 }
169
170
171 /* WD#? counter functions */
172 /*
173 * Just set counter value
174 */
175
zf_set_timer(unsigned short new,unsigned char n)176 static inline void zf_set_timer(unsigned short new, unsigned char n)
177 {
178 switch (n) {
179 case WD1:
180 zf_writew(COUNTER_1, new);
181 case WD2:
182 zf_writeb(COUNTER_2, new > 0xff ? 0xff : new);
183 default:
184 return;
185 }
186 }
187
188 /*
189 * stop hardware timer
190 */
zf_timer_off(void)191 static void zf_timer_off(void)
192 {
193 unsigned int ctrl_reg = 0;
194 unsigned long flags;
195
196 /* stop internal ping */
197 del_timer_sync(&zf_timer);
198
199 spin_lock_irqsave(&zf_port_lock, flags);
200 /* stop watchdog timer */
201 ctrl_reg = zf_get_control();
202 ctrl_reg |= (ENABLE_WD1|ENABLE_WD2); /* disable wd1 and wd2 */
203 ctrl_reg &= ~(ENABLE_WD1|ENABLE_WD2);
204 zf_set_control(ctrl_reg);
205 spin_unlock_irqrestore(&zf_port_lock, flags);
206
207 pr_info("Watchdog timer is now disabled\n");
208 }
209
210
211 /*
212 * start hardware timer
213 */
zf_timer_on(void)214 static void zf_timer_on(void)
215 {
216 unsigned int ctrl_reg = 0;
217 unsigned long flags;
218
219 spin_lock_irqsave(&zf_port_lock, flags);
220
221 zf_writeb(PULSE_LEN, 0xff);
222
223 zf_set_timer(ZF_CTIMEOUT, WD1);
224
225 /* user land ping */
226 next_heartbeat = jiffies + ZF_USER_TIMEO;
227
228 /* start the timer for internal ping */
229 mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
230
231 /* start watchdog timer */
232 ctrl_reg = zf_get_control();
233 ctrl_reg |= (ENABLE_WD1|zf_action);
234 zf_set_control(ctrl_reg);
235 spin_unlock_irqrestore(&zf_port_lock, flags);
236
237 pr_info("Watchdog timer is now enabled\n");
238 }
239
240
zf_ping(unsigned long data)241 static void zf_ping(unsigned long data)
242 {
243 unsigned int ctrl_reg = 0;
244 unsigned long flags;
245
246 zf_writeb(COUNTER_2, 0xff);
247
248 if (time_before(jiffies, next_heartbeat)) {
249 dprintk("time_before: %ld\n", next_heartbeat - jiffies);
250 /*
251 * reset event is activated by transition from 0 to 1 on
252 * RESET_WD1 bit and we assume that it is already zero...
253 */
254
255 spin_lock_irqsave(&zf_port_lock, flags);
256 ctrl_reg = zf_get_control();
257 ctrl_reg |= RESET_WD1;
258 zf_set_control(ctrl_reg);
259
260 /* ...and nothing changes until here */
261 ctrl_reg &= ~(RESET_WD1);
262 zf_set_control(ctrl_reg);
263 spin_unlock_irqrestore(&zf_port_lock, flags);
264
265 mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
266 } else
267 pr_crit("I will reset your machine\n");
268 }
269
zf_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)270 static ssize_t zf_write(struct file *file, const char __user *buf, size_t count,
271 loff_t *ppos)
272 {
273 /* See if we got the magic character */
274 if (count) {
275 /*
276 * no need to check for close confirmation
277 * no way to disable watchdog ;)
278 */
279 if (!nowayout) {
280 size_t ofs;
281 /*
282 * note: just in case someone wrote the magic character
283 * five months ago...
284 */
285 zf_expect_close = 0;
286
287 /* now scan */
288 for (ofs = 0; ofs != count; ofs++) {
289 char c;
290 if (get_user(c, buf + ofs))
291 return -EFAULT;
292 if (c == 'V') {
293 zf_expect_close = 42;
294 dprintk("zf_expect_close = 42\n");
295 }
296 }
297 }
298
299 /*
300 * Well, anyhow someone wrote to us,
301 * we should return that favour
302 */
303 next_heartbeat = jiffies + ZF_USER_TIMEO;
304 dprintk("user ping at %ld\n", jiffies);
305 }
306 return count;
307 }
308
zf_ioctl(struct file * file,unsigned int cmd,unsigned long arg)309 static long zf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
310 {
311 void __user *argp = (void __user *)arg;
312 int __user *p = argp;
313 switch (cmd) {
314 case WDIOC_GETSUPPORT:
315 if (copy_to_user(argp, &zf_info, sizeof(zf_info)))
316 return -EFAULT;
317 break;
318 case WDIOC_GETSTATUS:
319 case WDIOC_GETBOOTSTATUS:
320 return put_user(0, p);
321 case WDIOC_KEEPALIVE:
322 zf_ping(0);
323 break;
324 default:
325 return -ENOTTY;
326 }
327 return 0;
328 }
329
zf_open(struct inode * inode,struct file * file)330 static int zf_open(struct inode *inode, struct file *file)
331 {
332 if (test_and_set_bit(0, &zf_is_open))
333 return -EBUSY;
334 if (nowayout)
335 __module_get(THIS_MODULE);
336 zf_timer_on();
337 return nonseekable_open(inode, file);
338 }
339
zf_close(struct inode * inode,struct file * file)340 static int zf_close(struct inode *inode, struct file *file)
341 {
342 if (zf_expect_close == 42)
343 zf_timer_off();
344 else {
345 del_timer(&zf_timer);
346 pr_err("device file closed unexpectedly. Will not stop the WDT!\n");
347 }
348 clear_bit(0, &zf_is_open);
349 zf_expect_close = 0;
350 return 0;
351 }
352
353 /*
354 * Notifier for system down
355 */
356
zf_notify_sys(struct notifier_block * this,unsigned long code,void * unused)357 static int zf_notify_sys(struct notifier_block *this, unsigned long code,
358 void *unused)
359 {
360 if (code == SYS_DOWN || code == SYS_HALT)
361 zf_timer_off();
362 return NOTIFY_DONE;
363 }
364
365 static const struct file_operations zf_fops = {
366 .owner = THIS_MODULE,
367 .llseek = no_llseek,
368 .write = zf_write,
369 .unlocked_ioctl = zf_ioctl,
370 .open = zf_open,
371 .release = zf_close,
372 };
373
374 static struct miscdevice zf_miscdev = {
375 .minor = WATCHDOG_MINOR,
376 .name = "watchdog",
377 .fops = &zf_fops,
378 };
379
380
381 /*
382 * The device needs to learn about soft shutdowns in order to
383 * turn the timebomb registers off.
384 */
385 static struct notifier_block zf_notifier = {
386 .notifier_call = zf_notify_sys,
387 };
388
zf_show_action(int act)389 static void __init zf_show_action(int act)
390 {
391 static const char * const str[] = { "RESET", "SMI", "NMI", "SCI" };
392
393 pr_info("Watchdog using action = %s\n", str[act]);
394 }
395
zf_init(void)396 static int __init zf_init(void)
397 {
398 int ret;
399
400 pr_info("MachZ ZF-Logic Watchdog driver initializing\n");
401
402 ret = zf_get_ZFL_version();
403 if (!ret || ret == 0xffff) {
404 pr_warn("no ZF-Logic found\n");
405 return -ENODEV;
406 }
407
408 if (action <= 3 && action >= 0)
409 zf_action = zf_action >> action;
410 else
411 action = 0;
412
413 zf_show_action(action);
414
415 if (!request_region(ZF_IOBASE, 3, "MachZ ZFL WDT")) {
416 pr_err("cannot reserve I/O ports at %d\n", ZF_IOBASE);
417 ret = -EBUSY;
418 goto no_region;
419 }
420
421 ret = register_reboot_notifier(&zf_notifier);
422 if (ret) {
423 pr_err("can't register reboot notifier (err=%d)\n", ret);
424 goto no_reboot;
425 }
426
427 ret = misc_register(&zf_miscdev);
428 if (ret) {
429 pr_err("can't misc_register on minor=%d\n", WATCHDOG_MINOR);
430 goto no_misc;
431 }
432
433 zf_set_status(0);
434 zf_set_control(0);
435
436 return 0;
437
438 no_misc:
439 unregister_reboot_notifier(&zf_notifier);
440 no_reboot:
441 release_region(ZF_IOBASE, 3);
442 no_region:
443 return ret;
444 }
445
446
zf_exit(void)447 static void __exit zf_exit(void)
448 {
449 zf_timer_off();
450
451 misc_deregister(&zf_miscdev);
452 unregister_reboot_notifier(&zf_notifier);
453 release_region(ZF_IOBASE, 3);
454 }
455
456 module_init(zf_init);
457 module_exit(zf_exit);
458