1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * MachZ ZF-Logic Watchdog Timer driver for Linux
4 *
5 * The author does NOT admit liability nor provide warranty for
6 * any of this software. This material is provided "AS-IS" in
7 * the hope that it may be useful for others.
8 *
9 * Author: Fernando Fuganti <fuganti@conectiva.com.br>
10 *
11 * Based on sbc60xxwdt.c by Jakob Oestergaard
12 *
13 * We have two timers (wd#1, wd#2) driven by a 32 KHz clock with the
14 * following periods:
15 * wd#1 - 2 seconds;
16 * wd#2 - 7.2 ms;
17 * After the expiration of wd#1, it can generate a NMI, SCI, SMI, or
18 * a system RESET and it starts wd#2 that unconditionally will RESET
19 * the system when the counter reaches zero.
20 *
21 * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
22 * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
23 */
24
25 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
26
27 #include <linux/module.h>
28 #include <linux/moduleparam.h>
29 #include <linux/types.h>
30 #include <linux/timer.h>
31 #include <linux/jiffies.h>
32 #include <linux/miscdevice.h>
33 #include <linux/watchdog.h>
34 #include <linux/fs.h>
35 #include <linux/ioport.h>
36 #include <linux/notifier.h>
37 #include <linux/reboot.h>
38 #include <linux/init.h>
39 #include <linux/io.h>
40 #include <linux/uaccess.h>
41
42
43 /* ports */
44 #define ZF_IOBASE 0x218
45 #define INDEX 0x218
46 #define DATA_B 0x219
47 #define DATA_W 0x21A
48 #define DATA_D 0x21A
49
50 /* indexes */ /* size */
51 #define ZFL_VERSION 0x02 /* 16 */
52 #define CONTROL 0x10 /* 16 */
53 #define STATUS 0x12 /* 8 */
54 #define COUNTER_1 0x0C /* 16 */
55 #define COUNTER_2 0x0E /* 8 */
56 #define PULSE_LEN 0x0F /* 8 */
57
58 /* controls */
59 #define ENABLE_WD1 0x0001
60 #define ENABLE_WD2 0x0002
61 #define RESET_WD1 0x0010
62 #define RESET_WD2 0x0020
63 #define GEN_SCI 0x0100
64 #define GEN_NMI 0x0200
65 #define GEN_SMI 0x0400
66 #define GEN_RESET 0x0800
67
68
69 /* utilities */
70
71 #define WD1 0
72 #define WD2 1
73
74 #define zf_writew(port, data) { outb(port, INDEX); outw(data, DATA_W); }
75 #define zf_writeb(port, data) { outb(port, INDEX); outb(data, DATA_B); }
76 #define zf_get_ZFL_version() zf_readw(ZFL_VERSION)
77
78
zf_readw(unsigned char port)79 static unsigned short zf_readw(unsigned char port)
80 {
81 outb(port, INDEX);
82 return inw(DATA_W);
83 }
84
85
86 MODULE_AUTHOR("Fernando Fuganti <fuganti@conectiva.com.br>");
87 MODULE_DESCRIPTION("MachZ ZF-Logic Watchdog driver");
88 MODULE_LICENSE("GPL");
89
90 static bool nowayout = WATCHDOG_NOWAYOUT;
91 module_param(nowayout, bool, 0);
92 MODULE_PARM_DESC(nowayout,
93 "Watchdog cannot be stopped once started (default="
94 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
95
96 #define PFX "machzwd"
97
98 static const struct watchdog_info zf_info = {
99 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
100 .firmware_version = 1,
101 .identity = "ZF-Logic watchdog",
102 };
103
104
105 /*
106 * action refers to action taken when watchdog resets
107 * 0 = GEN_RESET
108 * 1 = GEN_SMI
109 * 2 = GEN_NMI
110 * 3 = GEN_SCI
111 * defaults to GEN_RESET (0)
112 */
113 static int action;
114 module_param(action, int, 0);
115 MODULE_PARM_DESC(action, "after watchdog resets, generate: "
116 "0 = RESET(*) 1 = SMI 2 = NMI 3 = SCI");
117
118 static void zf_ping(struct timer_list *unused);
119
120 static int zf_action = GEN_RESET;
121 static unsigned long zf_is_open;
122 static char zf_expect_close;
123 static DEFINE_SPINLOCK(zf_port_lock);
124 static DEFINE_TIMER(zf_timer, zf_ping);
125 static unsigned long next_heartbeat;
126
127
128 /* timeout for user land heart beat (10 seconds) */
129 #define ZF_USER_TIMEO (HZ*10)
130
131 /* timeout for hardware watchdog (~500ms) */
132 #define ZF_HW_TIMEO (HZ/2)
133
134 /* number of ticks on WD#1 (driven by a 32KHz clock, 2s) */
135 #define ZF_CTIMEOUT 0xffff
136
137 #ifndef ZF_DEBUG
138 #define dprintk(format, args...)
139 #else
140 #define dprintk(format, args...) \
141 pr_debug(":%s:%d: " format, __func__, __LINE__ , ## args)
142 #endif
143
144
zf_set_status(unsigned char new)145 static inline void zf_set_status(unsigned char new)
146 {
147 zf_writeb(STATUS, new);
148 }
149
150
151 /* CONTROL register functions */
152
zf_get_control(void)153 static inline unsigned short zf_get_control(void)
154 {
155 return zf_readw(CONTROL);
156 }
157
zf_set_control(unsigned short new)158 static inline void zf_set_control(unsigned short new)
159 {
160 zf_writew(CONTROL, new);
161 }
162
163
164 /* WD#? counter functions */
165 /*
166 * Just set counter value
167 */
168
zf_set_timer(unsigned short new,unsigned char n)169 static inline void zf_set_timer(unsigned short new, unsigned char n)
170 {
171 switch (n) {
172 case WD1:
173 zf_writew(COUNTER_1, new);
174 /* fall through */
175 case WD2:
176 zf_writeb(COUNTER_2, new > 0xff ? 0xff : new);
177 default:
178 return;
179 }
180 }
181
182 /*
183 * stop hardware timer
184 */
zf_timer_off(void)185 static void zf_timer_off(void)
186 {
187 unsigned int ctrl_reg = 0;
188 unsigned long flags;
189
190 /* stop internal ping */
191 del_timer_sync(&zf_timer);
192
193 spin_lock_irqsave(&zf_port_lock, flags);
194 /* stop watchdog timer */
195 ctrl_reg = zf_get_control();
196 ctrl_reg |= (ENABLE_WD1|ENABLE_WD2); /* disable wd1 and wd2 */
197 ctrl_reg &= ~(ENABLE_WD1|ENABLE_WD2);
198 zf_set_control(ctrl_reg);
199 spin_unlock_irqrestore(&zf_port_lock, flags);
200
201 pr_info("Watchdog timer is now disabled\n");
202 }
203
204
205 /*
206 * start hardware timer
207 */
zf_timer_on(void)208 static void zf_timer_on(void)
209 {
210 unsigned int ctrl_reg = 0;
211 unsigned long flags;
212
213 spin_lock_irqsave(&zf_port_lock, flags);
214
215 zf_writeb(PULSE_LEN, 0xff);
216
217 zf_set_timer(ZF_CTIMEOUT, WD1);
218
219 /* user land ping */
220 next_heartbeat = jiffies + ZF_USER_TIMEO;
221
222 /* start the timer for internal ping */
223 mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
224
225 /* start watchdog timer */
226 ctrl_reg = zf_get_control();
227 ctrl_reg |= (ENABLE_WD1|zf_action);
228 zf_set_control(ctrl_reg);
229 spin_unlock_irqrestore(&zf_port_lock, flags);
230
231 pr_info("Watchdog timer is now enabled\n");
232 }
233
234
zf_ping(struct timer_list * unused)235 static void zf_ping(struct timer_list *unused)
236 {
237 unsigned int ctrl_reg = 0;
238 unsigned long flags;
239
240 zf_writeb(COUNTER_2, 0xff);
241
242 if (time_before(jiffies, next_heartbeat)) {
243 dprintk("time_before: %ld\n", next_heartbeat - jiffies);
244 /*
245 * reset event is activated by transition from 0 to 1 on
246 * RESET_WD1 bit and we assume that it is already zero...
247 */
248
249 spin_lock_irqsave(&zf_port_lock, flags);
250 ctrl_reg = zf_get_control();
251 ctrl_reg |= RESET_WD1;
252 zf_set_control(ctrl_reg);
253
254 /* ...and nothing changes until here */
255 ctrl_reg &= ~(RESET_WD1);
256 zf_set_control(ctrl_reg);
257 spin_unlock_irqrestore(&zf_port_lock, flags);
258
259 mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
260 } else
261 pr_crit("I will reset your machine\n");
262 }
263
zf_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)264 static ssize_t zf_write(struct file *file, const char __user *buf, size_t count,
265 loff_t *ppos)
266 {
267 /* See if we got the magic character */
268 if (count) {
269 /*
270 * no need to check for close confirmation
271 * no way to disable watchdog ;)
272 */
273 if (!nowayout) {
274 size_t ofs;
275 /*
276 * note: just in case someone wrote the magic character
277 * five months ago...
278 */
279 zf_expect_close = 0;
280
281 /* now scan */
282 for (ofs = 0; ofs != count; ofs++) {
283 char c;
284 if (get_user(c, buf + ofs))
285 return -EFAULT;
286 if (c == 'V') {
287 zf_expect_close = 42;
288 dprintk("zf_expect_close = 42\n");
289 }
290 }
291 }
292
293 /*
294 * Well, anyhow someone wrote to us,
295 * we should return that favour
296 */
297 next_heartbeat = jiffies + ZF_USER_TIMEO;
298 dprintk("user ping at %ld\n", jiffies);
299 }
300 return count;
301 }
302
zf_ioctl(struct file * file,unsigned int cmd,unsigned long arg)303 static long zf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
304 {
305 void __user *argp = (void __user *)arg;
306 int __user *p = argp;
307 switch (cmd) {
308 case WDIOC_GETSUPPORT:
309 if (copy_to_user(argp, &zf_info, sizeof(zf_info)))
310 return -EFAULT;
311 break;
312 case WDIOC_GETSTATUS:
313 case WDIOC_GETBOOTSTATUS:
314 return put_user(0, p);
315 case WDIOC_KEEPALIVE:
316 zf_ping(NULL);
317 break;
318 default:
319 return -ENOTTY;
320 }
321 return 0;
322 }
323
zf_open(struct inode * inode,struct file * file)324 static int zf_open(struct inode *inode, struct file *file)
325 {
326 if (test_and_set_bit(0, &zf_is_open))
327 return -EBUSY;
328 if (nowayout)
329 __module_get(THIS_MODULE);
330 zf_timer_on();
331 return stream_open(inode, file);
332 }
333
zf_close(struct inode * inode,struct file * file)334 static int zf_close(struct inode *inode, struct file *file)
335 {
336 if (zf_expect_close == 42)
337 zf_timer_off();
338 else {
339 del_timer(&zf_timer);
340 pr_err("device file closed unexpectedly. Will not stop the WDT!\n");
341 }
342 clear_bit(0, &zf_is_open);
343 zf_expect_close = 0;
344 return 0;
345 }
346
347 /*
348 * Notifier for system down
349 */
350
zf_notify_sys(struct notifier_block * this,unsigned long code,void * unused)351 static int zf_notify_sys(struct notifier_block *this, unsigned long code,
352 void *unused)
353 {
354 if (code == SYS_DOWN || code == SYS_HALT)
355 zf_timer_off();
356 return NOTIFY_DONE;
357 }
358
359 static const struct file_operations zf_fops = {
360 .owner = THIS_MODULE,
361 .llseek = no_llseek,
362 .write = zf_write,
363 .unlocked_ioctl = zf_ioctl,
364 .open = zf_open,
365 .release = zf_close,
366 };
367
368 static struct miscdevice zf_miscdev = {
369 .minor = WATCHDOG_MINOR,
370 .name = "watchdog",
371 .fops = &zf_fops,
372 };
373
374
375 /*
376 * The device needs to learn about soft shutdowns in order to
377 * turn the timebomb registers off.
378 */
379 static struct notifier_block zf_notifier = {
380 .notifier_call = zf_notify_sys,
381 };
382
zf_show_action(int act)383 static void __init zf_show_action(int act)
384 {
385 static const char * const str[] = { "RESET", "SMI", "NMI", "SCI" };
386
387 pr_info("Watchdog using action = %s\n", str[act]);
388 }
389
zf_init(void)390 static int __init zf_init(void)
391 {
392 int ret;
393
394 pr_info("MachZ ZF-Logic Watchdog driver initializing\n");
395
396 ret = zf_get_ZFL_version();
397 if (!ret || ret == 0xffff) {
398 pr_warn("no ZF-Logic found\n");
399 return -ENODEV;
400 }
401
402 if (action <= 3 && action >= 0)
403 zf_action = zf_action >> action;
404 else
405 action = 0;
406
407 zf_show_action(action);
408
409 if (!request_region(ZF_IOBASE, 3, "MachZ ZFL WDT")) {
410 pr_err("cannot reserve I/O ports at %d\n", ZF_IOBASE);
411 ret = -EBUSY;
412 goto no_region;
413 }
414
415 ret = register_reboot_notifier(&zf_notifier);
416 if (ret) {
417 pr_err("can't register reboot notifier (err=%d)\n", ret);
418 goto no_reboot;
419 }
420
421 ret = misc_register(&zf_miscdev);
422 if (ret) {
423 pr_err("can't misc_register on minor=%d\n", WATCHDOG_MINOR);
424 goto no_misc;
425 }
426
427 zf_set_status(0);
428 zf_set_control(0);
429
430 return 0;
431
432 no_misc:
433 unregister_reboot_notifier(&zf_notifier);
434 no_reboot:
435 release_region(ZF_IOBASE, 3);
436 no_region:
437 return ret;
438 }
439
440
zf_exit(void)441 static void __exit zf_exit(void)
442 {
443 zf_timer_off();
444
445 misc_deregister(&zf_miscdev);
446 unregister_reboot_notifier(&zf_notifier);
447 release_region(ZF_IOBASE, 3);
448 }
449
450 module_init(zf_init);
451 module_exit(zf_exit);
452