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 fallthrough;
175 case WD2:
176 zf_writeb(COUNTER_2, new > 0xff ? 0xff : new);
177 fallthrough;
178 default:
179 return;
180 }
181 }
182
183 /*
184 * stop hardware timer
185 */
zf_timer_off(void)186 static void zf_timer_off(void)
187 {
188 unsigned int ctrl_reg = 0;
189 unsigned long flags;
190
191 /* stop internal ping */
192 del_timer_sync(&zf_timer);
193
194 spin_lock_irqsave(&zf_port_lock, flags);
195 /* stop watchdog timer */
196 ctrl_reg = zf_get_control();
197 ctrl_reg |= (ENABLE_WD1|ENABLE_WD2); /* disable wd1 and wd2 */
198 ctrl_reg &= ~(ENABLE_WD1|ENABLE_WD2);
199 zf_set_control(ctrl_reg);
200 spin_unlock_irqrestore(&zf_port_lock, flags);
201
202 pr_info("Watchdog timer is now disabled\n");
203 }
204
205
206 /*
207 * start hardware timer
208 */
zf_timer_on(void)209 static void zf_timer_on(void)
210 {
211 unsigned int ctrl_reg = 0;
212 unsigned long flags;
213
214 spin_lock_irqsave(&zf_port_lock, flags);
215
216 zf_writeb(PULSE_LEN, 0xff);
217
218 zf_set_timer(ZF_CTIMEOUT, WD1);
219
220 /* user land ping */
221 next_heartbeat = jiffies + ZF_USER_TIMEO;
222
223 /* start the timer for internal ping */
224 mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
225
226 /* start watchdog timer */
227 ctrl_reg = zf_get_control();
228 ctrl_reg |= (ENABLE_WD1|zf_action);
229 zf_set_control(ctrl_reg);
230 spin_unlock_irqrestore(&zf_port_lock, flags);
231
232 pr_info("Watchdog timer is now enabled\n");
233 }
234
235
zf_ping(struct timer_list * unused)236 static void zf_ping(struct timer_list *unused)
237 {
238 unsigned int ctrl_reg = 0;
239 unsigned long flags;
240
241 zf_writeb(COUNTER_2, 0xff);
242
243 if (time_before(jiffies, next_heartbeat)) {
244 dprintk("time_before: %ld\n", next_heartbeat - jiffies);
245 /*
246 * reset event is activated by transition from 0 to 1 on
247 * RESET_WD1 bit and we assume that it is already zero...
248 */
249
250 spin_lock_irqsave(&zf_port_lock, flags);
251 ctrl_reg = zf_get_control();
252 ctrl_reg |= RESET_WD1;
253 zf_set_control(ctrl_reg);
254
255 /* ...and nothing changes until here */
256 ctrl_reg &= ~(RESET_WD1);
257 zf_set_control(ctrl_reg);
258 spin_unlock_irqrestore(&zf_port_lock, flags);
259
260 mod_timer(&zf_timer, jiffies + ZF_HW_TIMEO);
261 } else
262 pr_crit("I will reset your machine\n");
263 }
264
zf_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)265 static ssize_t zf_write(struct file *file, const char __user *buf, size_t count,
266 loff_t *ppos)
267 {
268 /* See if we got the magic character */
269 if (count) {
270 /*
271 * no need to check for close confirmation
272 * no way to disable watchdog ;)
273 */
274 if (!nowayout) {
275 size_t ofs;
276 /*
277 * note: just in case someone wrote the magic character
278 * five months ago...
279 */
280 zf_expect_close = 0;
281
282 /* now scan */
283 for (ofs = 0; ofs != count; ofs++) {
284 char c;
285 if (get_user(c, buf + ofs))
286 return -EFAULT;
287 if (c == 'V') {
288 zf_expect_close = 42;
289 dprintk("zf_expect_close = 42\n");
290 }
291 }
292 }
293
294 /*
295 * Well, anyhow someone wrote to us,
296 * we should return that favour
297 */
298 next_heartbeat = jiffies + ZF_USER_TIMEO;
299 dprintk("user ping at %ld\n", jiffies);
300 }
301 return count;
302 }
303
zf_ioctl(struct file * file,unsigned int cmd,unsigned long arg)304 static long zf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
305 {
306 void __user *argp = (void __user *)arg;
307 int __user *p = argp;
308 switch (cmd) {
309 case WDIOC_GETSUPPORT:
310 if (copy_to_user(argp, &zf_info, sizeof(zf_info)))
311 return -EFAULT;
312 break;
313 case WDIOC_GETSTATUS:
314 case WDIOC_GETBOOTSTATUS:
315 return put_user(0, p);
316 case WDIOC_KEEPALIVE:
317 zf_ping(NULL);
318 break;
319 default:
320 return -ENOTTY;
321 }
322 return 0;
323 }
324
zf_open(struct inode * inode,struct file * file)325 static int zf_open(struct inode *inode, struct file *file)
326 {
327 if (test_and_set_bit(0, &zf_is_open))
328 return -EBUSY;
329 if (nowayout)
330 __module_get(THIS_MODULE);
331 zf_timer_on();
332 return stream_open(inode, file);
333 }
334
zf_close(struct inode * inode,struct file * file)335 static int zf_close(struct inode *inode, struct file *file)
336 {
337 if (zf_expect_close == 42)
338 zf_timer_off();
339 else {
340 del_timer(&zf_timer);
341 pr_err("device file closed unexpectedly. Will not stop the WDT!\n");
342 }
343 clear_bit(0, &zf_is_open);
344 zf_expect_close = 0;
345 return 0;
346 }
347
348 /*
349 * Notifier for system down
350 */
351
zf_notify_sys(struct notifier_block * this,unsigned long code,void * unused)352 static int zf_notify_sys(struct notifier_block *this, unsigned long code,
353 void *unused)
354 {
355 if (code == SYS_DOWN || code == SYS_HALT)
356 zf_timer_off();
357 return NOTIFY_DONE;
358 }
359
360 static const struct file_operations zf_fops = {
361 .owner = THIS_MODULE,
362 .write = zf_write,
363 .unlocked_ioctl = zf_ioctl,
364 .compat_ioctl = compat_ptr_ioctl,
365 .open = zf_open,
366 .release = zf_close,
367 };
368
369 static struct miscdevice zf_miscdev = {
370 .minor = WATCHDOG_MINOR,
371 .name = "watchdog",
372 .fops = &zf_fops,
373 };
374
375
376 /*
377 * The device needs to learn about soft shutdowns in order to
378 * turn the timebomb registers off.
379 */
380 static struct notifier_block zf_notifier = {
381 .notifier_call = zf_notify_sys,
382 };
383
zf_show_action(int act)384 static void __init zf_show_action(int act)
385 {
386 static const char * const str[] = { "RESET", "SMI", "NMI", "SCI" };
387
388 pr_info("Watchdog using action = %s\n", str[act]);
389 }
390
zf_init(void)391 static int __init zf_init(void)
392 {
393 int ret;
394
395 pr_info("MachZ ZF-Logic Watchdog driver initializing\n");
396
397 ret = zf_get_ZFL_version();
398 if (!ret || ret == 0xffff) {
399 pr_warn("no ZF-Logic found\n");
400 return -ENODEV;
401 }
402
403 if (action <= 3 && action >= 0)
404 zf_action = zf_action >> action;
405 else
406 action = 0;
407
408 zf_show_action(action);
409
410 if (!request_region(ZF_IOBASE, 3, "MachZ ZFL WDT")) {
411 pr_err("cannot reserve I/O ports at %d\n", ZF_IOBASE);
412 ret = -EBUSY;
413 goto no_region;
414 }
415
416 ret = register_reboot_notifier(&zf_notifier);
417 if (ret) {
418 pr_err("can't register reboot notifier (err=%d)\n", ret);
419 goto no_reboot;
420 }
421
422 ret = misc_register(&zf_miscdev);
423 if (ret) {
424 pr_err("can't misc_register on minor=%d\n", WATCHDOG_MINOR);
425 goto no_misc;
426 }
427
428 zf_set_status(0);
429 zf_set_control(0);
430
431 return 0;
432
433 no_misc:
434 unregister_reboot_notifier(&zf_notifier);
435 no_reboot:
436 release_region(ZF_IOBASE, 3);
437 no_region:
438 return ret;
439 }
440
441
zf_exit(void)442 static void __exit zf_exit(void)
443 {
444 zf_timer_off();
445
446 misc_deregister(&zf_miscdev);
447 unregister_reboot_notifier(&zf_notifier);
448 release_region(ZF_IOBASE, 3);
449 }
450
451 module_init(zf_init);
452 module_exit(zf_exit);
453