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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 | ||
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 | ||
145 | static inline void zf_set_status(unsigned char new) | |
146 | { | |
147 | zf_writeb(STATUS, new); | |
148 | } | |
149 | ||
150 | ||
151 | /* CONTROL register functions */ | |
152 | ||
153 | static inline unsigned short zf_get_control(void) | |
154 | { | |
155 | return zf_readw(CONTROL); | |
156 | } | |
157 | ||
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 | ||
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 | default: | |
178 | return; | |
179 | } | |
180 | } | |
181 | ||
182 | /* | |
183 | * stop hardware timer | |
184 | */ | |
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 | */ | |
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 | ||
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 | ||
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 | ||
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 | ||
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 | ||
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 | ||
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 | .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 | ||
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 | ||
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 | ||
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); |