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(value: 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 | fallthrough; |
178 | default: |
179 | return; |
180 | } |
181 | } |
182 | |
183 | /* |
184 | * stop hardware timer |
185 | */ |
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(timer: &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(new: ctrl_reg); |
200 | spin_unlock_irqrestore(lock: &zf_port_lock, flags); |
201 | |
202 | pr_info("Watchdog timer is now disabled\n" ); |
203 | } |
204 | |
205 | |
206 | /* |
207 | * start hardware timer |
208 | */ |
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(timer: &zf_timer, expires: 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(new: ctrl_reg); |
230 | spin_unlock_irqrestore(lock: &zf_port_lock, flags); |
231 | |
232 | pr_info("Watchdog timer is now enabled\n" ); |
233 | } |
234 | |
235 | |
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(new: ctrl_reg); |
254 | |
255 | /* ...and nothing changes until here */ |
256 | ctrl_reg &= ~(RESET_WD1); |
257 | zf_set_control(new: ctrl_reg); |
258 | spin_unlock_irqrestore(lock: &zf_port_lock, flags); |
259 | |
260 | mod_timer(timer: &zf_timer, expires: jiffies + ZF_HW_TIMEO); |
261 | } else |
262 | pr_crit("I will reset your machine\n" ); |
263 | } |
264 | |
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 | |
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(to: argp, from: &zf_info, n: 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 | |
325 | static int zf_open(struct inode *inode, struct file *file) |
326 | { |
327 | if (test_and_set_bit(nr: 0, addr: &zf_is_open)) |
328 | return -EBUSY; |
329 | if (nowayout) |
330 | __module_get(THIS_MODULE); |
331 | zf_timer_on(); |
332 | return stream_open(inode, filp: file); |
333 | } |
334 | |
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(timer: &zf_timer); |
341 | pr_err("device file closed unexpectedly. Will not stop the WDT!\n" ); |
342 | } |
343 | clear_bit(nr: 0, addr: &zf_is_open); |
344 | zf_expect_close = 0; |
345 | return 0; |
346 | } |
347 | |
348 | /* |
349 | * Notifier for system down |
350 | */ |
351 | |
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 | .llseek = no_llseek, |
363 | .write = zf_write, |
364 | .unlocked_ioctl = zf_ioctl, |
365 | .compat_ioctl = compat_ptr_ioctl, |
366 | .open = zf_open, |
367 | .release = zf_close, |
368 | }; |
369 | |
370 | static struct miscdevice zf_miscdev = { |
371 | .minor = WATCHDOG_MINOR, |
372 | .name = "watchdog" , |
373 | .fops = &zf_fops, |
374 | }; |
375 | |
376 | |
377 | /* |
378 | * The device needs to learn about soft shutdowns in order to |
379 | * turn the timebomb registers off. |
380 | */ |
381 | static struct notifier_block zf_notifier = { |
382 | .notifier_call = zf_notify_sys, |
383 | }; |
384 | |
385 | static void __init zf_show_action(int act) |
386 | { |
387 | static const char * const str[] = { "RESET" , "SMI" , "NMI" , "SCI" }; |
388 | |
389 | pr_info("Watchdog using action = %s\n" , str[act]); |
390 | } |
391 | |
392 | static int __init zf_init(void) |
393 | { |
394 | int ret; |
395 | |
396 | pr_info("MachZ ZF-Logic Watchdog driver initializing\n" ); |
397 | |
398 | ret = zf_get_ZFL_version(); |
399 | if (!ret || ret == 0xffff) { |
400 | pr_warn("no ZF-Logic found\n" ); |
401 | return -ENODEV; |
402 | } |
403 | |
404 | if (action <= 3 && action >= 0) |
405 | zf_action = zf_action >> action; |
406 | else |
407 | action = 0; |
408 | |
409 | zf_show_action(act: action); |
410 | |
411 | if (!request_region(ZF_IOBASE, 3, "MachZ ZFL WDT" )) { |
412 | pr_err("cannot reserve I/O ports at %d\n" , ZF_IOBASE); |
413 | ret = -EBUSY; |
414 | goto no_region; |
415 | } |
416 | |
417 | ret = register_reboot_notifier(&zf_notifier); |
418 | if (ret) { |
419 | pr_err("can't register reboot notifier (err=%d)\n" , ret); |
420 | goto no_reboot; |
421 | } |
422 | |
423 | ret = misc_register(misc: &zf_miscdev); |
424 | if (ret) { |
425 | pr_err("can't misc_register on minor=%d\n" , WATCHDOG_MINOR); |
426 | goto no_misc; |
427 | } |
428 | |
429 | zf_set_status(new: 0); |
430 | zf_set_control(new: 0); |
431 | |
432 | return 0; |
433 | |
434 | no_misc: |
435 | unregister_reboot_notifier(&zf_notifier); |
436 | no_reboot: |
437 | release_region(ZF_IOBASE, 3); |
438 | no_region: |
439 | return ret; |
440 | } |
441 | |
442 | |
443 | static void __exit zf_exit(void) |
444 | { |
445 | zf_timer_off(); |
446 | |
447 | misc_deregister(misc: &zf_miscdev); |
448 | unregister_reboot_notifier(&zf_notifier); |
449 | release_region(ZF_IOBASE, 3); |
450 | } |
451 | |
452 | module_init(zf_init); |
453 | module_exit(zf_exit); |
454 | |