1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * W83877F Computer Watchdog Timer driver |
4 | * |
5 | * Based on acquirewdt.c by Alan Cox, |
6 | * and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net> |
7 | * |
8 | * The authors do NOT admit liability nor provide warranty for |
9 | * any of this software. This material is provided "AS-IS" in |
10 | * the hope that it may be useful for others. |
11 | * |
12 | * (c) Copyright 2001 Scott Jennings <linuxdrivers@oro.net> |
13 | * |
14 | * 4/19 - 2001 [Initial revision] |
15 | * 9/27 - 2001 Added spinlocking |
16 | * 4/12 - 2002 [rob@osinvestor.com] Eliminate extra comments |
17 | * Eliminate fop_read |
18 | * Eliminate extra spin_unlock |
19 | * Added KERN_* tags to printks |
20 | * add CONFIG_WATCHDOG_NOWAYOUT support |
21 | * fix possible wdt_is_open race |
22 | * changed watchdog_info to correctly reflect what |
23 | * the driver offers |
24 | * added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS, |
25 | * WDIOC_SETTIMEOUT, |
26 | * WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls |
27 | * 09/8 - 2003 [wim@iguana.be] cleanup of trailing spaces |
28 | * added extra printk's for startup problems |
29 | * use module_param |
30 | * made timeout (the emulated heartbeat) a |
31 | * module_param |
32 | * made the keepalive ping an internal subroutine |
33 | * |
34 | * This WDT driver is different from most other Linux WDT |
35 | * drivers in that the driver will ping the watchdog by itself, |
36 | * because this particular WDT has a very short timeout (1.6 |
37 | * seconds) and it would be insane to count on any userspace |
38 | * daemon always getting scheduled within that time frame. |
39 | */ |
40 | |
41 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
42 | |
43 | #include <linux/module.h> |
44 | #include <linux/moduleparam.h> |
45 | #include <linux/types.h> |
46 | #include <linux/timer.h> |
47 | #include <linux/jiffies.h> |
48 | #include <linux/miscdevice.h> |
49 | #include <linux/watchdog.h> |
50 | #include <linux/fs.h> |
51 | #include <linux/ioport.h> |
52 | #include <linux/notifier.h> |
53 | #include <linux/reboot.h> |
54 | #include <linux/init.h> |
55 | #include <linux/io.h> |
56 | #include <linux/uaccess.h> |
57 | |
58 | #define OUR_NAME "w83877f_wdt" |
59 | |
60 | #define ENABLE_W83877F_PORT 0x3F0 |
61 | #define ENABLE_W83877F 0x87 |
62 | #define DISABLE_W83877F 0xAA |
63 | #define WDT_PING 0x443 |
64 | #define WDT_REGISTER 0x14 |
65 | #define WDT_ENABLE 0x9C |
66 | #define WDT_DISABLE 0x8C |
67 | |
68 | /* |
69 | * The W83877F seems to be fixed at 1.6s timeout (at least on the |
70 | * EMACS PC-104 board I'm using). If we reset the watchdog every |
71 | * ~250ms we should be safe. */ |
72 | |
73 | #define WDT_INTERVAL (HZ/4+1) |
74 | |
75 | /* |
76 | * We must not require too good response from the userspace daemon. |
77 | * Here we require the userspace daemon to send us a heartbeat |
78 | * char to /dev/watchdog every 30 seconds. |
79 | */ |
80 | |
81 | #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */ |
82 | /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */ |
83 | static int timeout = WATCHDOG_TIMEOUT; |
84 | module_param(timeout, int, 0); |
85 | MODULE_PARM_DESC(timeout, |
86 | "Watchdog timeout in seconds. (1<=timeout<=3600, default=" |
87 | __MODULE_STRING(WATCHDOG_TIMEOUT) ")" ); |
88 | |
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 | static void wdt_timer_ping(struct timer_list *); |
97 | static DEFINE_TIMER(timer, wdt_timer_ping); |
98 | static unsigned long next_heartbeat; |
99 | static unsigned long wdt_is_open; |
100 | static char wdt_expect_close; |
101 | static DEFINE_SPINLOCK(wdt_spinlock); |
102 | |
103 | /* |
104 | * Whack the dog |
105 | */ |
106 | |
107 | static void wdt_timer_ping(struct timer_list *unused) |
108 | { |
109 | /* If we got a heartbeat pulse within the WDT_US_INTERVAL |
110 | * we agree to ping the WDT |
111 | */ |
112 | if (time_before(jiffies, next_heartbeat)) { |
113 | /* Ping the WDT */ |
114 | spin_lock(lock: &wdt_spinlock); |
115 | |
116 | /* Ping the WDT by reading from WDT_PING */ |
117 | inb_p(WDT_PING); |
118 | |
119 | /* Re-set the timer interval */ |
120 | mod_timer(timer: &timer, expires: jiffies + WDT_INTERVAL); |
121 | |
122 | spin_unlock(lock: &wdt_spinlock); |
123 | |
124 | } else |
125 | pr_warn("Heartbeat lost! Will not ping the watchdog\n" ); |
126 | } |
127 | |
128 | /* |
129 | * Utility routines |
130 | */ |
131 | |
132 | static void wdt_change(int writeval) |
133 | { |
134 | unsigned long flags; |
135 | spin_lock_irqsave(&wdt_spinlock, flags); |
136 | |
137 | /* buy some time */ |
138 | inb_p(WDT_PING); |
139 | |
140 | /* make W83877F available */ |
141 | outb_p(ENABLE_W83877F, ENABLE_W83877F_PORT); |
142 | outb_p(ENABLE_W83877F, ENABLE_W83877F_PORT); |
143 | |
144 | /* enable watchdog */ |
145 | outb_p(WDT_REGISTER, ENABLE_W83877F_PORT); |
146 | outb_p(value: writeval, ENABLE_W83877F_PORT+1); |
147 | |
148 | /* lock the W8387FF away */ |
149 | outb_p(DISABLE_W83877F, ENABLE_W83877F_PORT); |
150 | |
151 | spin_unlock_irqrestore(lock: &wdt_spinlock, flags); |
152 | } |
153 | |
154 | static void wdt_startup(void) |
155 | { |
156 | next_heartbeat = jiffies + (timeout * HZ); |
157 | |
158 | /* Start the timer */ |
159 | mod_timer(timer: &timer, expires: jiffies + WDT_INTERVAL); |
160 | |
161 | wdt_change(WDT_ENABLE); |
162 | |
163 | pr_info("Watchdog timer is now enabled\n" ); |
164 | } |
165 | |
166 | static void wdt_turnoff(void) |
167 | { |
168 | /* Stop the timer */ |
169 | del_timer_sync(timer: &timer); |
170 | |
171 | wdt_change(WDT_DISABLE); |
172 | |
173 | pr_info("Watchdog timer is now disabled...\n" ); |
174 | } |
175 | |
176 | static void wdt_keepalive(void) |
177 | { |
178 | /* user land ping */ |
179 | next_heartbeat = jiffies + (timeout * HZ); |
180 | } |
181 | |
182 | /* |
183 | * /dev/watchdog handling |
184 | */ |
185 | |
186 | static ssize_t fop_write(struct file *file, const char __user *buf, |
187 | size_t count, loff_t *ppos) |
188 | { |
189 | /* See if we got the magic character 'V' and reload the timer */ |
190 | if (count) { |
191 | if (!nowayout) { |
192 | size_t ofs; |
193 | |
194 | /* note: just in case someone wrote the magic |
195 | character five months ago... */ |
196 | wdt_expect_close = 0; |
197 | |
198 | /* scan to see whether or not we got the |
199 | magic character */ |
200 | for (ofs = 0; ofs != count; ofs++) { |
201 | char c; |
202 | if (get_user(c, buf + ofs)) |
203 | return -EFAULT; |
204 | if (c == 'V') |
205 | wdt_expect_close = 42; |
206 | } |
207 | } |
208 | |
209 | /* someone wrote to us, we should restart timer */ |
210 | wdt_keepalive(); |
211 | } |
212 | return count; |
213 | } |
214 | |
215 | static int fop_open(struct inode *inode, struct file *file) |
216 | { |
217 | /* Just in case we're already talking to someone... */ |
218 | if (test_and_set_bit(nr: 0, addr: &wdt_is_open)) |
219 | return -EBUSY; |
220 | |
221 | /* Good, fire up the show */ |
222 | wdt_startup(); |
223 | return stream_open(inode, filp: file); |
224 | } |
225 | |
226 | static int fop_close(struct inode *inode, struct file *file) |
227 | { |
228 | if (wdt_expect_close == 42) |
229 | wdt_turnoff(); |
230 | else { |
231 | del_timer(timer: &timer); |
232 | pr_crit("device file closed unexpectedly. Will not stop the WDT!\n" ); |
233 | } |
234 | clear_bit(nr: 0, addr: &wdt_is_open); |
235 | wdt_expect_close = 0; |
236 | return 0; |
237 | } |
238 | |
239 | static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg) |
240 | { |
241 | void __user *argp = (void __user *)arg; |
242 | int __user *p = argp; |
243 | static const struct watchdog_info ident = { |
244 | .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
245 | | WDIOF_MAGICCLOSE, |
246 | .firmware_version = 1, |
247 | .identity = "W83877F" , |
248 | }; |
249 | |
250 | switch (cmd) { |
251 | case WDIOC_GETSUPPORT: |
252 | return copy_to_user(to: argp, from: &ident, n: sizeof(ident)) ? -EFAULT : 0; |
253 | case WDIOC_GETSTATUS: |
254 | case WDIOC_GETBOOTSTATUS: |
255 | return put_user(0, p); |
256 | case WDIOC_SETOPTIONS: |
257 | { |
258 | int new_options, retval = -EINVAL; |
259 | |
260 | if (get_user(new_options, p)) |
261 | return -EFAULT; |
262 | |
263 | if (new_options & WDIOS_DISABLECARD) { |
264 | wdt_turnoff(); |
265 | retval = 0; |
266 | } |
267 | |
268 | if (new_options & WDIOS_ENABLECARD) { |
269 | wdt_startup(); |
270 | retval = 0; |
271 | } |
272 | |
273 | return retval; |
274 | } |
275 | case WDIOC_KEEPALIVE: |
276 | wdt_keepalive(); |
277 | return 0; |
278 | case WDIOC_SETTIMEOUT: |
279 | { |
280 | int new_timeout; |
281 | |
282 | if (get_user(new_timeout, p)) |
283 | return -EFAULT; |
284 | |
285 | /* arbitrary upper limit */ |
286 | if (new_timeout < 1 || new_timeout > 3600) |
287 | return -EINVAL; |
288 | |
289 | timeout = new_timeout; |
290 | wdt_keepalive(); |
291 | } |
292 | fallthrough; |
293 | case WDIOC_GETTIMEOUT: |
294 | return put_user(timeout, p); |
295 | default: |
296 | return -ENOTTY; |
297 | } |
298 | } |
299 | |
300 | static const struct file_operations wdt_fops = { |
301 | .owner = THIS_MODULE, |
302 | .llseek = no_llseek, |
303 | .write = fop_write, |
304 | .open = fop_open, |
305 | .release = fop_close, |
306 | .unlocked_ioctl = fop_ioctl, |
307 | .compat_ioctl = compat_ptr_ioctl, |
308 | }; |
309 | |
310 | static struct miscdevice wdt_miscdev = { |
311 | .minor = WATCHDOG_MINOR, |
312 | .name = "watchdog" , |
313 | .fops = &wdt_fops, |
314 | }; |
315 | |
316 | /* |
317 | * Notifier for system down |
318 | */ |
319 | |
320 | static int wdt_notify_sys(struct notifier_block *this, unsigned long code, |
321 | void *unused) |
322 | { |
323 | if (code == SYS_DOWN || code == SYS_HALT) |
324 | wdt_turnoff(); |
325 | return NOTIFY_DONE; |
326 | } |
327 | |
328 | /* |
329 | * The WDT needs to learn about soft shutdowns in order to |
330 | * turn the timebomb registers off. |
331 | */ |
332 | |
333 | static struct notifier_block wdt_notifier = { |
334 | .notifier_call = wdt_notify_sys, |
335 | }; |
336 | |
337 | static void __exit w83877f_wdt_unload(void) |
338 | { |
339 | wdt_turnoff(); |
340 | |
341 | /* Deregister */ |
342 | misc_deregister(misc: &wdt_miscdev); |
343 | |
344 | unregister_reboot_notifier(&wdt_notifier); |
345 | release_region(WDT_PING, 1); |
346 | release_region(ENABLE_W83877F_PORT, 2); |
347 | } |
348 | |
349 | static int __init w83877f_wdt_init(void) |
350 | { |
351 | int rc = -EBUSY; |
352 | |
353 | if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */ |
354 | timeout = WATCHDOG_TIMEOUT; |
355 | pr_info("timeout value must be 1 <= x <= 3600, using %d\n" , |
356 | timeout); |
357 | } |
358 | |
359 | if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT" )) { |
360 | pr_err("I/O address 0x%04x already in use\n" , |
361 | ENABLE_W83877F_PORT); |
362 | rc = -EIO; |
363 | goto err_out; |
364 | } |
365 | |
366 | if (!request_region(WDT_PING, 1, "W8387FF WDT" )) { |
367 | pr_err("I/O address 0x%04x already in use\n" , WDT_PING); |
368 | rc = -EIO; |
369 | goto err_out_region1; |
370 | } |
371 | |
372 | rc = register_reboot_notifier(&wdt_notifier); |
373 | if (rc) { |
374 | pr_err("cannot register reboot notifier (err=%d)\n" , rc); |
375 | goto err_out_region2; |
376 | } |
377 | |
378 | rc = misc_register(misc: &wdt_miscdev); |
379 | if (rc) { |
380 | pr_err("cannot register miscdev on minor=%d (err=%d)\n" , |
381 | wdt_miscdev.minor, rc); |
382 | goto err_out_reboot; |
383 | } |
384 | |
385 | pr_info("WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n" , |
386 | timeout, nowayout); |
387 | |
388 | return 0; |
389 | |
390 | err_out_reboot: |
391 | unregister_reboot_notifier(&wdt_notifier); |
392 | err_out_region2: |
393 | release_region(WDT_PING, 1); |
394 | err_out_region1: |
395 | release_region(ENABLE_W83877F_PORT, 2); |
396 | err_out: |
397 | return rc; |
398 | } |
399 | |
400 | module_init(w83877f_wdt_init); |
401 | module_exit(w83877f_wdt_unload); |
402 | |
403 | MODULE_AUTHOR("Scott and Bill Jennings" ); |
404 | MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip" ); |
405 | MODULE_LICENSE("GPL" ); |
406 | |