1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * 60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x |
4 | * |
5 | * Based on acquirewdt.c by Alan Cox. |
6 | * |
7 | * The author does NOT admit liability nor provide warranty for |
8 | * any of this software. This material is provided "AS-IS" in |
9 | * the hope that it may be useful for others. |
10 | * |
11 | * (c) Copyright 2000 Jakob Oestergaard <jakob@unthought.net> |
12 | * |
13 | * 12/4 - 2000 [Initial revision] |
14 | * 25/4 - 2000 Added /dev/watchdog support |
15 | * 09/5 - 2001 [smj@oro.net] fixed fop_write to "return 1" |
16 | * on success |
17 | * 12/4 - 2002 [rob@osinvestor.com] eliminate fop_read |
18 | * fix possible wdt_is_open race |
19 | * add CONFIG_WATCHDOG_NOWAYOUT support |
20 | * remove lock_kernel/unlock_kernel pairs |
21 | * added KERN_* to printk's |
22 | * got rid of extraneous comments |
23 | * changed watchdog_info to correctly reflect what |
24 | * the driver offers |
25 | * added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS, |
26 | * WDIOC_SETTIMEOUT, WDIOC_GETTIMEOUT, and |
27 | * WDIOC_SETOPTIONS ioctls |
28 | * 09/8 - 2003 [wim@iguana.be] cleanup of trailing spaces |
29 | * use module_param |
30 | * made timeout (the emulated heartbeat) a |
31 | * module_param |
32 | * made the keepalive ping an internal subroutine |
33 | * made wdt_stop and wdt_start module params |
34 | * added extra printk's for startup problems |
35 | * added MODULE_AUTHOR and MODULE_DESCRIPTION info |
36 | * |
37 | * This WDT driver is different from the other Linux WDT |
38 | * drivers in the following ways: |
39 | * *) The driver will ping the watchdog by itself, because this |
40 | * particular WDT has a very short timeout (one second) and it |
41 | * would be insane to count on any userspace daemon always |
42 | * getting scheduled within that time frame. |
43 | */ |
44 | |
45 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
46 | |
47 | #include <linux/module.h> |
48 | #include <linux/moduleparam.h> |
49 | #include <linux/types.h> |
50 | #include <linux/timer.h> |
51 | #include <linux/jiffies.h> |
52 | #include <linux/miscdevice.h> |
53 | #include <linux/watchdog.h> |
54 | #include <linux/fs.h> |
55 | #include <linux/ioport.h> |
56 | #include <linux/notifier.h> |
57 | #include <linux/reboot.h> |
58 | #include <linux/init.h> |
59 | #include <linux/io.h> |
60 | #include <linux/uaccess.h> |
61 | |
62 | |
63 | #define OUR_NAME "sbc60xxwdt" |
64 | #define PFX OUR_NAME ": " |
65 | |
66 | /* |
67 | * You must set these - The driver cannot probe for the settings |
68 | */ |
69 | |
70 | static int wdt_stop = 0x45; |
71 | module_param(wdt_stop, int, 0); |
72 | MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)" ); |
73 | |
74 | static int wdt_start = 0x443; |
75 | module_param(wdt_start, int, 0); |
76 | MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)" ); |
77 | |
78 | /* |
79 | * The 60xx board can use watchdog timeout values from one second |
80 | * to several minutes. The default is one second, so if we reset |
81 | * the watchdog every ~250ms we should be safe. |
82 | */ |
83 | |
84 | #define WDT_INTERVAL (HZ/4+1) |
85 | |
86 | /* |
87 | * We must not require too good response from the userspace daemon. |
88 | * Here we require the userspace daemon to send us a heartbeat |
89 | * char to /dev/watchdog every 30 seconds. |
90 | * If the daemon pulses us every 25 seconds, we can still afford |
91 | * a 5 second scheduling delay on the (high priority) daemon. That |
92 | * should be sufficient for a box under any load. |
93 | */ |
94 | |
95 | #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */ |
96 | static int timeout = WATCHDOG_TIMEOUT; /* in seconds, multiplied by HZ to |
97 | get seconds to wait for a ping */ |
98 | module_param(timeout, int, 0); |
99 | MODULE_PARM_DESC(timeout, |
100 | "Watchdog timeout in seconds. (1<=timeout<=3600, default=" |
101 | __MODULE_STRING(WATCHDOG_TIMEOUT) ")" ); |
102 | |
103 | static bool nowayout = WATCHDOG_NOWAYOUT; |
104 | module_param(nowayout, bool, 0); |
105 | MODULE_PARM_DESC(nowayout, |
106 | "Watchdog cannot be stopped once started (default=" |
107 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")" ); |
108 | |
109 | static void wdt_timer_ping(struct timer_list *); |
110 | static DEFINE_TIMER(timer, wdt_timer_ping); |
111 | static unsigned long next_heartbeat; |
112 | static unsigned long wdt_is_open; |
113 | static char wdt_expect_close; |
114 | |
115 | /* |
116 | * Whack the dog |
117 | */ |
118 | |
119 | static void wdt_timer_ping(struct timer_list *unused) |
120 | { |
121 | /* If we got a heartbeat pulse within the WDT_US_INTERVAL |
122 | * we agree to ping the WDT |
123 | */ |
124 | if (time_before(jiffies, next_heartbeat)) { |
125 | /* Ping the WDT by reading from wdt_start */ |
126 | inb_p(port: wdt_start); |
127 | /* Re-set the timer interval */ |
128 | mod_timer(timer: &timer, expires: jiffies + WDT_INTERVAL); |
129 | } else |
130 | pr_warn("Heartbeat lost! Will not ping the watchdog\n" ); |
131 | } |
132 | |
133 | /* |
134 | * Utility routines |
135 | */ |
136 | |
137 | static void wdt_startup(void) |
138 | { |
139 | next_heartbeat = jiffies + (timeout * HZ); |
140 | |
141 | /* Start the timer */ |
142 | mod_timer(timer: &timer, expires: jiffies + WDT_INTERVAL); |
143 | pr_info("Watchdog timer is now enabled\n" ); |
144 | } |
145 | |
146 | static void wdt_turnoff(void) |
147 | { |
148 | /* Stop the timer */ |
149 | del_timer_sync(timer: &timer); |
150 | inb_p(port: wdt_stop); |
151 | pr_info("Watchdog timer is now disabled...\n" ); |
152 | } |
153 | |
154 | static void wdt_keepalive(void) |
155 | { |
156 | /* user land ping */ |
157 | next_heartbeat = jiffies + (timeout * HZ); |
158 | } |
159 | |
160 | /* |
161 | * /dev/watchdog handling |
162 | */ |
163 | |
164 | static ssize_t fop_write(struct file *file, const char __user *buf, |
165 | size_t count, loff_t *ppos) |
166 | { |
167 | /* See if we got the magic character 'V' and reload the timer */ |
168 | if (count) { |
169 | if (!nowayout) { |
170 | size_t ofs; |
171 | |
172 | /* note: just in case someone wrote the |
173 | magic character five months ago... */ |
174 | wdt_expect_close = 0; |
175 | |
176 | /* scan to see whether or not we got the |
177 | magic character */ |
178 | for (ofs = 0; ofs != count; ofs++) { |
179 | char c; |
180 | if (get_user(c, buf + ofs)) |
181 | return -EFAULT; |
182 | if (c == 'V') |
183 | wdt_expect_close = 42; |
184 | } |
185 | } |
186 | |
187 | /* Well, anyhow someone wrote to us, we should |
188 | return that favour */ |
189 | wdt_keepalive(); |
190 | } |
191 | return count; |
192 | } |
193 | |
194 | static int fop_open(struct inode *inode, struct file *file) |
195 | { |
196 | /* Just in case we're already talking to someone... */ |
197 | if (test_and_set_bit(nr: 0, addr: &wdt_is_open)) |
198 | return -EBUSY; |
199 | |
200 | if (nowayout) |
201 | __module_get(THIS_MODULE); |
202 | |
203 | /* Good, fire up the show */ |
204 | wdt_startup(); |
205 | return stream_open(inode, filp: file); |
206 | } |
207 | |
208 | static int fop_close(struct inode *inode, struct file *file) |
209 | { |
210 | if (wdt_expect_close == 42) |
211 | wdt_turnoff(); |
212 | else { |
213 | del_timer(timer: &timer); |
214 | pr_crit("device file closed unexpectedly. Will not stop the WDT!\n" ); |
215 | } |
216 | clear_bit(nr: 0, addr: &wdt_is_open); |
217 | wdt_expect_close = 0; |
218 | return 0; |
219 | } |
220 | |
221 | static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg) |
222 | { |
223 | void __user *argp = (void __user *)arg; |
224 | int __user *p = argp; |
225 | static const struct watchdog_info ident = { |
226 | .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | |
227 | WDIOF_MAGICCLOSE, |
228 | .firmware_version = 1, |
229 | .identity = "SBC60xx" , |
230 | }; |
231 | |
232 | switch (cmd) { |
233 | case WDIOC_GETSUPPORT: |
234 | return copy_to_user(to: argp, from: &ident, n: sizeof(ident)) ? -EFAULT : 0; |
235 | case WDIOC_GETSTATUS: |
236 | case WDIOC_GETBOOTSTATUS: |
237 | return put_user(0, p); |
238 | case WDIOC_SETOPTIONS: |
239 | { |
240 | int new_options, retval = -EINVAL; |
241 | if (get_user(new_options, p)) |
242 | return -EFAULT; |
243 | if (new_options & WDIOS_DISABLECARD) { |
244 | wdt_turnoff(); |
245 | retval = 0; |
246 | } |
247 | if (new_options & WDIOS_ENABLECARD) { |
248 | wdt_startup(); |
249 | retval = 0; |
250 | } |
251 | return retval; |
252 | } |
253 | case WDIOC_KEEPALIVE: |
254 | wdt_keepalive(); |
255 | return 0; |
256 | case WDIOC_SETTIMEOUT: |
257 | { |
258 | int new_timeout; |
259 | if (get_user(new_timeout, p)) |
260 | return -EFAULT; |
261 | /* arbitrary upper limit */ |
262 | if (new_timeout < 1 || new_timeout > 3600) |
263 | return -EINVAL; |
264 | |
265 | timeout = new_timeout; |
266 | wdt_keepalive(); |
267 | } |
268 | fallthrough; |
269 | case WDIOC_GETTIMEOUT: |
270 | return put_user(timeout, p); |
271 | default: |
272 | return -ENOTTY; |
273 | } |
274 | } |
275 | |
276 | static const struct file_operations wdt_fops = { |
277 | .owner = THIS_MODULE, |
278 | .llseek = no_llseek, |
279 | .write = fop_write, |
280 | .open = fop_open, |
281 | .release = fop_close, |
282 | .unlocked_ioctl = fop_ioctl, |
283 | .compat_ioctl = compat_ptr_ioctl, |
284 | }; |
285 | |
286 | static struct miscdevice wdt_miscdev = { |
287 | .minor = WATCHDOG_MINOR, |
288 | .name = "watchdog" , |
289 | .fops = &wdt_fops, |
290 | }; |
291 | |
292 | /* |
293 | * Notifier for system down |
294 | */ |
295 | |
296 | static int wdt_notify_sys(struct notifier_block *this, unsigned long code, |
297 | void *unused) |
298 | { |
299 | if (code == SYS_DOWN || code == SYS_HALT) |
300 | wdt_turnoff(); |
301 | return NOTIFY_DONE; |
302 | } |
303 | |
304 | /* |
305 | * The WDT needs to learn about soft shutdowns in order to |
306 | * turn the timebomb registers off. |
307 | */ |
308 | |
309 | static struct notifier_block wdt_notifier = { |
310 | .notifier_call = wdt_notify_sys, |
311 | }; |
312 | |
313 | static void __exit sbc60xxwdt_unload(void) |
314 | { |
315 | wdt_turnoff(); |
316 | |
317 | /* Deregister */ |
318 | misc_deregister(misc: &wdt_miscdev); |
319 | |
320 | unregister_reboot_notifier(&wdt_notifier); |
321 | if ((wdt_stop != 0x45) && (wdt_stop != wdt_start)) |
322 | release_region(wdt_stop, 1); |
323 | release_region(wdt_start, 1); |
324 | } |
325 | |
326 | static int __init sbc60xxwdt_init(void) |
327 | { |
328 | int rc = -EBUSY; |
329 | |
330 | if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */ |
331 | timeout = WATCHDOG_TIMEOUT; |
332 | pr_info("timeout value must be 1 <= x <= 3600, using %d\n" , |
333 | timeout); |
334 | } |
335 | |
336 | if (!request_region(wdt_start, 1, "SBC 60XX WDT" )) { |
337 | pr_err("I/O address 0x%04x already in use\n" , wdt_start); |
338 | rc = -EIO; |
339 | goto err_out; |
340 | } |
341 | |
342 | /* We cannot reserve 0x45 - the kernel already has! */ |
343 | if (wdt_stop != 0x45 && wdt_stop != wdt_start) { |
344 | if (!request_region(wdt_stop, 1, "SBC 60XX WDT" )) { |
345 | pr_err("I/O address 0x%04x already in use\n" , wdt_stop); |
346 | rc = -EIO; |
347 | goto err_out_region1; |
348 | } |
349 | } |
350 | |
351 | rc = register_reboot_notifier(&wdt_notifier); |
352 | if (rc) { |
353 | pr_err("cannot register reboot notifier (err=%d)\n" , rc); |
354 | goto err_out_region2; |
355 | } |
356 | |
357 | rc = misc_register(misc: &wdt_miscdev); |
358 | if (rc) { |
359 | pr_err("cannot register miscdev on minor=%d (err=%d)\n" , |
360 | wdt_miscdev.minor, rc); |
361 | goto err_out_reboot; |
362 | } |
363 | pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n" , |
364 | timeout, nowayout); |
365 | |
366 | return 0; |
367 | |
368 | err_out_reboot: |
369 | unregister_reboot_notifier(&wdt_notifier); |
370 | err_out_region2: |
371 | if (wdt_stop != 0x45 && wdt_stop != wdt_start) |
372 | release_region(wdt_stop, 1); |
373 | err_out_region1: |
374 | release_region(wdt_start, 1); |
375 | err_out: |
376 | return rc; |
377 | } |
378 | |
379 | module_init(sbc60xxwdt_init); |
380 | module_exit(sbc60xxwdt_unload); |
381 | |
382 | MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>" ); |
383 | MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver" ); |
384 | MODULE_LICENSE("GPL" ); |
385 | |