1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | /* |
3 | * IB700 Single Board Computer WDT driver |
4 | * |
5 | * (c) Copyright 2001 Charles Howes <chowes@vsol.net> |
6 | * |
7 | * Based on advantechwdt.c which is based on acquirewdt.c which |
8 | * is based on wdt.c. |
9 | * |
10 | * (c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl> |
11 | * |
12 | * Based on acquirewdt.c which is based on wdt.c. |
13 | * Original copyright messages: |
14 | * |
15 | * (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>, |
16 | * All Rights Reserved. |
17 | * |
18 | * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide |
19 | * warranty for any of this software. This material is provided |
20 | * "AS-IS" and at no charge. |
21 | * |
22 | * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk> |
23 | * |
24 | * 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com> |
25 | * Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT |
26 | * Added timeout module option to override default |
27 | * |
28 | */ |
29 | |
30 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
31 | |
32 | #include <linux/module.h> |
33 | #include <linux/types.h> |
34 | #include <linux/miscdevice.h> |
35 | #include <linux/watchdog.h> |
36 | #include <linux/ioport.h> |
37 | #include <linux/fs.h> |
38 | #include <linux/init.h> |
39 | #include <linux/spinlock.h> |
40 | #include <linux/moduleparam.h> |
41 | #include <linux/platform_device.h> |
42 | #include <linux/io.h> |
43 | #include <linux/uaccess.h> |
44 | |
45 | |
46 | static struct platform_device *ibwdt_platform_device; |
47 | static unsigned long ibwdt_is_open; |
48 | static DEFINE_SPINLOCK(ibwdt_lock); |
49 | static char expect_close; |
50 | |
51 | /* Module information */ |
52 | #define DRV_NAME "ib700wdt" |
53 | |
54 | /* |
55 | * |
56 | * Watchdog Timer Configuration |
57 | * |
58 | * The function of the watchdog timer is to reset the system |
59 | * automatically and is defined at I/O port 0443H. To enable the |
60 | * watchdog timer and allow the system to reset, write I/O port 0443H. |
61 | * To disable the timer, write I/O port 0441H for the system to stop the |
62 | * watchdog function. The timer has a tolerance of 20% for its |
63 | * intervals. |
64 | * |
65 | * The following describes how the timer should be programmed. |
66 | * |
67 | * Enabling Watchdog: |
68 | * MOV AX,000FH (Choose the values from 0 to F) |
69 | * MOV DX,0443H |
70 | * OUT DX,AX |
71 | * |
72 | * Disabling Watchdog: |
73 | * MOV AX,000FH (Any value is fine.) |
74 | * MOV DX,0441H |
75 | * OUT DX,AX |
76 | * |
77 | * Watchdog timer control table: |
78 | * Level Value Time/sec | Level Value Time/sec |
79 | * 1 F 0 | 9 7 16 |
80 | * 2 E 2 | 10 6 18 |
81 | * 3 D 4 | 11 5 20 |
82 | * 4 C 6 | 12 4 22 |
83 | * 5 B 8 | 13 3 24 |
84 | * 6 A 10 | 14 2 26 |
85 | * 7 9 12 | 15 1 28 |
86 | * 8 8 14 | 16 0 30 |
87 | * |
88 | */ |
89 | |
90 | #define WDT_STOP 0x441 |
91 | #define WDT_START 0x443 |
92 | |
93 | /* Default timeout */ |
94 | #define WATCHDOG_TIMEOUT 30 /* 30 seconds +/- 20% */ |
95 | static int timeout = WATCHDOG_TIMEOUT; /* in seconds */ |
96 | module_param(timeout, int, 0); |
97 | MODULE_PARM_DESC(timeout, |
98 | "Watchdog timeout in seconds. 0<= timeout <=30, default=" |
99 | __MODULE_STRING(WATCHDOG_TIMEOUT) "." ); |
100 | |
101 | static bool nowayout = WATCHDOG_NOWAYOUT; |
102 | module_param(nowayout, bool, 0); |
103 | MODULE_PARM_DESC(nowayout, |
104 | "Watchdog cannot be stopped once started (default=" |
105 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")" ); |
106 | |
107 | |
108 | /* |
109 | * Watchdog Operations |
110 | */ |
111 | |
112 | static void ibwdt_ping(void) |
113 | { |
114 | int wd_margin = 15 - ((timeout + 1) / 2); |
115 | |
116 | spin_lock(lock: &ibwdt_lock); |
117 | |
118 | /* Write a watchdog value */ |
119 | outb_p(value: wd_margin, WDT_START); |
120 | |
121 | spin_unlock(lock: &ibwdt_lock); |
122 | } |
123 | |
124 | static void ibwdt_disable(void) |
125 | { |
126 | spin_lock(lock: &ibwdt_lock); |
127 | outb_p(value: 0, WDT_STOP); |
128 | spin_unlock(lock: &ibwdt_lock); |
129 | } |
130 | |
131 | static int ibwdt_set_heartbeat(int t) |
132 | { |
133 | if (t < 0 || t > 30) |
134 | return -EINVAL; |
135 | |
136 | timeout = t; |
137 | return 0; |
138 | } |
139 | |
140 | /* |
141 | * /dev/watchdog handling |
142 | */ |
143 | |
144 | static ssize_t ibwdt_write(struct file *file, const char __user *buf, |
145 | size_t count, loff_t *ppos) |
146 | { |
147 | if (count) { |
148 | if (!nowayout) { |
149 | size_t i; |
150 | |
151 | /* In case it was set long ago */ |
152 | expect_close = 0; |
153 | |
154 | for (i = 0; i != count; i++) { |
155 | char c; |
156 | if (get_user(c, buf + i)) |
157 | return -EFAULT; |
158 | if (c == 'V') |
159 | expect_close = 42; |
160 | } |
161 | } |
162 | ibwdt_ping(); |
163 | } |
164 | return count; |
165 | } |
166 | |
167 | static long ibwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg) |
168 | { |
169 | int new_margin; |
170 | void __user *argp = (void __user *)arg; |
171 | int __user *p = argp; |
172 | |
173 | static const struct watchdog_info ident = { |
174 | .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
175 | | WDIOF_MAGICCLOSE, |
176 | .firmware_version = 1, |
177 | .identity = "IB700 WDT" , |
178 | }; |
179 | |
180 | switch (cmd) { |
181 | case WDIOC_GETSUPPORT: |
182 | if (copy_to_user(to: argp, from: &ident, n: sizeof(ident))) |
183 | return -EFAULT; |
184 | break; |
185 | |
186 | case WDIOC_GETSTATUS: |
187 | case WDIOC_GETBOOTSTATUS: |
188 | return put_user(0, p); |
189 | |
190 | case WDIOC_SETOPTIONS: |
191 | { |
192 | int options, retval = -EINVAL; |
193 | |
194 | if (get_user(options, p)) |
195 | return -EFAULT; |
196 | |
197 | if (options & WDIOS_DISABLECARD) { |
198 | ibwdt_disable(); |
199 | retval = 0; |
200 | } |
201 | if (options & WDIOS_ENABLECARD) { |
202 | ibwdt_ping(); |
203 | retval = 0; |
204 | } |
205 | return retval; |
206 | } |
207 | case WDIOC_KEEPALIVE: |
208 | ibwdt_ping(); |
209 | break; |
210 | |
211 | case WDIOC_SETTIMEOUT: |
212 | if (get_user(new_margin, p)) |
213 | return -EFAULT; |
214 | if (ibwdt_set_heartbeat(t: new_margin)) |
215 | return -EINVAL; |
216 | ibwdt_ping(); |
217 | fallthrough; |
218 | |
219 | case WDIOC_GETTIMEOUT: |
220 | return put_user(timeout, p); |
221 | |
222 | default: |
223 | return -ENOTTY; |
224 | } |
225 | return 0; |
226 | } |
227 | |
228 | static int ibwdt_open(struct inode *inode, struct file *file) |
229 | { |
230 | if (test_and_set_bit(nr: 0, addr: &ibwdt_is_open)) |
231 | return -EBUSY; |
232 | if (nowayout) |
233 | __module_get(THIS_MODULE); |
234 | |
235 | /* Activate */ |
236 | ibwdt_ping(); |
237 | return stream_open(inode, filp: file); |
238 | } |
239 | |
240 | static int ibwdt_close(struct inode *inode, struct file *file) |
241 | { |
242 | if (expect_close == 42) { |
243 | ibwdt_disable(); |
244 | } else { |
245 | pr_crit("WDT device closed unexpectedly. WDT will not stop!\n" ); |
246 | ibwdt_ping(); |
247 | } |
248 | clear_bit(nr: 0, addr: &ibwdt_is_open); |
249 | expect_close = 0; |
250 | return 0; |
251 | } |
252 | |
253 | /* |
254 | * Kernel Interfaces |
255 | */ |
256 | |
257 | static const struct file_operations ibwdt_fops = { |
258 | .owner = THIS_MODULE, |
259 | .llseek = no_llseek, |
260 | .write = ibwdt_write, |
261 | .unlocked_ioctl = ibwdt_ioctl, |
262 | .compat_ioctl = compat_ptr_ioctl, |
263 | .open = ibwdt_open, |
264 | .release = ibwdt_close, |
265 | }; |
266 | |
267 | static struct miscdevice ibwdt_miscdev = { |
268 | .minor = WATCHDOG_MINOR, |
269 | .name = "watchdog" , |
270 | .fops = &ibwdt_fops, |
271 | }; |
272 | |
273 | /* |
274 | * Init & exit routines |
275 | */ |
276 | |
277 | static int __init ibwdt_probe(struct platform_device *dev) |
278 | { |
279 | int res; |
280 | |
281 | #if WDT_START != WDT_STOP |
282 | if (!request_region(WDT_STOP, 1, "IB700 WDT" )) { |
283 | pr_err("STOP method I/O %X is not available\n" , WDT_STOP); |
284 | res = -EIO; |
285 | goto out_nostopreg; |
286 | } |
287 | #endif |
288 | |
289 | if (!request_region(WDT_START, 1, "IB700 WDT" )) { |
290 | pr_err("START method I/O %X is not available\n" , WDT_START); |
291 | res = -EIO; |
292 | goto out_nostartreg; |
293 | } |
294 | |
295 | /* Check that the heartbeat value is within it's range ; |
296 | * if not reset to the default */ |
297 | if (ibwdt_set_heartbeat(t: timeout)) { |
298 | ibwdt_set_heartbeat(WATCHDOG_TIMEOUT); |
299 | pr_info("timeout value must be 0<=x<=30, using %d\n" , timeout); |
300 | } |
301 | |
302 | res = misc_register(misc: &ibwdt_miscdev); |
303 | if (res) { |
304 | pr_err("failed to register misc device\n" ); |
305 | goto out_nomisc; |
306 | } |
307 | return 0; |
308 | |
309 | out_nomisc: |
310 | release_region(WDT_START, 1); |
311 | out_nostartreg: |
312 | #if WDT_START != WDT_STOP |
313 | release_region(WDT_STOP, 1); |
314 | #endif |
315 | out_nostopreg: |
316 | return res; |
317 | } |
318 | |
319 | static void ibwdt_remove(struct platform_device *dev) |
320 | { |
321 | misc_deregister(misc: &ibwdt_miscdev); |
322 | release_region(WDT_START, 1); |
323 | #if WDT_START != WDT_STOP |
324 | release_region(WDT_STOP, 1); |
325 | #endif |
326 | } |
327 | |
328 | static void ibwdt_shutdown(struct platform_device *dev) |
329 | { |
330 | /* Turn the WDT off if we have a soft shutdown */ |
331 | ibwdt_disable(); |
332 | } |
333 | |
334 | static struct platform_driver ibwdt_driver = { |
335 | .remove_new = ibwdt_remove, |
336 | .shutdown = ibwdt_shutdown, |
337 | .driver = { |
338 | .name = DRV_NAME, |
339 | }, |
340 | }; |
341 | |
342 | static int __init ibwdt_init(void) |
343 | { |
344 | int err; |
345 | |
346 | pr_info("WDT driver for IB700 single board computer initialising\n" ); |
347 | |
348 | ibwdt_platform_device = platform_device_register_simple(DRV_NAME, |
349 | id: -1, NULL, num: 0); |
350 | if (IS_ERR(ptr: ibwdt_platform_device)) |
351 | return PTR_ERR(ptr: ibwdt_platform_device); |
352 | |
353 | err = platform_driver_probe(&ibwdt_driver, ibwdt_probe); |
354 | if (err) |
355 | goto unreg_platform_device; |
356 | |
357 | return 0; |
358 | |
359 | unreg_platform_device: |
360 | platform_device_unregister(ibwdt_platform_device); |
361 | return err; |
362 | } |
363 | |
364 | static void __exit ibwdt_exit(void) |
365 | { |
366 | platform_device_unregister(ibwdt_platform_device); |
367 | platform_driver_unregister(&ibwdt_driver); |
368 | pr_info("Watchdog Module Unloaded\n" ); |
369 | } |
370 | |
371 | module_init(ibwdt_init); |
372 | module_exit(ibwdt_exit); |
373 | |
374 | MODULE_AUTHOR("Charles Howes <chowes@vsol.net>" ); |
375 | MODULE_DESCRIPTION("IB700 SBC watchdog driver" ); |
376 | MODULE_LICENSE("GPL" ); |
377 | |
378 | /* end of ib700wdt.c */ |
379 | |