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
ibwdt_ping(void)112 static void ibwdt_ping(void)
113 {
114 int wd_margin = 15 - ((timeout + 1) / 2);
115
116 spin_lock(&ibwdt_lock);
117
118 /* Write a watchdog value */
119 outb_p(wd_margin, WDT_START);
120
121 spin_unlock(&ibwdt_lock);
122 }
123
ibwdt_disable(void)124 static void ibwdt_disable(void)
125 {
126 spin_lock(&ibwdt_lock);
127 outb_p(0, WDT_STOP);
128 spin_unlock(&ibwdt_lock);
129 }
130
ibwdt_set_heartbeat(int t)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
ibwdt_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)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
ibwdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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(argp, &ident, 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(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
ibwdt_open(struct inode * inode,struct file * file)228 static int ibwdt_open(struct inode *inode, struct file *file)
229 {
230 if (test_and_set_bit(0, &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, file);
238 }
239
ibwdt_close(struct inode * inode,struct file * file)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(0, &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
ibwdt_probe(struct platform_device * dev)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(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(&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
ibwdt_remove(struct platform_device * dev)319 static void ibwdt_remove(struct platform_device *dev)
320 {
321 misc_deregister(&ibwdt_miscdev);
322 release_region(WDT_START, 1);
323 #if WDT_START != WDT_STOP
324 release_region(WDT_STOP, 1);
325 #endif
326 }
327
ibwdt_shutdown(struct platform_device * dev)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
ibwdt_init(void)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 -1, NULL, 0);
350 if (IS_ERR(ibwdt_platform_device))
351 return PTR_ERR(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
ibwdt_exit(void)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