xref: /linux/drivers/watchdog/ib700wdt.c (revision e70140ba0d2b1a30467d4af6bcfe761327b9ec95)
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 	.write		= ibwdt_write,
260 	.unlocked_ioctl	= ibwdt_ioctl,
261 	.compat_ioctl	= compat_ptr_ioctl,
262 	.open		= ibwdt_open,
263 	.release	= ibwdt_close,
264 };
265 
266 static struct miscdevice ibwdt_miscdev = {
267 	.minor = WATCHDOG_MINOR,
268 	.name = "watchdog",
269 	.fops = &ibwdt_fops,
270 };
271 
272 /*
273  *	Init & exit routines
274  */
275 
ibwdt_probe(struct platform_device * dev)276 static int __init ibwdt_probe(struct platform_device *dev)
277 {
278 	int res;
279 
280 #if WDT_START != WDT_STOP
281 	if (!request_region(WDT_STOP, 1, "IB700 WDT")) {
282 		pr_err("STOP method I/O %X is not available\n", WDT_STOP);
283 		res = -EIO;
284 		goto out_nostopreg;
285 	}
286 #endif
287 
288 	if (!request_region(WDT_START, 1, "IB700 WDT")) {
289 		pr_err("START method I/O %X is not available\n", WDT_START);
290 		res = -EIO;
291 		goto out_nostartreg;
292 	}
293 
294 	/* Check that the heartbeat value is within it's range ;
295 	 * if not reset to the default */
296 	if (ibwdt_set_heartbeat(timeout)) {
297 		ibwdt_set_heartbeat(WATCHDOG_TIMEOUT);
298 		pr_info("timeout value must be 0<=x<=30, using %d\n", timeout);
299 	}
300 
301 	res = misc_register(&ibwdt_miscdev);
302 	if (res) {
303 		pr_err("failed to register misc device\n");
304 		goto out_nomisc;
305 	}
306 	return 0;
307 
308 out_nomisc:
309 	release_region(WDT_START, 1);
310 out_nostartreg:
311 #if WDT_START != WDT_STOP
312 	release_region(WDT_STOP, 1);
313 #endif
314 out_nostopreg:
315 	return res;
316 }
317 
ibwdt_remove(struct platform_device * dev)318 static void ibwdt_remove(struct platform_device *dev)
319 {
320 	misc_deregister(&ibwdt_miscdev);
321 	release_region(WDT_START, 1);
322 #if WDT_START != WDT_STOP
323 	release_region(WDT_STOP, 1);
324 #endif
325 }
326 
ibwdt_shutdown(struct platform_device * dev)327 static void ibwdt_shutdown(struct platform_device *dev)
328 {
329 	/* Turn the WDT off if we have a soft shutdown */
330 	ibwdt_disable();
331 }
332 
333 static struct platform_driver ibwdt_driver = {
334 	.remove		= ibwdt_remove,
335 	.shutdown	= ibwdt_shutdown,
336 	.driver		= {
337 		.name	= DRV_NAME,
338 	},
339 };
340 
ibwdt_init(void)341 static int __init ibwdt_init(void)
342 {
343 	int err;
344 
345 	pr_info("WDT driver for IB700 single board computer initialising\n");
346 
347 	ibwdt_platform_device = platform_device_register_simple(DRV_NAME,
348 								-1, NULL, 0);
349 	if (IS_ERR(ibwdt_platform_device))
350 		return PTR_ERR(ibwdt_platform_device);
351 
352 	err = platform_driver_probe(&ibwdt_driver, ibwdt_probe);
353 	if (err)
354 		goto unreg_platform_device;
355 
356 	return 0;
357 
358 unreg_platform_device:
359 	platform_device_unregister(ibwdt_platform_device);
360 	return err;
361 }
362 
ibwdt_exit(void)363 static void __exit ibwdt_exit(void)
364 {
365 	platform_device_unregister(ibwdt_platform_device);
366 	platform_driver_unregister(&ibwdt_driver);
367 	pr_info("Watchdog Module Unloaded\n");
368 }
369 
370 module_init(ibwdt_init);
371 module_exit(ibwdt_exit);
372 
373 MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
374 MODULE_DESCRIPTION("IB700 SBC watchdog driver");
375 MODULE_LICENSE("GPL");
376 
377 /* end of ib700wdt.c */
378