1/*
2 *	SBC8360 Watchdog driver
3 *
4 *	(c) Copyright 2005 Webcon, Inc.
5 *
6 *	Based on ib700wdt.c, which is based on advantechwdt.c which is based
7 *      on acquirewdt.c which is based on wdt.c.
8 *
9 *	(c) Copyright 2001 Charles Howes <chowes@vsol.net>
10 *
11 *      Based on advantechwdt.c which is based on acquirewdt.c which
12 *       is based on wdt.c.
13 *
14 *	(c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
15 *
16 *	Based on acquirewdt.c which is based on wdt.c.
17 *	Original copyright messages:
18 *
19 *	(c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
20 *				http://www.redhat.com
21 *
22 *	This program is free software; you can redistribute it and/or
23 *	modify it under the terms of the GNU General Public License
24 *	as published by the Free Software Foundation; either version
25 *	2 of the License, or (at your option) any later version.
26 *
27 *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
28 *	warranty for any of this software. This material is provided
29 *	"AS-IS" and at no charge.
30 *
31 *	(c) Copyright 1995    Alan Cox <alan@redhat.com>
32 *
33 *      14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
34 *           Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
35 *           Added timeout module option to override default
36 *
37 */
38
39#include <linux/module.h>
40#include <linux/types.h>
41#include <linux/miscdevice.h>
42#include <linux/watchdog.h>
43#include <linux/ioport.h>
44#include <linux/delay.h>
45#include <linux/notifier.h>
46#include <linux/fs.h>
47#include <linux/reboot.h>
48#include <linux/init.h>
49#include <linux/spinlock.h>
50#include <linux/moduleparam.h>
51
52#include <asm/io.h>
53#include <asm/uaccess.h>
54#include <asm/system.h>
55
56static unsigned long sbc8360_is_open;
57static spinlock_t sbc8360_lock;
58static char expect_close;
59
60#define PFX "sbc8360: "
61
62/*
63 *
64 * Watchdog Timer Configuration
65 *
66 * The function of the watchdog timer is to reset the system automatically
67 * and is defined at I/O port 0120H and 0121H.  To enable the watchdog timer
68 * and allow the system to reset, write appropriate values from the table
69 * below to I/O port 0120H and 0121H.  To disable the timer, write a zero
70 * value to I/O port 0121H for the system to stop the watchdog function.
71 *
72 * The following describes how the timer should be programmed (according to
73 * the vendor documentation)
74 *
75 * Enabling Watchdog:
76 * MOV AX,000AH (enable, phase I)
77 * MOV DX,0120H
78 * OUT DX,AX
79 * MOV AX,000BH (enable, phase II)
80 * MOV DX,0120H
81 * OUT DX,AX
82 * MOV AX,000nH (set multiplier n, from 1-4)
83 * MOV DX,0120H
84 * OUT DX,AX
85 * MOV AX,000mH (set base timer m, from 0-F)
86 * MOV DX,0121H
87 * OUT DX,AX
88 *
89 * Reset timer:
90 * MOV AX,000mH (same as set base timer, above)
91 * MOV DX,0121H
92 * OUT DX,AX
93 *
94 * Disabling Watchdog:
95 * MOV AX,0000H (a zero value)
96 * MOV DX,0120H
97 * OUT DX,AX
98 *
99 * Watchdog timeout configuration values:
100 *		N
101 *	M |	1	2	3	4
102 *	--|----------------------------------
103 *	0 |	0.5s	5s	50s	100s
104 *	1 |	1s	10s	100s	200s
105 *	2 |	1.5s	15s	150s	300s
106 *	3 |	2s	20s	200s	400s
107 *	4 |	2.5s	25s	250s	500s
108 *	5 |	3s	30s	300s	600s
109 *	6 |	3.5s	35s	350s	700s
110 *	7 |	4s	40s	400s	800s
111 *	8 |	4.5s	45s	450s	900s
112 *	9 |	5s	50s	500s	1000s
113 *	A |	5.5s	55s	550s	1100s
114 *	B |	6s	60s	600s	1200s
115 *	C |	6.5s	65s	650s	1300s
116 *	D |	7s	70s	700s	1400s
117 *	E |	7.5s	75s	750s	1500s
118 *	F |	8s	80s 	800s 	1600s
119 *
120 * Another way to say the same things is:
121 *  For N=1, Timeout = (M+1) * 0.5s
122 *  For N=2, Timeout = (M+1) * 5s
123 *  For N=3, Timeout = (M+1) * 50s
124 *  For N=4, Timeout = (M+1) * 100s
125 *
126 */
127
128static int wd_times[64][2] = {
129	{0, 1},			/* 0  = 0.5s */
130	{1, 1},			/* 1  = 1s   */
131	{2, 1},			/* 2  = 1.5s */
132	{3, 1},			/* 3  = 2s   */
133	{4, 1},			/* 4  = 2.5s */
134	{5, 1},			/* 5  = 3s   */
135	{6, 1},			/* 6  = 3.5s */
136	{7, 1},			/* 7  = 4s   */
137	{8, 1},			/* 8  = 4.5s */
138	{9, 1},			/* 9  = 5s   */
139	{0xA, 1},		/* 10 = 5.5s */
140	{0xB, 1},		/* 11 = 6s   */
141	{0xC, 1},		/* 12 = 6.5s */
142	{0xD, 1},		/* 13 = 7s   */
143	{0xE, 1},		/* 14 = 7.5s */
144	{0xF, 1},		/* 15 = 8s   */
145	{0, 2},			/* 16 = 5s  */
146	{1, 2},			/* 17 = 10s */
147	{2, 2},			/* 18 = 15s */
148	{3, 2},			/* 19 = 20s */
149	{4, 2},			/* 20 = 25s */
150	{5, 2},			/* 21 = 30s */
151	{6, 2},			/* 22 = 35s */
152	{7, 2},			/* 23 = 40s */
153	{8, 2},			/* 24 = 45s */
154	{9, 2},			/* 25 = 50s */
155	{0xA, 2},		/* 26 = 55s */
156	{0xB, 2},		/* 27 = 60s */
157	{0xC, 2},		/* 28 = 65s */
158	{0xD, 2},		/* 29 = 70s */
159	{0xE, 2},		/* 30 = 75s */
160	{0xF, 2},		/* 31 = 80s */
161	{0, 3},			/* 32 = 50s  */
162	{1, 3},			/* 33 = 100s */
163	{2, 3},			/* 34 = 150s */
164	{3, 3},			/* 35 = 200s */
165	{4, 3},			/* 36 = 250s */
166	{5, 3},			/* 37 = 300s */
167	{6, 3},			/* 38 = 350s */
168	{7, 3},			/* 39 = 400s */
169	{8, 3},			/* 40 = 450s */
170	{9, 3},			/* 41 = 500s */
171	{0xA, 3},		/* 42 = 550s */
172	{0xB, 3},		/* 43 = 600s */
173	{0xC, 3},		/* 44 = 650s */
174	{0xD, 3},		/* 45 = 700s */
175	{0xE, 3},		/* 46 = 750s */
176	{0xF, 3},		/* 47 = 800s */
177	{0, 4},			/* 48 = 100s */
178	{1, 4},			/* 49 = 200s */
179	{2, 4},			/* 50 = 300s */
180	{3, 4},			/* 51 = 400s */
181	{4, 4},			/* 52 = 500s */
182	{5, 4},			/* 53 = 600s */
183	{6, 4},			/* 54 = 700s */
184	{7, 4},			/* 55 = 800s */
185	{8, 4},			/* 56 = 900s */
186	{9, 4},			/* 57 = 1000s */
187	{0xA, 4},		/* 58 = 1100s */
188	{0xB, 4},		/* 59 = 1200s */
189	{0xC, 4},		/* 60 = 1300s */
190	{0xD, 4},		/* 61 = 1400s */
191	{0xE, 4},		/* 62 = 1500s */
192	{0xF, 4}		/* 63 = 1600s */
193};
194
195#define SBC8360_ENABLE 0x120
196#define SBC8360_BASETIME 0x121
197
198static int timeout = 27;
199static int wd_margin = 0xB;
200static int wd_multiplier = 2;
201static int nowayout = WATCHDOG_NOWAYOUT;
202
203module_param(timeout, int, 0);
204MODULE_PARM_DESC(timeout, "Index into timeout table (0-63) (default=27 (60s))");
205module_param(nowayout, int, 0);
206MODULE_PARM_DESC(nowayout,
207		 "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
208
209/*
210 *	Kernel methods.
211 */
212
213/* Activate and pre-configure watchdog */
214static void sbc8360_activate(void)
215{
216	/* Enable the watchdog */
217	outb(0x0A, SBC8360_ENABLE);
218	msleep_interruptible(100);
219	outb(0x0B, SBC8360_ENABLE);
220	msleep_interruptible(100);
221	/* Set timeout multiplier */
222	outb(wd_multiplier, SBC8360_ENABLE);
223	msleep_interruptible(100);
224	/* Nothing happens until first sbc8360_ping() */
225}
226
227/* Kernel pings watchdog */
228static void sbc8360_ping(void)
229{
230	/* Write the base timer register */
231	outb(wd_margin, SBC8360_BASETIME);
232}
233
234/* Userspace pings kernel driver, or requests clean close */
235static ssize_t sbc8360_write(struct file *file, const char __user * buf,
236			     size_t count, loff_t * ppos)
237{
238	if (count) {
239		if (!nowayout) {
240			size_t i;
241
242			/* In case it was set long ago */
243			expect_close = 0;
244
245			for (i = 0; i != count; i++) {
246				char c;
247				if (get_user(c, buf + i))
248					return -EFAULT;
249				if (c == 'V')
250					expect_close = 42;
251			}
252		}
253		sbc8360_ping();
254	}
255	return count;
256}
257
258static int sbc8360_open(struct inode *inode, struct file *file)
259{
260	spin_lock(&sbc8360_lock);
261	if (test_and_set_bit(0, &sbc8360_is_open)) {
262		spin_unlock(&sbc8360_lock);
263		return -EBUSY;
264	}
265	if (nowayout)
266		__module_get(THIS_MODULE);
267
268	/* Activate and ping once to start the countdown */
269	spin_unlock(&sbc8360_lock);
270	sbc8360_activate();
271	sbc8360_ping();
272	return nonseekable_open(inode, file);
273}
274
275static int sbc8360_close(struct inode *inode, struct file *file)
276{
277	spin_lock(&sbc8360_lock);
278	if (expect_close == 42)
279		outb(0, SBC8360_ENABLE);
280	else
281		printk(KERN_CRIT PFX
282		       "SBC8360 device closed unexpectedly.  SBC8360 will not stop!\n");
283
284	clear_bit(0, &sbc8360_is_open);
285	expect_close = 0;
286	spin_unlock(&sbc8360_lock);
287	return 0;
288}
289
290/*
291 *	Notifier for system down
292 */
293
294static int sbc8360_notify_sys(struct notifier_block *this, unsigned long code,
295			      void *unused)
296{
297	if (code == SYS_DOWN || code == SYS_HALT) {
298		/* Disable the SBC8360 Watchdog */
299		outb(0, SBC8360_ENABLE);
300	}
301	return NOTIFY_DONE;
302}
303
304/*
305 *	Kernel Interfaces
306 */
307
308static const struct file_operations sbc8360_fops = {
309	.owner = THIS_MODULE,
310	.llseek = no_llseek,
311	.write = sbc8360_write,
312	.open = sbc8360_open,
313	.release = sbc8360_close,
314};
315
316static struct miscdevice sbc8360_miscdev = {
317	.minor = WATCHDOG_MINOR,
318	.name = "watchdog",
319	.fops = &sbc8360_fops,
320};
321
322/*
323 *	The SBC8360 needs to learn about soft shutdowns in order to
324 *	turn the timebomb registers off.
325 */
326
327static struct notifier_block sbc8360_notifier = {
328	.notifier_call = sbc8360_notify_sys,
329};
330
331static int __init sbc8360_init(void)
332{
333	int res;
334	unsigned long int mseconds = 60000;
335
336	if (timeout < 0 || timeout > 63) {
337		printk(KERN_ERR PFX "Invalid timeout index (must be 0-63).\n");
338		res = -EINVAL;
339		goto out;
340	}
341
342	if (!request_region(SBC8360_ENABLE, 1, "SBC8360")) {
343		printk(KERN_ERR PFX "ENABLE method I/O %X is not available.\n",
344		       SBC8360_ENABLE);
345		res = -EIO;
346		goto out;
347	}
348	if (!request_region(SBC8360_BASETIME, 1, "SBC8360")) {
349		printk(KERN_ERR PFX
350		       "BASETIME method I/O %X is not available.\n",
351		       SBC8360_BASETIME);
352		res = -EIO;
353		goto out_nobasetimereg;
354	}
355
356	res = register_reboot_notifier(&sbc8360_notifier);
357	if (res) {
358		printk(KERN_ERR PFX "Failed to register reboot notifier.\n");
359		goto out_noreboot;
360	}
361
362	spin_lock_init(&sbc8360_lock);
363	res = misc_register(&sbc8360_miscdev);
364	if (res) {
365		printk(KERN_ERR PFX "failed to register misc device\n");
366		goto out_nomisc;
367	}
368
369	wd_margin = wd_times[timeout][0];
370	wd_multiplier = wd_times[timeout][1];
371
372	if (wd_multiplier == 1)
373		mseconds = (wd_margin + 1) * 500;
374	else if (wd_multiplier == 2)
375		mseconds = (wd_margin + 1) * 5000;
376	else if (wd_multiplier == 3)
377		mseconds = (wd_margin + 1) * 50000;
378	else if (wd_multiplier == 4)
379		mseconds = (wd_margin + 1) * 100000;
380
381	/* My kingdom for the ability to print "0.5 seconds" in the kernel! */
382	printk(KERN_INFO PFX "Timeout set at %ld ms.\n", mseconds);
383
384	return 0;
385
386      out_nomisc:
387	unregister_reboot_notifier(&sbc8360_notifier);
388      out_noreboot:
389	release_region(SBC8360_BASETIME, 1);
390      out_nobasetimereg:
391	release_region(SBC8360_ENABLE, 1);
392      out:
393	return res;
394}
395
396static void __exit sbc8360_exit(void)
397{
398	misc_deregister(&sbc8360_miscdev);
399	unregister_reboot_notifier(&sbc8360_notifier);
400	release_region(SBC8360_ENABLE, 1);
401	release_region(SBC8360_BASETIME, 1);
402}
403
404module_init(sbc8360_init);
405module_exit(sbc8360_exit);
406
407MODULE_AUTHOR("Ian E. Morgan <imorgan@webcon.ca>");
408MODULE_DESCRIPTION("SBC8360 watchdog driver");
409MODULE_LICENSE("GPL");
410MODULE_VERSION("1.01");
411MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
412
413/* end of sbc8360.c */
414