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@lxorguk.ukuu.org.uk>,
20 *						All Rights Reserved.
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@lxorguk.ukuu.org.uk>
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
40
41#include <linux/module.h>
42#include <linux/types.h>
43#include <linux/miscdevice.h>
44#include <linux/watchdog.h>
45#include <linux/ioport.h>
46#include <linux/delay.h>
47#include <linux/notifier.h>
48#include <linux/fs.h>
49#include <linux/reboot.h>
50#include <linux/init.h>
51#include <linux/spinlock.h>
52#include <linux/moduleparam.h>
53#include <linux/io.h>
54#include <linux/uaccess.h>
55
56
57static unsigned long sbc8360_is_open;
58static char expect_close;
59
60/*
61 *
62 * Watchdog Timer Configuration
63 *
64 * The function of the watchdog timer is to reset the system automatically
65 * and is defined at I/O port 0120H and 0121H.  To enable the watchdog timer
66 * and allow the system to reset, write appropriate values from the table
67 * below to I/O port 0120H and 0121H.  To disable the timer, write a zero
68 * value to I/O port 0121H for the system to stop the watchdog function.
69 *
70 * The following describes how the timer should be programmed (according to
71 * the vendor documentation)
72 *
73 * Enabling Watchdog:
74 * MOV AX,000AH (enable, phase I)
75 * MOV DX,0120H
76 * OUT DX,AX
77 * MOV AX,000BH (enable, phase II)
78 * MOV DX,0120H
79 * OUT DX,AX
80 * MOV AX,000nH (set multiplier n, from 1-4)
81 * MOV DX,0120H
82 * OUT DX,AX
83 * MOV AX,000mH (set base timer m, from 0-F)
84 * MOV DX,0121H
85 * OUT DX,AX
86 *
87 * Reset timer:
88 * MOV AX,000mH (same as set base timer, above)
89 * MOV DX,0121H
90 * OUT DX,AX
91 *
92 * Disabling Watchdog:
93 * MOV AX,0000H (a zero value)
94 * MOV DX,0120H
95 * OUT DX,AX
96 *
97 * Watchdog timeout configuration values:
98 *		N
99 *	M |	1	2	3	4
100 *	--|----------------------------------
101 *	0 |	0.5s	5s	50s	100s
102 *	1 |	1s	10s	100s	200s
103 *	2 |	1.5s	15s	150s	300s
104 *	3 |	2s	20s	200s	400s
105 *	4 |	2.5s	25s	250s	500s
106 *	5 |	3s	30s	300s	600s
107 *	6 |	3.5s	35s	350s	700s
108 *	7 |	4s	40s	400s	800s
109 *	8 |	4.5s	45s	450s	900s
110 *	9 |	5s	50s	500s	1000s
111 *	A |	5.5s	55s	550s	1100s
112 *	B |	6s	60s	600s	1200s
113 *	C |	6.5s	65s	650s	1300s
114 *	D |	7s	70s	700s	1400s
115 *	E |	7.5s	75s	750s	1500s
116 *	F |	8s	80s	800s	1600s
117 *
118 * Another way to say the same things is:
119 *  For N=1, Timeout = (M+1) * 0.5s
120 *  For N=2, Timeout = (M+1) * 5s
121 *  For N=3, Timeout = (M+1) * 50s
122 *  For N=4, Timeout = (M+1) * 100s
123 *
124 */
125
126static int wd_times[64][2] = {
127	{0, 1},			/* 0  = 0.5s */
128	{1, 1},			/* 1  = 1s   */
129	{2, 1},			/* 2  = 1.5s */
130	{3, 1},			/* 3  = 2s   */
131	{4, 1},			/* 4  = 2.5s */
132	{5, 1},			/* 5  = 3s   */
133	{6, 1},			/* 6  = 3.5s */
134	{7, 1},			/* 7  = 4s   */
135	{8, 1},			/* 8  = 4.5s */
136	{9, 1},			/* 9  = 5s   */
137	{0xA, 1},		/* 10 = 5.5s */
138	{0xB, 1},		/* 11 = 6s   */
139	{0xC, 1},		/* 12 = 6.5s */
140	{0xD, 1},		/* 13 = 7s   */
141	{0xE, 1},		/* 14 = 7.5s */
142	{0xF, 1},		/* 15 = 8s   */
143	{0, 2},			/* 16 = 5s  */
144	{1, 2},			/* 17 = 10s */
145	{2, 2},			/* 18 = 15s */
146	{3, 2},			/* 19 = 20s */
147	{4, 2},			/* 20 = 25s */
148	{5, 2},			/* 21 = 30s */
149	{6, 2},			/* 22 = 35s */
150	{7, 2},			/* 23 = 40s */
151	{8, 2},			/* 24 = 45s */
152	{9, 2},			/* 25 = 50s */
153	{0xA, 2},		/* 26 = 55s */
154	{0xB, 2},		/* 27 = 60s */
155	{0xC, 2},		/* 28 = 65s */
156	{0xD, 2},		/* 29 = 70s */
157	{0xE, 2},		/* 30 = 75s */
158	{0xF, 2},		/* 31 = 80s */
159	{0, 3},			/* 32 = 50s  */
160	{1, 3},			/* 33 = 100s */
161	{2, 3},			/* 34 = 150s */
162	{3, 3},			/* 35 = 200s */
163	{4, 3},			/* 36 = 250s */
164	{5, 3},			/* 37 = 300s */
165	{6, 3},			/* 38 = 350s */
166	{7, 3},			/* 39 = 400s */
167	{8, 3},			/* 40 = 450s */
168	{9, 3},			/* 41 = 500s */
169	{0xA, 3},		/* 42 = 550s */
170	{0xB, 3},		/* 43 = 600s */
171	{0xC, 3},		/* 44 = 650s */
172	{0xD, 3},		/* 45 = 700s */
173	{0xE, 3},		/* 46 = 750s */
174	{0xF, 3},		/* 47 = 800s */
175	{0, 4},			/* 48 = 100s */
176	{1, 4},			/* 49 = 200s */
177	{2, 4},			/* 50 = 300s */
178	{3, 4},			/* 51 = 400s */
179	{4, 4},			/* 52 = 500s */
180	{5, 4},			/* 53 = 600s */
181	{6, 4},			/* 54 = 700s */
182	{7, 4},			/* 55 = 800s */
183	{8, 4},			/* 56 = 900s */
184	{9, 4},			/* 57 = 1000s */
185	{0xA, 4},		/* 58 = 1100s */
186	{0xB, 4},		/* 59 = 1200s */
187	{0xC, 4},		/* 60 = 1300s */
188	{0xD, 4},		/* 61 = 1400s */
189	{0xE, 4},		/* 62 = 1500s */
190	{0xF, 4}		/* 63 = 1600s */
191};
192
193#define SBC8360_ENABLE 0x120
194#define SBC8360_BASETIME 0x121
195
196static int timeout = 27;
197static int wd_margin = 0xB;
198static int wd_multiplier = 2;
199static bool nowayout = WATCHDOG_NOWAYOUT;
200
201module_param(timeout, int, 0);
202MODULE_PARM_DESC(timeout, "Index into timeout table (0-63) (default=27 (60s))");
203module_param(nowayout, bool, 0);
204MODULE_PARM_DESC(nowayout,
205		 "Watchdog cannot be stopped once started (default="
206				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
207
208/*
209 *	Kernel methods.
210 */
211
212/* Activate and pre-configure watchdog */
213static void sbc8360_activate(void)
214{
215	/* Enable the watchdog */
216	outb(0x0A, SBC8360_ENABLE);
217	msleep_interruptible(100);
218	outb(0x0B, SBC8360_ENABLE);
219	msleep_interruptible(100);
220	/* Set timeout multiplier */
221	outb(wd_multiplier, SBC8360_ENABLE);
222	msleep_interruptible(100);
223	/* Nothing happens until first sbc8360_ping() */
224}
225
226/* Kernel pings watchdog */
227static void sbc8360_ping(void)
228{
229	/* Write the base timer register */
230	outb(wd_margin, SBC8360_BASETIME);
231}
232
233/* stop watchdog */
234static void sbc8360_stop(void)
235{
236	/* De-activate the watchdog */
237	outb(0, SBC8360_ENABLE);
238}
239
240/* Userspace pings kernel driver, or requests clean close */
241static ssize_t sbc8360_write(struct file *file, const char __user *buf,
242			     size_t count, loff_t *ppos)
243{
244	if (count) {
245		if (!nowayout) {
246			size_t i;
247
248			/* In case it was set long ago */
249			expect_close = 0;
250
251			for (i = 0; i != count; i++) {
252				char c;
253				if (get_user(c, buf + i))
254					return -EFAULT;
255				if (c == 'V')
256					expect_close = 42;
257			}
258		}
259		sbc8360_ping();
260	}
261	return count;
262}
263
264static int sbc8360_open(struct inode *inode, struct file *file)
265{
266	if (test_and_set_bit(0, &sbc8360_is_open))
267		return -EBUSY;
268	if (nowayout)
269		__module_get(THIS_MODULE);
270
271	/* Activate and ping once to start the countdown */
272	sbc8360_activate();
273	sbc8360_ping();
274	return nonseekable_open(inode, file);
275}
276
277static int sbc8360_close(struct inode *inode, struct file *file)
278{
279	if (expect_close == 42)
280		sbc8360_stop();
281	else
282		pr_crit("SBC8360 device closed unexpectedly.  SBC8360 will not stop!\n");
283
284	clear_bit(0, &sbc8360_is_open);
285	expect_close = 0;
286	return 0;
287}
288
289/*
290 *	Notifier for system down
291 */
292
293static int sbc8360_notify_sys(struct notifier_block *this, unsigned long code,
294			      void *unused)
295{
296	if (code == SYS_DOWN || code == SYS_HALT)
297		sbc8360_stop();	/* Disable the SBC8360 Watchdog */
298
299	return NOTIFY_DONE;
300}
301
302/*
303 *	Kernel Interfaces
304 */
305
306static const struct file_operations sbc8360_fops = {
307	.owner = THIS_MODULE,
308	.llseek = no_llseek,
309	.write = sbc8360_write,
310	.open = sbc8360_open,
311	.release = sbc8360_close,
312};
313
314static struct miscdevice sbc8360_miscdev = {
315	.minor = WATCHDOG_MINOR,
316	.name = "watchdog",
317	.fops = &sbc8360_fops,
318};
319
320/*
321 *	The SBC8360 needs to learn about soft shutdowns in order to
322 *	turn the timebomb registers off.
323 */
324
325static struct notifier_block sbc8360_notifier = {
326	.notifier_call = sbc8360_notify_sys,
327};
328
329static int __init sbc8360_init(void)
330{
331	int res;
332	unsigned long int mseconds = 60000;
333
334	if (timeout < 0 || timeout > 63) {
335		pr_err("Invalid timeout index (must be 0-63)\n");
336		res = -EINVAL;
337		goto out;
338	}
339
340	if (!request_region(SBC8360_ENABLE, 1, "SBC8360")) {
341		pr_err("ENABLE method I/O %X is not available\n",
342		       SBC8360_ENABLE);
343		res = -EIO;
344		goto out;
345	}
346	if (!request_region(SBC8360_BASETIME, 1, "SBC8360")) {
347		pr_err("BASETIME method I/O %X is not available\n",
348		       SBC8360_BASETIME);
349		res = -EIO;
350		goto out_nobasetimereg;
351	}
352
353	res = register_reboot_notifier(&sbc8360_notifier);
354	if (res) {
355		pr_err("Failed to register reboot notifier\n");
356		goto out_noreboot;
357	}
358
359	res = misc_register(&sbc8360_miscdev);
360	if (res) {
361		pr_err("failed to register misc device\n");
362		goto out_nomisc;
363	}
364
365	wd_margin = wd_times[timeout][0];
366	wd_multiplier = wd_times[timeout][1];
367
368	if (wd_multiplier == 1)
369		mseconds = (wd_margin + 1) * 500;
370	else if (wd_multiplier == 2)
371		mseconds = (wd_margin + 1) * 5000;
372	else if (wd_multiplier == 3)
373		mseconds = (wd_margin + 1) * 50000;
374	else if (wd_multiplier == 4)
375		mseconds = (wd_margin + 1) * 100000;
376
377	/* My kingdom for the ability to print "0.5 seconds" in the kernel! */
378	pr_info("Timeout set at %ld ms\n", mseconds);
379
380	return 0;
381
382out_nomisc:
383	unregister_reboot_notifier(&sbc8360_notifier);
384out_noreboot:
385	release_region(SBC8360_BASETIME, 1);
386out_nobasetimereg:
387	release_region(SBC8360_ENABLE, 1);
388out:
389	return res;
390}
391
392static void __exit sbc8360_exit(void)
393{
394	misc_deregister(&sbc8360_miscdev);
395	unregister_reboot_notifier(&sbc8360_notifier);
396	release_region(SBC8360_ENABLE, 1);
397	release_region(SBC8360_BASETIME, 1);
398}
399
400module_init(sbc8360_init);
401module_exit(sbc8360_exit);
402
403MODULE_AUTHOR("Ian E. Morgan <imorgan@webcon.ca>");
404MODULE_DESCRIPTION("SBC8360 watchdog driver");
405MODULE_LICENSE("GPL");
406MODULE_VERSION("1.01");
407
408/* end of sbc8360.c */
409