1/*
2 *	IB700 Single Board Computer WDT driver
3 *
4 *	(c) Copyright 2001 Charles Howes <chowes@vsol.net>
5 *
6 *	Based on advantechwdt.c which is based on acquirewdt.c which
7 *	is based on wdt.c.
8 *
9 *	(c) Copyright 2000-2001 Marek Michalkiewicz <marekm@linux.org.pl>
10 *
11 *	Based on acquirewdt.c which is based on wdt.c.
12 *	Original copyright messages:
13 *
14 *	(c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
15 *				http://www.redhat.com
16 *
17 *	This program is free software; you can redistribute it and/or
18 *	modify it under the terms of the GNU General Public License
19 *	as published by the Free Software Foundation; either version
20 *	2 of the License, or (at your option) any later version.
21 *
22 *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
23 *	warranty for any of this software. This material is provided
24 *	"AS-IS" and at no charge.
25 *
26 *	(c) Copyright 1995    Alan Cox <alan@redhat.com>
27 *
28 *	14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
29 *	     Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
30 *	     Added timeout module option to override default
31 *
32 */
33
34#include <linux/module.h>
35#include <linux/types.h>
36#include <linux/miscdevice.h>
37#include <linux/watchdog.h>
38#include <linux/ioport.h>
39#include <linux/fs.h>
40#include <linux/init.h>
41#include <linux/spinlock.h>
42#include <linux/moduleparam.h>
43#include <linux/platform_device.h>
44
45#include <asm/io.h>
46#include <asm/uaccess.h>
47#include <asm/system.h>
48
49static struct platform_device *ibwdt_platform_device;
50static unsigned long ibwdt_is_open;
51static spinlock_t ibwdt_lock;
52static char expect_close;
53
54/* Module information */
55#define DRV_NAME "ib700wdt"
56#define PFX DRV_NAME ": "
57
58/*
59 *
60 * Watchdog Timer Configuration
61 *
62 * The function of the watchdog timer is to reset the system
63 * automatically and is defined at I/O port 0443H.  To enable the
64 * watchdog timer and allow the system to reset, write I/O port 0443H.
65 * To disable the timer, write I/O port 0441H for the system to stop the
66 * watchdog function.  The timer has a tolerance of 20% for its
67 * intervals.
68 *
69 * The following describes how the timer should be programmed.
70 *
71 * Enabling Watchdog:
72 * MOV AX,000FH (Choose the values from 0 to F)
73 * MOV DX,0443H
74 * OUT DX,AX
75 *
76 * Disabling Watchdog:
77 * MOV AX,000FH (Any value is fine.)
78 * MOV DX,0441H
79 * OUT DX,AX
80 *
81 * Watchdog timer control table:
82 * Level   Value  Time/sec | Level Value Time/sec
83 *   1       F       0     |   9     7      16
84 *   2       E       2     |   10    6      18
85 *   3       D       4     |   11    5      20
86 *   4       C       6     |   12    4      22
87 *   5       B       8     |   13    3      24
88 *   6       A       10    |   14    2      26
89 *   7       9       12    |   15    1      28
90 *   8       8       14    |   16    0      30
91 *
92 */
93
94static int wd_times[] = {
95	30,	/* 0x0 */
96	28,	/* 0x1 */
97	26,	/* 0x2 */
98	24,	/* 0x3 */
99	22,	/* 0x4 */
100	20,	/* 0x5 */
101	18,	/* 0x6 */
102	16,	/* 0x7 */
103	14,	/* 0x8 */
104	12,	/* 0x9 */
105	10,	/* 0xA */
106	8,	/* 0xB */
107	6,	/* 0xC */
108	4,	/* 0xD */
109	2,	/* 0xE */
110	0,	/* 0xF */
111};
112
113#define WDT_STOP 0x441
114#define WDT_START 0x443
115
116/* Default timeout */
117#define WD_TIMO 0		/* 30 seconds +/- 20%, from table */
118
119static int wd_margin = WD_TIMO;
120
121static int nowayout = WATCHDOG_NOWAYOUT;
122module_param(nowayout, int, 0);
123MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
124
125
126/*
127 *	Watchdog Operations
128 */
129
130static void
131ibwdt_ping(void)
132{
133	spin_lock(&ibwdt_lock);
134
135	/* Write a watchdog value */
136	outb_p(wd_margin, WDT_START);
137
138	spin_unlock(&ibwdt_lock);
139}
140
141static void
142ibwdt_disable(void)
143{
144	spin_lock(&ibwdt_lock);
145	outb_p(0, WDT_STOP);
146	spin_unlock(&ibwdt_lock);
147}
148
149static int
150ibwdt_set_heartbeat(int t)
151{
152	int i;
153
154	if ((t < 0) || (t > 30))
155		return -EINVAL;
156
157	for (i = 0x0F; i > -1; i--)
158		if (wd_times[i] > t)
159			break;
160	wd_margin = i;
161	return 0;
162}
163
164/*
165 *	/dev/watchdog handling
166 */
167
168static ssize_t
169ibwdt_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
170{
171	if (count) {
172		if (!nowayout) {
173			size_t i;
174
175			/* In case it was set long ago */
176			expect_close = 0;
177
178			for (i = 0; i != count; i++) {
179				char c;
180				if (get_user(c, buf + i))
181					return -EFAULT;
182				if (c == 'V')
183					expect_close = 42;
184			}
185		}
186		ibwdt_ping();
187	}
188	return count;
189}
190
191static int
192ibwdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
193	  unsigned long arg)
194{
195	int new_margin;
196	void __user *argp = (void __user *)arg;
197	int __user *p = argp;
198
199	static struct watchdog_info ident = {
200		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
201		.firmware_version = 1,
202		.identity = "IB700 WDT",
203	};
204
205	switch (cmd) {
206	case WDIOC_GETSUPPORT:
207	  if (copy_to_user(argp, &ident, sizeof(ident)))
208	    return -EFAULT;
209	  break;
210
211	case WDIOC_GETSTATUS:
212	case WDIOC_GETBOOTSTATUS:
213	  return put_user(0, p);
214
215	case WDIOC_KEEPALIVE:
216	  ibwdt_ping();
217	  break;
218
219	case WDIOC_SETTIMEOUT:
220	  if (get_user(new_margin, p))
221		  return -EFAULT;
222	  if (ibwdt_set_heartbeat(new_margin))
223		  return -EINVAL;
224	  ibwdt_ping();
225	  /* Fall */
226
227	case WDIOC_GETTIMEOUT:
228	  return put_user(wd_times[wd_margin], p);
229
230	case WDIOC_SETOPTIONS:
231	{
232	  int options, retval = -EINVAL;
233
234	  if (get_user(options, p))
235	    return -EFAULT;
236
237	  if (options & WDIOS_DISABLECARD) {
238	    ibwdt_disable();
239	    retval = 0;
240	  }
241
242	  if (options & WDIOS_ENABLECARD) {
243	    ibwdt_ping();
244	    retval = 0;
245	  }
246
247	  return retval;
248	}
249
250	default:
251	  return -ENOTTY;
252	}
253	return 0;
254}
255
256static int
257ibwdt_open(struct inode *inode, struct file *file)
258{
259	if (test_and_set_bit(0, &ibwdt_is_open)) {
260		return -EBUSY;
261	}
262	if (nowayout)
263		__module_get(THIS_MODULE);
264
265	/* Activate */
266	ibwdt_ping();
267	return nonseekable_open(inode, file);
268}
269
270static int
271ibwdt_close(struct inode *inode, struct file *file)
272{
273	if (expect_close == 42) {
274		ibwdt_disable();
275	} else {
276		printk(KERN_CRIT PFX "WDT device closed unexpectedly.  WDT will not stop!\n");
277		ibwdt_ping();
278	}
279	clear_bit(0, &ibwdt_is_open);
280	expect_close = 0;
281	return 0;
282}
283
284/*
285 *	Kernel Interfaces
286 */
287
288static const struct file_operations ibwdt_fops = {
289	.owner		= THIS_MODULE,
290	.llseek		= no_llseek,
291	.write		= ibwdt_write,
292	.ioctl		= ibwdt_ioctl,
293	.open		= ibwdt_open,
294	.release	= ibwdt_close,
295};
296
297static struct miscdevice ibwdt_miscdev = {
298	.minor = WATCHDOG_MINOR,
299	.name = "watchdog",
300	.fops = &ibwdt_fops,
301};
302
303/*
304 *	Init & exit routines
305 */
306
307static int __devinit ibwdt_probe(struct platform_device *dev)
308{
309	int res;
310
311	spin_lock_init(&ibwdt_lock);
312
313#if WDT_START != WDT_STOP
314	if (!request_region(WDT_STOP, 1, "IB700 WDT")) {
315		printk (KERN_ERR PFX "STOP method I/O %X is not available.\n", WDT_STOP);
316		res = -EIO;
317		goto out_nostopreg;
318	}
319#endif
320
321	if (!request_region(WDT_START, 1, "IB700 WDT")) {
322		printk (KERN_ERR PFX "START method I/O %X is not available.\n", WDT_START);
323		res = -EIO;
324		goto out_nostartreg;
325	}
326
327	res = misc_register(&ibwdt_miscdev);
328	if (res) {
329		printk (KERN_ERR PFX "failed to register misc device\n");
330		goto out_nomisc;
331	}
332	return 0;
333
334out_nomisc:
335	release_region(WDT_START, 1);
336out_nostartreg:
337#if WDT_START != WDT_STOP
338	release_region(WDT_STOP, 1);
339#endif
340out_nostopreg:
341	return res;
342}
343
344static int __devexit ibwdt_remove(struct platform_device *dev)
345{
346	misc_deregister(&ibwdt_miscdev);
347	release_region(WDT_START,1);
348#if WDT_START != WDT_STOP
349	release_region(WDT_STOP,1);
350#endif
351	return 0;
352}
353
354static void ibwdt_shutdown(struct platform_device *dev)
355{
356	/* Turn the WDT off if we have a soft shutdown */
357	ibwdt_disable();
358}
359
360static struct platform_driver ibwdt_driver = {
361	.probe		= ibwdt_probe,
362	.remove		= __devexit_p(ibwdt_remove),
363	.shutdown	= ibwdt_shutdown,
364	.driver		= {
365		.owner	= THIS_MODULE,
366		.name	= DRV_NAME,
367	},
368};
369
370static int __init ibwdt_init(void)
371{
372	int err;
373
374	printk(KERN_INFO PFX "WDT driver for IB700 single board computer initialising.\n");
375
376	err = platform_driver_register(&ibwdt_driver);
377	if (err)
378		return err;
379
380	ibwdt_platform_device = platform_device_register_simple(DRV_NAME, -1, NULL, 0);
381	if (IS_ERR(ibwdt_platform_device)) {
382		err = PTR_ERR(ibwdt_platform_device);
383		goto unreg_platform_driver;
384	}
385
386	return 0;
387
388unreg_platform_driver:
389	platform_driver_unregister(&ibwdt_driver);
390	return err;
391}
392
393static void __exit ibwdt_exit(void)
394{
395	platform_device_unregister(ibwdt_platform_device);
396	platform_driver_unregister(&ibwdt_driver);
397	printk(KERN_INFO PFX "Watchdog Module Unloaded.\n");
398}
399
400module_init(ibwdt_init);
401module_exit(ibwdt_exit);
402
403MODULE_AUTHOR("Charles Howes <chowes@vsol.net>");
404MODULE_DESCRIPTION("IB700 SBC watchdog driver");
405MODULE_LICENSE("GPL");
406MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
407
408/* end of ib700wdt.c */
409