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  • only in /asuswrt-rt-n18u-9.0.0.4.380.2695/release/src-rt-6.x.4708/linux/linux-2.6.36/drivers/watchdog/
1/*
2 *	Intel 21285 watchdog driver
3 *	Copyright (c) Phil Blundell <pb@nexus.co.uk>, 1998
4 *
5 *	based on
6 *
7 *	SoftDog	0.05:	A Software Watchdog Device
8 *
9 *	(c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
10 *						All Rights Reserved.
11 *
12 *	This program is free software; you can redistribute it and/or
13 *	modify it under the terms of the GNU General Public License
14 *	as published by the Free Software Foundation; either version
15 *	2 of the License, or (at your option) any later version.
16 *
17 */
18
19#include <linux/module.h>
20#include <linux/moduleparam.h>
21#include <linux/types.h>
22#include <linux/kernel.h>
23#include <linux/fs.h>
24#include <linux/mm.h>
25#include <linux/miscdevice.h>
26#include <linux/watchdog.h>
27#include <linux/reboot.h>
28#include <linux/init.h>
29#include <linux/interrupt.h>
30#include <linux/uaccess.h>
31#include <linux/irq.h>
32#include <mach/hardware.h>
33
34#include <asm/mach-types.h>
35#include <asm/hardware/dec21285.h>
36
37/*
38 * Define this to stop the watchdog actually rebooting the machine.
39 */
40#undef ONLY_TESTING
41
42static unsigned int soft_margin = 60;		/* in seconds */
43static unsigned int reload;
44static unsigned long timer_alive;
45
46#ifdef ONLY_TESTING
47/*
48 *	If the timer expires..
49 */
50static void watchdog_fire(int irq, void *dev_id)
51{
52	printk(KERN_CRIT "Watchdog: Would Reboot.\n");
53	*CSR_TIMER4_CNTL = 0;
54	*CSR_TIMER4_CLR = 0;
55}
56#endif
57
58/*
59 *	Refresh the timer.
60 */
61static void watchdog_ping(void)
62{
63	*CSR_TIMER4_LOAD = reload;
64}
65
66/*
67 *	Allow only one person to hold it open
68 */
69static int watchdog_open(struct inode *inode, struct file *file)
70{
71	int ret;
72
73	if (*CSR_SA110_CNTL & (1 << 13))
74		return -EBUSY;
75
76	if (test_and_set_bit(1, &timer_alive))
77		return -EBUSY;
78
79	reload = soft_margin * (mem_fclk_21285 / 256);
80
81	*CSR_TIMER4_CLR = 0;
82	watchdog_ping();
83	*CSR_TIMER4_CNTL = TIMER_CNTL_ENABLE | TIMER_CNTL_AUTORELOAD
84		| TIMER_CNTL_DIV256;
85
86#ifdef ONLY_TESTING
87	ret = request_irq(IRQ_TIMER4, watchdog_fire, 0, "watchdog", NULL);
88	if (ret) {
89		*CSR_TIMER4_CNTL = 0;
90		clear_bit(1, &timer_alive);
91	}
92#else
93	/*
94	 * Setting this bit is irreversible; once enabled, there is
95	 * no way to disable the watchdog.
96	 */
97	*CSR_SA110_CNTL |= 1 << 13;
98
99	ret = 0;
100#endif
101	nonseekable_open(inode, file);
102	return ret;
103}
104
105/*
106 *	Shut off the timer.
107 *	Note: if we really have enabled the watchdog, there
108 *	is no way to turn off.
109 */
110static int watchdog_release(struct inode *inode, struct file *file)
111{
112#ifdef ONLY_TESTING
113	free_irq(IRQ_TIMER4, NULL);
114	clear_bit(1, &timer_alive);
115#endif
116	return 0;
117}
118
119static ssize_t watchdog_write(struct file *file, const char __user *data,
120			      size_t len, loff_t *ppos)
121{
122	/*
123	 *	Refresh the timer.
124	 */
125	if (len)
126		watchdog_ping();
127
128	return len;
129}
130
131static const struct watchdog_info ident = {
132	.options	= WDIOF_SETTIMEOUT,
133	.identity	= "Footbridge Watchdog",
134};
135
136static long watchdog_ioctl(struct file *file, unsigned int cmd,
137			   unsigned long arg)
138{
139	unsigned int new_margin;
140	int __user *int_arg = (int __user *)arg;
141	int ret = -ENOTTY;
142
143	switch (cmd) {
144	case WDIOC_GETSUPPORT:
145		ret = 0;
146		if (copy_to_user((void __user *)arg, &ident, sizeof(ident)))
147			ret = -EFAULT;
148		break;
149
150	case WDIOC_GETSTATUS:
151	case WDIOC_GETBOOTSTATUS:
152		ret = put_user(0, int_arg);
153		break;
154
155	case WDIOC_KEEPALIVE:
156		watchdog_ping();
157		ret = 0;
158		break;
159
160	case WDIOC_SETTIMEOUT:
161		ret = get_user(new_margin, int_arg);
162		if (ret)
163			break;
164
165		/* Arbitrary, can't find the card's limits */
166		if (new_margin < 0 || new_margin > 60) {
167			ret = -EINVAL;
168			break;
169		}
170
171		soft_margin = new_margin;
172		reload = soft_margin * (mem_fclk_21285 / 256);
173		watchdog_ping();
174		/* Fall */
175	case WDIOC_GETTIMEOUT:
176		ret = put_user(soft_margin, int_arg);
177		break;
178	}
179	return ret;
180}
181
182static const struct file_operations watchdog_fops = {
183	.owner		= THIS_MODULE,
184	.llseek		= no_llseek,
185	.write		= watchdog_write,
186	.unlocked_ioctl	= watchdog_ioctl,
187	.open		= watchdog_open,
188	.release	= watchdog_release,
189};
190
191static struct miscdevice watchdog_miscdev = {
192	.minor		= WATCHDOG_MINOR,
193	.name		= "watchdog",
194	.fops		= &watchdog_fops,
195};
196
197static int __init footbridge_watchdog_init(void)
198{
199	int retval;
200
201	if (machine_is_netwinder())
202		return -ENODEV;
203
204	retval = misc_register(&watchdog_miscdev);
205	if (retval < 0)
206		return retval;
207
208	printk(KERN_INFO
209		"Footbridge Watchdog Timer: 0.01, timer margin: %d sec\n",
210								soft_margin);
211
212	if (machine_is_cats())
213		printk(KERN_WARNING
214		  "Warning: Watchdog reset may not work on this machine.\n");
215	return 0;
216}
217
218static void __exit footbridge_watchdog_exit(void)
219{
220	misc_deregister(&watchdog_miscdev);
221}
222
223MODULE_AUTHOR("Phil Blundell <pb@nexus.co.uk>");
224MODULE_DESCRIPTION("Footbridge watchdog driver");
225MODULE_LICENSE("GPL");
226MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
227
228module_param(soft_margin, int, 0);
229MODULE_PARM_DESC(soft_margin, "Watchdog timeout in seconds");
230
231module_init(footbridge_watchdog_init);
232module_exit(footbridge_watchdog_exit);
233