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