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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20
21#include <linux/module.h>
22#include <linux/moduleparam.h>
23#include <linux/types.h>
24#include <linux/kernel.h>
25#include <linux/fs.h>
26#include <linux/mm.h>
27#include <linux/miscdevice.h>
28#include <linux/watchdog.h>
29#include <linux/reboot.h>
30#include <linux/init.h>
31#include <linux/interrupt.h>
32#include <linux/uaccess.h>
33#include <linux/irq.h>
34#include <mach/hardware.h>
35
36#include <asm/mach-types.h>
37#include <asm/system_info.h>
38#include <asm/hardware/dec21285.h>
39
40/*
41 * Define this to stop the watchdog actually rebooting the machine.
42 */
43#undef ONLY_TESTING
44
45static unsigned int soft_margin = 60;		/* in seconds */
46static unsigned int reload;
47static unsigned long timer_alive;
48
49#ifdef ONLY_TESTING
50/*
51 *	If the timer expires..
52 */
53static void watchdog_fire(int irq, void *dev_id)
54{
55	pr_crit("Would Reboot\n");
56	*CSR_TIMER4_CNTL = 0;
57	*CSR_TIMER4_CLR = 0;
58}
59#endif
60
61/*
62 *	Refresh the timer.
63 */
64static void watchdog_ping(void)
65{
66	*CSR_TIMER4_LOAD = reload;
67}
68
69/*
70 *	Allow only one person to hold it open
71 */
72static int watchdog_open(struct inode *inode, struct file *file)
73{
74	int ret;
75
76	if (*CSR_SA110_CNTL & (1 << 13))
77		return -EBUSY;
78
79	if (test_and_set_bit(1, &timer_alive))
80		return -EBUSY;
81
82	reload = soft_margin * (mem_fclk_21285 / 256);
83
84	*CSR_TIMER4_CLR = 0;
85	watchdog_ping();
86	*CSR_TIMER4_CNTL = TIMER_CNTL_ENABLE | TIMER_CNTL_AUTORELOAD
87		| TIMER_CNTL_DIV256;
88
89#ifdef ONLY_TESTING
90	ret = request_irq(IRQ_TIMER4, watchdog_fire, 0, "watchdog", NULL);
91	if (ret) {
92		*CSR_TIMER4_CNTL = 0;
93		clear_bit(1, &timer_alive);
94	}
95#else
96	/*
97	 * Setting this bit is irreversible; once enabled, there is
98	 * no way to disable the watchdog.
99	 */
100	*CSR_SA110_CNTL |= 1 << 13;
101
102	ret = 0;
103#endif
104	nonseekable_open(inode, file);
105	return ret;
106}
107
108/*
109 *	Shut off the timer.
110 *	Note: if we really have enabled the watchdog, there
111 *	is no way to turn off.
112 */
113static int watchdog_release(struct inode *inode, struct file *file)
114{
115#ifdef ONLY_TESTING
116	free_irq(IRQ_TIMER4, NULL);
117	clear_bit(1, &timer_alive);
118#endif
119	return 0;
120}
121
122static ssize_t watchdog_write(struct file *file, const char __user *data,
123			      size_t len, loff_t *ppos)
124{
125	/*
126	 *	Refresh the timer.
127	 */
128	if (len)
129		watchdog_ping();
130
131	return len;
132}
133
134static const struct watchdog_info ident = {
135	.options	= WDIOF_SETTIMEOUT,
136	.identity	= "Footbridge Watchdog",
137};
138
139static long watchdog_ioctl(struct file *file, unsigned int cmd,
140			   unsigned long arg)
141{
142	int __user *int_arg = (int __user *)arg;
143	int new_margin, ret = -ENOTTY;
144
145	switch (cmd) {
146	case WDIOC_GETSUPPORT:
147		ret = 0;
148		if (copy_to_user((void __user *)arg, &ident, sizeof(ident)))
149			ret = -EFAULT;
150		break;
151
152	case WDIOC_GETSTATUS:
153	case WDIOC_GETBOOTSTATUS:
154		ret = put_user(0, int_arg);
155		break;
156
157	case WDIOC_KEEPALIVE:
158		watchdog_ping();
159		ret = 0;
160		break;
161
162	case WDIOC_SETTIMEOUT:
163		ret = get_user(new_margin, int_arg);
164		if (ret)
165			break;
166
167		/* Arbitrary, can't find the card's limits */
168		if (new_margin < 0 || new_margin > 60) {
169			ret = -EINVAL;
170			break;
171		}
172
173		soft_margin = new_margin;
174		reload = soft_margin * (mem_fclk_21285 / 256);
175		watchdog_ping();
176		/* Fall */
177	case WDIOC_GETTIMEOUT:
178		ret = put_user(soft_margin, int_arg);
179		break;
180	}
181	return ret;
182}
183
184static const struct file_operations watchdog_fops = {
185	.owner		= THIS_MODULE,
186	.llseek		= no_llseek,
187	.write		= watchdog_write,
188	.unlocked_ioctl	= watchdog_ioctl,
189	.open		= watchdog_open,
190	.release	= watchdog_release,
191};
192
193static struct miscdevice watchdog_miscdev = {
194	.minor		= WATCHDOG_MINOR,
195	.name		= "watchdog",
196	.fops		= &watchdog_fops,
197};
198
199static int __init footbridge_watchdog_init(void)
200{
201	int retval;
202
203	if (machine_is_netwinder())
204		return -ENODEV;
205
206	retval = misc_register(&watchdog_miscdev);
207	if (retval < 0)
208		return retval;
209
210	pr_info("Footbridge Watchdog Timer: 0.01, timer margin: %d sec\n",
211		soft_margin);
212
213	if (machine_is_cats())
214		pr_warn("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");
226
227module_param(soft_margin, int, 0);
228MODULE_PARM_DESC(soft_margin, "Watchdog timeout in seconds");
229
230module_init(footbridge_watchdog_init);
231module_exit(footbridge_watchdog_exit);
232