1/*
2 *	IndyDog	0.3	A Hardware Watchdog Device for SGI IP22
3 *
4 *	(c) Copyright 2002 Guido Guenther <agx@sigxcpu.org>, All Rights Reserved.
5 *
6 *	This program is free software; you can redistribute it and/or
7 *	modify it under the terms of the GNU General Public License
8 *	as published by the Free Software Foundation; either version
9 *	2 of the License, or (at your option) any later version.
10 *
11 *	based on softdog.c by Alan Cox <alan@redhat.com>
12 */
13
14#include <linux/module.h>
15#include <linux/moduleparam.h>
16#include <linux/types.h>
17#include <linux/kernel.h>
18#include <linux/fs.h>
19#include <linux/mm.h>
20#include <linux/miscdevice.h>
21#include <linux/watchdog.h>
22#include <linux/notifier.h>
23#include <linux/reboot.h>
24#include <linux/init.h>
25#include <asm/uaccess.h>
26#include <asm/sgi/mc.h>
27
28#define PFX "indydog: "
29static int indydog_alive;
30
31#define WATCHDOG_TIMEOUT 30		/* 30 sec default timeout */
32
33static int nowayout = WATCHDOG_NOWAYOUT;
34module_param(nowayout, int, 0);
35MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
36
37static void indydog_start(void)
38{
39	u32 mc_ctrl0 = sgimc->cpuctrl0;
40
41	mc_ctrl0 = sgimc->cpuctrl0 | SGIMC_CCTRL0_WDOG;
42	sgimc->cpuctrl0 = mc_ctrl0;
43}
44
45static void indydog_stop(void)
46{
47	u32 mc_ctrl0 = sgimc->cpuctrl0;
48
49	mc_ctrl0 &= ~SGIMC_CCTRL0_WDOG;
50	sgimc->cpuctrl0 = mc_ctrl0;
51
52	printk(KERN_INFO PFX "Stopped watchdog timer.\n");
53}
54
55static void indydog_ping(void)
56{
57	sgimc->watchdogt = 0;
58}
59
60/*
61 *	Allow only one person to hold it open
62 */
63static int indydog_open(struct inode *inode, struct file *file)
64{
65	if (indydog_alive)
66		return -EBUSY;
67
68	if (nowayout)
69		__module_get(THIS_MODULE);
70
71	/* Activate timer */
72	indydog_start();
73	indydog_ping();
74
75	indydog_alive = 1;
76	printk(KERN_INFO "Started watchdog timer.\n");
77
78	return nonseekable_open(inode, file);
79}
80
81static int indydog_release(struct inode *inode, struct file *file)
82{
83	/* Shut off the timer.
84	 * Lock it in if it's a module and we defined ...NOWAYOUT */
85	if (!nowayout)
86		indydog_stop();		/* Turn the WDT off */
87
88	indydog_alive = 0;
89
90	return 0;
91}
92
93static ssize_t indydog_write(struct file *file, const char *data, size_t len, loff_t *ppos)
94{
95	/* Refresh the timer. */
96	if (len) {
97		indydog_ping();
98	}
99	return len;
100}
101
102static int indydog_ioctl(struct inode *inode, struct file *file,
103	unsigned int cmd, unsigned long arg)
104{
105	int options, retval = -EINVAL;
106	static struct watchdog_info ident = {
107		.options		= WDIOF_KEEPALIVEPING |
108					  WDIOF_MAGICCLOSE,
109		.firmware_version	= 0,
110		.identity		= "Hardware Watchdog for SGI IP22",
111	};
112
113	switch (cmd) {
114		default:
115			return -ENOTTY;
116		case WDIOC_GETSUPPORT:
117			if (copy_to_user((struct watchdog_info *)arg,
118					 &ident, sizeof(ident)))
119				return -EFAULT;
120			return 0;
121		case WDIOC_GETSTATUS:
122		case WDIOC_GETBOOTSTATUS:
123			return put_user(0,(int *)arg);
124		case WDIOC_KEEPALIVE:
125			indydog_ping();
126			return 0;
127		case WDIOC_GETTIMEOUT:
128			return put_user(WATCHDOG_TIMEOUT,(int *)arg);
129		case WDIOC_SETOPTIONS:
130		{
131			if (get_user(options, (int *)arg))
132				return -EFAULT;
133
134			if (options & WDIOS_DISABLECARD) {
135				indydog_stop();
136				retval = 0;
137			}
138
139			if (options & WDIOS_ENABLECARD) {
140				indydog_start();
141				retval = 0;
142			}
143
144			return retval;
145		}
146	}
147}
148
149static int indydog_notify_sys(struct notifier_block *this, unsigned long code, void *unused)
150{
151	if (code == SYS_DOWN || code == SYS_HALT)
152		indydog_stop();		/* Turn the WDT off */
153
154	return NOTIFY_DONE;
155}
156
157static const struct file_operations indydog_fops = {
158	.owner		= THIS_MODULE,
159	.llseek		= no_llseek,
160	.write		= indydog_write,
161	.ioctl		= indydog_ioctl,
162	.open		= indydog_open,
163	.release	= indydog_release,
164};
165
166static struct miscdevice indydog_miscdev = {
167	.minor		= WATCHDOG_MINOR,
168	.name		= "watchdog",
169	.fops		= &indydog_fops,
170};
171
172static struct notifier_block indydog_notifier = {
173	.notifier_call = indydog_notify_sys,
174};
175
176static char banner[] __initdata =
177	KERN_INFO PFX "Hardware Watchdog Timer for SGI IP22: 0.3\n";
178
179static int __init watchdog_init(void)
180{
181	int ret;
182
183	ret = register_reboot_notifier(&indydog_notifier);
184	if (ret) {
185		printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
186			ret);
187		return ret;
188	}
189
190	ret = misc_register(&indydog_miscdev);
191	if (ret) {
192		printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
193			WATCHDOG_MINOR, ret);
194		unregister_reboot_notifier(&indydog_notifier);
195		return ret;
196	}
197
198	printk(banner);
199
200	return 0;
201}
202
203static void __exit watchdog_exit(void)
204{
205	misc_deregister(&indydog_miscdev);
206	unregister_reboot_notifier(&indydog_notifier);
207}
208
209module_init(watchdog_init);
210module_exit(watchdog_exit);
211
212MODULE_AUTHOR("Guido Guenther <agx@sigxcpu.org>");
213MODULE_DESCRIPTION("Hardware Watchdog Device for SGI IP22");
214MODULE_LICENSE("GPL");
215MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
216