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