1/*
2 *	SBC EPX C3 0.1	A Hardware Watchdog Device for the Winsystems EPX-C3
3 *	single board computer
4 *
5 *	(c) Copyright 2006 Calin A. Culianu <calin@ajvar.org>, All Rights
6 *	Reserved.
7 *
8 *	This program is free software; you can redistribute it and/or
9 *	modify it under the terms of the GNU General Public License
10 *	as published by the Free Software Foundation; either version
11 *	2 of the License, or (at your option) any later version.
12 *
13 *	based on softdog.c by Alan Cox <alan@lxorguk.ukuu.org.uk>
14 */
15
16#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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/notifier.h>
27#include <linux/reboot.h>
28#include <linux/init.h>
29#include <linux/ioport.h>
30#include <linux/uaccess.h>
31#include <linux/io.h>
32
33static int epx_c3_alive;
34
35#define WATCHDOG_TIMEOUT 1		/* 1 sec default timeout */
36
37static bool nowayout = WATCHDOG_NOWAYOUT;
38module_param(nowayout, bool, 0);
39MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
40					__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
41
42#define EPXC3_WATCHDOG_CTL_REG 0x1ee /* write 1 to enable, 0 to disable */
43#define EPXC3_WATCHDOG_PET_REG 0x1ef /* write anything to pet once enabled */
44
45static void epx_c3_start(void)
46{
47	outb(1, EPXC3_WATCHDOG_CTL_REG);
48}
49
50static void epx_c3_stop(void)
51{
52
53	outb(0, EPXC3_WATCHDOG_CTL_REG);
54
55	pr_info("Stopped watchdog timer\n");
56}
57
58static void epx_c3_pet(void)
59{
60	outb(1, EPXC3_WATCHDOG_PET_REG);
61}
62
63/*
64 *	Allow only one person to hold it open
65 */
66static int epx_c3_open(struct inode *inode, struct file *file)
67{
68	if (epx_c3_alive)
69		return -EBUSY;
70
71	if (nowayout)
72		__module_get(THIS_MODULE);
73
74	/* Activate timer */
75	epx_c3_start();
76	epx_c3_pet();
77
78	epx_c3_alive = 1;
79	pr_info("Started watchdog timer\n");
80
81	return nonseekable_open(inode, file);
82}
83
84static int epx_c3_release(struct inode *inode, struct file *file)
85{
86	/* Shut off the timer.
87	 * Lock it in if it's a module and we defined ...NOWAYOUT */
88	if (!nowayout)
89		epx_c3_stop();		/* Turn the WDT off */
90
91	epx_c3_alive = 0;
92
93	return 0;
94}
95
96static ssize_t epx_c3_write(struct file *file, const char __user *data,
97			size_t len, loff_t *ppos)
98{
99	/* Refresh the timer. */
100	if (len)
101		epx_c3_pet();
102	return len;
103}
104
105static long epx_c3_ioctl(struct file *file, unsigned int cmd,
106						unsigned long arg)
107{
108	int options, retval = -EINVAL;
109	int __user *argp = (void __user *)arg;
110	static const struct watchdog_info ident = {
111		.options		= WDIOF_KEEPALIVEPING,
112		.firmware_version	= 0,
113		.identity		= "Winsystems EPX-C3 H/W Watchdog",
114	};
115
116	switch (cmd) {
117	case WDIOC_GETSUPPORT:
118		if (copy_to_user(argp, &ident, sizeof(ident)))
119			return -EFAULT;
120		return 0;
121	case WDIOC_GETSTATUS:
122	case WDIOC_GETBOOTSTATUS:
123		return put_user(0, argp);
124	case WDIOC_SETOPTIONS:
125		if (get_user(options, argp))
126			return -EFAULT;
127
128		if (options & WDIOS_DISABLECARD) {
129			epx_c3_stop();
130			retval = 0;
131		}
132
133		if (options & WDIOS_ENABLECARD) {
134			epx_c3_start();
135			retval = 0;
136		}
137
138		return retval;
139	case WDIOC_KEEPALIVE:
140		epx_c3_pet();
141		return 0;
142	case WDIOC_GETTIMEOUT:
143		return put_user(WATCHDOG_TIMEOUT, argp);
144	default:
145		return -ENOTTY;
146	}
147}
148
149static int epx_c3_notify_sys(struct notifier_block *this, unsigned long code,
150				void *unused)
151{
152	if (code == SYS_DOWN || code == SYS_HALT)
153		epx_c3_stop();		/* Turn the WDT off */
154
155	return NOTIFY_DONE;
156}
157
158static const struct file_operations epx_c3_fops = {
159	.owner		= THIS_MODULE,
160	.llseek		= no_llseek,
161	.write		= epx_c3_write,
162	.unlocked_ioctl	= epx_c3_ioctl,
163	.open		= epx_c3_open,
164	.release	= epx_c3_release,
165};
166
167static struct miscdevice epx_c3_miscdev = {
168	.minor		= WATCHDOG_MINOR,
169	.name		= "watchdog",
170	.fops		= &epx_c3_fops,
171};
172
173static struct notifier_block epx_c3_notifier = {
174	.notifier_call = epx_c3_notify_sys,
175};
176
177static int __init watchdog_init(void)
178{
179	int ret;
180
181	if (!request_region(EPXC3_WATCHDOG_CTL_REG, 2, "epxc3_watchdog"))
182		return -EBUSY;
183
184	ret = register_reboot_notifier(&epx_c3_notifier);
185	if (ret) {
186		pr_err("cannot register reboot notifier (err=%d)\n", ret);
187		goto out;
188	}
189
190	ret = misc_register(&epx_c3_miscdev);
191	if (ret) {
192		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
193		       WATCHDOG_MINOR, ret);
194		unregister_reboot_notifier(&epx_c3_notifier);
195		goto out;
196	}
197
198	pr_info("Hardware Watchdog Timer for Winsystems EPX-C3 SBC: 0.1\n");
199
200	return 0;
201
202out:
203	release_region(EPXC3_WATCHDOG_CTL_REG, 2);
204	return ret;
205}
206
207static void __exit watchdog_exit(void)
208{
209	misc_deregister(&epx_c3_miscdev);
210	unregister_reboot_notifier(&epx_c3_notifier);
211	release_region(EPXC3_WATCHDOG_CTL_REG, 2);
212}
213
214module_init(watchdog_init);
215module_exit(watchdog_exit);
216
217MODULE_AUTHOR("Calin A. Culianu <calin@ajvar.org>");
218MODULE_DESCRIPTION("Hardware Watchdog Device for Winsystems EPX-C3 SBC.  "
219	"Note that there is no way to probe for this device -- "
220	"so only use it if you are *sure* you are running on this specific "
221	"SBC system from Winsystems!  It writes to IO ports 0x1ee and 0x1ef!");
222MODULE_LICENSE("GPL");
223