aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/scx200_wdt.c
blob: d55882bca31926f46b517ffdf953257f49c0dba8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
/* drivers/char/watchdog/scx200_wdt.c

   National Semiconductor SCx200 Watchdog support

   Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>

   Some code taken from:
   National Semiconductor PC87307/PC97307 (ala SC1200) WDT driver
   (c) Copyright 2002 Zwane Mwaikambo <zwane@commfireservices.com>

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The author(s) of this software shall not be held liable for damages
   of any nature resulting due to the use of this software. This
   software is provided AS-IS with no warranties. */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <linux/scx200.h>

#include <asm/uaccess.h>
#include <asm/io.h>

#define NAME "scx200_wdt"

MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
MODULE_DESCRIPTION("NatSemi SCx200 Watchdog Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

static int margin = 60;		/* in seconds */
module_param(margin, int, 0);
MODULE_PARM_DESC(margin, "Watchdog margin in seconds");

static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");

static u16 wdto_restart;
static struct semaphore open_semaphore;
static char expect_close;

/* Bits of the WDCNFG register */
#define W_ENABLE 0x00fa		/* Enable watchdog */
#define W_DISABLE 0x0000	/* Disable watchdog */

/* The scaling factor for the timer, this depends on the value of W_ENABLE */
#define W_SCALE (32768/1024)

static void scx200_wdt_ping(void)
{
	outw(wdto_restart, scx200_cb_base + SCx200_WDT_WDTO);
}

static void scx200_wdt_update_margin(void)
{
	printk(KERN_INFO NAME ": timer margin %d seconds\n", margin);
	wdto_restart = margin * W_SCALE;
}

static void scx200_wdt_enable(void)
{
	printk(KERN_DEBUG NAME ": enabling watchdog timer, wdto_restart = %d\n",
	       wdto_restart);

	outw(0, scx200_cb_base + SCx200_WDT_WDTO);
	outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
	outw(W_ENABLE, scx200_cb_base + SCx200_WDT_WDCNFG);

	scx200_wdt_ping();
}

static void scx200_wdt_disable(void)
{
	printk(KERN_DEBUG NAME ": disabling watchdog timer\n");

	outw(0, scx200_cb_base + SCx200_WDT_WDTO);
	outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
	outw(W_DISABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
}

static int scx200_wdt_open(struct inode *inode, struct file *file)
{
	/* only allow one at a time */
	if (down_trylock(&open_semaphore))
		return -EBUSY;
	scx200_wdt_enable();

	return nonseekable_open(inode, file);
}

static int scx200_wdt_release(struct inode *inode, struct file *file)
{
	if (expect_close != 42) {
		printk(KERN_WARNING NAME ": watchdog device closed unexpectedly, will not disable the watchdog timer\n");
	} else if (!nowayout) {
		scx200_wdt_disable();
	}
	expect_close = 0;
	up(&open_semaphore);

	return 0;
}

static int scx200_wdt_notify_sys(struct notifier_block *this,
				      unsigned long code, void *unused)
{
	if (code == SYS_HALT || code == SYS_POWER_OFF)
		if (!nowayout)
			scx200_wdt_disable();

	return NOTIFY_DONE;
}

static struct notifier_block scx200_wdt_notifier =
{
	.notifier_call = scx200_wdt_notify_sys,
};

static ssize_t scx200_wdt_write(struct file *file, const char __user *data,
				     size_t len, loff_t *ppos)
{
	/* check for a magic close character */
	if (len)
	{
		size_t i;

		scx200_wdt_ping();

		expect_close = 0;
		for (i = 0; i < len; ++i) {
			char c;
			if (get_user(c, data+i))
				return -EFAULT;
			if (c == 'V')
				expect_close = 42;
		}

		return len;
	}

	return 0;
}

static int scx200_wdt_ioctl(struct inode *inode, struct file *file,
	unsigned int cmd, unsigned long arg)
{
	void __user *argp = (void __user *)arg;
	int __user *p = argp;
	static struct watchdog_info ident = {
		.identity = "NatSemi SCx200 Watchdog",
		.firmware_version = 1,
		.options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING),
	};
	int new_margin;

	switch (cmd) {
	default:
		return -ENOTTY;
	case WDIOC_GETSUPPORT:
		if(copy_to_user(argp, &ident, sizeof(ident)))
			return -EFAULT;
		return 0;
	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		if (put_user(0, p))
			return -EFAULT;
		return 0;
	case WDIOC_KEEPALIVE:
		scx200_wdt_ping();
		return 0;
	case WDIOC_SETTIMEOUT:
		if (get_user(new_margin, p))
			return -EFAULT;
		if (new_margin < 1)
			return -EINVAL;
		margin = new_margin;
		scx200_wdt_update_margin();
		scx200_wdt_ping();
	case WDIOC_GETTIMEOUT:
		if (put_user(margin, p))
			return -EFAULT;
		return 0;
	}
}

static const struct file_operations scx200_wdt_fops = {
	.owner	 = THIS_MODULE,
	.llseek	 = no_llseek,
	.write   = scx200_wdt_write,
	.ioctl   = scx200_wdt_ioctl,
	.open    = scx200_wdt_open,
	.release = scx200_wdt_release,
};

static struct miscdevice scx200_wdt_miscdev = {
	.minor = WATCHDOG_MINOR,
	.name  = "watchdog",
	.fops  = &scx200_wdt_fops,
};

static int __init scx200_wdt_init(void)
{
	int r;

	printk(KERN_DEBUG NAME ": NatSemi SCx200 Watchdog Driver\n");

	/* check that we have found the configuration block */
	if (!scx200_cb_present())
		return -ENODEV;

	if (!request_region(scx200_cb_base + SCx200_WDT_OFFSET,
			    SCx200_WDT_SIZE,
			    "NatSemi SCx200 Watchdog")) {
		printk(KERN_WARNING NAME ": watchdog I/O region busy\n");
		return -EBUSY;
	}

	scx200_wdt_update_margin();
	scx200_wdt_disable();

	sema_init(&open_semaphore, 1);

	r = register_reboot_notifier(&scx200_wdt_notifier);
	if (r) {
		printk(KERN_ERR NAME ": unable to register reboot notifier");
		release_region(scx200_cb_base + SCx200_WDT_OFFSET,
				SCx200_WDT_SIZE);
		return r;
	}

	r = misc_register(&scx200_wdt_miscdev);
	if (r) {
		unregister_reboot_notifier(&scx200_wdt_notifier);
		release_region(scx200_cb_base + SCx200_WDT_OFFSET,
				SCx200_WDT_SIZE);
		return r;
	}

	return 0;
}

static void __exit scx200_wdt_cleanup(void)
{
	misc_deregister(&scx200_wdt_miscdev);
	unregister_reboot_notifier(&scx200_wdt_notifier);
	release_region(scx200_cb_base + SCx200_WDT_OFFSET,
		       SCx200_WDT_SIZE);
}

module_init(scx200_wdt_init);
module_exit(scx200_wdt_cleanup);

/*
    Local variables:
        compile-command: "make -k -C ../.. SUBDIRS=drivers/char modules"
        c-basic-offset: 8
    End:
*/