summaryrefslogtreecommitdiffstats
path: root/drivers/char/watchdog/ep93xx_wdt.c
blob: 9021dbb78299e6af800d09f2b50222386ba91375 (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
/*
 * Watchdog driver for Cirrus Logic EP93xx family of devices.
 *
 * Copyright (c) 2004 Ray Lehtiniemi
 * Copyright (c) 2006 Tower Technologies
 * Based on ep93xx driver, bits from alim7101_wdt.c
 *
 * Authors: Ray Lehtiniemi <rayl@mail.com>,
 *	Alessandro Zummo <a.zummo@towertech.it>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 *
 * This watchdog fires after 250msec, which is a too short interval
 * for us to rely on the user space daemon alone. So we ping the
 * wdt each ~200msec and eventually stop doing it if the user space
 * daemon dies.
 *
 * TODO:
 *
 *	- Test last reset from watchdog status
 *	- Add a few missing ioctls
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/timer.h>

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

#define WDT_VERSION	"0.3"
#define PFX		"ep93xx_wdt: "

/* default timeout (secs) */
#define WDT_TIMEOUT 30

static int nowayout = WATCHDOG_NOWAYOUT;
static int timeout = WDT_TIMEOUT;

static struct timer_list timer;
static unsigned long next_heartbeat;
static unsigned long wdt_status;
static unsigned long boot_status;

#define WDT_IN_USE		0
#define WDT_OK_TO_CLOSE		1

#define EP93XX_WDT_REG(x)	(EP93XX_WATCHDOG_BASE + (x))
#define EP93XX_WDT_WATCHDOG	EP93XX_WDT_REG(0x00)
#define EP93XX_WDT_WDSTATUS	EP93XX_WDT_REG(0x04)

/* reset the wdt every ~200ms */
#define WDT_INTERVAL (HZ/5)

static void wdt_enable(void)
{
	__raw_writew(0xaaaa, EP93XX_WDT_WATCHDOG);
}

static void wdt_disable(void)
{
	__raw_writew(0xaa55, EP93XX_WDT_WATCHDOG);
}

static inline void wdt_ping(void)
{
	__raw_writew(0x5555, EP93XX_WDT_WATCHDOG);
}

static void wdt_startup(void)
{
	next_heartbeat = jiffies + (timeout * HZ);

	wdt_enable();
	mod_timer(&timer, jiffies + WDT_INTERVAL);
}

static void wdt_shutdown(void)
{
	del_timer_sync(&timer);
	wdt_disable();
}

static void wdt_keepalive(void)
{
	/* user land ping */
	next_heartbeat = jiffies + (timeout * HZ);
}

static int ep93xx_wdt_open(struct inode *inode, struct file *file)
{
	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
		return -EBUSY;

	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);

	wdt_startup();

	return nonseekable_open(inode, file);
}

static ssize_t
ep93xx_wdt_write(struct file *file, const char __user *data, size_t len,
		 loff_t *ppos)
{
	/* Can't seek (pwrite) on this device */
	if (*ppos != file->f_pos)
		return -ESPIPE;

	if (len) {
		if (!nowayout) {
			size_t i;

			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);

			for (i = 0; i != len; i++) {
				char c;

				if (get_user(c, data + i))
					return -EFAULT;

				if (c == 'V')
					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
				else
					clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
			}
		}
		wdt_keepalive();
	}

	return len;
}

static struct watchdog_info ident = {
	.options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
	.identity = "EP93xx Watchdog",
};

static int
ep93xx_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
		 unsigned long arg)
{
	int ret = -ENOIOCTLCMD;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
				sizeof(ident)) ? -EFAULT : 0;
		break;

	case WDIOC_GETSTATUS:
		ret = put_user(0, (int __user *)arg);
		break;

	case WDIOC_GETBOOTSTATUS:
		ret = put_user(boot_status, (int __user *)arg);
		break;

	case WDIOC_GETTIMEOUT:
		/* actually, it is 0.250 seconds.... */
		ret = put_user(1, (int __user *)arg);
		break;

	case WDIOC_KEEPALIVE:
		wdt_keepalive();
		ret = 0;
		break;
	}
	return ret;
}

static int ep93xx_wdt_release(struct inode *inode, struct file *file)
{
	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
		wdt_shutdown();
	else
		printk(KERN_CRIT PFX "Device closed unexpectedly - "
			"timer will not stop\n");

	clear_bit(WDT_IN_USE, &wdt_status);
	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);

	return 0;
}

static struct file_operations ep93xx_wdt_fops = {
	.owner		= THIS_MODULE,
	.write		= ep93xx_wdt_write,
	.ioctl		= ep93xx_wdt_ioctl,
	.open		= ep93xx_wdt_open,
	.release	= ep93xx_wdt_release,
};

static struct miscdevice ep93xx_wdt_miscdev = {
	.minor		= WATCHDOG_MINOR,
	.name		= "watchdog",
	.fops		= &ep93xx_wdt_fops,
};

static void ep93xx_timer_ping(unsigned long data)
{
	if (time_before(jiffies, next_heartbeat))
		wdt_ping();

	/* Re-set the timer interval */
	mod_timer(&timer, jiffies + WDT_INTERVAL);
}

static int __init ep93xx_wdt_init(void)
{
	int err;

	err = misc_register(&ep93xx_wdt_miscdev);

	boot_status = __raw_readl(EP93XX_WDT_WATCHDOG) & 0x01 ? 1 : 0;

	printk(KERN_INFO PFX "EP93XX watchdog, driver version "
		WDT_VERSION "%s\n",
		(__raw_readl(EP93XX_WDT_WATCHDOG) & 0x08)
		? " (nCS1 disable detected)" : "");

	if (timeout < 1 || timeout > 3600) {
		timeout = WDT_TIMEOUT;
		printk(KERN_INFO PFX
			"timeout value must be 1<=x<=3600, using %d\n",
			timeout);
	}

	setup_timer(&timer, ep93xx_timer_ping, 1);
	return err;
}

static void __exit ep93xx_wdt_exit(void)
{
	wdt_shutdown();
	misc_deregister(&ep93xx_wdt_miscdev);
}

module_init(ep93xx_wdt_init);
module_exit(ep93xx_wdt_exit);

module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");

module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");

MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>,"
		"Alessandro Zummo <a.zummo@towertech.it>");
MODULE_DESCRIPTION("EP93xx Watchdog");
MODULE_LICENSE("GPL");
MODULE_VERSION(WDT_VERSION);
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);