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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/* drivers/char/watchdog/scx200_wdt.c
2
3 National Semiconductor SCx200 Watchdog support
4
5 Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
6
7 Some code taken from:
8 National Semiconductor PC87307/PC97307 (ala SC1200) WDT driver
9 (c) Copyright 2002 Zwane Mwaikambo <zwane@commfireservices.com>
10
11 This program is free software; you can redistribute it and/or
12 modify it under the terms of the GNU General Public License as
13 published by the Free Software Foundation; either version 2 of the
14 License, or (at your option) any later version.
15
16 The author(s) of this software shall not be held liable for damages
17 of any nature resulting due to the use of this software. This
18 software is provided AS-IS with no warranties. */
19
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/module.h>
21#include <linux/moduleparam.h>
22#include <linux/init.h>
23#include <linux/miscdevice.h>
24#include <linux/watchdog.h>
25#include <linux/notifier.h>
26#include <linux/reboot.h>
27#include <linux/fs.h>
Jean Delvare6473d162007-03-06 02:45:12 -080028#include <linux/ioport.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/scx200.h>
30
31#include <asm/uaccess.h>
32#include <asm/io.h>
33
34#define NAME "scx200_wdt"
35
36MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
37MODULE_DESCRIPTION("NatSemi SCx200 Watchdog Driver");
38MODULE_LICENSE("GPL");
39MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
40
Linus Torvalds1da177e2005-04-16 15:20:36 -070041static int margin = 60; /* in seconds */
42module_param(margin, int, 0);
43MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
44
Andrey Panin4bfdf372005-07-27 11:43:58 -070045static int nowayout = WATCHDOG_NOWAYOUT;
Linus Torvalds1da177e2005-04-16 15:20:36 -070046module_param(nowayout, int, 0);
47MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
48
49static u16 wdto_restart;
50static struct semaphore open_semaphore;
51static char expect_close;
52
53/* Bits of the WDCNFG register */
54#define W_ENABLE 0x00fa /* Enable watchdog */
55#define W_DISABLE 0x0000 /* Disable watchdog */
56
57/* The scaling factor for the timer, this depends on the value of W_ENABLE */
58#define W_SCALE (32768/1024)
59
60static void scx200_wdt_ping(void)
61{
62 outw(wdto_restart, scx200_cb_base + SCx200_WDT_WDTO);
63}
64
65static void scx200_wdt_update_margin(void)
66{
67 printk(KERN_INFO NAME ": timer margin %d seconds\n", margin);
68 wdto_restart = margin * W_SCALE;
69}
70
71static void scx200_wdt_enable(void)
72{
73 printk(KERN_DEBUG NAME ": enabling watchdog timer, wdto_restart = %d\n",
74 wdto_restart);
75
76 outw(0, scx200_cb_base + SCx200_WDT_WDTO);
77 outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
78 outw(W_ENABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
79
80 scx200_wdt_ping();
81}
82
83static void scx200_wdt_disable(void)
84{
85 printk(KERN_DEBUG NAME ": disabling watchdog timer\n");
86
87 outw(0, scx200_cb_base + SCx200_WDT_WDTO);
88 outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
89 outw(W_DISABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
90}
91
92static int scx200_wdt_open(struct inode *inode, struct file *file)
93{
94 /* only allow one at a time */
95 if (down_trylock(&open_semaphore))
96 return -EBUSY;
97 scx200_wdt_enable();
98
99 return nonseekable_open(inode, file);
100}
101
102static int scx200_wdt_release(struct inode *inode, struct file *file)
103{
104 if (expect_close != 42) {
105 printk(KERN_WARNING NAME ": watchdog device closed unexpectedly, will not disable the watchdog timer\n");
106 } else if (!nowayout) {
107 scx200_wdt_disable();
108 }
109 expect_close = 0;
110 up(&open_semaphore);
111
112 return 0;
113}
114
115static int scx200_wdt_notify_sys(struct notifier_block *this,
116 unsigned long code, void *unused)
117{
118 if (code == SYS_HALT || code == SYS_POWER_OFF)
119 if (!nowayout)
120 scx200_wdt_disable();
121
122 return NOTIFY_DONE;
123}
124
125static struct notifier_block scx200_wdt_notifier =
126{
127 .notifier_call = scx200_wdt_notify_sys,
128};
129
130static ssize_t scx200_wdt_write(struct file *file, const char __user *data,
131 size_t len, loff_t *ppos)
132{
133 /* check for a magic close character */
134 if (len)
135 {
136 size_t i;
137
138 scx200_wdt_ping();
139
140 expect_close = 0;
141 for (i = 0; i < len; ++i) {
142 char c;
143 if (get_user(c, data+i))
144 return -EFAULT;
145 if (c == 'V')
146 expect_close = 42;
147 }
148
149 return len;
150 }
151
152 return 0;
153}
154
155static int scx200_wdt_ioctl(struct inode *inode, struct file *file,
156 unsigned int cmd, unsigned long arg)
157{
158 void __user *argp = (void __user *)arg;
159 int __user *p = argp;
160 static struct watchdog_info ident = {
161 .identity = "NatSemi SCx200 Watchdog",
162 .firmware_version = 1,
163 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING),
164 };
165 int new_margin;
166
167 switch (cmd) {
168 default:
Samuel Tardieu795b89d2006-09-09 17:34:31 +0200169 return -ENOTTY;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170 case WDIOC_GETSUPPORT:
171 if(copy_to_user(argp, &ident, sizeof(ident)))
172 return -EFAULT;
173 return 0;
174 case WDIOC_GETSTATUS:
175 case WDIOC_GETBOOTSTATUS:
176 if (put_user(0, p))
177 return -EFAULT;
178 return 0;
179 case WDIOC_KEEPALIVE:
180 scx200_wdt_ping();
181 return 0;
182 case WDIOC_SETTIMEOUT:
183 if (get_user(new_margin, p))
184 return -EFAULT;
185 if (new_margin < 1)
186 return -EINVAL;
187 margin = new_margin;
188 scx200_wdt_update_margin();
189 scx200_wdt_ping();
190 case WDIOC_GETTIMEOUT:
191 if (put_user(margin, p))
192 return -EFAULT;
193 return 0;
194 }
195}
196
Arjan van de Ven62322d22006-07-03 00:24:21 -0700197static const struct file_operations scx200_wdt_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198 .owner = THIS_MODULE,
199 .llseek = no_llseek,
200 .write = scx200_wdt_write,
201 .ioctl = scx200_wdt_ioctl,
202 .open = scx200_wdt_open,
203 .release = scx200_wdt_release,
204};
205
206static struct miscdevice scx200_wdt_miscdev = {
207 .minor = WATCHDOG_MINOR,
Olaf Hering2dab3ca2005-08-17 08:58:34 +0200208 .name = "watchdog",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 .fops = &scx200_wdt_fops,
210};
211
212static int __init scx200_wdt_init(void)
213{
214 int r;
215
216 printk(KERN_DEBUG NAME ": NatSemi SCx200 Watchdog Driver\n");
217
218 /* check that we have found the configuration block */
219 if (!scx200_cb_present())
220 return -ENODEV;
221
222 if (!request_region(scx200_cb_base + SCx200_WDT_OFFSET,
223 SCx200_WDT_SIZE,
224 "NatSemi SCx200 Watchdog")) {
225 printk(KERN_WARNING NAME ": watchdog I/O region busy\n");
226 return -EBUSY;
227 }
228
229 scx200_wdt_update_margin();
230 scx200_wdt_disable();
231
232 sema_init(&open_semaphore, 1);
233
Wim Van Sebroeckc6cb13a2007-12-26 20:32:51 +0000234 r = register_reboot_notifier(&scx200_wdt_notifier);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 if (r) {
Wim Van Sebroeckc6cb13a2007-12-26 20:32:51 +0000236 printk(KERN_ERR NAME ": unable to register reboot notifier");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
238 SCx200_WDT_SIZE);
239 return r;
240 }
241
Wim Van Sebroeckc6cb13a2007-12-26 20:32:51 +0000242 r = misc_register(&scx200_wdt_miscdev);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243 if (r) {
Wim Van Sebroeckc6cb13a2007-12-26 20:32:51 +0000244 unregister_reboot_notifier(&scx200_wdt_notifier);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
246 SCx200_WDT_SIZE);
247 return r;
248 }
249
250 return 0;
251}
252
253static void __exit scx200_wdt_cleanup(void)
254{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255 misc_deregister(&scx200_wdt_miscdev);
Wim Van Sebroeckc6cb13a2007-12-26 20:32:51 +0000256 unregister_reboot_notifier(&scx200_wdt_notifier);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
258 SCx200_WDT_SIZE);
259}
260
261module_init(scx200_wdt_init);
262module_exit(scx200_wdt_cleanup);
263
264/*
265 Local variables:
266 compile-command: "make -k -C ../.. SUBDIRS=drivers/char modules"
267 c-basic-offset: 8
268 End:
269*/