1 /* 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
20 #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>
28 #include <linux/ioport.h>
29 #include <linux/scx200.h>
30 #include <linux/uaccess.h>
31 #include <linux/io.h>
32
33 #define NAME "scx200_wdt"
34
35 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
36 MODULE_DESCRIPTION("NatSemi SCx200 Watchdog Driver");
37 MODULE_LICENSE("GPL");
38 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
39
40 static int margin = 60; /* in seconds */
41 module_param(margin, int, 0);
42 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
43
44 static int nowayout = WATCHDOG_NOWAYOUT;
45 module_param(nowayout, int, 0);
46 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
47
48 static u16 wdto_restart;
49 static char expect_close;
50 static unsigned long open_lock;
51 static DEFINE_SPINLOCK(scx_lock);
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
scx200_wdt_ping(void)60 static void scx200_wdt_ping(void)
61 {
62 spin_lock(&scx_lock);
63 outw(wdto_restart, scx200_cb_base + SCx200_WDT_WDTO);
64 spin_unlock(&scx_lock);
65 }
66
scx200_wdt_update_margin(void)67 static void scx200_wdt_update_margin(void)
68 {
69 printk(KERN_INFO NAME ": timer margin %d seconds\n", margin);
70 wdto_restart = margin * W_SCALE;
71 }
72
scx200_wdt_enable(void)73 static void scx200_wdt_enable(void)
74 {
75 printk(KERN_DEBUG NAME ": enabling watchdog timer, wdto_restart = %d\n",
76 wdto_restart);
77
78 spin_lock(&scx_lock);
79 outw(0, scx200_cb_base + SCx200_WDT_WDTO);
80 outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
81 outw(W_ENABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
82 spin_unlock(&scx_lock);
83
84 scx200_wdt_ping();
85 }
86
scx200_wdt_disable(void)87 static void scx200_wdt_disable(void)
88 {
89 printk(KERN_DEBUG NAME ": disabling watchdog timer\n");
90
91 spin_lock(&scx_lock);
92 outw(0, scx200_cb_base + SCx200_WDT_WDTO);
93 outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
94 outw(W_DISABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
95 spin_unlock(&scx_lock);
96 }
97
scx200_wdt_open(struct inode * inode,struct file * file)98 static int scx200_wdt_open(struct inode *inode, struct file *file)
99 {
100 /* only allow one at a time */
101 if (test_and_set_bit(0, &open_lock))
102 return -EBUSY;
103 scx200_wdt_enable();
104
105 return nonseekable_open(inode, file);
106 }
107
scx200_wdt_release(struct inode * inode,struct file * file)108 static int scx200_wdt_release(struct inode *inode, struct file *file)
109 {
110 if (expect_close != 42)
111 printk(KERN_WARNING NAME ": watchdog device closed unexpectedly, will not disable the watchdog timer\n");
112 else if (!nowayout)
113 scx200_wdt_disable();
114 expect_close = 0;
115 clear_bit(0, &open_lock);
116
117 return 0;
118 }
119
scx200_wdt_notify_sys(struct notifier_block * this,unsigned long code,void * unused)120 static int scx200_wdt_notify_sys(struct notifier_block *this,
121 unsigned long code, void *unused)
122 {
123 if (code == SYS_HALT || code == SYS_POWER_OFF)
124 if (!nowayout)
125 scx200_wdt_disable();
126
127 return NOTIFY_DONE;
128 }
129
130 static struct notifier_block scx200_wdt_notifier = {
131 .notifier_call = scx200_wdt_notify_sys,
132 };
133
scx200_wdt_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)134 static ssize_t scx200_wdt_write(struct file *file, const char __user *data,
135 size_t len, loff_t *ppos)
136 {
137 /* check for a magic close character */
138 if (len) {
139 size_t i;
140
141 scx200_wdt_ping();
142
143 expect_close = 0;
144 for (i = 0; i < len; ++i) {
145 char c;
146 if (get_user(c, data + i))
147 return -EFAULT;
148 if (c == 'V')
149 expect_close = 42;
150 }
151
152 return len;
153 }
154
155 return 0;
156 }
157
scx200_wdt_ioctl(struct file * file,unsigned int cmd,unsigned long arg)158 static long scx200_wdt_ioctl(struct file *file, unsigned int cmd,
159 unsigned long arg)
160 {
161 void __user *argp = (void __user *)arg;
162 int __user *p = argp;
163 static const struct watchdog_info ident = {
164 .identity = "NatSemi SCx200 Watchdog",
165 .firmware_version = 1,
166 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
167 };
168 int new_margin;
169
170 switch (cmd) {
171 case WDIOC_GETSUPPORT:
172 if (copy_to_user(argp, &ident, sizeof(ident)))
173 return -EFAULT;
174 return 0;
175 case WDIOC_GETSTATUS:
176 case WDIOC_GETBOOTSTATUS:
177 if (put_user(0, p))
178 return -EFAULT;
179 return 0;
180 case WDIOC_KEEPALIVE:
181 scx200_wdt_ping();
182 return 0;
183 case WDIOC_SETTIMEOUT:
184 if (get_user(new_margin, p))
185 return -EFAULT;
186 if (new_margin < 1)
187 return -EINVAL;
188 margin = new_margin;
189 scx200_wdt_update_margin();
190 scx200_wdt_ping();
191 case WDIOC_GETTIMEOUT:
192 if (put_user(margin, p))
193 return -EFAULT;
194 return 0;
195 default:
196 return -ENOTTY;
197 }
198 }
199
200 static const struct file_operations scx200_wdt_fops = {
201 .owner = THIS_MODULE,
202 .llseek = no_llseek,
203 .write = scx200_wdt_write,
204 .unlocked_ioctl = scx200_wdt_ioctl,
205 .open = scx200_wdt_open,
206 .release = scx200_wdt_release,
207 };
208
209 static struct miscdevice scx200_wdt_miscdev = {
210 .minor = WATCHDOG_MINOR,
211 .name = "watchdog",
212 .fops = &scx200_wdt_fops,
213 };
214
scx200_wdt_init(void)215 static int __init scx200_wdt_init(void)
216 {
217 int r;
218
219 printk(KERN_DEBUG NAME ": NatSemi SCx200 Watchdog Driver\n");
220
221 /* check that we have found the configuration block */
222 if (!scx200_cb_present())
223 return -ENODEV;
224
225 if (!request_region(scx200_cb_base + SCx200_WDT_OFFSET,
226 SCx200_WDT_SIZE,
227 "NatSemi SCx200 Watchdog")) {
228 printk(KERN_WARNING NAME ": watchdog I/O region busy\n");
229 return -EBUSY;
230 }
231
232 scx200_wdt_update_margin();
233 scx200_wdt_disable();
234
235 r = register_reboot_notifier(&scx200_wdt_notifier);
236 if (r) {
237 printk(KERN_ERR NAME ": unable to register reboot notifier");
238 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
239 SCx200_WDT_SIZE);
240 return r;
241 }
242
243 r = misc_register(&scx200_wdt_miscdev);
244 if (r) {
245 unregister_reboot_notifier(&scx200_wdt_notifier);
246 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
247 SCx200_WDT_SIZE);
248 return r;
249 }
250
251 return 0;
252 }
253
scx200_wdt_cleanup(void)254 static void __exit scx200_wdt_cleanup(void)
255 {
256 misc_deregister(&scx200_wdt_miscdev);
257 unregister_reboot_notifier(&scx200_wdt_notifier);
258 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
259 SCx200_WDT_SIZE);
260 }
261
262 module_init(scx200_wdt_init);
263 module_exit(scx200_wdt_cleanup);
264
265 /*
266 Local variables:
267 compile-command: "make -k -C ../.. SUBDIRS=drivers/char modules"
268 c-basic-offset: 8
269 End:
270 */
271