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 Som 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/config.h>
21 #include <linux/module.h>
22 #include <linux/moduleparam.h>
23 #include <linux/init.h>
24 #include <linux/miscdevice.h>
25 #include <linux/watchdog.h>
26 #include <linux/notifier.h>
27 #include <linux/reboot.h>
28 #include <linux/fs.h>
29 #include <linux/pci.h>
30 #include <linux/scx200.h>
31
32 #include <asm/uaccess.h>
33 #include <asm/io.h>
34
35 #define NAME "scx200_wdt"
36
37 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
38 MODULE_DESCRIPTION("NatSemi SCx200 Watchdog Driver");
39 MODULE_LICENSE("GPL");
40 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
41
42 #ifndef CONFIG_WATCHDOG_NOWAYOUT
43 #define CONFIG_WATCHDOG_NOWAYOUT 0
44 #endif
45
46 static int margin = 60; /* in seconds */
47 module_param(margin, int, 0);
48 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
49
50 static int nowayout = CONFIG_WATCHDOG_NOWAYOUT;
51 module_param(nowayout, int, 0);
52 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
53
54 static u16 wdto_restart;
55 static struct semaphore open_semaphore;
56 static char expect_close;
57
58 /* Bits of the WDCNFG register */
59 #define W_ENABLE 0x00fa /* Enable watchdog */
60 #define W_DISABLE 0x0000 /* Disable watchdog */
61
62 /* The scaling factor for the timer, this depends on the value of W_ENABLE */
63 #define W_SCALE (32768/1024)
64
65 static void scx200_wdt_ping(void)
66 {
67 outw(wdto_restart, SCx200_CB_BASE + SCx200_WDT_WDTO);
68 }
69
70 static void scx200_wdt_update_margin(void)
71 {
72 printk(KERN_INFO NAME ": timer margin %d seconds\n", margin);
73 wdto_restart = margin * W_SCALE;
74 }
75
76 static void scx200_wdt_enable(void)
77 {
78 printk(KERN_DEBUG NAME ": enabling watchdog timer, wdto_restart = %d\n",
79 wdto_restart);
80
81 outw(0, SCx200_CB_BASE + SCx200_WDT_WDTO);
82 outb(SCx200_WDT_WDSTS_WDOVF, SCx200_CB_BASE + SCx200_WDT_WDSTS);
83 outw(W_ENABLE, SCx200_CB_BASE + SCx200_WDT_WDCNFG);
84
85 scx200_wdt_ping();
86 }
87
88 static void scx200_wdt_disable(void)
89 {
90 printk(KERN_DEBUG NAME ": disabling watchdog timer\n");
91
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 }
96
97 static int scx200_wdt_open(struct inode *inode, struct file *file)
98 {
99 /* only allow one at a time */
100 if (down_trylock(&open_semaphore))
101 return -EBUSY;
102 scx200_wdt_enable();
103
104 return nonseekable_open(inode, file);
105 }
106
107 static int scx200_wdt_release(struct inode *inode, struct file *file)
108 {
109 if (expect_close != 42) {
110 printk(KERN_WARNING NAME ": watchdog device closed unexpectedly, will not disable the watchdog timer\n");
111 } else if (!nowayout) {
112 scx200_wdt_disable();
113 }
114 expect_close = 0;
115 up(&open_semaphore);
116
117 return 0;
118 }
119
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 {
132 .notifier_call = scx200_wdt_notify_sys,
133 };
134
135 static ssize_t scx200_wdt_write(struct file *file, const char __user *data,
136 size_t len, loff_t *ppos)
137 {
138 /* check for a magic close character */
139 if (len)
140 {
141 size_t i;
142
143 scx200_wdt_ping();
144
145 expect_close = 0;
146 for (i = 0; i < len; ++i) {
147 char c;
148 if (get_user(c, data+i))
149 return -EFAULT;
150 if (c == 'V')
151 expect_close = 42;
152 }
153
154 return len;
155 }
156
157 return 0;
158 }
159
160 static int scx200_wdt_ioctl(struct inode *inode, struct file *file,
161 unsigned int cmd, unsigned long arg)
162 {
163 void __user *argp = (void __user *)arg;
164 int __user *p = argp;
165 static struct watchdog_info ident = {
166 .identity = "NatSemi SCx200 Watchdog",
167 .firmware_version = 1,
168 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING),
169 };
170 int new_margin;
171
172 switch (cmd) {
173 default:
174 return -ENOIOCTLCMD;
175 case WDIOC_GETSUPPORT:
176 if(copy_to_user(argp, &ident, sizeof(ident)))
177 return -EFAULT;
178 return 0;
179 case WDIOC_GETSTATUS:
180 case WDIOC_GETBOOTSTATUS:
181 if (put_user(0, p))
182 return -EFAULT;
183 return 0;
184 case WDIOC_KEEPALIVE:
185 scx200_wdt_ping();
186 return 0;
187 case WDIOC_SETTIMEOUT:
188 if (get_user(new_margin, p))
189 return -EFAULT;
190 if (new_margin < 1)
191 return -EINVAL;
192 margin = new_margin;
193 scx200_wdt_update_margin();
194 scx200_wdt_ping();
195 case WDIOC_GETTIMEOUT:
196 if (put_user(margin, p))
197 return -EFAULT;
198 return 0;
199 }
200 }
201
202 static struct file_operations scx200_wdt_fops = {
203 .owner = THIS_MODULE,
204 .llseek = no_llseek,
205 .write = scx200_wdt_write,
206 .ioctl = scx200_wdt_ioctl,
207 .open = scx200_wdt_open,
208 .release = scx200_wdt_release,
209 };
210
211 static struct miscdevice scx200_wdt_miscdev = {
212 .minor = WATCHDOG_MINOR,
213 .name = NAME,
214 .fops = &scx200_wdt_fops,
215 };
216
217 static int __init scx200_wdt_init(void)
218 {
219 int r;
220 static struct pci_device_id ns_sc[] = {
221 { PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SCx200_BRIDGE) },
222 { PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SC1100_BRIDGE) },
223 { },
224 };
225
226 printk(KERN_DEBUG NAME ": NatSemi SCx200 Watchdog Driver\n");
227
228 /*
229 * First check that this really is a NatSemi SCx200 CPU or a Geode
230 * SC1100 processor
231 */
232 if (!pci_dev_present(ns_sc))
233 return -ENODEV;
234
235 /* More sanity checks, verify that the configuration block is there */
236 if (!scx200_cb_probe(SCx200_CB_BASE)) {
237 printk(KERN_WARNING NAME ": no configuration block found\n");
238 return -ENODEV;
239 }
240
241 if (!request_region(SCx200_CB_BASE + SCx200_WDT_OFFSET,
242 SCx200_WDT_SIZE,
243 "NatSemi SCx200 Watchdog")) {
244 printk(KERN_WARNING NAME ": watchdog I/O region busy\n");
245 return -EBUSY;
246 }
247
248 scx200_wdt_update_margin();
249 scx200_wdt_disable();
250
251 sema_init(&open_semaphore, 1);
252
253 r = misc_register(&scx200_wdt_miscdev);
254 if (r) {
255 release_region(SCx200_CB_BASE + SCx200_WDT_OFFSET,
256 SCx200_WDT_SIZE);
257 return r;
258 }
259
260 r = register_reboot_notifier(&scx200_wdt_notifier);
261 if (r) {
262 printk(KERN_ERR NAME ": unable to register reboot notifier");
263 misc_deregister(&scx200_wdt_miscdev);
264 release_region(SCx200_CB_BASE + SCx200_WDT_OFFSET,
265 SCx200_WDT_SIZE);
266 return r;
267 }
268
269 return 0;
270 }
271
272 static void __exit scx200_wdt_cleanup(void)
273 {
274 unregister_reboot_notifier(&scx200_wdt_notifier);
275 misc_deregister(&scx200_wdt_miscdev);
276 release_region(SCx200_CB_BASE + SCx200_WDT_OFFSET,
277 SCx200_WDT_SIZE);
278 }
279
280 module_init(scx200_wdt_init);
281 module_exit(scx200_wdt_cleanup);
282
283 /*
284 Local variables:
285 compile-command: "make -k -C ../.. SUBDIRS=drivers/char modules"
286 c-basic-offset: 8
287 End:
288 */
289
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