1 /*
2 * SBC EPX C3 0.1 A Hardware Watchdog Device for the Winsystems EPX-C3
3 * single board computer
4 *
5 * (c) Copyright 2006 Calin A. Culianu <calin@ajvar.org>, All Rights
6 * Reserved.
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
12 *
13 * based on softdog.c by Alan Cox <alan@lxorguk.ukuu.org.uk>
14 */
15
16 #include <linux/module.h>
17 #include <linux/moduleparam.h>
18 #include <linux/types.h>
19 #include <linux/kernel.h>
20 #include <linux/fs.h>
21 #include <linux/mm.h>
22 #include <linux/miscdevice.h>
23 #include <linux/watchdog.h>
24 #include <linux/notifier.h>
25 #include <linux/reboot.h>
26 #include <linux/init.h>
27 #include <linux/ioport.h>
28 #include <linux/uaccess.h>
29 #include <linux/io.h>
30
31 #define PFX "epx_c3: "
32 static int epx_c3_alive;
33
34 #define WATCHDOG_TIMEOUT 1 /* 1 sec default timeout */
35
36 static int nowayout = WATCHDOG_NOWAYOUT;
37 module_param(nowayout, int, 0);
38 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
39 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
40
41 #define EPXC3_WATCHDOG_CTL_REG 0x1ee /* write 1 to enable, 0 to disable */
42 #define EPXC3_WATCHDOG_PET_REG 0x1ef /* write anything to pet once enabled */
43
44 static void epx_c3_start(void)
45 {
46 outb(1, EPXC3_WATCHDOG_CTL_REG);
47 }
48
49 static void epx_c3_stop(void)
50 {
51
52 outb(0, EPXC3_WATCHDOG_CTL_REG);
53
54 printk(KERN_INFO PFX "Stopped watchdog timer.\n");
55 }
56
57 static void epx_c3_pet(void)
58 {
59 outb(1, EPXC3_WATCHDOG_PET_REG);
60 }
61
62 /*
63 * Allow only one person to hold it open
64 */
65 static int epx_c3_open(struct inode *inode, struct file *file)
66 {
67 if (epx_c3_alive)
68 return -EBUSY;
69
70 if (nowayout)
71 __module_get(THIS_MODULE);
72
73 /* Activate timer */
74 epx_c3_start();
75 epx_c3_pet();
76
77 epx_c3_alive = 1;
78 printk(KERN_INFO "Started watchdog timer.\n");
79
80 return nonseekable_open(inode, file);
81 }
82
83 static int epx_c3_release(struct inode *inode, struct file *file)
84 {
85 /* Shut off the timer.
86 * Lock it in if it's a module and we defined ...NOWAYOUT */
87 if (!nowayout)
88 epx_c3_stop(); /* Turn the WDT off */
89
90 epx_c3_alive = 0;
91
92 return 0;
93 }
94
95 static ssize_t epx_c3_write(struct file *file, const char __user *data,
96 size_t len, loff_t *ppos)
97 {
98 /* Refresh the timer. */
99 if (len)
100 epx_c3_pet();
101 return len;
102 }
103
104 static long epx_c3_ioctl(struct file *file, unsigned int cmd,
105 unsigned long arg)
106 {
107 int options, retval = -EINVAL;
108 int __user *argp = (void __user *)arg;
109 static const struct watchdog_info ident = {
110 .options = WDIOF_KEEPALIVEPING,
111 .firmware_version = 0,
112 .identity = "Winsystems EPX-C3 H/W Watchdog",
113 };
114
115 switch (cmd) {
116 case WDIOC_GETSUPPORT:
117 if (copy_to_user(argp, &ident, sizeof(ident)))
118 return -EFAULT;
119 return 0;
120 case WDIOC_GETSTATUS:
121 case WDIOC_GETBOOTSTATUS:
122 return put_user(0, argp);
123 case WDIOC_SETOPTIONS:
124 if (get_user(options, argp))
125 return -EFAULT;
126
127 if (options & WDIOS_DISABLECARD) {
128 epx_c3_stop();
129 retval = 0;
130 }
131
132 if (options & WDIOS_ENABLECARD) {
133 epx_c3_start();
134 retval = 0;
135 }
136
137 return retval;
138 case WDIOC_KEEPALIVE:
139 epx_c3_pet();
140 return 0;
141 case WDIOC_GETTIMEOUT:
142 return put_user(WATCHDOG_TIMEOUT, argp);
143 default:
144 return -ENOTTY;
145 }
146 }
147
148 static int epx_c3_notify_sys(struct notifier_block *this, unsigned long code,
149 void *unused)
150 {
151 if (code == SYS_DOWN || code == SYS_HALT)
152 epx_c3_stop(); /* Turn the WDT off */
153
154 return NOTIFY_DONE;
155 }
156
157 static const struct file_operations epx_c3_fops = {
158 .owner = THIS_MODULE,
159 .llseek = no_llseek,
160 .write = epx_c3_write,
161 .unlocked_ioctl = epx_c3_ioctl,
162 .open = epx_c3_open,
163 .release = epx_c3_release,
164 };
165
166 static struct miscdevice epx_c3_miscdev = {
167 .minor = WATCHDOG_MINOR,
168 .name = "watchdog",
169 .fops = &epx_c3_fops,
170 };
171
172 static struct notifier_block epx_c3_notifier = {
173 .notifier_call = epx_c3_notify_sys,
174 };
175
176 static const char banner[] __initdata = KERN_INFO PFX
177 "Hardware Watchdog Timer for Winsystems EPX-C3 SBC: 0.1\n";
178
179 static int __init watchdog_init(void)
180 {
181 int ret;
182
183 if (!request_region(EPXC3_WATCHDOG_CTL_REG, 2, "epxc3_watchdog"))
184 return -EBUSY;
185
186 ret = register_reboot_notifier(&epx_c3_notifier);
187 if (ret) {
188 printk(KERN_ERR PFX "cannot register reboot notifier "
189 "(err=%d)\n", ret);
190 goto out;
191 }
192
193 ret = misc_register(&epx_c3_miscdev);
194 if (ret) {
195 printk(KERN_ERR PFX "cannot register miscdev on minor=%d "
196 "(err=%d)\n", WATCHDOG_MINOR, ret);
197 unregister_reboot_notifier(&epx_c3_notifier);
198 goto out;
199 }
200
201 printk(banner);
202
203 return 0;
204
205 out:
206 release_region(EPXC3_WATCHDOG_CTL_REG, 2);
207 return ret;
208 }
209
210 static void __exit watchdog_exit(void)
211 {
212 misc_deregister(&epx_c3_miscdev);
213 unregister_reboot_notifier(&epx_c3_notifier);
214 release_region(EPXC3_WATCHDOG_CTL_REG, 2);
215 }
216
217 module_init(watchdog_init);
218 module_exit(watchdog_exit);
219
220 MODULE_AUTHOR("Calin A. Culianu <calin@ajvar.org>");
221 MODULE_DESCRIPTION("Hardware Watchdog Device for Winsystems EPX-C3 SBC. "
222 "Note that there is no way to probe for this device -- "
223 "so only use it if you are *sure* you are runnning on this specific "
224 "SBC system from Winsystems! It writes to IO ports 0x1ee and 0x1ef!");
225 MODULE_LICENSE("GPL");
226 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
227
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