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@redhat.com>
14 */
15
16 #include <linux/module.h>
17 #include <linux/moduleparam.h>
18 #include <linux/config.h>
19 #include <linux/types.h>
20 #include <linux/kernel.h>
21 #include <linux/fs.h>
22 #include <linux/mm.h>
23 #include <linux/miscdevice.h>
24 #include <linux/watchdog.h>
25 #include <linux/notifier.h>
26 #include <linux/reboot.h>
27 #include <linux/init.h>
28 #include <linux/ioport.h>
29 #include <asm/uaccess.h>
30 #include <asm/io.h>
31
32 #define PFX "epx_c3: "
33 static int epx_c3_alive;
34
35 #define WATCHDOG_TIMEOUT 1 /* 1 sec default timeout */
36
37 static int nowayout = WATCHDOG_NOWAYOUT;
38 module_param(nowayout, int, 0);
39 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_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 int epx_c3_ioctl(struct inode *inode, struct file *file,
105 unsigned int cmd, unsigned long arg)
106 {
107 int options, retval = -EINVAL;
108 int __user *argp = (void __user *)arg;
109 static struct watchdog_info ident = {
110 .options = WDIOF_KEEPALIVEPING |
111 WDIOF_MAGICCLOSE,
112 .firmware_version = 0,
113 .identity = "Winsystems EPX-C3 H/W Watchdog",
114 };
115
116 switch (cmd) {
117 case WDIOC_GETSUPPORT:
118 if (copy_to_user(argp, &ident, sizeof(ident)))
119 return -EFAULT;
120 return 0;
121 case WDIOC_GETSTATUS:
122 case WDIOC_GETBOOTSTATUS:
123 return put_user(0, argp);
124 case WDIOC_KEEPALIVE:
125 epx_c3_pet();
126 return 0;
127 case WDIOC_GETTIMEOUT:
128 return put_user(WATCHDOG_TIMEOUT, argp);
129 case WDIOC_SETOPTIONS:
130 if (get_user(options, argp))
131 return -EFAULT;
132
133 if (options & WDIOS_DISABLECARD) {
134 epx_c3_stop();
135 retval = 0;
136 }
137
138 if (options & WDIOS_ENABLECARD) {
139 epx_c3_start();
140 retval = 0;
141 }
142
143 return retval;
144 default:
145 return -ENOIOCTLCMD;
146 }
147 }
148
149 static int epx_c3_notify_sys(struct notifier_block *this, unsigned long code,
150 void *unused)
151 {
152 if (code == SYS_DOWN || code == SYS_HALT)
153 epx_c3_stop(); /* Turn the WDT off */
154
155 return NOTIFY_DONE;
156 }
157
158 static struct file_operations epx_c3_fops = {
159 .owner = THIS_MODULE,
160 .llseek = no_llseek,
161 .write = epx_c3_write,
162 .ioctl = epx_c3_ioctl,
163 .open = epx_c3_open,
164 .release = epx_c3_release,
165 };
166
167 static struct miscdevice epx_c3_miscdev = {
168 .minor = WATCHDOG_MINOR,
169 .name = "watchdog",
170 .fops = &epx_c3_fops,
171 };
172
173 static struct notifier_block epx_c3_notifier = {
174 .notifier_call = epx_c3_notify_sys,
175 };
176
177 static const char banner[] __initdata =
178 KERN_INFO PFX "Hardware Watchdog Timer for Winsystems EPX-C3 SBC: 0.1\n";
179
180 static int __init watchdog_init(void)
181 {
182 int ret;
183
184 if (!request_region(EPXC3_WATCHDOG_CTL_REG, 2, "epxc3_watchdog"))
185 return -EBUSY;
186
187 ret = register_reboot_notifier(&epx_c3_notifier);
188 if (ret) {
189 printk(KERN_ERR PFX "cannot register reboot notifier "
190 "(err=%d)\n", ret);
191 goto out;
192 }
193
194 ret = misc_register(&epx_c3_miscdev);
195 if (ret) {
196 printk(KERN_ERR PFX "cannot register miscdev on minor=%d "
197 "(err=%d)\n", WATCHDOG_MINOR, ret);
198 unregister_reboot_notifier(&epx_c3_notifier);
199 goto out;
200 }
201
202 printk(banner);
203
204 return 0;
205
206 out:
207 release_region(EPXC3_WATCHDOG_CTL_REG, 2);
208 return ret;
209 }
210
211 static void __exit watchdog_exit(void)
212 {
213 misc_deregister(&epx_c3_miscdev);
214 unregister_reboot_notifier(&epx_c3_notifier);
215 release_region(EPXC3_WATCHDOG_CTL_REG, 2);
216 }
217
218 module_init(watchdog_init);
219 module_exit(watchdog_exit);
220
221 MODULE_AUTHOR("Calin A. Culianu <calin@ajvar.org>");
222 MODULE_DESCRIPTION("Hardware Watchdog Device for Winsystems EPX-C3 SBC. Note that there is no way to probe for this device -- so only use it if you are *sure* you are runnning on this specific SBC system from Winsystems! It writes to IO ports 0x1ee and 0x1ef!");
223 MODULE_LICENSE("GPL");
224 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
225
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