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11
12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14#include <linux/module.h>
15#include <linux/moduleparam.h>
16#include <linux/types.h>
17#include <linux/kernel.h>
18#include <linux/fs.h>
19#include <linux/mm.h>
20#include <linux/miscdevice.h>
21#include <linux/watchdog.h>
22#include <linux/notifier.h>
23#include <linux/reboot.h>
24#include <linux/init.h>
25#include <linux/ioport.h>
26#include <linux/uaccess.h>
27#include <linux/io.h>
28
29static int epx_c3_alive;
30
31#define WATCHDOG_TIMEOUT 1
32
33static bool nowayout = WATCHDOG_NOWAYOUT;
34module_param(nowayout, bool, 0);
35MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
36 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
37
38#define EPXC3_WATCHDOG_CTL_REG 0x1ee
39#define EPXC3_WATCHDOG_PET_REG 0x1ef
40
41static void epx_c3_start(void)
42{
43 outb(1, EPXC3_WATCHDOG_CTL_REG);
44}
45
46static void epx_c3_stop(void)
47{
48
49 outb(0, EPXC3_WATCHDOG_CTL_REG);
50
51 pr_info("Stopped watchdog timer\n");
52}
53
54static void epx_c3_pet(void)
55{
56 outb(1, EPXC3_WATCHDOG_PET_REG);
57}
58
59
60
61
62static int epx_c3_open(struct inode *inode, struct file *file)
63{
64 if (epx_c3_alive)
65 return -EBUSY;
66
67 if (nowayout)
68 __module_get(THIS_MODULE);
69
70
71 epx_c3_start();
72 epx_c3_pet();
73
74 epx_c3_alive = 1;
75 pr_info("Started watchdog timer\n");
76
77 return stream_open(inode, file);
78}
79
80static int epx_c3_release(struct inode *inode, struct file *file)
81{
82
83
84 if (!nowayout)
85 epx_c3_stop();
86
87 epx_c3_alive = 0;
88
89 return 0;
90}
91
92static ssize_t epx_c3_write(struct file *file, const char __user *data,
93 size_t len, loff_t *ppos)
94{
95
96 if (len)
97 epx_c3_pet();
98 return len;
99}
100
101static long epx_c3_ioctl(struct file *file, unsigned int cmd,
102 unsigned long arg)
103{
104 int options, retval = -EINVAL;
105 int __user *argp = (void __user *)arg;
106 static const struct watchdog_info ident = {
107 .options = WDIOF_KEEPALIVEPING,
108 .firmware_version = 0,
109 .identity = "Winsystems EPX-C3 H/W Watchdog",
110 };
111
112 switch (cmd) {
113 case WDIOC_GETSUPPORT:
114 if (copy_to_user(argp, &ident, sizeof(ident)))
115 return -EFAULT;
116 return 0;
117 case WDIOC_GETSTATUS:
118 case WDIOC_GETBOOTSTATUS:
119 return put_user(0, argp);
120 case WDIOC_SETOPTIONS:
121 if (get_user(options, argp))
122 return -EFAULT;
123
124 if (options & WDIOS_DISABLECARD) {
125 epx_c3_stop();
126 retval = 0;
127 }
128
129 if (options & WDIOS_ENABLECARD) {
130 epx_c3_start();
131 retval = 0;
132 }
133
134 return retval;
135 case WDIOC_KEEPALIVE:
136 epx_c3_pet();
137 return 0;
138 case WDIOC_GETTIMEOUT:
139 return put_user(WATCHDOG_TIMEOUT, argp);
140 default:
141 return -ENOTTY;
142 }
143}
144
145static int epx_c3_notify_sys(struct notifier_block *this, unsigned long code,
146 void *unused)
147{
148 if (code == SYS_DOWN || code == SYS_HALT)
149 epx_c3_stop();
150
151 return NOTIFY_DONE;
152}
153
154static const struct file_operations epx_c3_fops = {
155 .owner = THIS_MODULE,
156 .llseek = no_llseek,
157 .write = epx_c3_write,
158 .unlocked_ioctl = epx_c3_ioctl,
159 .compat_ioctl = compat_ptr_ioctl,
160 .open = epx_c3_open,
161 .release = epx_c3_release,
162};
163
164static struct miscdevice epx_c3_miscdev = {
165 .minor = WATCHDOG_MINOR,
166 .name = "watchdog",
167 .fops = &epx_c3_fops,
168};
169
170static struct notifier_block epx_c3_notifier = {
171 .notifier_call = epx_c3_notify_sys,
172};
173
174static int __init watchdog_init(void)
175{
176 int ret;
177
178 if (!request_region(EPXC3_WATCHDOG_CTL_REG, 2, "epxc3_watchdog"))
179 return -EBUSY;
180
181 ret = register_reboot_notifier(&epx_c3_notifier);
182 if (ret) {
183 pr_err("cannot register reboot notifier (err=%d)\n", ret);
184 goto out;
185 }
186
187 ret = misc_register(&epx_c3_miscdev);
188 if (ret) {
189 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
190 WATCHDOG_MINOR, ret);
191 unregister_reboot_notifier(&epx_c3_notifier);
192 goto out;
193 }
194
195 pr_info("Hardware Watchdog Timer for Winsystems EPX-C3 SBC: 0.1\n");
196
197 return 0;
198
199out:
200 release_region(EPXC3_WATCHDOG_CTL_REG, 2);
201 return ret;
202}
203
204static void __exit watchdog_exit(void)
205{
206 misc_deregister(&epx_c3_miscdev);
207 unregister_reboot_notifier(&epx_c3_notifier);
208 release_region(EPXC3_WATCHDOG_CTL_REG, 2);
209}
210
211module_init(watchdog_init);
212module_exit(watchdog_exit);
213
214MODULE_AUTHOR("Calin A. Culianu <calin@ajvar.org>");
215MODULE_DESCRIPTION("Hardware Watchdog Device for Winsystems EPX-C3 SBC. "
216 "Note that there is no way to probe for this device -- "
217 "so only use it if you are *sure* you are running on this specific "
218 "SBC system from Winsystems! It writes to IO ports 0x1ee and 0x1ef!");
219MODULE_LICENSE("GPL");
220
