1 /*
2 * Watchdog driver for Atmel AT91RM9200 (Thunder)
3 *
4 * Copyright (C) 2003 SAN People (Pty) Ltd
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12 #include <linux/config.h>
13 #include <linux/errno.h>
14 #include <linux/fs.h>
15 #include <linux/init.h>
16 #include <linux/kernel.h>
17 #include <linux/miscdevice.h>
18 #include <linux/module.h>
19 #include <linux/moduleparam.h>
20 #include <linux/types.h>
21 #include <linux/watchdog.h>
22 #include <asm/bitops.h>
23 #include <asm/uaccess.h>
24
25
26 #define WDT_DEFAULT_TIME 5 /* 5 seconds */
27 #define WDT_MAX_TIME 256 /* 256 seconds */
28
29 static int wdt_time = WDT_DEFAULT_TIME;
30 static int nowayout = WATCHDOG_NOWAYOUT;
31
32 module_param(wdt_time, int, 0);
33 MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="__MODULE_STRING(WDT_DEFAULT_TIME) ")");
34
35 module_param(nowayout, int, 0);
36 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
37
38
39 static unsigned long at91wdt_busy;
40
41 /* ......................................................................... */
42
43 /*
44 * Disable the watchdog.
45 */
46 static void inline at91_wdt_stop(void)
47 {
48 at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN);
49 }
50
51 /*
52 * Enable and reset the watchdog.
53 */
54 static void inline at91_wdt_start(void)
55 {
56 at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN | (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
57 at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
58 }
59
60 /*
61 * Reload the watchdog timer. (ie, pat the watchdog)
62 */
63 static void inline at91_wdt_reload(void)
64 {
65 at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
66 }
67
68 /* ......................................................................... */
69
70 /*
71 * Watchdog device is opened, and watchdog starts running.
72 */
73 static int at91_wdt_open(struct inode *inode, struct file *file)
74 {
75 if (test_and_set_bit(0, &at91wdt_busy))
76 return -EBUSY;
77
78 at91_wdt_start();
79 return nonseekable_open(inode, file);
80 }
81
82 /*
83 * Close the watchdog device.
84 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
85 * disabled.
86 */
87 static int at91_wdt_close(struct inode *inode, struct file *file)
88 {
89 if (!nowayout)
90 at91_wdt_stop(); /* Disable the watchdog when file is closed */
91
92 clear_bit(0, &at91wdt_busy);
93 return 0;
94 }
95
96 /*
97 * Change the watchdog time interval.
98 */
99 static int at91_wdt_settimeout(int new_time)
100 {
101 /*
102 * All counting occurs at SLOW_CLOCK / 128 = 0.256 Hz
103 *
104 * Since WDV is a 16-bit counter, the maximum period is
105 * 65536 / 0.256 = 256 seconds.
106 */
107 if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
108 return -EINVAL;
109
110 /* Set new watchdog time. It will be used when at91_wdt_start() is called. */
111 wdt_time = new_time;
112 return 0;
113 }
114
115 static struct watchdog_info at91_wdt_info = {
116 .identity = "at91 watchdog",
117 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
118 };
119
120 /*
121 * Handle commands from user-space.
122 */
123 static int at91_wdt_ioctl(struct inode *inode, struct file *file,
124 unsigned int cmd, unsigned long arg)
125 {
126 void __user *argp = (void __user *)arg;
127 int __user *p = argp;
128 int new_value;
129
130 switch(cmd) {
131 case WDIOC_KEEPALIVE:
132 at91_wdt_reload(); /* pat the watchdog */
133 return 0;
134
135 case WDIOC_GETSUPPORT:
136 return copy_to_user(argp, &at91_wdt_info, sizeof(at91_wdt_info)) ? -EFAULT : 0;
137
138 case WDIOC_SETTIMEOUT:
139 if (get_user(new_value, p))
140 return -EFAULT;
141
142 if (at91_wdt_settimeout(new_value))
143 return -EINVAL;
144
145 /* Enable new time value */
146 at91_wdt_start();
147
148 /* Return current value */
149 return put_user(wdt_time, p);
150
151 case WDIOC_GETTIMEOUT:
152 return put_user(wdt_time, p);
153
154 case WDIOC_GETSTATUS:
155 case WDIOC_GETBOOTSTATUS:
156 return put_user(0, p);
157
158 case WDIOC_SETOPTIONS:
159 if (get_user(new_value, p))
160 return -EFAULT;
161
162 if (new_value & WDIOS_DISABLECARD)
163 at91_wdt_stop();
164 if (new_value & WDIOS_ENABLECARD)
165 at91_wdt_start();
166 return 0;
167
168 default:
169 return -ENOIOCTLCMD;
170 }
171 }
172
173 /*
174 * Pat the watchdog whenever device is written to.
175 */
176 static ssize_t at91_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
177 {
178 at91_wdt_reload(); /* pat the watchdog */
179 return len;
180 }
181
182 /* ......................................................................... */
183
184 static struct file_operations at91wdt_fops = {
185 .owner = THIS_MODULE,
186 .llseek = no_llseek,
187 .ioctl = at91_wdt_ioctl,
188 .open = at91_wdt_open,
189 .release = at91_wdt_close,
190 .write = at91_wdt_write,
191 };
192
193 static struct miscdevice at91wdt_miscdev = {
194 .minor = WATCHDOG_MINOR,
195 .name = "watchdog",
196 .fops = &at91wdt_fops,
197 };
198
199 static int __init at91_wdt_init(void)
200 {
201 int res;
202
203 /* Check that the heartbeat value is within range; if not reset to the default */
204 if (at91_wdt_settimeout(wdt_time)) {
205 at91_wdt_settimeout(WDT_DEFAULT_TIME);
206 printk(KERN_INFO "at91_wdt: wdt_time value must be 1 <= wdt_time <= 256, using %d\n", wdt_time);
207 }
208
209 res = misc_register(&at91wdt_miscdev);
210 if (res)
211 return res;
212
213 printk("AT91 Watchdog Timer enabled (%d seconds, nowayout=%d)\n", wdt_time, nowayout);
214 return 0;
215 }
216
217 static void __exit at91_wdt_exit(void)
218 {
219 misc_deregister(&at91wdt_miscdev);
220 }
221
222 module_init(at91_wdt_init);
223 module_exit(at91_wdt_exit);
224
225 MODULE_AUTHOR("Andrew Victor");
226 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
227 MODULE_LICENSE("GPL");
228 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
229
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