2 * Watchdog driver for Atmel AT91RM9200 (Thunder)
4 * Copyright (C) 2003 SAN People (Pty) Ltd
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.
12 #include <linux/config.h>
13 #include <linux/errno.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>
26 #define WDT_DEFAULT_TIME 5 /* 5 seconds */
27 #define WDT_MAX_TIME 256 /* 256 seconds */
29 static int wdt_time
= WDT_DEFAULT_TIME
;
30 static int nowayout
= WATCHDOG_NOWAYOUT
;
32 module_param(wdt_time
, int, 0);
33 MODULE_PARM_DESC(wdt_time
, "Watchdog time in seconds. (default="__MODULE_STRING(WDT_DEFAULT_TIME
) ")");
35 module_param(nowayout
, int, 0);
36 MODULE_PARM_DESC(nowayout
, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT
) ")");
39 static unsigned long at91wdt_busy
;
41 /* ......................................................................... */
44 * Disable the watchdog.
46 static void inline at91_wdt_stop(void)
48 at91_sys_write(AT91_ST_WDMR
, AT91_ST_EXTEN
);
52 * Enable and reset the watchdog.
54 static void inline at91_wdt_start(void)
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
);
61 * Reload the watchdog timer. (ie, pat the watchdog)
63 static void inline at91_wdt_reload(void)
65 at91_sys_write(AT91_ST_CR
, AT91_ST_WDRST
);
68 /* ......................................................................... */
71 * Watchdog device is opened, and watchdog starts running.
73 static int at91_wdt_open(struct inode
*inode
, struct file
*file
)
75 if (test_and_set_bit(0, &at91wdt_busy
))
79 return nonseekable_open(inode
, file
);
83 * Close the watchdog device.
84 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
87 static int at91_wdt_close(struct inode
*inode
, struct file
*file
)
90 at91_wdt_stop(); /* Disable the watchdog when file is closed */
92 clear_bit(0, &at91wdt_busy
);
97 * Change the watchdog time interval.
99 static int at91_wdt_settimeout(int new_time
)
102 * All counting occurs at SLOW_CLOCK / 128 = 0.256 Hz
104 * Since WDV is a 16-bit counter, the maximum period is
105 * 65536 / 0.256 = 256 seconds.
107 if ((new_time
<= 0) || (new_time
> WDT_MAX_TIME
))
110 /* Set new watchdog time. It will be used when at91_wdt_start() is called. */
115 static struct watchdog_info at91_wdt_info
= {
116 .identity
= "at91 watchdog",
117 .options
= WDIOF_SETTIMEOUT
| WDIOF_KEEPALIVEPING
,
121 * Handle commands from user-space.
123 static int at91_wdt_ioctl(struct inode
*inode
, struct file
*file
,
124 unsigned int cmd
, unsigned long arg
)
126 void __user
*argp
= (void __user
*)arg
;
127 int __user
*p
= argp
;
131 case WDIOC_KEEPALIVE
:
132 at91_wdt_reload(); /* pat the watchdog */
135 case WDIOC_GETSUPPORT
:
136 return copy_to_user(argp
, &at91_wdt_info
, sizeof(at91_wdt_info
)) ? -EFAULT
: 0;
138 case WDIOC_SETTIMEOUT
:
139 if (get_user(new_value
, p
))
142 if (at91_wdt_settimeout(new_value
))
145 /* Enable new time value */
148 /* Return current value */
149 return put_user(wdt_time
, p
);
151 case WDIOC_GETTIMEOUT
:
152 return put_user(wdt_time
, p
);
154 case WDIOC_GETSTATUS
:
155 case WDIOC_GETBOOTSTATUS
:
156 return put_user(0, p
);
158 case WDIOC_SETOPTIONS
:
159 if (get_user(new_value
, p
))
162 if (new_value
& WDIOS_DISABLECARD
)
164 if (new_value
& WDIOS_ENABLECARD
)
174 * Pat the watchdog whenever device is written to.
176 static ssize_t
at91_wdt_write(struct file
*file
, const char *data
, size_t len
, loff_t
*ppos
)
178 at91_wdt_reload(); /* pat the watchdog */
182 /* ......................................................................... */
184 static struct file_operations at91wdt_fops
= {
185 .owner
= THIS_MODULE
,
187 .ioctl
= at91_wdt_ioctl
,
188 .open
= at91_wdt_open
,
189 .release
= at91_wdt_close
,
190 .write
= at91_wdt_write
,
193 static struct miscdevice at91wdt_miscdev
= {
194 .minor
= WATCHDOG_MINOR
,
196 .fops
= &at91wdt_fops
,
199 static int __init
at91_wdt_init(void)
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
);
209 res
= misc_register(&at91wdt_miscdev
);
213 printk("AT91 Watchdog Timer enabled (%d seconds, nowayout=%d)\n", wdt_time
, nowayout
);
217 static void __exit
at91_wdt_exit(void)
219 misc_deregister(&at91wdt_miscdev
);
222 module_init(at91_wdt_init
);
223 module_exit(at91_wdt_exit
);
225 MODULE_AUTHOR("Andrew Victor");
226 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
227 MODULE_LICENSE("GPL");
228 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR
);