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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14 #include <linux/bitops.h>
15 #include <linux/errno.h>
17 #include <linux/init.h>
19 #include <linux/kernel.h>
20 #include <linux/miscdevice.h>
21 #include <linux/module.h>
22 #include <linux/moduleparam.h>
23 #include <linux/platform_device.h>
24 #include <linux/types.h>
25 #include <linux/watchdog.h>
26 #include <linux/uaccess.h>
27 #include <mach/at91_st.h>
29 #define WDT_DEFAULT_TIME 5 /* seconds */
30 #define WDT_MAX_TIME 256 /* seconds */
32 static int wdt_time = WDT_DEFAULT_TIME;
33 static int nowayout = WATCHDOG_NOWAYOUT;
35 module_param(wdt_time, int, 0);
36 MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
37 __MODULE_STRING(WDT_DEFAULT_TIME) ")");
39 #ifdef CONFIG_WATCHDOG_NOWAYOUT
40 module_param(nowayout, int, 0);
41 MODULE_PARM_DESC(nowayout,
42 "Watchdog cannot be stopped once started (default="
43 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
47 static unsigned long at91wdt_busy;
49 /* ......................................................................... */
52 * Disable the watchdog.
54 static inline void at91_wdt_stop(void)
56 at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN);
60 * Enable and reset the watchdog.
62 static inline void at91_wdt_start(void)
64 at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN |
65 (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
66 at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
70 * Reload the watchdog timer. (ie, pat the watchdog)
72 static inline void at91_wdt_reload(void)
74 at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
77 /* ......................................................................... */
80 * Watchdog device is opened, and watchdog starts running.
82 static int at91_wdt_open(struct inode *inode, struct file *file)
84 if (test_and_set_bit(0, &at91wdt_busy))
88 return nonseekable_open(inode, file);
92 * Close the watchdog device.
93 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
96 static int at91_wdt_close(struct inode *inode, struct file *file)
98 /* Disable the watchdog when file is closed */
102 clear_bit(0, &at91wdt_busy);
107 * Change the watchdog time interval.
109 static int at91_wdt_settimeout(int new_time)
112 * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
114 * Since WDV is a 16-bit counter, the maximum period is
115 * 65536 / 256 = 256 seconds.
117 if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
120 /* Set new watchdog time. It will be used when
121 at91_wdt_start() is called. */
126 static const struct watchdog_info at91_wdt_info = {
127 .identity = "at91 watchdog",
128 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
132 * Handle commands from user-space.
134 static long at91_wdt_ioctl(struct file *file,
135 unsigned int cmd, unsigned long arg)
137 void __user *argp = (void __user *)arg;
138 int __user *p = argp;
142 case WDIOC_GETSUPPORT:
143 return copy_to_user(argp, &at91_wdt_info,
144 sizeof(at91_wdt_info)) ? -EFAULT : 0;
145 case WDIOC_GETSTATUS:
146 case WDIOC_GETBOOTSTATUS:
147 return put_user(0, p);
148 case WDIOC_SETOPTIONS:
149 if (get_user(new_value, p))
151 if (new_value & WDIOS_DISABLECARD)
153 if (new_value & WDIOS_ENABLECARD)
156 case WDIOC_KEEPALIVE:
157 at91_wdt_reload(); /* pat the watchdog */
159 case WDIOC_SETTIMEOUT:
160 if (get_user(new_value, p))
162 if (at91_wdt_settimeout(new_value))
164 /* Enable new time value */
166 /* Return current value */
167 return put_user(wdt_time, p);
168 case WDIOC_GETTIMEOUT:
169 return put_user(wdt_time, p);
176 * Pat the watchdog whenever device is written to.
178 static ssize_t at91_wdt_write(struct file *file, const char *data,
179 size_t len, loff_t *ppos)
181 at91_wdt_reload(); /* pat the watchdog */
185 /* ......................................................................... */
187 static const struct file_operations at91wdt_fops = {
188 .owner = THIS_MODULE,
190 .unlocked_ioctl = at91_wdt_ioctl,
191 .open = at91_wdt_open,
192 .release = at91_wdt_close,
193 .write = at91_wdt_write,
196 static struct miscdevice at91wdt_miscdev = {
197 .minor = WATCHDOG_MINOR,
199 .fops = &at91wdt_fops,
202 static int __devinit at91wdt_probe(struct platform_device *pdev)
206 if (at91wdt_miscdev.parent)
208 at91wdt_miscdev.parent = &pdev->dev;
210 res = misc_register(&at91wdt_miscdev);
214 pr_info("AT91 Watchdog Timer enabled (%d seconds%s)\n",
215 wdt_time, nowayout ? ", nowayout" : "");
219 static int __devexit at91wdt_remove(struct platform_device *pdev)
223 res = misc_deregister(&at91wdt_miscdev);
225 at91wdt_miscdev.parent = NULL;
230 static void at91wdt_shutdown(struct platform_device *pdev)
237 static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
243 static int at91wdt_resume(struct platform_device *pdev)
251 #define at91wdt_suspend NULL
252 #define at91wdt_resume NULL
255 static struct platform_driver at91wdt_driver = {
256 .probe = at91wdt_probe,
257 .remove = __devexit_p(at91wdt_remove),
258 .shutdown = at91wdt_shutdown,
259 .suspend = at91wdt_suspend,
260 .resume = at91wdt_resume,
263 .owner = THIS_MODULE,
267 static int __init at91_wdt_init(void)
269 /* Check that the heartbeat value is within range;
270 if not reset to the default */
271 if (at91_wdt_settimeout(wdt_time)) {
272 at91_wdt_settimeout(WDT_DEFAULT_TIME);
273 pr_info("wdt_time value must be 1 <= wdt_time <= 256, using %d\n",
277 return platform_driver_register(&at91wdt_driver);
280 static void __exit at91_wdt_exit(void)
282 platform_driver_unregister(&at91wdt_driver);
285 module_init(at91_wdt_init);
286 module_exit(at91_wdt_exit);
288 MODULE_AUTHOR("Andrew Victor");
289 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
290 MODULE_LICENSE("GPL");
291 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
292 MODULE_ALIAS("platform:at91_wdt");