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Andrew Victor853807f2006-03-14 11:11:04 +02001/*
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
Andrew Victor853807f2006-03-14 11:11:04 +020012#include <linux/errno.h>
13#include <linux/fs.h>
14#include <linux/init.h>
15#include <linux/kernel.h>
16#include <linux/miscdevice.h>
17#include <linux/module.h>
18#include <linux/moduleparam.h>
Andrew Victordfc7bd92006-05-21 15:32:59 +020019#include <linux/platform_device.h>
Andrew Victor853807f2006-03-14 11:11:04 +020020#include <linux/types.h>
21#include <linux/watchdog.h>
22#include <asm/bitops.h>
23#include <asm/uaccess.h>
24
25
Andrew Victordfc7bd92006-05-21 15:32:59 +020026#define WDT_DEFAULT_TIME 5 /* seconds */
27#define WDT_MAX_TIME 256 /* seconds */
Andrew Victor853807f2006-03-14 11:11:04 +020028
29static int wdt_time = WDT_DEFAULT_TIME;
30static int nowayout = WATCHDOG_NOWAYOUT;
31
32module_param(wdt_time, int, 0);
33MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="__MODULE_STRING(WDT_DEFAULT_TIME) ")");
34
Andrew Victordfc7bd92006-05-21 15:32:59 +020035#ifdef CONFIG_WATCHDOG_NOWAYOUT
Andrew Victor853807f2006-03-14 11:11:04 +020036module_param(nowayout, int, 0);
37MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
Andrew Victordfc7bd92006-05-21 15:32:59 +020038#endif
Andrew Victor853807f2006-03-14 11:11:04 +020039
40
41static unsigned long at91wdt_busy;
42
43/* ......................................................................... */
44
45/*
46 * Disable the watchdog.
47 */
48static void inline at91_wdt_stop(void)
49{
50 at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN);
51}
52
53/*
54 * Enable and reset the watchdog.
55 */
56static void inline at91_wdt_start(void)
57{
58 at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN | (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
59 at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
60}
61
62/*
63 * Reload the watchdog timer. (ie, pat the watchdog)
64 */
65static void inline at91_wdt_reload(void)
66{
67 at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
68}
69
70/* ......................................................................... */
71
72/*
73 * Watchdog device is opened, and watchdog starts running.
74 */
75static int at91_wdt_open(struct inode *inode, struct file *file)
76{
77 if (test_and_set_bit(0, &at91wdt_busy))
78 return -EBUSY;
79
80 at91_wdt_start();
81 return nonseekable_open(inode, file);
82}
83
84/*
85 * Close the watchdog device.
86 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
87 * disabled.
88 */
89static int at91_wdt_close(struct inode *inode, struct file *file)
90{
91 if (!nowayout)
92 at91_wdt_stop(); /* Disable the watchdog when file is closed */
93
94 clear_bit(0, &at91wdt_busy);
95 return 0;
96}
97
98/*
99 * Change the watchdog time interval.
100 */
101static int at91_wdt_settimeout(int new_time)
102{
103 /*
104 * All counting occurs at SLOW_CLOCK / 128 = 0.256 Hz
105 *
106 * Since WDV is a 16-bit counter, the maximum period is
107 * 65536 / 0.256 = 256 seconds.
108 */
109 if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
110 return -EINVAL;
111
112 /* Set new watchdog time. It will be used when at91_wdt_start() is called. */
113 wdt_time = new_time;
114 return 0;
115}
116
117static struct watchdog_info at91_wdt_info = {
118 .identity = "at91 watchdog",
119 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
120};
121
122/*
123 * Handle commands from user-space.
124 */
125static int at91_wdt_ioctl(struct inode *inode, struct file *file,
126 unsigned int cmd, unsigned long arg)
127{
128 void __user *argp = (void __user *)arg;
129 int __user *p = argp;
130 int new_value;
131
132 switch(cmd) {
133 case WDIOC_KEEPALIVE:
134 at91_wdt_reload(); /* pat the watchdog */
135 return 0;
136
137 case WDIOC_GETSUPPORT:
138 return copy_to_user(argp, &at91_wdt_info, sizeof(at91_wdt_info)) ? -EFAULT : 0;
139
140 case WDIOC_SETTIMEOUT:
141 if (get_user(new_value, p))
142 return -EFAULT;
Andrew Victordfc7bd92006-05-21 15:32:59 +0200143
Andrew Victor853807f2006-03-14 11:11:04 +0200144 if (at91_wdt_settimeout(new_value))
145 return -EINVAL;
146
147 /* Enable new time value */
148 at91_wdt_start();
149
150 /* Return current value */
151 return put_user(wdt_time, p);
152
153 case WDIOC_GETTIMEOUT:
154 return put_user(wdt_time, p);
155
156 case WDIOC_GETSTATUS:
157 case WDIOC_GETBOOTSTATUS:
158 return put_user(0, p);
159
160 case WDIOC_SETOPTIONS:
161 if (get_user(new_value, p))
162 return -EFAULT;
163
164 if (new_value & WDIOS_DISABLECARD)
165 at91_wdt_stop();
166 if (new_value & WDIOS_ENABLECARD)
167 at91_wdt_start();
168 return 0;
169
170 default:
171 return -ENOIOCTLCMD;
172 }
173}
174
175/*
176 * Pat the watchdog whenever device is written to.
177 */
178static ssize_t at91_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
179{
180 at91_wdt_reload(); /* pat the watchdog */
181 return len;
182}
183
184/* ......................................................................... */
185
Arjan van de Ven62322d22006-07-03 00:24:21 -0700186static const struct file_operations at91wdt_fops = {
Andrew Victor853807f2006-03-14 11:11:04 +0200187 .owner = THIS_MODULE,
188 .llseek = no_llseek,
189 .ioctl = at91_wdt_ioctl,
190 .open = at91_wdt_open,
191 .release = at91_wdt_close,
192 .write = at91_wdt_write,
193};
194
195static struct miscdevice at91wdt_miscdev = {
196 .minor = WATCHDOG_MINOR,
197 .name = "watchdog",
198 .fops = &at91wdt_fops,
199};
200
Andrew Victordfc7bd92006-05-21 15:32:59 +0200201static int __init at91wdt_probe(struct platform_device *pdev)
Andrew Victor853807f2006-03-14 11:11:04 +0200202{
203 int res;
204
Andrew Victordfc7bd92006-05-21 15:32:59 +0200205 if (at91wdt_miscdev.dev)
206 return -EBUSY;
207 at91wdt_miscdev.dev = &pdev->dev;
Andrew Victor853807f2006-03-14 11:11:04 +0200208
209 res = misc_register(&at91wdt_miscdev);
210 if (res)
211 return res;
212
Andrew Victordfc7bd92006-05-21 15:32:59 +0200213 printk("AT91 Watchdog Timer enabled (%d seconds%s)\n", wdt_time, nowayout ? ", nowayout" : "");
Andrew Victor853807f2006-03-14 11:11:04 +0200214 return 0;
215}
216
Andrew Victordfc7bd92006-05-21 15:32:59 +0200217static int __exit at91wdt_remove(struct platform_device *pdev)
218{
219 int res;
220
221 res = misc_deregister(&at91wdt_miscdev);
222 if (!res)
223 at91wdt_miscdev.dev = NULL;
224
225 return res;
226}
227
228static void at91wdt_shutdown(struct platform_device *pdev)
229{
230 at91_wdt_stop();
231}
232
233#ifdef CONFIG_PM
234
235static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
236{
237 at91_wdt_stop();
238 return 0;
239}
240
241static int at91wdt_resume(struct platform_device *pdev)
242{
243 if (at91wdt_busy)
244 at91_wdt_start();
245 return 0;
246}
247
248#else
249#define at91wdt_suspend NULL
250#define at91wdt_resume NULL
251#endif
252
253static struct platform_driver at91wdt_driver = {
254 .probe = at91wdt_probe,
255 .remove = __exit_p(at91wdt_remove),
256 .shutdown = at91wdt_shutdown,
257 .suspend = at91wdt_suspend,
258 .resume = at91wdt_resume,
259 .driver = {
260 .name = "at91_wdt",
261 .owner = THIS_MODULE,
262 },
263};
264
265static int __init at91_wdt_init(void)
266{
267 /* Check that the heartbeat value is within range; if not reset to the default */
268 if (at91_wdt_settimeout(wdt_time)) {
269 at91_wdt_settimeout(WDT_DEFAULT_TIME);
270 pr_info("at91_wdt: wdt_time value must be 1 <= wdt_time <= 256, using %d\n", wdt_time);
271 }
272
273 return platform_driver_register(&at91wdt_driver);
274}
275
Andrew Victor853807f2006-03-14 11:11:04 +0200276static void __exit at91_wdt_exit(void)
277{
Andrew Victordfc7bd92006-05-21 15:32:59 +0200278 platform_driver_unregister(&at91wdt_driver);
Andrew Victor853807f2006-03-14 11:11:04 +0200279}
280
281module_init(at91_wdt_init);
282module_exit(at91_wdt_exit);
283
284MODULE_AUTHOR("Andrew Victor");
285MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
286MODULE_LICENSE("GPL");
287MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);