tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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/bitops.h>
13#include <linux/errno.h>
14#include <linux/fs.h>
15#include <linux/init.h>
16#include <linux/io.h>
17#include <linux/kernel.h>
18#include <linux/miscdevice.h>
19#include <linux/module.h>
20#include <linux/moduleparam.h>
21#include <linux/platform_device.h>
22#include <linux/types.h>
23#include <linux/watchdog.h>
24#include <linux/uaccess.h>
25#include <mach/at91_st.h>
26
27#define WDT_DEFAULT_TIME 5 /* seconds */
28#define WDT_MAX_TIME 256 /* seconds */
29
30static int wdt_time = WDT_DEFAULT_TIME;
31static int nowayout = WATCHDOG_NOWAYOUT;
32
33module_param(wdt_time, int, 0);
34MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
35 __MODULE_STRING(WDT_DEFAULT_TIME) ")");
36
37#ifdef CONFIG_WATCHDOG_NOWAYOUT
38module_param(nowayout, int, 0);
39MODULE_PARM_DESC(nowayout,
40 "Watchdog cannot be stopped once started (default="
41 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
42#endif
43
44
45static unsigned long at91wdt_busy;
46
47/* ......................................................................... */
48
49/*
50 * Disable the watchdog.
51 */
52static inline void at91_wdt_stop(void)
53{
54 at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN);
55}
56
57/*
58 * Enable and reset the watchdog.
59 */
60static inline void at91_wdt_start(void)
61{
62 at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN |
63 (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
64 at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
65}
66
67/*
68 * Reload the watchdog timer. (ie, pat the watchdog)
69 */
70static inline void at91_wdt_reload(void)
71{
72 at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
73}
74
75/* ......................................................................... */
76
77/*
78 * Watchdog device is opened, and watchdog starts running.
79 */
80static int at91_wdt_open(struct inode *inode, struct file *file)
81{
82 if (test_and_set_bit(0, &at91wdt_busy))
83 return -EBUSY;
84
85 at91_wdt_start();
86 return nonseekable_open(inode, file);
87}
88
89/*
90 * Close the watchdog device.
91 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
92 * disabled.
93 */
94static int at91_wdt_close(struct inode *inode, struct file *file)
95{
96 /* Disable the watchdog when file is closed */
97 if (!nowayout)
98 at91_wdt_stop();
99
100 clear_bit(0, &at91wdt_busy);
101 return 0;
102}
103
104/*
105 * Change the watchdog time interval.
106 */
107static int at91_wdt_settimeout(int new_time)
108{
109 /*
110 * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
111 *
112 * Since WDV is a 16-bit counter, the maximum period is
113 * 65536 / 256 = 256 seconds.
114 */
115 if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
116 return -EINVAL;
117
118 /* Set new watchdog time. It will be used when
119 at91_wdt_start() is called. */
120 wdt_time = new_time;
121 return 0;
122}
123
124static struct watchdog_info at91_wdt_info = {
125 .identity = "at91 watchdog",
126 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
127};
128
129/*
130 * Handle commands from user-space.
131 */
132static long at91_wdt_ioctl(struct file *file,
133 unsigned int cmd, unsigned long arg)
134{
135 void __user *argp = (void __user *)arg;
136 int __user *p = argp;
137 int new_value;
138
139 switch (cmd) {
140 case WDIOC_GETSUPPORT:
141 return copy_to_user(argp, &at91_wdt_info,
142 sizeof(at91_wdt_info)) ? -EFAULT : 0;
143 case WDIOC_GETSTATUS:
144 case WDIOC_GETBOOTSTATUS:
145 return put_user(0, p);
146 case WDIOC_SETOPTIONS:
147 if (get_user(new_value, p))
148 return -EFAULT;
149 if (new_value & WDIOS_DISABLECARD)
150 at91_wdt_stop();
151 if (new_value & WDIOS_ENABLECARD)
152 at91_wdt_start();
153 return 0;
154 case WDIOC_KEEPALIVE:
155 at91_wdt_reload(); /* pat the watchdog */
156 return 0;
157 case WDIOC_SETTIMEOUT:
158 if (get_user(new_value, p))
159 return -EFAULT;
160 if (at91_wdt_settimeout(new_value))
161 return -EINVAL;
162 /* Enable new time value */
163 at91_wdt_start();
164 /* Return current value */
165 return put_user(wdt_time, p);
166 case WDIOC_GETTIMEOUT:
167 return put_user(wdt_time, p);
168 default:
169 return -ENOTTY;
170 }
171}
172
173/*
174 * Pat the watchdog whenever device is written to.
175 */
176static ssize_t at91_wdt_write(struct file *file, const char *data,
177 size_t len, loff_t *ppos)
178{
179 at91_wdt_reload(); /* pat the watchdog */
180 return len;
181}
182
183/* ......................................................................... */
184
185static const struct file_operations at91wdt_fops = {
186 .owner = THIS_MODULE,
187 .llseek = no_llseek,
188 .unlocked_ioctl = at91_wdt_ioctl,
189 .open = at91_wdt_open,
190 .release = at91_wdt_close,
191 .write = at91_wdt_write,
192};
193
194static struct miscdevice at91wdt_miscdev = {
195 .minor = WATCHDOG_MINOR,
196 .name = "watchdog",
197 .fops = &at91wdt_fops,
198};
199
200static int __devinit at91wdt_probe(struct platform_device *pdev)
201{
202 int res;
203
204 if (at91wdt_miscdev.parent)
205 return -EBUSY;
206 at91wdt_miscdev.parent = &pdev->dev;
207
208 res = misc_register(&at91wdt_miscdev);
209 if (res)
210 return res;
211
212 printk(KERN_INFO "AT91 Watchdog Timer enabled (%d seconds%s)\n",
213 wdt_time, nowayout ? ", nowayout" : "");
214 return 0;
215}
216
217static int __devexit at91wdt_remove(struct platform_device *pdev)
218{
219 int res;
220
221 res = misc_deregister(&at91wdt_miscdev);
222 if (!res)
223 at91wdt_miscdev.parent = 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 = __devexit_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;
268 if not reset to the default */
269 if (at91_wdt_settimeout(wdt_time)) {
270 at91_wdt_settimeout(WDT_DEFAULT_TIME);
271 pr_info("at91_wdt: wdt_time value must be 1 <= wdt_time <= 256"
272 ", using %d\n", wdt_time);
273 }
274
275 return platform_driver_register(&at91wdt_driver);
276}
277
278static void __exit at91_wdt_exit(void)
279{
280 platform_driver_unregister(&at91wdt_driver);
281}
282
283module_init(at91_wdt_init);
284module_exit(at91_wdt_exit);
285
286MODULE_AUTHOR("Andrew Victor");
287MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
288MODULE_LICENSE("GPL");
289MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
290MODULE_ALIAS("platform:at91_wdt");