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Renaud CERRATOe6bb42e2008-06-23 17:05:49 +02001/*
2 * Watchdog driver for Atmel AT91SAM9x processors.
3 *
4 * Copyright (C) 2008 Renaud CERRATO r.cerrato@til-technologies.fr
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/*
13 * The Watchdog Timer Mode Register can be only written to once. If the
14 * timeout need to be set from Linux, be sure that the bootstrap or the
15 * bootloader doesn't write to this register.
16 */
17
18#include <linux/errno.h>
19#include <linux/fs.h>
20#include <linux/init.h>
Andrew Victor2af29b72009-02-11 21:23:10 +010021#include <linux/io.h>
Renaud CERRATOe6bb42e2008-06-23 17:05:49 +020022#include <linux/kernel.h>
23#include <linux/miscdevice.h>
24#include <linux/module.h>
25#include <linux/moduleparam.h>
26#include <linux/platform_device.h>
27#include <linux/types.h>
28#include <linux/watchdog.h>
29#include <linux/jiffies.h>
30#include <linux/timer.h>
31#include <linux/bitops.h>
32#include <linux/uaccess.h>
33
Andrew Victorc1dfda32008-11-06 12:53:42 -080034#include <mach/at91_wdt.h>
Renaud CERRATOe6bb42e2008-06-23 17:05:49 +020035
36#define DRV_NAME "AT91SAM9 Watchdog"
37
38/* AT91SAM9 watchdog runs a 12bit counter @ 256Hz,
39 * use this to convert a watchdog
40 * value from/to milliseconds.
41 */
42#define ms_to_ticks(t) (((t << 8) / 1000) - 1)
43#define ticks_to_ms(t) (((t + 1) * 1000) >> 8)
44
45/* Hardware timeout in seconds */
46#define WDT_HW_TIMEOUT 2
47
48/* Timer heartbeat (500ms) */
49#define WDT_TIMEOUT (HZ/2)
50
51/* User land timeout */
52#define WDT_HEARTBEAT 15
53static int heartbeat = WDT_HEARTBEAT;
54module_param(heartbeat, int, 0);
55MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
56 "(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
57
58static int nowayout = WATCHDOG_NOWAYOUT;
59module_param(nowayout, int, 0);
60MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
61 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
62
63static void at91_ping(unsigned long data);
64
65static struct {
66 unsigned long next_heartbeat; /* the next_heartbeat for the timer */
67 unsigned long open;
68 char expect_close;
69 struct timer_list timer; /* The timer that pings the watchdog */
70} at91wdt_private;
71
72/* ......................................................................... */
73
74
75/*
76 * Reload the watchdog timer. (ie, pat the watchdog)
77 */
78static inline void at91_wdt_reset(void)
79{
80 at91_sys_write(AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
81}
82
83/*
84 * Timer tick
85 */
86static void at91_ping(unsigned long data)
87{
88 if (time_before(jiffies, at91wdt_private.next_heartbeat) ||
89 (!nowayout && !at91wdt_private.open)) {
90 at91_wdt_reset();
91 mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
92 } else
93 printk(KERN_CRIT DRV_NAME": I will reset your machine !\n");
94}
95
96/*
97 * Watchdog device is opened, and watchdog starts running.
98 */
99static int at91_wdt_open(struct inode *inode, struct file *file)
100{
101 if (test_and_set_bit(0, &at91wdt_private.open))
102 return -EBUSY;
103
104 at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
105 mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
106
107 return nonseekable_open(inode, file);
108}
109
110/*
111 * Close the watchdog device.
112 */
113static int at91_wdt_close(struct inode *inode, struct file *file)
114{
115 clear_bit(0, &at91wdt_private.open);
116
117 /* stop internal ping */
118 if (!at91wdt_private.expect_close)
119 del_timer(&at91wdt_private.timer);
120
121 at91wdt_private.expect_close = 0;
122 return 0;
123}
124
125/*
126 * Set the watchdog time interval in 1/256Hz (write-once)
127 * Counter is 12 bit.
128 */
129static int at91_wdt_settimeout(unsigned int timeout)
130{
131 unsigned int reg;
132 unsigned int mr;
133
134 /* Check if disabled */
135 mr = at91_sys_read(AT91_WDT_MR);
136 if (mr & AT91_WDT_WDDIS) {
137 printk(KERN_ERR DRV_NAME": sorry, watchdog is disabled\n");
138 return -EIO;
139 }
140
141 /*
142 * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
143 *
144 * Since WDV is a 12-bit counter, the maximum period is
145 * 4096 / 256 = 16 seconds.
146 */
147 reg = AT91_WDT_WDRSTEN /* causes watchdog reset */
148 /* | AT91_WDT_WDRPROC causes processor reset only */
149 | AT91_WDT_WDDBGHLT /* disabled in debug mode */
150 | AT91_WDT_WDD /* restart at any time */
151 | (timeout & AT91_WDT_WDV); /* timer value */
152 at91_sys_write(AT91_WDT_MR, reg);
153
154 return 0;
155}
156
157static const struct watchdog_info at91_wdt_info = {
158 .identity = DRV_NAME,
159 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
160};
161
162/*
163 * Handle commands from user-space.
164 */
165static long at91_wdt_ioctl(struct file *file,
166 unsigned int cmd, unsigned long arg)
167{
168 void __user *argp = (void __user *)arg;
169 int __user *p = argp;
170 int new_value;
171
172 switch (cmd) {
173 case WDIOC_GETSUPPORT:
174 return copy_to_user(argp, &at91_wdt_info,
175 sizeof(at91_wdt_info)) ? -EFAULT : 0;
176
177 case WDIOC_GETSTATUS:
178 case WDIOC_GETBOOTSTATUS:
179 return put_user(0, p);
180
181 case WDIOC_KEEPALIVE:
182 at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
183 return 0;
184
185 case WDIOC_SETTIMEOUT:
186 if (get_user(new_value, p))
187 return -EFAULT;
188
189 heartbeat = new_value;
190 at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
191
192 return put_user(new_value, p); /* return current value */
193
194 case WDIOC_GETTIMEOUT:
195 return put_user(heartbeat, p);
196 }
197 return -ENOTTY;
198}
199
200/*
201 * Pat the watchdog whenever device is written to.
202 */
203static ssize_t at91_wdt_write(struct file *file, const char *data, size_t len,
Wim Van Sebroeck143a2e52009-03-18 08:35:09 +0000204 loff_t *ppos)
Renaud CERRATOe6bb42e2008-06-23 17:05:49 +0200205{
206 if (!len)
207 return 0;
208
209 /* Scan for magic character */
210 if (!nowayout) {
211 size_t i;
212
213 at91wdt_private.expect_close = 0;
214
215 for (i = 0; i < len; i++) {
216 char c;
217 if (get_user(c, data + i))
218 return -EFAULT;
219 if (c == 'V') {
220 at91wdt_private.expect_close = 42;
221 break;
222 }
223 }
224 }
225
226 at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
227
228 return len;
229}
230
231/* ......................................................................... */
232
233static const struct file_operations at91wdt_fops = {
234 .owner = THIS_MODULE,
235 .llseek = no_llseek,
236 .unlocked_ioctl = at91_wdt_ioctl,
237 .open = at91_wdt_open,
238 .release = at91_wdt_close,
239 .write = at91_wdt_write,
240};
241
242static struct miscdevice at91wdt_miscdev = {
243 .minor = WATCHDOG_MINOR,
244 .name = "watchdog",
245 .fops = &at91wdt_fops,
246};
247
248static int __init at91wdt_probe(struct platform_device *pdev)
249{
250 int res;
251
252 if (at91wdt_miscdev.parent)
253 return -EBUSY;
254 at91wdt_miscdev.parent = &pdev->dev;
255
256 /* Set watchdog */
257 res = at91_wdt_settimeout(ms_to_ticks(WDT_HW_TIMEOUT * 1000));
258 if (res)
259 return res;
260
261 res = misc_register(&at91wdt_miscdev);
262 if (res)
263 return res;
264
265 at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
266 setup_timer(&at91wdt_private.timer, at91_ping, 0);
267 mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
268
269 printk(KERN_INFO DRV_NAME " enabled (heartbeat=%d sec, nowayout=%d)\n",
270 heartbeat, nowayout);
271
272 return 0;
273}
274
275static int __exit at91wdt_remove(struct platform_device *pdev)
276{
277 int res;
278
279 res = misc_deregister(&at91wdt_miscdev);
280 if (!res)
281 at91wdt_miscdev.parent = NULL;
282
283 return res;
284}
285
286#ifdef CONFIG_PM
287
288static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
289{
290 return 0;
291}
292
293static int at91wdt_resume(struct platform_device *pdev)
294{
295 return 0;
296}
297
298#else
299#define at91wdt_suspend NULL
300#define at91wdt_resume NULL
301#endif
302
303static struct platform_driver at91wdt_driver = {
304 .remove = __exit_p(at91wdt_remove),
305 .suspend = at91wdt_suspend,
306 .resume = at91wdt_resume,
307 .driver = {
308 .name = "at91_wdt",
309 .owner = THIS_MODULE,
310 },
311};
312
313static int __init at91sam_wdt_init(void)
314{
315 return platform_driver_probe(&at91wdt_driver, at91wdt_probe);
316}
317
318static void __exit at91sam_wdt_exit(void)
319{
320 platform_driver_unregister(&at91wdt_driver);
321}
322
323module_init(at91sam_wdt_init);
324module_exit(at91sam_wdt_exit);
325
326MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>");
327MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors");
328MODULE_LICENSE("GPL");
329MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);