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/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>
19#include <linux/platform_device.h>
20#include <linux/types.h>
21#include <linux/watchdog.h>
22#include <asm/bitops.h>
23#include <asm/uaccess.h>
24#include <asm/arch/at91_st.h>
25
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="__MODULE_STRING(WDT_DEFAULT_TIME) ")");
35
36#ifdef CONFIG_WATCHDOG_NOWAYOUT
37module_param(nowayout, int, 0);
38MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
39#endif
40
41
42static unsigned long at91wdt_busy;
43
44/* ......................................................................... */
45
46/*
47 * Disable the watchdog.
48 */
49static void inline at91_wdt_stop(void)
50{
51	at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN);
52}
53
54/*
55 * Enable and reset the watchdog.
56 */
57static void inline at91_wdt_start(void)
58{
59	at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN | (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
60	at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
61}
62
63/*
64 * Reload the watchdog timer.  (ie, pat the watchdog)
65 */
66static void inline at91_wdt_reload(void)
67{
68	at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
69}
70
71/* ......................................................................... */
72
73/*
74 * Watchdog device is opened, and watchdog starts running.
75 */
76static int at91_wdt_open(struct inode *inode, struct file *file)
77{
78	if (test_and_set_bit(0, &at91wdt_busy))
79		return -EBUSY;
80
81	at91_wdt_start();
82	return nonseekable_open(inode, file);
83}
84
85/*
86 * Close the watchdog device.
87 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
88 *  disabled.
89 */
90static int at91_wdt_close(struct inode *inode, struct file *file)
91{
92	if (!nowayout)
93		at91_wdt_stop();	/* Disable the watchdog when file is closed */
94
95	clear_bit(0, &at91wdt_busy);
96	return 0;
97}
98
99/*
100 * Change the watchdog time interval.
101 */
102static int at91_wdt_settimeout(int new_time)
103{
104	/*
105	 * All counting occurs at SLOW_CLOCK / 128 = 0.256 Hz
106	 *
107	 * Since WDV is a 16-bit counter, the maximum period is
108	 * 65536 / 0.256 = 256 seconds.
109	 */
110	if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
111		return -EINVAL;
112
113	/* Set new watchdog time. It will be used when at91_wdt_start() is called. */
114	wdt_time = new_time;
115	return 0;
116}
117
118static struct watchdog_info at91_wdt_info = {
119	.identity	= "at91 watchdog",
120	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
121};
122
123/*
124 * Handle commands from user-space.
125 */
126static int at91_wdt_ioctl(struct inode *inode, struct file *file,
127		unsigned int cmd, unsigned long arg)
128{
129	void __user *argp = (void __user *)arg;
130	int __user *p = argp;
131	int new_value;
132
133	switch(cmd) {
134		case WDIOC_KEEPALIVE:
135			at91_wdt_reload();	/* pat the watchdog */
136			return 0;
137
138		case WDIOC_GETSUPPORT:
139			return copy_to_user(argp, &at91_wdt_info, sizeof(at91_wdt_info)) ? -EFAULT : 0;
140
141		case WDIOC_SETTIMEOUT:
142			if (get_user(new_value, p))
143				return -EFAULT;
144
145			if (at91_wdt_settimeout(new_value))
146				return -EINVAL;
147
148			/* Enable new time value */
149			at91_wdt_start();
150
151			/* Return current value */
152			return put_user(wdt_time, p);
153
154		case WDIOC_GETTIMEOUT:
155			return put_user(wdt_time, p);
156
157		case WDIOC_GETSTATUS:
158		case WDIOC_GETBOOTSTATUS:
159			return put_user(0, p);
160
161		case WDIOC_SETOPTIONS:
162			if (get_user(new_value, p))
163				return -EFAULT;
164
165			if (new_value & WDIOS_DISABLECARD)
166				at91_wdt_stop();
167			if (new_value & WDIOS_ENABLECARD)
168				at91_wdt_start();
169			return 0;
170
171		default:
172			return -ENOTTY;
173	}
174}
175
176/*
177 * Pat the watchdog whenever device is written to.
178 */
179static ssize_t at91_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
180{
181	at91_wdt_reload();		/* pat the watchdog */
182	return len;
183}
184
185/* ......................................................................... */
186
187static const struct file_operations at91wdt_fops = {
188	.owner		= THIS_MODULE,
189	.llseek		= no_llseek,
190	.ioctl		= at91_wdt_ioctl,
191	.open		= at91_wdt_open,
192	.release	= at91_wdt_close,
193	.write		= at91_wdt_write,
194};
195
196static struct miscdevice at91wdt_miscdev = {
197	.minor		= WATCHDOG_MINOR,
198	.name		= "watchdog",
199	.fops		= &at91wdt_fops,
200};
201
202static int __init at91wdt_probe(struct platform_device *pdev)
203{
204	int res;
205
206	if (at91wdt_miscdev.parent)
207		return -EBUSY;
208	at91wdt_miscdev.parent = &pdev->dev;
209
210	res = misc_register(&at91wdt_miscdev);
211	if (res)
212		return res;
213
214	printk("AT91 Watchdog Timer enabled (%d seconds%s)\n", wdt_time, nowayout ? ", nowayout" : "");
215	return 0;
216}
217
218static int __exit at91wdt_remove(struct platform_device *pdev)
219{
220	int res;
221
222	res = misc_deregister(&at91wdt_miscdev);
223	if (!res)
224		at91wdt_miscdev.parent = NULL;
225
226	return res;
227}
228
229static void at91wdt_shutdown(struct platform_device *pdev)
230{
231	at91_wdt_stop();
232}
233
234#ifdef CONFIG_PM
235
236static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
237{
238	at91_wdt_stop();
239	return 0;
240}
241
242static int at91wdt_resume(struct platform_device *pdev)
243{
244	if (at91wdt_busy)
245		at91_wdt_start();
246		return 0;
247}
248
249#else
250#define at91wdt_suspend NULL
251#define at91wdt_resume	NULL
252#endif
253
254static struct platform_driver at91wdt_driver = {
255	.probe		= at91wdt_probe,
256	.remove		= __exit_p(at91wdt_remove),
257	.shutdown	= at91wdt_shutdown,
258	.suspend	= at91wdt_suspend,
259	.resume		= at91wdt_resume,
260	.driver		= {
261		.name	= "at91_wdt",
262		.owner	= THIS_MODULE,
263	},
264};
265
266static int __init at91_wdt_init(void)
267{
268	/* Check that the heartbeat value is within range; 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, using %d\n", wdt_time);
272	}
273
274	return platform_driver_register(&at91wdt_driver);
275}
276
277static void __exit at91_wdt_exit(void)
278{
279	platform_driver_unregister(&at91wdt_driver);
280}
281
282module_init(at91_wdt_init);
283module_exit(at91_wdt_exit);
284
285MODULE_AUTHOR("Andrew Victor");
286MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
287MODULE_LICENSE("GPL");
288MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
289