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/kernel.h>
17 #include <linux/miscdevice.h>
18 #include <linux/module.h>
19 #include <linux/moduleparam.h>
20 #include <linux/platform_device.h>
21 #include <linux/types.h>
22 #include <linux/watchdog.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
30 static int wdt_time = WDT_DEFAULT_TIME;
31 static int nowayout = WATCHDOG_NOWAYOUT;
32
33 module_param(wdt_time, int, 0);
34 MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="__MODULE_STRING(WDT_DEFAULT_TIME) ")");
35
36 #ifdef CONFIG_WATCHDOG_NOWAYOUT
37 module_param(nowayout, int, 0);
38 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
39 #endif
40
41
42 static unsigned long at91wdt_busy;
43
44 /* ......................................................................... */
45
46 /*
47 * Disable the watchdog.
48 */
49 static 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 */
57 static 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 */
66 static 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 */
76 static 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 */
90 static 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 */
102 static 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
118 static 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 */
126 static 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 */
179 static 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
187 static 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
196 static struct miscdevice at91wdt_miscdev = {
197 .minor = WATCHDOG_MINOR,
198 .name = "watchdog",
199 .fops = &at91wdt_fops,
200 };
201
202 static 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
218 static 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
229 static void at91wdt_shutdown(struct platform_device *pdev)
230 {
231 at91_wdt_stop();
232 }
233
234 #ifdef CONFIG_PM
235
236 static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
237 {
238 at91_wdt_stop();
239 return 0;
240 }
241
242 static 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
254 static 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
266 static 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
277 static void __exit at91_wdt_exit(void)
278 {
279 platform_driver_unregister(&at91wdt_driver);
280 }
281
282 module_init(at91_wdt_init);
283 module_exit(at91_wdt_exit);
284
285 MODULE_AUTHOR("Andrew Victor");
286 MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
287 MODULE_LICENSE("GPL");
288 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
289 MODULE_ALIAS("platform:at91_wdt");
290
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