1 /*
2 * Watchdog driver for Kendin/Micrel KS8695.
3 *
4 * (C) 2007 Andrew Victor
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11 #include <linux/bitops.h>
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 <linux/io.h>
23 #include <linux/uaccess.h>
24 #include <mach/timex.h>
25 #include <mach/regs-timer.h>
26
27 #define WDT_DEFAULT_TIME 5 /* seconds */
28 #define WDT_MAX_TIME 171 /* 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="
35 __MODULE_STRING(WDT_DEFAULT_TIME) ")");
36
37 #ifdef CONFIG_WATCHDOG_NOWAYOUT
38 module_param(nowayout, int, 0);
39 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
40 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
41 #endif
42
43
44 static unsigned long ks8695wdt_busy;
45 static spinlock_t ks8695_lock;
46
47 /* ......................................................................... */
48
49 /*
50 * Disable the watchdog.
51 */
52 static inline void ks8695_wdt_stop(void)
53 {
54 unsigned long tmcon;
55
56 spin_lock(&ks8695_lock);
57 /* disable timer0 */
58 tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
59 __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
60 spin_unlock(&ks8695_lock);
61 }
62
63 /*
64 * Enable and reset the watchdog.
65 */
66 static inline void ks8695_wdt_start(void)
67 {
68 unsigned long tmcon;
69 unsigned long tval = wdt_time * KS8695_CLOCK_RATE;
70
71 spin_lock(&ks8695_lock);
72 /* disable timer0 */
73 tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
74 __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
75
76 /* program timer0 */
77 __raw_writel(tval | T0TC_WATCHDOG, KS8695_TMR_VA + KS8695_T0TC);
78
79 /* re-enable timer0 */
80 tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
81 __raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
82 spin_unlock(&ks8695_lock);
83 }
84
85 /*
86 * Reload the watchdog timer. (ie, pat the watchdog)
87 */
88 static inline void ks8695_wdt_reload(void)
89 {
90 unsigned long tmcon;
91
92 spin_lock(&ks8695_lock);
93 /* disable, then re-enable timer0 */
94 tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
95 __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
96 __raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
97 spin_unlock(&ks8695_lock);
98 }
99
100 /*
101 * Change the watchdog time interval.
102 */
103 static int ks8695_wdt_settimeout(int new_time)
104 {
105 /*
106 * All counting occurs at KS8695_CLOCK_RATE / 128 = 0.256 Hz
107 *
108 * Since WDV is a 16-bit counter, the maximum period is
109 * 65536 / 0.256 = 256 seconds.
110 */
111 if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
112 return -EINVAL;
113
114 /* Set new watchdog time. It will be used when
115 ks8695_wdt_start() is called. */
116 wdt_time = new_time;
117 return 0;
118 }
119
120 /* ......................................................................... */
121
122 /*
123 * Watchdog device is opened, and watchdog starts running.
124 */
125 static int ks8695_wdt_open(struct inode *inode, struct file *file)
126 {
127 if (test_and_set_bit(0, &ks8695wdt_busy))
128 return -EBUSY;
129
130 ks8695_wdt_start();
131 return nonseekable_open(inode, file);
132 }
133
134 /*
135 * Close the watchdog device.
136 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
137 * disabled.
138 */
139 static int ks8695_wdt_close(struct inode *inode, struct file *file)
140 {
141 /* Disable the watchdog when file is closed */
142 if (!nowayout)
143 ks8695_wdt_stop();
144 clear_bit(0, &ks8695wdt_busy);
145 return 0;
146 }
147
148 static struct watchdog_info ks8695_wdt_info = {
149 .identity = "ks8695 watchdog",
150 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
151 };
152
153 /*
154 * Handle commands from user-space.
155 */
156 static long ks8695_wdt_ioctl(struct file *file, unsigned int cmd,
157 unsigned long arg)
158 {
159 void __user *argp = (void __user *)arg;
160 int __user *p = argp;
161 int new_value;
162
163 switch (cmd) {
164 case WDIOC_GETSUPPORT:
165 return copy_to_user(argp, &ks8695_wdt_info,
166 sizeof(ks8695_wdt_info)) ? -EFAULT : 0;
167 case WDIOC_GETSTATUS:
168 case WDIOC_GETBOOTSTATUS:
169 return put_user(0, p);
170 case WDIOC_SETOPTIONS:
171 if (get_user(new_value, p))
172 return -EFAULT;
173 if (new_value & WDIOS_DISABLECARD)
174 ks8695_wdt_stop();
175 if (new_value & WDIOS_ENABLECARD)
176 ks8695_wdt_start();
177 return 0;
178 case WDIOC_KEEPALIVE:
179 ks8695_wdt_reload(); /* pat the watchdog */
180 return 0;
181 case WDIOC_SETTIMEOUT:
182 if (get_user(new_value, p))
183 return -EFAULT;
184 if (ks8695_wdt_settimeout(new_value))
185 return -EINVAL;
186 /* Enable new time value */
187 ks8695_wdt_start();
188 /* Return current value */
189 return put_user(wdt_time, p);
190 case WDIOC_GETTIMEOUT:
191 return put_user(wdt_time, p);
192 default:
193 return -ENOTTY;
194 }
195 }
196
197 /*
198 * Pat the watchdog whenever device is written to.
199 */
200 static ssize_t ks8695_wdt_write(struct file *file, const char *data,
201 size_t len, loff_t *ppos)
202 {
203 ks8695_wdt_reload(); /* pat the watchdog */
204 return len;
205 }
206
207 /* ......................................................................... */
208
209 static const struct file_operations ks8695wdt_fops = {
210 .owner = THIS_MODULE,
211 .llseek = no_llseek,
212 .unlocked_ioctl = ks8695_wdt_ioctl,
213 .open = ks8695_wdt_open,
214 .release = ks8695_wdt_close,
215 .write = ks8695_wdt_write,
216 };
217
218 static struct miscdevice ks8695wdt_miscdev = {
219 .minor = WATCHDOG_MINOR,
220 .name = "watchdog",
221 .fops = &ks8695wdt_fops,
222 };
223
224 static int __devinit ks8695wdt_probe(struct platform_device *pdev)
225 {
226 int res;
227
228 if (ks8695wdt_miscdev.parent)
229 return -EBUSY;
230 ks8695wdt_miscdev.parent = &pdev->dev;
231
232 res = misc_register(&ks8695wdt_miscdev);
233 if (res)
234 return res;
235
236 printk(KERN_INFO "KS8695 Watchdog Timer enabled (%d seconds%s)\n",
237 wdt_time, nowayout ? ", nowayout" : "");
238 return 0;
239 }
240
241 static int __devexit ks8695wdt_remove(struct platform_device *pdev)
242 {
243 int res;
244
245 res = misc_deregister(&ks8695wdt_miscdev);
246 if (!res)
247 ks8695wdt_miscdev.parent = NULL;
248
249 return res;
250 }
251
252 static void ks8695wdt_shutdown(struct platform_device *pdev)
253 {
254 ks8695_wdt_stop();
255 }
256
257 #ifdef CONFIG_PM
258
259 static int ks8695wdt_suspend(struct platform_device *pdev, pm_message_t message)
260 {
261 ks8695_wdt_stop();
262 return 0;
263 }
264
265 static int ks8695wdt_resume(struct platform_device *pdev)
266 {
267 if (ks8695wdt_busy)
268 ks8695_wdt_start();
269 return 0;
270 }
271
272 #else
273 #define ks8695wdt_suspend NULL
274 #define ks8695wdt_resume NULL
275 #endif
276
277 static struct platform_driver ks8695wdt_driver = {
278 .probe = ks8695wdt_probe,
279 .remove = __devexit_p(ks8695wdt_remove),
280 .shutdown = ks8695wdt_shutdown,
281 .suspend = ks8695wdt_suspend,
282 .resume = ks8695wdt_resume,
283 .driver = {
284 .name = "ks8695_wdt",
285 .owner = THIS_MODULE,
286 },
287 };
288
289 static int __init ks8695_wdt_init(void)
290 {
291 spin_lock_init(&ks8695_lock);
292 /* Check that the heartbeat value is within range;
293 if not reset to the default */
294 if (ks8695_wdt_settimeout(wdt_time)) {
295 ks8695_wdt_settimeout(WDT_DEFAULT_TIME);
296 pr_info("ks8695_wdt: wdt_time value must be 1 <= wdt_time <= %i"
297 ", using %d\n", wdt_time, WDT_MAX_TIME);
298 }
299 return platform_driver_register(&ks8695wdt_driver);
300 }
301
302 static void __exit ks8695_wdt_exit(void)
303 {
304 platform_driver_unregister(&ks8695wdt_driver);
305 }
306
307 module_init(ks8695_wdt_init);
308 module_exit(ks8695_wdt_exit);
309
310 MODULE_AUTHOR("Andrew Victor");
311 MODULE_DESCRIPTION("Watchdog driver for KS8695");
312 MODULE_LICENSE("GPL");
313 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
314 MODULE_ALIAS("platform:ks8695_wdt");
315
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