Merge git://git.infradead.org/mtd-2.6
[linux-2.6] / drivers / char / watchdog / ks8695_wdt.c
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/errno.h>
12 #include <linux/fs.h>
13 #include <linux/init.h>
14 #include <linux/kernel.h>
15 #include <linux/miscdevice.h>
16 #include <linux/module.h>
17 #include <linux/moduleparam.h>
18 #include <linux/platform_device.h>
19 #include <linux/types.h>
20 #include <linux/watchdog.h>
21 #include <asm/bitops.h>
22 #include <asm/io.h>
23 #include <asm/uaccess.h>
24 #include <asm/arch/regs-timer.h>
25
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="__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 ks8695wdt_busy;
43
44 /* ......................................................................... */
45
46 /*
47  * Disable the watchdog.
48  */
49 static void inline ks8695_wdt_stop(void)
50 {
51         unsigned long tmcon;
52
53         /* disable timer0 */
54         tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
55         __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
56 }
57
58 /*
59  * Enable and reset the watchdog.
60  */
61 static void inline ks8695_wdt_start(void)
62 {
63         unsigned long tmcon;
64         unsigned long tval = wdt_time * CLOCK_TICK_RATE;
65
66         /* disable timer0 */
67         tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
68         __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
69
70         /* program timer0 */
71         __raw_writel(tval | T0TC_WATCHDOG, KS8695_TMR_VA + KS8695_T0TC);
72
73         /* re-enable timer0 */
74         tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
75         __raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
76 }
77
78 /*
79  * Reload the watchdog timer.  (ie, pat the watchdog)
80  */
81 static void inline ks8695_wdt_reload(void)
82 {
83         unsigned long tmcon;
84
85         /* disable, then re-enable timer0 */
86         tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
87         __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
88         __raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
89 }
90
91 /*
92  * Change the watchdog time interval.
93  */
94 static int ks8695_wdt_settimeout(int new_time)
95 {
96         /*
97          * All counting occurs at SLOW_CLOCK / 128 = 0.256 Hz
98          *
99          * Since WDV is a 16-bit counter, the maximum period is
100          * 65536 / 0.256 = 256 seconds.
101          */
102         if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
103                 return -EINVAL;
104
105         /* Set new watchdog time. It will be used when ks8695_wdt_start() is called. */
106         wdt_time = new_time;
107         return 0;
108 }
109
110 /* ......................................................................... */
111
112 /*
113  * Watchdog device is opened, and watchdog starts running.
114  */
115 static int ks8695_wdt_open(struct inode *inode, struct file *file)
116 {
117         if (test_and_set_bit(0, &ks8695wdt_busy))
118                 return -EBUSY;
119
120         ks8695_wdt_start();
121         return nonseekable_open(inode, file);
122 }
123
124 /*
125  * Close the watchdog device.
126  * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
127  *  disabled.
128  */
129 static int ks8695_wdt_close(struct inode *inode, struct file *file)
130 {
131         if (!nowayout)
132                 ks8695_wdt_stop();      /* Disable the watchdog when file is closed */
133
134         clear_bit(0, &ks8695wdt_busy);
135         return 0;
136 }
137
138 static struct watchdog_info ks8695_wdt_info = {
139         .identity       = "ks8695 watchdog",
140         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
141 };
142
143 /*
144  * Handle commands from user-space.
145  */
146 static int ks8695_wdt_ioctl(struct inode *inode, struct file *file,
147                 unsigned int cmd, unsigned long arg)
148 {
149         void __user *argp = (void __user *)arg;
150         int __user *p = argp;
151         int new_value;
152
153         switch(cmd) {
154                 case WDIOC_KEEPALIVE:
155                         ks8695_wdt_reload();    /* pat the watchdog */
156                         return 0;
157
158                 case WDIOC_GETSUPPORT:
159                         return copy_to_user(argp, &ks8695_wdt_info, sizeof(ks8695_wdt_info)) ? -EFAULT : 0;
160
161                 case WDIOC_SETTIMEOUT:
162                         if (get_user(new_value, p))
163                                 return -EFAULT;
164
165                         if (ks8695_wdt_settimeout(new_value))
166                                 return -EINVAL;
167
168                         /* Enable new time value */
169                         ks8695_wdt_start();
170
171                         /* Return current value */
172                         return put_user(wdt_time, p);
173
174                 case WDIOC_GETTIMEOUT:
175                         return put_user(wdt_time, p);
176
177                 case WDIOC_GETSTATUS:
178                 case WDIOC_GETBOOTSTATUS:
179                         return put_user(0, p);
180
181                 case WDIOC_SETOPTIONS:
182                         if (get_user(new_value, p))
183                                 return -EFAULT;
184
185                         if (new_value & WDIOS_DISABLECARD)
186                                 ks8695_wdt_stop();
187                         if (new_value & WDIOS_ENABLECARD)
188                                 ks8695_wdt_start();
189                         return 0;
190
191                 default:
192                         return -ENOTTY;
193         }
194 }
195
196 /*
197  * Pat the watchdog whenever device is written to.
198  */
199 static ssize_t ks8695_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
200 {
201         ks8695_wdt_reload();            /* pat the watchdog */
202         return len;
203 }
204
205 /* ......................................................................... */
206
207 static const struct file_operations ks8695wdt_fops = {
208         .owner          = THIS_MODULE,
209         .llseek         = no_llseek,
210         .ioctl          = ks8695_wdt_ioctl,
211         .open           = ks8695_wdt_open,
212         .release        = ks8695_wdt_close,
213         .write          = ks8695_wdt_write,
214 };
215
216 static struct miscdevice ks8695wdt_miscdev = {
217         .minor          = WATCHDOG_MINOR,
218         .name           = "watchdog",
219         .fops           = &ks8695wdt_fops,
220 };
221
222 static int __init ks8695wdt_probe(struct platform_device *pdev)
223 {
224         int res;
225
226         if (ks8695wdt_miscdev.parent)
227                 return -EBUSY;
228         ks8695wdt_miscdev.parent = &pdev->dev;
229
230         res = misc_register(&ks8695wdt_miscdev);
231         if (res)
232                 return res;
233
234         printk("KS8695 Watchdog Timer enabled (%d seconds%s)\n", wdt_time, nowayout ? ", nowayout" : "");
235         return 0;
236 }
237
238 static int __exit ks8695wdt_remove(struct platform_device *pdev)
239 {
240         int res;
241
242         res = misc_deregister(&ks8695wdt_miscdev);
243         if (!res)
244                 ks8695wdt_miscdev.parent = NULL;
245
246         return res;
247 }
248
249 static void ks8695wdt_shutdown(struct platform_device *pdev)
250 {
251         ks8695_wdt_stop();
252 }
253
254 #ifdef CONFIG_PM
255
256 static int ks8695wdt_suspend(struct platform_device *pdev, pm_message_t message)
257 {
258         ks8695_wdt_stop();
259         return 0;
260 }
261
262 static int ks8695wdt_resume(struct platform_device *pdev)
263 {
264         if (ks8695wdt_busy)
265                 ks8695_wdt_start();
266         return 0;
267 }
268
269 #else
270 #define ks8695wdt_suspend NULL
271 #define ks8695wdt_resume        NULL
272 #endif
273
274 static struct platform_driver ks8695wdt_driver = {
275         .probe          = ks8695wdt_probe,
276         .remove         = __exit_p(ks8695wdt_remove),
277         .shutdown       = ks8695wdt_shutdown,
278         .suspend        = ks8695wdt_suspend,
279         .resume         = ks8695wdt_resume,
280         .driver         = {
281                 .name   = "ks8695_wdt",
282                 .owner  = THIS_MODULE,
283         },
284 };
285
286 static int __init ks8695_wdt_init(void)
287 {
288         /* Check that the heartbeat value is within range; if not reset to the default */
289         if (ks8695_wdt_settimeout(wdt_time)) {
290                 ks8695_wdt_settimeout(WDT_DEFAULT_TIME);
291                 pr_info("ks8695_wdt: wdt_time value must be 1 <= wdt_time <= %i, using %d\n", wdt_time, WDT_MAX_TIME);
292         }
293
294         return platform_driver_register(&ks8695wdt_driver);
295 }
296
297 static void __exit ks8695_wdt_exit(void)
298 {
299         platform_driver_unregister(&ks8695wdt_driver);
300 }
301
302 module_init(ks8695_wdt_init);
303 module_exit(ks8695_wdt_exit);
304
305 MODULE_AUTHOR("Andrew Victor");
306 MODULE_DESCRIPTION("Watchdog driver for KS8695");
307 MODULE_LICENSE("GPL");
308 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);