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[karo-tx-linux.git] / drivers / 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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13 #include <linux/bitops.h>
14 #include <linux/errno.h>
15 #include <linux/fs.h>
16 #include <linux/init.h>
17 #include <linux/kernel.h>
18 #include <linux/miscdevice.h>
19 #include <linux/module.h>
20 #include <linux/moduleparam.h>
21 #include <linux/platform_device.h>
22 #include <linux/types.h>
23 #include <linux/watchdog.h>
24 #include <linux/io.h>
25 #include <linux/uaccess.h>
26 #include <mach/hardware.h>
27
28 #define KS8695_TMR_OFFSET       (0xF0000 + 0xE400)
29 #define KS8695_TMR_VA           (KS8695_IO_VA + KS8695_TMR_OFFSET)
30
31 /*
32  * Timer registers
33  */
34 #define KS8695_TMCON            (0x00)          /* Timer Control Register */
35 #define KS8695_T0TC             (0x08)          /* Timer 0 Timeout Count Register */
36 #define TMCON_T0EN              (1 << 0)        /* Timer 0 Enable */
37
38 /* Timer0 Timeout Counter Register */
39 #define T0TC_WATCHDOG           (0xff)          /* Enable watchdog mode */
40
41 #define WDT_DEFAULT_TIME        5       /* seconds */
42 #define WDT_MAX_TIME            171     /* seconds */
43
44 static int wdt_time = WDT_DEFAULT_TIME;
45 static bool nowayout = WATCHDOG_NOWAYOUT;
46
47 module_param(wdt_time, int, 0);
48 MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
49                                         __MODULE_STRING(WDT_DEFAULT_TIME) ")");
50
51 #ifdef CONFIG_WATCHDOG_NOWAYOUT
52 module_param(nowayout, bool, 0);
53 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
54                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
55 #endif
56
57
58 static unsigned long ks8695wdt_busy;
59 static DEFINE_SPINLOCK(ks8695_lock);
60
61 /* ......................................................................... */
62
63 /*
64  * Disable the watchdog.
65  */
66 static inline void ks8695_wdt_stop(void)
67 {
68         unsigned long tmcon;
69
70         spin_lock(&ks8695_lock);
71         /* disable timer0 */
72         tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
73         __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
74         spin_unlock(&ks8695_lock);
75 }
76
77 /*
78  * Enable and reset the watchdog.
79  */
80 static inline void ks8695_wdt_start(void)
81 {
82         unsigned long tmcon;
83         unsigned long tval = wdt_time * KS8695_CLOCK_RATE;
84
85         spin_lock(&ks8695_lock);
86         /* disable timer0 */
87         tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
88         __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
89
90         /* program timer0 */
91         __raw_writel(tval | T0TC_WATCHDOG, KS8695_TMR_VA + KS8695_T0TC);
92
93         /* re-enable timer0 */
94         tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
95         __raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
96         spin_unlock(&ks8695_lock);
97 }
98
99 /*
100  * Reload the watchdog timer.  (ie, pat the watchdog)
101  */
102 static inline void ks8695_wdt_reload(void)
103 {
104         unsigned long tmcon;
105
106         spin_lock(&ks8695_lock);
107         /* disable, then re-enable timer0 */
108         tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
109         __raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
110         __raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
111         spin_unlock(&ks8695_lock);
112 }
113
114 /*
115  * Change the watchdog time interval.
116  */
117 static int ks8695_wdt_settimeout(int new_time)
118 {
119         /*
120          * All counting occurs at KS8695_CLOCK_RATE / 128 = 0.256 Hz
121          *
122          * Since WDV is a 16-bit counter, the maximum period is
123          * 65536 / 0.256 = 256 seconds.
124          */
125         if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
126                 return -EINVAL;
127
128         /* Set new watchdog time. It will be used when
129            ks8695_wdt_start() is called. */
130         wdt_time = new_time;
131         return 0;
132 }
133
134 /* ......................................................................... */
135
136 /*
137  * Watchdog device is opened, and watchdog starts running.
138  */
139 static int ks8695_wdt_open(struct inode *inode, struct file *file)
140 {
141         if (test_and_set_bit(0, &ks8695wdt_busy))
142                 return -EBUSY;
143
144         ks8695_wdt_start();
145         return nonseekable_open(inode, file);
146 }
147
148 /*
149  * Close the watchdog device.
150  * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
151  *  disabled.
152  */
153 static int ks8695_wdt_close(struct inode *inode, struct file *file)
154 {
155         /* Disable the watchdog when file is closed */
156         if (!nowayout)
157                 ks8695_wdt_stop();
158         clear_bit(0, &ks8695wdt_busy);
159         return 0;
160 }
161
162 static const struct watchdog_info ks8695_wdt_info = {
163         .identity       = "ks8695 watchdog",
164         .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
165 };
166
167 /*
168  * Handle commands from user-space.
169  */
170 static long ks8695_wdt_ioctl(struct file *file, unsigned int cmd,
171                                                         unsigned long arg)
172 {
173         void __user *argp = (void __user *)arg;
174         int __user *p = argp;
175         int new_value;
176
177         switch (cmd) {
178         case WDIOC_GETSUPPORT:
179                 return copy_to_user(argp, &ks8695_wdt_info,
180                                         sizeof(ks8695_wdt_info)) ? -EFAULT : 0;
181         case WDIOC_GETSTATUS:
182         case WDIOC_GETBOOTSTATUS:
183                 return put_user(0, p);
184         case WDIOC_SETOPTIONS:
185                 if (get_user(new_value, p))
186                         return -EFAULT;
187                 if (new_value & WDIOS_DISABLECARD)
188                         ks8695_wdt_stop();
189                 if (new_value & WDIOS_ENABLECARD)
190                         ks8695_wdt_start();
191                 return 0;
192         case WDIOC_KEEPALIVE:
193                 ks8695_wdt_reload();    /* pat the watchdog */
194                 return 0;
195         case WDIOC_SETTIMEOUT:
196                 if (get_user(new_value, p))
197                         return -EFAULT;
198                 if (ks8695_wdt_settimeout(new_value))
199                         return -EINVAL;
200                 /* Enable new time value */
201                 ks8695_wdt_start();
202                 /* Return current value */
203                 return put_user(wdt_time, p);
204         case WDIOC_GETTIMEOUT:
205                 return put_user(wdt_time, p);
206         default:
207                 return -ENOTTY;
208         }
209 }
210
211 /*
212  * Pat the watchdog whenever device is written to.
213  */
214 static ssize_t ks8695_wdt_write(struct file *file, const char *data,
215                                                 size_t len, loff_t *ppos)
216 {
217         ks8695_wdt_reload();            /* pat the watchdog */
218         return len;
219 }
220
221 /* ......................................................................... */
222
223 static const struct file_operations ks8695wdt_fops = {
224         .owner          = THIS_MODULE,
225         .llseek         = no_llseek,
226         .unlocked_ioctl = ks8695_wdt_ioctl,
227         .open           = ks8695_wdt_open,
228         .release        = ks8695_wdt_close,
229         .write          = ks8695_wdt_write,
230 };
231
232 static struct miscdevice ks8695wdt_miscdev = {
233         .minor          = WATCHDOG_MINOR,
234         .name           = "watchdog",
235         .fops           = &ks8695wdt_fops,
236 };
237
238 static int ks8695wdt_probe(struct platform_device *pdev)
239 {
240         int res;
241
242         if (ks8695wdt_miscdev.parent)
243                 return -EBUSY;
244         ks8695wdt_miscdev.parent = &pdev->dev;
245
246         res = misc_register(&ks8695wdt_miscdev);
247         if (res)
248                 return res;
249
250         pr_info("KS8695 Watchdog Timer enabled (%d seconds%s)\n",
251                 wdt_time, nowayout ? ", nowayout" : "");
252         return 0;
253 }
254
255 static int ks8695wdt_remove(struct platform_device *pdev)
256 {
257         misc_deregister(&ks8695wdt_miscdev);
258         ks8695wdt_miscdev.parent = NULL;
259
260         return 0;
261 }
262
263 static void ks8695wdt_shutdown(struct platform_device *pdev)
264 {
265         ks8695_wdt_stop();
266 }
267
268 #ifdef CONFIG_PM
269
270 static int ks8695wdt_suspend(struct platform_device *pdev, pm_message_t message)
271 {
272         ks8695_wdt_stop();
273         return 0;
274 }
275
276 static int ks8695wdt_resume(struct platform_device *pdev)
277 {
278         if (ks8695wdt_busy)
279                 ks8695_wdt_start();
280         return 0;
281 }
282
283 #else
284 #define ks8695wdt_suspend NULL
285 #define ks8695wdt_resume        NULL
286 #endif
287
288 static struct platform_driver ks8695wdt_driver = {
289         .probe          = ks8695wdt_probe,
290         .remove         = ks8695wdt_remove,
291         .shutdown       = ks8695wdt_shutdown,
292         .suspend        = ks8695wdt_suspend,
293         .resume         = ks8695wdt_resume,
294         .driver         = {
295                 .name   = "ks8695_wdt",
296         },
297 };
298
299 static int __init ks8695_wdt_init(void)
300 {
301         /* Check that the heartbeat value is within range;
302            if not reset to the default */
303         if (ks8695_wdt_settimeout(wdt_time)) {
304                 ks8695_wdt_settimeout(WDT_DEFAULT_TIME);
305                 pr_info("ks8695_wdt: wdt_time value must be 1 <= wdt_time <= %i"
306                                         ", using %d\n", wdt_time, WDT_MAX_TIME);
307         }
308         return platform_driver_register(&ks8695wdt_driver);
309 }
310
311 static void __exit ks8695_wdt_exit(void)
312 {
313         platform_driver_unregister(&ks8695wdt_driver);
314 }
315
316 module_init(ks8695_wdt_init);
317 module_exit(ks8695_wdt_exit);
318
319 MODULE_AUTHOR("Andrew Victor");
320 MODULE_DESCRIPTION("Watchdog driver for KS8695");
321 MODULE_LICENSE("GPL");
322 MODULE_ALIAS("platform:ks8695_wdt");