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Linux/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         int res;
258 
259         res = misc_deregister(&ks8695wdt_miscdev);
260         if (!res)
261                 ks8695wdt_miscdev.parent = NULL;
262 
263         return res;
264 }
265 
266 static void ks8695wdt_shutdown(struct platform_device *pdev)
267 {
268         ks8695_wdt_stop();
269 }
270 
271 #ifdef CONFIG_PM
272 
273 static int ks8695wdt_suspend(struct platform_device *pdev, pm_message_t message)
274 {
275         ks8695_wdt_stop();
276         return 0;
277 }
278 
279 static int ks8695wdt_resume(struct platform_device *pdev)
280 {
281         if (ks8695wdt_busy)
282                 ks8695_wdt_start();
283         return 0;
284 }
285 
286 #else
287 #define ks8695wdt_suspend NULL
288 #define ks8695wdt_resume        NULL
289 #endif
290 
291 static struct platform_driver ks8695wdt_driver = {
292         .probe          = ks8695wdt_probe,
293         .remove         = ks8695wdt_remove,
294         .shutdown       = ks8695wdt_shutdown,
295         .suspend        = ks8695wdt_suspend,
296         .resume         = ks8695wdt_resume,
297         .driver         = {
298                 .name   = "ks8695_wdt",
299                 .owner  = THIS_MODULE,
300         },
301 };
302 
303 static int __init ks8695_wdt_init(void)
304 {
305         /* Check that the heartbeat value is within range;
306            if not reset to the default */
307         if (ks8695_wdt_settimeout(wdt_time)) {
308                 ks8695_wdt_settimeout(WDT_DEFAULT_TIME);
309                 pr_info("ks8695_wdt: wdt_time value must be 1 <= wdt_time <= %i"
310                                         ", using %d\n", wdt_time, WDT_MAX_TIME);
311         }
312         return platform_driver_register(&ks8695wdt_driver);
313 }
314 
315 static void __exit ks8695_wdt_exit(void)
316 {
317         platform_driver_unregister(&ks8695wdt_driver);
318 }
319 
320 module_init(ks8695_wdt_init);
321 module_exit(ks8695_wdt_exit);
322 
323 MODULE_AUTHOR("Andrew Victor");
324 MODULE_DESCRIPTION("Watchdog driver for KS8695");
325 MODULE_LICENSE("GPL");
326 MODULE_ALIAS("platform:ks8695_wdt");
327 

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