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 #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 * CLOCK_TICK_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 SLOW_CLOCK / 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 __init 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 __exit 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         = __exit_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, using %d\n",
 297                                                         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");