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