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");