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