linux/drivers/watchdog/ks8695_wdt.c
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   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
  30static int wdt_time = WDT_DEFAULT_TIME;
  31static int nowayout = WATCHDOG_NOWAYOUT;
  32
  33module_param(wdt_time, int, 0);
  34MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
  35                                        __MODULE_STRING(WDT_DEFAULT_TIME) ")");
  36
  37#ifdef CONFIG_WATCHDOG_NOWAYOUT
  38module_param(nowayout, int, 0);
  39MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  40                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  41#endif
  42
  43
  44static unsigned long ks8695wdt_busy;
  45static spinlock_t ks8695_lock;
  46
  47/* ......................................................................... */
  48
  49/*
  50 * Disable the watchdog.
  51 */
  52static 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 */
  66static inline void ks8695_wdt_start(void)
  67{
  68        unsigned long tmcon;
  69        unsigned long tval = wdt_time * KS8695_CLOCK_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 */
  88static 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 */
 103static int ks8695_wdt_settimeout(int new_time)
 104{
 105        /*
 106         * All counting occurs at KS8695_CLOCK_RATE / 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 */
 125static 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 */
 139static 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
 148static const 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 */
 156static 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 */
 200static 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
 209static 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
 218static struct miscdevice ks8695wdt_miscdev = {
 219        .minor          = WATCHDOG_MINOR,
 220        .name           = "watchdog",
 221        .fops           = &ks8695wdt_fops,
 222};
 223
 224static int __devinit 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
 241static int __devexit 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
 252static void ks8695wdt_shutdown(struct platform_device *pdev)
 253{
 254        ks8695_wdt_stop();
 255}
 256
 257#ifdef CONFIG_PM
 258
 259static int ks8695wdt_suspend(struct platform_device *pdev, pm_message_t message)
 260{
 261        ks8695_wdt_stop();
 262        return 0;
 263}
 264
 265static 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
 277static struct platform_driver ks8695wdt_driver = {
 278        .probe          = ks8695wdt_probe,
 279        .remove         = __devexit_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
 289static 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"
 297                                        ", using %d\n", wdt_time, WDT_MAX_TIME);
 298        }
 299        return platform_driver_register(&ks8695wdt_driver);
 300}
 301
 302static void __exit ks8695_wdt_exit(void)
 303{
 304        platform_driver_unregister(&ks8695wdt_driver);
 305}
 306
 307module_init(ks8695_wdt_init);
 308module_exit(ks8695_wdt_exit);
 309
 310MODULE_AUTHOR("Andrew Victor");
 311MODULE_DESCRIPTION("Watchdog driver for KS8695");
 312MODULE_LICENSE("GPL");
 313MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 314MODULE_ALIAS("platform:ks8695_wdt");
 315