linux/drivers/watchdog/at91rm9200_wdt.c
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   1/*
   2 * Watchdog driver for Atmel AT91RM9200 (Thunder)
   3 *
   4 *  Copyright (C) 2003 SAN People (Pty) Ltd
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public License
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the License, or (at your option) any later version.
  10 */
  11
  12#include <linux/bitops.h>
  13#include <linux/errno.h>
  14#include <linux/fs.h>
  15#include <linux/init.h>
  16#include <linux/io.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/uaccess.h>
  25#include <mach/at91_st.h>
  26
  27#define WDT_DEFAULT_TIME        5       /* seconds */
  28#define WDT_MAX_TIME            256     /* 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,
  40                "Watchdog cannot be stopped once started (default="
  41                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  42#endif
  43
  44
  45static unsigned long at91wdt_busy;
  46
  47/* ......................................................................... */
  48
  49/*
  50 * Disable the watchdog.
  51 */
  52static inline void at91_wdt_stop(void)
  53{
  54        at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN);
  55}
  56
  57/*
  58 * Enable and reset the watchdog.
  59 */
  60static inline void at91_wdt_start(void)
  61{
  62        at91_sys_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN |
  63                                (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
  64        at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
  65}
  66
  67/*
  68 * Reload the watchdog timer.  (ie, pat the watchdog)
  69 */
  70static inline void at91_wdt_reload(void)
  71{
  72        at91_sys_write(AT91_ST_CR, AT91_ST_WDRST);
  73}
  74
  75/* ......................................................................... */
  76
  77/*
  78 * Watchdog device is opened, and watchdog starts running.
  79 */
  80static int at91_wdt_open(struct inode *inode, struct file *file)
  81{
  82        if (test_and_set_bit(0, &at91wdt_busy))
  83                return -EBUSY;
  84
  85        at91_wdt_start();
  86        return nonseekable_open(inode, file);
  87}
  88
  89/*
  90 * Close the watchdog device.
  91 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
  92 *  disabled.
  93 */
  94static int at91_wdt_close(struct inode *inode, struct file *file)
  95{
  96        /* Disable the watchdog when file is closed */
  97        if (!nowayout)
  98                at91_wdt_stop();
  99
 100        clear_bit(0, &at91wdt_busy);
 101        return 0;
 102}
 103
 104/*
 105 * Change the watchdog time interval.
 106 */
 107static int at91_wdt_settimeout(int new_time)
 108{
 109        /*
 110         * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
 111         *
 112         * Since WDV is a 16-bit counter, the maximum period is
 113         * 65536 / 256 = 256 seconds.
 114         */
 115        if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
 116                return -EINVAL;
 117
 118        /* Set new watchdog time. It will be used when
 119           at91_wdt_start() is called. */
 120        wdt_time = new_time;
 121        return 0;
 122}
 123
 124static const struct watchdog_info at91_wdt_info = {
 125        .identity       = "at91 watchdog",
 126        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 127};
 128
 129/*
 130 * Handle commands from user-space.
 131 */
 132static long at91_wdt_ioctl(struct file *file,
 133                                        unsigned int cmd, unsigned long arg)
 134{
 135        void __user *argp = (void __user *)arg;
 136        int __user *p = argp;
 137        int new_value;
 138
 139        switch (cmd) {
 140        case WDIOC_GETSUPPORT:
 141                return copy_to_user(argp, &at91_wdt_info,
 142                                sizeof(at91_wdt_info)) ? -EFAULT : 0;
 143        case WDIOC_GETSTATUS:
 144        case WDIOC_GETBOOTSTATUS:
 145                return put_user(0, p);
 146        case WDIOC_SETOPTIONS:
 147                if (get_user(new_value, p))
 148                        return -EFAULT;
 149                if (new_value & WDIOS_DISABLECARD)
 150                        at91_wdt_stop();
 151                if (new_value & WDIOS_ENABLECARD)
 152                        at91_wdt_start();
 153                return 0;
 154        case WDIOC_KEEPALIVE:
 155                at91_wdt_reload();      /* pat the watchdog */
 156                return 0;
 157        case WDIOC_SETTIMEOUT:
 158                if (get_user(new_value, p))
 159                        return -EFAULT;
 160                if (at91_wdt_settimeout(new_value))
 161                        return -EINVAL;
 162                /* Enable new time value */
 163                at91_wdt_start();
 164                /* Return current value */
 165                return put_user(wdt_time, p);
 166        case WDIOC_GETTIMEOUT:
 167                return put_user(wdt_time, p);
 168        default:
 169                return -ENOTTY;
 170        }
 171}
 172
 173/*
 174 * Pat the watchdog whenever device is written to.
 175 */
 176static ssize_t at91_wdt_write(struct file *file, const char *data,
 177                                                size_t len, loff_t *ppos)
 178{
 179        at91_wdt_reload();              /* pat the watchdog */
 180        return len;
 181}
 182
 183/* ......................................................................... */
 184
 185static const struct file_operations at91wdt_fops = {
 186        .owner          = THIS_MODULE,
 187        .llseek         = no_llseek,
 188        .unlocked_ioctl = at91_wdt_ioctl,
 189        .open           = at91_wdt_open,
 190        .release        = at91_wdt_close,
 191        .write          = at91_wdt_write,
 192};
 193
 194static struct miscdevice at91wdt_miscdev = {
 195        .minor          = WATCHDOG_MINOR,
 196        .name           = "watchdog",
 197        .fops           = &at91wdt_fops,
 198};
 199
 200static int __devinit at91wdt_probe(struct platform_device *pdev)
 201{
 202        int res;
 203
 204        if (at91wdt_miscdev.parent)
 205                return -EBUSY;
 206        at91wdt_miscdev.parent = &pdev->dev;
 207
 208        res = misc_register(&at91wdt_miscdev);
 209        if (res)
 210                return res;
 211
 212        printk(KERN_INFO "AT91 Watchdog Timer enabled (%d seconds%s)\n",
 213                                wdt_time, nowayout ? ", nowayout" : "");
 214        return 0;
 215}
 216
 217static int __devexit at91wdt_remove(struct platform_device *pdev)
 218{
 219        int res;
 220
 221        res = misc_deregister(&at91wdt_miscdev);
 222        if (!res)
 223                at91wdt_miscdev.parent = NULL;
 224
 225        return res;
 226}
 227
 228static void at91wdt_shutdown(struct platform_device *pdev)
 229{
 230        at91_wdt_stop();
 231}
 232
 233#ifdef CONFIG_PM
 234
 235static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
 236{
 237        at91_wdt_stop();
 238        return 0;
 239}
 240
 241static int at91wdt_resume(struct platform_device *pdev)
 242{
 243        if (at91wdt_busy)
 244                at91_wdt_start();
 245        return 0;
 246}
 247
 248#else
 249#define at91wdt_suspend NULL
 250#define at91wdt_resume  NULL
 251#endif
 252
 253static struct platform_driver at91wdt_driver = {
 254        .probe          = at91wdt_probe,
 255        .remove         = __devexit_p(at91wdt_remove),
 256        .shutdown       = at91wdt_shutdown,
 257        .suspend        = at91wdt_suspend,
 258        .resume         = at91wdt_resume,
 259        .driver         = {
 260                .name   = "at91_wdt",
 261                .owner  = THIS_MODULE,
 262        },
 263};
 264
 265static int __init at91_wdt_init(void)
 266{
 267        /* Check that the heartbeat value is within range;
 268           if not reset to the default */
 269        if (at91_wdt_settimeout(wdt_time)) {
 270                at91_wdt_settimeout(WDT_DEFAULT_TIME);
 271                pr_info("at91_wdt: wdt_time value must be 1 <= wdt_time <= 256"
 272                                                ", using %d\n", wdt_time);
 273        }
 274
 275        return platform_driver_register(&at91wdt_driver);
 276}
 277
 278static void __exit at91_wdt_exit(void)
 279{
 280        platform_driver_unregister(&at91wdt_driver);
 281}
 282
 283module_init(at91_wdt_init);
 284module_exit(at91_wdt_exit);
 285
 286MODULE_AUTHOR("Andrew Victor");
 287MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
 288MODULE_LICENSE("GPL");
 289MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 290MODULE_ALIAS("platform:at91_wdt");
 291