linux/drivers/watchdog/at91rm9200_wdt.c
<<
>>
Prefs
   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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14#include <linux/bitops.h>
  15#include <linux/errno.h>
  16#include <linux/fs.h>
  17#include <linux/init.h>
  18#include <linux/io.h>
  19#include <linux/kernel.h>
  20#include <linux/miscdevice.h>
  21#include <linux/module.h>
  22#include <linux/moduleparam.h>
  23#include <linux/platform_device.h>
  24#include <linux/types.h>
  25#include <linux/watchdog.h>
  26#include <linux/uaccess.h>
  27#include <mach/at91_st.h>
  28
  29#define WDT_DEFAULT_TIME        5       /* seconds */
  30#define WDT_MAX_TIME            256     /* seconds */
  31
  32static int wdt_time = WDT_DEFAULT_TIME;
  33static bool nowayout = WATCHDOG_NOWAYOUT;
  34
  35module_param(wdt_time, int, 0);
  36MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
  37                                __MODULE_STRING(WDT_DEFAULT_TIME) ")");
  38
  39#ifdef CONFIG_WATCHDOG_NOWAYOUT
  40module_param(nowayout, bool, 0);
  41MODULE_PARM_DESC(nowayout,
  42                "Watchdog cannot be stopped once started (default="
  43                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  44#endif
  45
  46
  47static unsigned long at91wdt_busy;
  48
  49/* ......................................................................... */
  50
  51/*
  52 * Disable the watchdog.
  53 */
  54static inline void at91_wdt_stop(void)
  55{
  56        at91_st_write(AT91_ST_WDMR, AT91_ST_EXTEN);
  57}
  58
  59/*
  60 * Enable and reset the watchdog.
  61 */
  62static inline void at91_wdt_start(void)
  63{
  64        at91_st_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN |
  65                                (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
  66        at91_st_write(AT91_ST_CR, AT91_ST_WDRST);
  67}
  68
  69/*
  70 * Reload the watchdog timer.  (ie, pat the watchdog)
  71 */
  72static inline void at91_wdt_reload(void)
  73{
  74        at91_st_write(AT91_ST_CR, AT91_ST_WDRST);
  75}
  76
  77/* ......................................................................... */
  78
  79/*
  80 * Watchdog device is opened, and watchdog starts running.
  81 */
  82static int at91_wdt_open(struct inode *inode, struct file *file)
  83{
  84        if (test_and_set_bit(0, &at91wdt_busy))
  85                return -EBUSY;
  86
  87        at91_wdt_start();
  88        return nonseekable_open(inode, file);
  89}
  90
  91/*
  92 * Close the watchdog device.
  93 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
  94 *  disabled.
  95 */
  96static int at91_wdt_close(struct inode *inode, struct file *file)
  97{
  98        /* Disable the watchdog when file is closed */
  99        if (!nowayout)
 100                at91_wdt_stop();
 101
 102        clear_bit(0, &at91wdt_busy);
 103        return 0;
 104}
 105
 106/*
 107 * Change the watchdog time interval.
 108 */
 109static int at91_wdt_settimeout(int new_time)
 110{
 111        /*
 112         * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
 113         *
 114         * Since WDV is a 16-bit counter, the maximum period is
 115         * 65536 / 256 = 256 seconds.
 116         */
 117        if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
 118                return -EINVAL;
 119
 120        /* Set new watchdog time. It will be used when
 121           at91_wdt_start() is called. */
 122        wdt_time = new_time;
 123        return 0;
 124}
 125
 126static const struct watchdog_info at91_wdt_info = {
 127        .identity       = "at91 watchdog",
 128        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 129};
 130
 131/*
 132 * Handle commands from user-space.
 133 */
 134static long at91_wdt_ioctl(struct file *file,
 135                                        unsigned int cmd, unsigned long arg)
 136{
 137        void __user *argp = (void __user *)arg;
 138        int __user *p = argp;
 139        int new_value;
 140
 141        switch (cmd) {
 142        case WDIOC_GETSUPPORT:
 143                return copy_to_user(argp, &at91_wdt_info,
 144                                sizeof(at91_wdt_info)) ? -EFAULT : 0;
 145        case WDIOC_GETSTATUS:
 146        case WDIOC_GETBOOTSTATUS:
 147                return put_user(0, p);
 148        case WDIOC_SETOPTIONS:
 149                if (get_user(new_value, p))
 150                        return -EFAULT;
 151                if (new_value & WDIOS_DISABLECARD)
 152                        at91_wdt_stop();
 153                if (new_value & WDIOS_ENABLECARD)
 154                        at91_wdt_start();
 155                return 0;
 156        case WDIOC_KEEPALIVE:
 157                at91_wdt_reload();      /* pat the watchdog */
 158                return 0;
 159        case WDIOC_SETTIMEOUT:
 160                if (get_user(new_value, p))
 161                        return -EFAULT;
 162                if (at91_wdt_settimeout(new_value))
 163                        return -EINVAL;
 164                /* Enable new time value */
 165                at91_wdt_start();
 166                /* Return current value */
 167                return put_user(wdt_time, p);
 168        case WDIOC_GETTIMEOUT:
 169                return put_user(wdt_time, p);
 170        default:
 171                return -ENOTTY;
 172        }
 173}
 174
 175/*
 176 * Pat the watchdog whenever device is written to.
 177 */
 178static ssize_t at91_wdt_write(struct file *file, const char *data,
 179                                                size_t len, loff_t *ppos)
 180{
 181        at91_wdt_reload();              /* pat the watchdog */
 182        return len;
 183}
 184
 185/* ......................................................................... */
 186
 187static const struct file_operations at91wdt_fops = {
 188        .owner          = THIS_MODULE,
 189        .llseek         = no_llseek,
 190        .unlocked_ioctl = at91_wdt_ioctl,
 191        .open           = at91_wdt_open,
 192        .release        = at91_wdt_close,
 193        .write          = at91_wdt_write,
 194};
 195
 196static struct miscdevice at91wdt_miscdev = {
 197        .minor          = WATCHDOG_MINOR,
 198        .name           = "watchdog",
 199        .fops           = &at91wdt_fops,
 200};
 201
 202static int at91wdt_probe(struct platform_device *pdev)
 203{
 204        int res;
 205
 206        if (at91wdt_miscdev.parent)
 207                return -EBUSY;
 208        at91wdt_miscdev.parent = &pdev->dev;
 209
 210        res = misc_register(&at91wdt_miscdev);
 211        if (res)
 212                return res;
 213
 214        pr_info("AT91 Watchdog Timer enabled (%d seconds%s)\n",
 215                wdt_time, nowayout ? ", nowayout" : "");
 216        return 0;
 217}
 218
 219static int at91wdt_remove(struct platform_device *pdev)
 220{
 221        int res;
 222
 223        res = misc_deregister(&at91wdt_miscdev);
 224        if (!res)
 225                at91wdt_miscdev.parent = NULL;
 226
 227        return res;
 228}
 229
 230static void at91wdt_shutdown(struct platform_device *pdev)
 231{
 232        at91_wdt_stop();
 233}
 234
 235#ifdef CONFIG_PM
 236
 237static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
 238{
 239        at91_wdt_stop();
 240        return 0;
 241}
 242
 243static int at91wdt_resume(struct platform_device *pdev)
 244{
 245        if (at91wdt_busy)
 246                at91_wdt_start();
 247        return 0;
 248}
 249
 250#else
 251#define at91wdt_suspend NULL
 252#define at91wdt_resume  NULL
 253#endif
 254
 255static struct platform_driver at91wdt_driver = {
 256        .probe          = at91wdt_probe,
 257        .remove         = at91wdt_remove,
 258        .shutdown       = at91wdt_shutdown,
 259        .suspend        = at91wdt_suspend,
 260        .resume         = at91wdt_resume,
 261        .driver         = {
 262                .name   = "at91_wdt",
 263                .owner  = THIS_MODULE,
 264        },
 265};
 266
 267static int __init at91_wdt_init(void)
 268{
 269        /* Check that the heartbeat value is within range;
 270           if not reset to the default */
 271        if (at91_wdt_settimeout(wdt_time)) {
 272                at91_wdt_settimeout(WDT_DEFAULT_TIME);
 273                pr_info("wdt_time value must be 1 <= wdt_time <= 256, using %d\n",
 274                        wdt_time);
 275        }
 276
 277        return platform_driver_register(&at91wdt_driver);
 278}
 279
 280static void __exit at91_wdt_exit(void)
 281{
 282        platform_driver_unregister(&at91wdt_driver);
 283}
 284
 285module_init(at91_wdt_init);
 286module_exit(at91_wdt_exit);
 287
 288MODULE_AUTHOR("Andrew Victor");
 289MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
 290MODULE_LICENSE("GPL");
 291MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 292MODULE_ALIAS("platform:at91_wdt");
 293
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.