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#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 <linux/of.h>
  28#include <linux/of_device.h>
  29#include <mach/at91_st.h>
  30
  31#define WDT_DEFAULT_TIME        5       /* seconds */
  32#define WDT_MAX_TIME            256     /* seconds */
  33
  34static int wdt_time = WDT_DEFAULT_TIME;
  35static bool nowayout = WATCHDOG_NOWAYOUT;
  36
  37module_param(wdt_time, int, 0);
  38MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
  39                                __MODULE_STRING(WDT_DEFAULT_TIME) ")");
  40
  41#ifdef CONFIG_WATCHDOG_NOWAYOUT
  42module_param(nowayout, bool, 0);
  43MODULE_PARM_DESC(nowayout,
  44                "Watchdog cannot be stopped once started (default="
  45                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  46#endif
  47
  48
  49static unsigned long at91wdt_busy;
  50
  51/* ......................................................................... */
  52
  53/*
  54 * Disable the watchdog.
  55 */
  56static inline void at91_wdt_stop(void)
  57{
  58        at91_st_write(AT91_ST_WDMR, AT91_ST_EXTEN);
  59}
  60
  61/*
  62 * Enable and reset the watchdog.
  63 */
  64static inline void at91_wdt_start(void)
  65{
  66        at91_st_write(AT91_ST_WDMR, AT91_ST_EXTEN | AT91_ST_RSTEN |
  67                                (((65536 * wdt_time) >> 8) & AT91_ST_WDV));
  68        at91_st_write(AT91_ST_CR, AT91_ST_WDRST);
  69}
  70
  71/*
  72 * Reload the watchdog timer.  (ie, pat the watchdog)
  73 */
  74static inline void at91_wdt_reload(void)
  75{
  76        at91_st_write(AT91_ST_CR, AT91_ST_WDRST);
  77}
  78
  79/* ......................................................................... */
  80
  81/*
  82 * Watchdog device is opened, and watchdog starts running.
  83 */
  84static int at91_wdt_open(struct inode *inode, struct file *file)
  85{
  86        if (test_and_set_bit(0, &at91wdt_busy))
  87                return -EBUSY;
  88
  89        at91_wdt_start();
  90        return nonseekable_open(inode, file);
  91}
  92
  93/*
  94 * Close the watchdog device.
  95 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
  96 *  disabled.
  97 */
  98static int at91_wdt_close(struct inode *inode, struct file *file)
  99{
 100        /* Disable the watchdog when file is closed */
 101        if (!nowayout)
 102                at91_wdt_stop();
 103
 104        clear_bit(0, &at91wdt_busy);
 105        return 0;
 106}
 107
 108/*
 109 * Change the watchdog time interval.
 110 */
 111static int at91_wdt_settimeout(int new_time)
 112{
 113        /*
 114         * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
 115         *
 116         * Since WDV is a 16-bit counter, the maximum period is
 117         * 65536 / 256 = 256 seconds.
 118         */
 119        if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
 120                return -EINVAL;
 121
 122        /* Set new watchdog time. It will be used when
 123           at91_wdt_start() is called. */
 124        wdt_time = new_time;
 125        return 0;
 126}
 127
 128static const struct watchdog_info at91_wdt_info = {
 129        .identity       = "at91 watchdog",
 130        .options        = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 131};
 132
 133/*
 134 * Handle commands from user-space.
 135 */
 136static long at91_wdt_ioctl(struct file *file,
 137                                        unsigned int cmd, unsigned long arg)
 138{
 139        void __user *argp = (void __user *)arg;
 140        int __user *p = argp;
 141        int new_value;
 142
 143        switch (cmd) {
 144        case WDIOC_GETSUPPORT:
 145                return copy_to_user(argp, &at91_wdt_info,
 146                                sizeof(at91_wdt_info)) ? -EFAULT : 0;
 147        case WDIOC_GETSTATUS:
 148        case WDIOC_GETBOOTSTATUS:
 149                return put_user(0, p);
 150        case WDIOC_SETOPTIONS:
 151                if (get_user(new_value, p))
 152                        return -EFAULT;
 153                if (new_value & WDIOS_DISABLECARD)
 154                        at91_wdt_stop();
 155                if (new_value & WDIOS_ENABLECARD)
 156                        at91_wdt_start();
 157                return 0;
 158        case WDIOC_KEEPALIVE:
 159                at91_wdt_reload();      /* pat the watchdog */
 160                return 0;
 161        case WDIOC_SETTIMEOUT:
 162                if (get_user(new_value, p))
 163                        return -EFAULT;
 164                if (at91_wdt_settimeout(new_value))
 165                        return -EINVAL;
 166                /* Enable new time value */
 167                at91_wdt_start();
 168                /* Return current value */
 169                return put_user(wdt_time, p);
 170        case WDIOC_GETTIMEOUT:
 171                return put_user(wdt_time, p);
 172        default:
 173                return -ENOTTY;
 174        }
 175}
 176
 177/*
 178 * Pat the watchdog whenever device is written to.
 179 */
 180static ssize_t at91_wdt_write(struct file *file, const char *data,
 181                                                size_t len, loff_t *ppos)
 182{
 183        at91_wdt_reload();              /* pat the watchdog */
 184        return len;
 185}
 186
 187/* ......................................................................... */
 188
 189static const struct file_operations at91wdt_fops = {
 190        .owner          = THIS_MODULE,
 191        .llseek         = no_llseek,
 192        .unlocked_ioctl = at91_wdt_ioctl,
 193        .open           = at91_wdt_open,
 194        .release        = at91_wdt_close,
 195        .write          = at91_wdt_write,
 196};
 197
 198static struct miscdevice at91wdt_miscdev = {
 199        .minor          = WATCHDOG_MINOR,
 200        .name           = "watchdog",
 201        .fops           = &at91wdt_fops,
 202};
 203
 204static int at91wdt_probe(struct platform_device *pdev)
 205{
 206        int res;
 207
 208        if (at91wdt_miscdev.parent)
 209                return -EBUSY;
 210        at91wdt_miscdev.parent = &pdev->dev;
 211
 212        res = misc_register(&at91wdt_miscdev);
 213        if (res)
 214                return res;
 215
 216        pr_info("AT91 Watchdog Timer enabled (%d seconds%s)\n",
 217                wdt_time, nowayout ? ", nowayout" : "");
 218        return 0;
 219}
 220
 221static int at91wdt_remove(struct platform_device *pdev)
 222{
 223        int res;
 224
 225        res = misc_deregister(&at91wdt_miscdev);
 226        if (!res)
 227                at91wdt_miscdev.parent = NULL;
 228
 229        return res;
 230}
 231
 232static void at91wdt_shutdown(struct platform_device *pdev)
 233{
 234        at91_wdt_stop();
 235}
 236
 237#ifdef CONFIG_PM
 238
 239static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
 240{
 241        at91_wdt_stop();
 242        return 0;
 243}
 244
 245static int at91wdt_resume(struct platform_device *pdev)
 246{
 247        if (at91wdt_busy)
 248                at91_wdt_start();
 249        return 0;
 250}
 251
 252#else
 253#define at91wdt_suspend NULL
 254#define at91wdt_resume  NULL
 255#endif
 256
 257static const struct of_device_id at91_wdt_dt_ids[] = {
 258        { .compatible = "atmel,at91rm9200-wdt" },
 259        { /* sentinel */ }
 260};
 261MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
 262
 263static struct platform_driver at91wdt_driver = {
 264        .probe          = at91wdt_probe,
 265        .remove         = at91wdt_remove,
 266        .shutdown       = at91wdt_shutdown,
 267        .suspend        = at91wdt_suspend,
 268        .resume         = at91wdt_resume,
 269        .driver         = {
 270                .name   = "at91_wdt",
 271                .owner  = THIS_MODULE,
 272                .of_match_table = of_match_ptr(at91_wdt_dt_ids),
 273        },
 274};
 275
 276static int __init at91_wdt_init(void)
 277{
 278        /* Check that the heartbeat value is within range;
 279           if not reset to the default */
 280        if (at91_wdt_settimeout(wdt_time)) {
 281                at91_wdt_settimeout(WDT_DEFAULT_TIME);
 282                pr_info("wdt_time value must be 1 <= wdt_time <= 256, using %d\n",
 283                        wdt_time);
 284        }
 285
 286        return platform_driver_register(&at91wdt_driver);
 287}
 288
 289static void __exit at91_wdt_exit(void)
 290{
 291        platform_driver_unregister(&at91wdt_driver);
 292}
 293
 294module_init(at91_wdt_init);
 295module_exit(at91_wdt_exit);
 296
 297MODULE_AUTHOR("Andrew Victor");
 298MODULE_DESCRIPTION("Watchdog driver for Atmel AT91RM9200");
 299MODULE_LICENSE("GPL");
 300MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 301MODULE_ALIAS("platform:at91_wdt");
 302
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