linux/drivers/watchdog/bcm47xx_wdt.c
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   1/*
   2 *  Watchdog driver for Broadcom BCM47XX
   3 *
   4 *  Copyright (C) 2008 Aleksandar Radovanovic <biblbroks@sezampro.rs>
   5 *  Copyright (C) 2009 Matthieu CASTET <castet.matthieu@free.fr>
   6 *
   7 *  This program is free software; you can redistribute it and/or
   8 *  modify it under the terms of the GNU General Public License
   9 *  as published by the Free Software Foundation; either version
  10 *  2 of the License, or (at your option) any later version.
  11 */
  12
  13#include <linux/bitops.h>
  14#include <linux/errno.h>
  15#include <linux/fs.h>
  16#include <linux/init.h>
  17#include <linux/kernel.h>
  18#include <linux/miscdevice.h>
  19#include <linux/module.h>
  20#include <linux/moduleparam.h>
  21#include <linux/reboot.h>
  22#include <linux/types.h>
  23#include <linux/uaccess.h>
  24#include <linux/watchdog.h>
  25#include <linux/timer.h>
  26#include <linux/jiffies.h>
  27#include <linux/ssb/ssb_embedded.h>
  28#include <asm/mach-bcm47xx/bcm47xx.h>
  29
  30#define DRV_NAME                "bcm47xx_wdt"
  31
  32#define WDT_DEFAULT_TIME        30      /* seconds */
  33#define WDT_MAX_TIME            255     /* seconds */
  34
  35static int wdt_time = WDT_DEFAULT_TIME;
  36static int nowayout = WATCHDOG_NOWAYOUT;
  37
  38module_param(wdt_time, int, 0);
  39MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
  40                                __MODULE_STRING(WDT_DEFAULT_TIME) ")");
  41
  42#ifdef CONFIG_WATCHDOG_NOWAYOUT
  43module_param(nowayout, int, 0);
  44MODULE_PARM_DESC(nowayout,
  45                "Watchdog cannot be stopped once started (default="
  46                                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  47#endif
  48
  49static unsigned long bcm47xx_wdt_busy;
  50static char expect_release;
  51static struct timer_list wdt_timer;
  52static atomic_t ticks;
  53
  54static inline void bcm47xx_wdt_hw_start(void)
  55{
  56        /* this is 2,5s on 100Mhz clock  and 2s on 133 Mhz */
  57        ssb_watchdog_timer_set(&ssb_bcm47xx, 0xfffffff);
  58}
  59
  60static inline int bcm47xx_wdt_hw_stop(void)
  61{
  62        return ssb_watchdog_timer_set(&ssb_bcm47xx, 0);
  63}
  64
  65static void bcm47xx_timer_tick(unsigned long unused)
  66{
  67        if (!atomic_dec_and_test(&ticks)) {
  68                bcm47xx_wdt_hw_start();
  69                mod_timer(&wdt_timer, jiffies + HZ);
  70        } else {
  71                printk(KERN_CRIT DRV_NAME "Watchdog will fire soon!!!\n");
  72        }
  73}
  74
  75static inline void bcm47xx_wdt_pet(void)
  76{
  77        atomic_set(&ticks, wdt_time);
  78}
  79
  80static void bcm47xx_wdt_start(void)
  81{
  82        bcm47xx_wdt_pet();
  83        bcm47xx_timer_tick(0);
  84}
  85
  86static void bcm47xx_wdt_pause(void)
  87{
  88        del_timer_sync(&wdt_timer);
  89        bcm47xx_wdt_hw_stop();
  90}
  91
  92static void bcm47xx_wdt_stop(void)
  93{
  94        bcm47xx_wdt_pause();
  95}
  96
  97static int bcm47xx_wdt_settimeout(int new_time)
  98{
  99        if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
 100                return -EINVAL;
 101
 102        wdt_time = new_time;
 103        return 0;
 104}
 105
 106static int bcm47xx_wdt_open(struct inode *inode, struct file *file)
 107{
 108        if (test_and_set_bit(0, &bcm47xx_wdt_busy))
 109                return -EBUSY;
 110
 111        bcm47xx_wdt_start();
 112        return nonseekable_open(inode, file);
 113}
 114
 115static int bcm47xx_wdt_release(struct inode *inode, struct file *file)
 116{
 117        if (expect_release == 42) {
 118                bcm47xx_wdt_stop();
 119        } else {
 120                printk(KERN_CRIT DRV_NAME
 121                        ": Unexpected close, not stopping watchdog!\n");
 122                bcm47xx_wdt_start();
 123        }
 124
 125        clear_bit(0, &bcm47xx_wdt_busy);
 126        expect_release = 0;
 127        return 0;
 128}
 129
 130static ssize_t bcm47xx_wdt_write(struct file *file, const char __user *data,
 131                                size_t len, loff_t *ppos)
 132{
 133        if (len) {
 134                if (!nowayout) {
 135                        size_t i;
 136
 137                        expect_release = 0;
 138
 139                        for (i = 0; i != len; i++) {
 140                                char c;
 141                                if (get_user(c, data + i))
 142                                        return -EFAULT;
 143                                if (c == 'V')
 144                                        expect_release = 42;
 145                        }
 146                }
 147                bcm47xx_wdt_pet();
 148        }
 149        return len;
 150}
 151
 152static const struct watchdog_info bcm47xx_wdt_info = {
 153        .identity       = DRV_NAME,
 154        .options        = WDIOF_SETTIMEOUT |
 155                                WDIOF_KEEPALIVEPING |
 156                                WDIOF_MAGICCLOSE,
 157};
 158
 159static long bcm47xx_wdt_ioctl(struct file *file,
 160                                        unsigned int cmd, unsigned long arg)
 161{
 162        void __user *argp = (void __user *)arg;
 163        int __user *p = argp;
 164        int new_value, retval = -EINVAL;
 165
 166        switch (cmd) {
 167        case WDIOC_GETSUPPORT:
 168                return copy_to_user(argp, &bcm47xx_wdt_info,
 169                                sizeof(bcm47xx_wdt_info)) ? -EFAULT : 0;
 170
 171        case WDIOC_GETSTATUS:
 172        case WDIOC_GETBOOTSTATUS:
 173                return put_user(0, p);
 174
 175        case WDIOC_SETOPTIONS:
 176                if (get_user(new_value, p))
 177                        return -EFAULT;
 178
 179                if (new_value & WDIOS_DISABLECARD) {
 180                        bcm47xx_wdt_stop();
 181                        retval = 0;
 182                }
 183
 184                if (new_value & WDIOS_ENABLECARD) {
 185                        bcm47xx_wdt_start();
 186                        retval = 0;
 187                }
 188
 189                return retval;
 190
 191        case WDIOC_KEEPALIVE:
 192                bcm47xx_wdt_pet();
 193                return 0;
 194
 195        case WDIOC_SETTIMEOUT:
 196                if (get_user(new_value, p))
 197                        return -EFAULT;
 198
 199                if (bcm47xx_wdt_settimeout(new_value))
 200                        return -EINVAL;
 201
 202                bcm47xx_wdt_pet();
 203
 204        case WDIOC_GETTIMEOUT:
 205                return put_user(wdt_time, p);
 206
 207        default:
 208                return -ENOTTY;
 209        }
 210}
 211
 212static int bcm47xx_wdt_notify_sys(struct notifier_block *this,
 213        unsigned long code, void *unused)
 214{
 215        if (code == SYS_DOWN || code == SYS_HALT)
 216                bcm47xx_wdt_stop();
 217        return NOTIFY_DONE;
 218}
 219
 220static const struct file_operations bcm47xx_wdt_fops = {
 221        .owner          = THIS_MODULE,
 222        .llseek         = no_llseek,
 223        .unlocked_ioctl = bcm47xx_wdt_ioctl,
 224        .open           = bcm47xx_wdt_open,
 225        .release        = bcm47xx_wdt_release,
 226        .write          = bcm47xx_wdt_write,
 227};
 228
 229static struct miscdevice bcm47xx_wdt_miscdev = {
 230        .minor          = WATCHDOG_MINOR,
 231        .name           = "watchdog",
 232        .fops           = &bcm47xx_wdt_fops,
 233};
 234
 235static struct notifier_block bcm47xx_wdt_notifier = {
 236        .notifier_call = bcm47xx_wdt_notify_sys,
 237};
 238
 239static int __init bcm47xx_wdt_init(void)
 240{
 241        int ret;
 242
 243        if (bcm47xx_wdt_hw_stop() < 0)
 244                return -ENODEV;
 245
 246        setup_timer(&wdt_timer, bcm47xx_timer_tick, 0L);
 247
 248        if (bcm47xx_wdt_settimeout(wdt_time)) {
 249                bcm47xx_wdt_settimeout(WDT_DEFAULT_TIME);
 250                printk(KERN_INFO DRV_NAME ": "
 251                        "wdt_time value must be 0 < wdt_time < %d, using %d\n",
 252                        (WDT_MAX_TIME + 1), wdt_time);
 253        }
 254
 255        ret = register_reboot_notifier(&bcm47xx_wdt_notifier);
 256        if (ret)
 257                return ret;
 258
 259        ret = misc_register(&bcm47xx_wdt_miscdev);
 260        if (ret) {
 261                unregister_reboot_notifier(&bcm47xx_wdt_notifier);
 262                return ret;
 263        }
 264
 265        printk(KERN_INFO "BCM47xx Watchdog Timer enabled (%d seconds%s)\n",
 266                                wdt_time, nowayout ? ", nowayout" : "");
 267        return 0;
 268}
 269
 270static void __exit bcm47xx_wdt_exit(void)
 271{
 272        if (!nowayout)
 273                bcm47xx_wdt_stop();
 274
 275        misc_deregister(&bcm47xx_wdt_miscdev);
 276
 277        unregister_reboot_notifier(&bcm47xx_wdt_notifier);
 278}
 279
 280module_init(bcm47xx_wdt_init);
 281module_exit(bcm47xx_wdt_exit);
 282
 283MODULE_AUTHOR("Aleksandar Radovanovic");
 284MODULE_DESCRIPTION("Watchdog driver for Broadcom BCM47xx");
 285MODULE_LICENSE("GPL");
 286MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 287