drivers/watchdog/bcm47xx_wdt.c

   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
  35 static int wdt_time = WDT_DEFAULT_TIME;
  36 static int nowayout = WATCHDOG_NOWAYOUT;
  37
  38 module_param(wdt_time, int, 0);
  39 MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
  40                                 __MODULE_STRING(WDT_DEFAULT_TIME) ")");
  41
  42 #ifdef CONFIG_WATCHDOG_NOWAYOUT
  43 module_param(nowayout, int, 0);
  44 MODULE_PARM_DESC(nowayout,
  45                 "Watchdog cannot be stopped once started (default="
  46                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  47 #endif
  48
  49 static unsigned long bcm47xx_wdt_busy;
  50 static char expect_release;
  51 static struct timer_list wdt_timer;
  52 static atomic_t ticks;
  53
  54 static 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
  60 static inline int bcm47xx_wdt_hw_stop(void)
  61 {
  62         return ssb_watchdog_timer_set(&ssb_bcm47xx, 0);
  63 }
  64
  65 static 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
  75 static inline void bcm47xx_wdt_pet(void)
  76 {
  77         atomic_set(&ticks, wdt_time);
  78 }
  79
  80 static void bcm47xx_wdt_start(void)
  81 {
  82         bcm47xx_wdt_pet();
  83         bcm47xx_timer_tick(0);
  84 }
  85
  86 static void bcm47xx_wdt_pause(void)
  87 {
  88         del_timer_sync(&wdt_timer);
  89         bcm47xx_wdt_hw_stop();
  90 }
  91
  92 static void bcm47xx_wdt_stop(void)
  93 {
  94         bcm47xx_wdt_pause();
  95 }
  96
  97 static 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
 106 static 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
 115 static 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
 130 static 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
 152 static struct watchdog_info bcm47xx_wdt_info = {
 153         .identity       = DRV_NAME,
 154         .options        = WDIOF_SETTIMEOUT |
 155                                 WDIOF_KEEPALIVEPING |
 156                                 WDIOF_MAGICCLOSE,
 157 };
 158
 159 static 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
 212 static 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
 220 static 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
 229 static struct miscdevice bcm47xx_wdt_miscdev = {
 230         .minor          = WATCHDOG_MINOR,
 231         .name           = "watchdog",
 232         .fops           = &bcm47xx_wdt_fops,
 233 };
 234
 235 static struct notifier_block bcm47xx_wdt_notifier = {
 236         .notifier_call = bcm47xx_wdt_notify_sys,
 237 };
 238
 239 static 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
 270 static 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
 280 module_init(bcm47xx_wdt_init);
 281 module_exit(bcm47xx_wdt_exit);
 282
 283 MODULE_AUTHOR("Aleksandar Radovanovic");
 284 MODULE_DESCRIPTION("Watchdog driver for Broadcom BCM47xx");
 285 MODULE_LICENSE("GPL");
 286 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);