release/src-rt-6.x.4708/linux/linux-2.6.36/drivers/watchdog/wdt285.c

   1 /*
   2  *      Intel 21285 watchdog driver
   3  *      Copyright (c) Phil Blundell <pb@nexus.co.uk>, 1998
   4  *
   5  *      based on
   6  *
   7  *      SoftDog 0.05:   A Software Watchdog Device
   8  *
   9  *      (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
  10  *                                              All Rights Reserved.
  11  *
  12  *      This program is free software; you can redistribute it and/or
  13  *      modify it under the terms of the GNU General Public License
  14  *      as published by the Free Software Foundation; either version
  15  *      2 of the License, or (at your option) any later version.
  16  *
  17  */
  18
  19 #include <linux/module.h>
  20 #include <linux/moduleparam.h>
  21 #include <linux/types.h>
  22 #include <linux/kernel.h>
  23 #include <linux/fs.h>
  24 #include <linux/mm.h>
  25 #include <linux/miscdevice.h>
  26 #include <linux/watchdog.h>
  27 #include <linux/reboot.h>
  28 #include <linux/init.h>
  29 #include <linux/interrupt.h>
  30 #include <linux/uaccess.h>
  31 #include <linux/irq.h>
  32 #include <mach/hardware.h>
  33
  34 #include <asm/mach-types.h>
  35 #include <asm/hardware/dec21285.h>
  36
  37 /*
  38  * Define this to stop the watchdog actually rebooting the machine.
  39  */
  40 #undef ONLY_TESTING
  41
  42 static unsigned int soft_margin = 60;           /* in seconds */
  43 static unsigned int reload;
  44 static unsigned long timer_alive;
  45
  46 #ifdef ONLY_TESTING
  47 /*
  48  *      If the timer expires..
  49  */
  50 static void watchdog_fire(int irq, void *dev_id)
  51 {
  52         printk(KERN_CRIT "Watchdog: Would Reboot.\n");
  53         *CSR_TIMER4_CNTL = 0;
  54         *CSR_TIMER4_CLR = 0;
  55 }
  56 #endif
  57
  58 /*
  59  *      Refresh the timer.
  60  */
  61 static void watchdog_ping(void)
  62 {
  63         *CSR_TIMER4_LOAD = reload;
  64 }
  65
  66 /*
  67  *      Allow only one person to hold it open
  68  */
  69 static int watchdog_open(struct inode *inode, struct file *file)
  70 {
  71         int ret;
  72
  73         if (*CSR_SA110_CNTL & (1 << 13))
  74                 return -EBUSY;
  75
  76         if (test_and_set_bit(1, &timer_alive))
  77                 return -EBUSY;
  78
  79         reload = soft_margin * (mem_fclk_21285 / 256);
  80
  81         *CSR_TIMER4_CLR = 0;
  82         watchdog_ping();
  83         *CSR_TIMER4_CNTL = TIMER_CNTL_ENABLE | TIMER_CNTL_AUTORELOAD
  84                 | TIMER_CNTL_DIV256;
  85
  86 #ifdef ONLY_TESTING
  87         ret = request_irq(IRQ_TIMER4, watchdog_fire, 0, "watchdog", NULL);
  88         if (ret) {
  89                 *CSR_TIMER4_CNTL = 0;
  90                 clear_bit(1, &timer_alive);
  91         }
  92 #else
  93         /*
  94          * Setting this bit is irreversible; once enabled, there is
  95          * no way to disable the watchdog.
  96          */
  97         *CSR_SA110_CNTL |= 1 << 13;
  98
  99         ret = 0;
 100 #endif
 101         nonseekable_open(inode, file);
 102         return ret;
 103 }
 104
 105 /*
 106  *      Shut off the timer.
 107  *      Note: if we really have enabled the watchdog, there
 108  *      is no way to turn off.
 109  */
 110 static int watchdog_release(struct inode *inode, struct file *file)
 111 {
 112 #ifdef ONLY_TESTING
 113         free_irq(IRQ_TIMER4, NULL);
 114         clear_bit(1, &timer_alive);
 115 #endif
 116         return 0;
 117 }
 118
 119 static ssize_t watchdog_write(struct file *file, const char __user *data,
 120                               size_t len, loff_t *ppos)
 121 {
 122         /*
 123          *      Refresh the timer.
 124          */
 125         if (len)
 126                 watchdog_ping();
 127
 128         return len;
 129 }
 130
 131 static const struct watchdog_info ident = {
 132         .options        = WDIOF_SETTIMEOUT,
 133         .identity       = "Footbridge Watchdog",
 134 };
 135
 136 static long watchdog_ioctl(struct file *file, unsigned int cmd,
 137                            unsigned long arg)
 138 {
 139         unsigned int new_margin;
 140         int __user *int_arg = (int __user *)arg;
 141         int ret = -ENOTTY;
 142
 143         switch (cmd) {
 144         case WDIOC_GETSUPPORT:
 145                 ret = 0;
 146                 if (copy_to_user((void __user *)arg, &ident, sizeof(ident)))
 147                         ret = -EFAULT;
 148                 break;
 149
 150         case WDIOC_GETSTATUS:
 151         case WDIOC_GETBOOTSTATUS:
 152                 ret = put_user(0, int_arg);
 153                 break;
 154
 155         case WDIOC_KEEPALIVE:
 156                 watchdog_ping();
 157                 ret = 0;
 158                 break;
 159
 160         case WDIOC_SETTIMEOUT:
 161                 ret = get_user(new_margin, int_arg);
 162                 if (ret)
 163                         break;
 164
 165                 /* Arbitrary, can't find the card's limits */
 166                 if (new_margin < 0 || new_margin > 60) {
 167                         ret = -EINVAL;
 168                         break;
 169                 }
 170
 171                 soft_margin = new_margin;
 172                 reload = soft_margin * (mem_fclk_21285 / 256);
 173                 watchdog_ping();
 174                 /* Fall */
 175         case WDIOC_GETTIMEOUT:
 176                 ret = put_user(soft_margin, int_arg);
 177                 break;
 178         }
 179         return ret;
 180 }
 181
 182 static const struct file_operations watchdog_fops = {
 183         .owner          = THIS_MODULE,
 184         .llseek         = no_llseek,
 185         .write          = watchdog_write,
 186         .unlocked_ioctl = watchdog_ioctl,
 187         .open           = watchdog_open,
 188         .release        = watchdog_release,
 189 };
 190
 191 static struct miscdevice watchdog_miscdev = {
 192         .minor          = WATCHDOG_MINOR,
 193         .name           = "watchdog",
 194         .fops           = &watchdog_fops,
 195 };
 196
 197 static int __init footbridge_watchdog_init(void)
 198 {
 199         int retval;
 200
 201         if (machine_is_netwinder())
 202                 return -ENODEV;
 203
 204         retval = misc_register(&watchdog_miscdev);
 205         if (retval < 0)
 206                 return retval;
 207
 208         printk(KERN_INFO
 209                 "Footbridge Watchdog Timer: 0.01, timer margin: %d sec\n",
 210                                                                 soft_margin);
 211
 212         if (machine_is_cats())
 213                 printk(KERN_WARNING
 214                   "Warning: Watchdog reset may not work on this machine.\n");
 215         return 0;
 216 }
 217
 218 static void __exit footbridge_watchdog_exit(void)
 219 {
 220         misc_deregister(&watchdog_miscdev);
 221 }
 222
 223 MODULE_AUTHOR("Phil Blundell <pb@nexus.co.uk>");
 224 MODULE_DESCRIPTION("Footbridge watchdog driver");
 225 MODULE_LICENSE("GPL");
 226 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 227
 228 module_param(soft_margin, int, 0);
 229 MODULE_PARM_DESC(soft_margin, "Watchdog timeout in seconds");
 230
 231 module_init(footbridge_watchdog_init);
 232 module_exit(footbridge_watchdog_exit);