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