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