drivers/char/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@cymru.net>, All Rights Reserved.
  10  *                              http://www.cymru.net
  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/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/system.h>
  34 #include <asm/dec21285.h>
  35
  36 /*
  37  * Define this to stop the watchdog actually rebooting the machine.
  38  */
  39 #undef ONLY_TESTING
  40
  41 #define TIMER_MARGIN    60              /* (secs) Default is 1 minute */
  42
  43 #define FCLK    (50*1000*1000)          /* 50MHz */
  44
  45 static int soft_margin = TIMER_MARGIN;  /* in seconds */
  46 static int timer_alive = 0;
  47
  48 #ifdef ONLY_TESTING
  49 /*
  50  *      If the timer expires..
  51  */
  52
  53 static void watchdog_fire(int irq, void *dev_id, struct pt_regs *regs)
  54 {
  55         printk(KERN_CRIT "Watchdog: Would Reboot.\n");
  56         *CSR_TIMER4_CNTL = 0;
  57         *CSR_TIMER4_CLR = 0;
  58 }
  59 #endif
  60
  61 static void watchdog_ping(void)
  62 {
  63         /*
  64          *      Refresh the timer.
  65          */
  66         *CSR_TIMER4_LOAD = soft_margin * (FCLK / 256);
  67 }
  68
  69 /*
  70  *      Allow only one person to hold it open
  71  */
  72
  73 static int watchdog_open(struct inode *inode, struct file *file)
  74 {
  75         if(timer_alive)
  76                 return -EBUSY;
  77         MOD_INC_USE_COUNT;
  78         /*
  79          *      Ahead watchdog factor ten, Mr Sulu
  80          */
  81         *CSR_TIMER4_CLR = 0;
  82         watchdog_ping();
  83         *CSR_TIMER4_CNTL = TIMER_CNTL_ENABLE | TIMER_CNTL_AUTORELOAD
  84                 | TIMER_CNTL_DIV256;
  85 #ifdef ONLY_TESTING
  86         request_irq(IRQ_TIMER4, watchdog_fire, 0, "watchdog", NULL);
  87 #else
  88         *CSR_SA110_CNTL |= 1 << 13;
  89 #endif
  90         timer_alive = 1;
  91         return 0;
  92 }
  93
  94 static int watchdog_release(struct inode *inode, struct file *file)
  95 {
  96 #ifdef ONLY_TESTING
  97         free_irq(IRQ_TIMER4, NULL);
  98         timer_alive = 0;
  99         MOD_DEC_USE_COUNT;
 100 #else
 101         /*
 102          *      It's irreversible!
 103          */
 104 #endif
 105         return 0;
 106 }
 107
 108 static ssize_t watchdog_write(struct file *file, const char *data, size_t len, loff_t *ppos)
 109 {
 110         /*  Can't seek (pwrite) on this device  */
 111         if (ppos != &file->f_pos)
 112                 return -ESPIPE;
 113
 114         /*
 115          *      Refresh the timer.
 116          */
 117         if(len)
 118         {
 119                 watchdog_ping();
 120                 return 1;
 121         }
 122         return 0;
 123 }
 124
 125 static int watchdog_ioctl(struct inode *inode, struct file *file,
 126         unsigned int cmd, unsigned long arg)
 127 {
 128         int i;
 129         static struct watchdog_info ident=
 130         {
 131                 0,
 132                 0,
 133                 "Footbridge Watchdog"
 134         };
 135         switch(cmd)
 136         {
 137                 default:
 138                         return -ENOIOCTLCMD;
 139                 case WDIOC_GETSUPPORT:
 140                         i = verify_area(VERIFY_WRITE, (void*) arg, sizeof(struct watchdog_info));
 141                         if (i)
 142                                 return i;
 143                         else
 144                                 return copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident));
 145                 case WDIOC_GETSTATUS:
 146                 case WDIOC_GETBOOTSTATUS:
 147                         return put_user(0,(int *)arg);
 148                 case WDIOC_KEEPALIVE:
 149                         watchdog_ping();
 150                         return 0;
 151         }
 152 }
 153
 154 static struct file_operations watchdog_fops=
 155 {
 156         write:          watchdog_write,
 157         ioctl:          watchdog_ioctl,
 158         open:           watchdog_open,
 159         release:        watchdog_release,
 160 };
 161
 162 static struct miscdevice watchdog_miscdev=
 163 {
 164         WATCHDOG_MINOR,
 165         "watchdog",
 166         &watchdog_fops
 167 };
 168
 169 static int __init footbridge_watchdog_init(void)
 170 {
 171         if (machine_is_netwinder())
 172                 return -ENODEV;
 173
 174         misc_register(&watchdog_miscdev);
 175         printk("Footbridge Watchdog Timer: 0.01, timer margin: %d sec\n",
 176                soft_margin);
 177         if (machine_is_cats())
 178                 printk("Warning: Watchdog reset may not work on this machine.\n");
 179         return 0;
 180 }
 181
 182 static void __exit footbridge_watchdog_exit(void)
 183 {
 184         misc_deregister(&watchdog_miscdev);
 185 }
 186
 187 EXPORT_NO_SYMBOLS;
 188
 189 MODULE_AUTHOR("Phil Blundell <pb@nexus.co.uk>");
 190 MODULE_DESCRIPTION("21285 watchdog driver");
 191
 192 MODULE_PARM(soft_margin,"i");
 193 MODULE_PARM_DESC(soft_margin,"Watchdog timeout in seconds");
 194
 195 module_init(footbridge_watchdog_init);
 196 module_exit(footbridge_watchdog_exit);