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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  20
  21 #include <linux/module.h>
  22 #include <linux/moduleparam.h>
  23 #include <linux/types.h>
  24 #include <linux/kernel.h>
  25 #include <linux/fs.h>
  26 #include <linux/mm.h>
  27 #include <linux/miscdevice.h>
  28 #include <linux/watchdog.h>
  29 #include <linux/reboot.h>
  30 #include <linux/init.h>
  31 #include <linux/interrupt.h>
  32 #include <linux/uaccess.h>
  33 #include <linux/irq.h>
  34 #include <mach/hardware.h>
  35
  36 #include <asm/mach-types.h>
  37 #include <asm/hardware/dec21285.h>
  38
  39 /*
  40  * Define this to stop the watchdog actually rebooting the machine.
  41  */
  42 #undef ONLY_TESTING
  43
  44 static unsigned int soft_margin = 60;           /* in seconds */
  45 static unsigned int reload;
  46 static unsigned long timer_alive;
  47
  48 #ifdef ONLY_TESTING
  49 /*
  50  *      If the timer expires..
  51  */
  52 static void watchdog_fire(int irq, void *dev_id)
  53 {
  54         pr_crit("Would Reboot\n");
  55         *CSR_TIMER4_CNTL = 0;
  56         *CSR_TIMER4_CLR = 0;
  57 }
  58 #endif
  59
  60 /*
  61  *      Refresh the timer.
  62  */
  63 static void watchdog_ping(void)
  64 {
  65         *CSR_TIMER4_LOAD = reload;
  66 }
  67
  68 /*
  69  *      Allow only one person to hold it open
  70  */
  71 static int watchdog_open(struct inode *inode, struct file *file)
  72 {
  73         int ret;
  74
  75         if (*CSR_SA110_CNTL & (1 << 13))
  76                 return -EBUSY;
  77
  78         if (test_and_set_bit(1, &timer_alive))
  79                 return -EBUSY;
  80
  81         reload = soft_margin * (mem_fclk_21285 / 256);
  82
  83         *CSR_TIMER4_CLR = 0;
  84         watchdog_ping();
  85         *CSR_TIMER4_CNTL = TIMER_CNTL_ENABLE | TIMER_CNTL_AUTORELOAD
  86                 | TIMER_CNTL_DIV256;
  87
  88 #ifdef ONLY_TESTING
  89         ret = request_irq(IRQ_TIMER4, watchdog_fire, 0, "watchdog", NULL);
  90         if (ret) {
  91                 *CSR_TIMER4_CNTL = 0;
  92                 clear_bit(1, &timer_alive);
  93         }
  94 #else
  95         /*
  96          * Setting this bit is irreversible; once enabled, there is
  97          * no way to disable the watchdog.
  98          */
  99         *CSR_SA110_CNTL |= 1 << 13;
 100
 101         ret = 0;
 102 #endif
 103         nonseekable_open(inode, file);
 104         return ret;
 105 }
 106
 107 /*
 108  *      Shut off the timer.
 109  *      Note: if we really have enabled the watchdog, there
 110  *      is no way to turn off.
 111  */
 112 static int watchdog_release(struct inode *inode, struct file *file)
 113 {
 114 #ifdef ONLY_TESTING
 115         free_irq(IRQ_TIMER4, NULL);
 116         clear_bit(1, &timer_alive);
 117 #endif
 118         return 0;
 119 }
 120
 121 static ssize_t watchdog_write(struct file *file, const char __user *data,
 122                               size_t len, loff_t *ppos)
 123 {
 124         /*
 125          *      Refresh the timer.
 126          */
 127         if (len)
 128                 watchdog_ping();
 129
 130         return len;
 131 }
 132
 133 static const struct watchdog_info ident = {
 134         .options        = WDIOF_SETTIMEOUT,
 135         .identity       = "Footbridge Watchdog",
 136 };
 137
 138 static long watchdog_ioctl(struct file *file, unsigned int cmd,
 139                            unsigned long arg)
 140 {
 141         unsigned int new_margin;
 142         int __user *int_arg = (int __user *)arg;
 143         int ret = -ENOTTY;
 144
 145         switch (cmd) {
 146         case WDIOC_GETSUPPORT:
 147                 ret = 0;
 148                 if (copy_to_user((void __user *)arg, &ident, sizeof(ident)))
 149                         ret = -EFAULT;
 150                 break;
 151
 152         case WDIOC_GETSTATUS:
 153         case WDIOC_GETBOOTSTATUS:
 154                 ret = put_user(0, int_arg);
 155                 break;
 156
 157         case WDIOC_KEEPALIVE:
 158                 watchdog_ping();
 159                 ret = 0;
 160                 break;
 161
 162         case WDIOC_SETTIMEOUT:
 163                 ret = get_user(new_margin, int_arg);
 164                 if (ret)
 165                         break;
 166
 167                 /* Arbitrary, can't find the card's limits */
 168                 if (new_margin < 0 || new_margin > 60) {
 169                         ret = -EINVAL;
 170                         break;
 171                 }
 172
 173                 soft_margin = new_margin;
 174                 reload = soft_margin * (mem_fclk_21285 / 256);
 175                 watchdog_ping();
 176                 /* Fall */
 177         case WDIOC_GETTIMEOUT:
 178                 ret = put_user(soft_margin, int_arg);
 179                 break;
 180         }
 181         return ret;
 182 }
 183
 184 static const struct file_operations watchdog_fops = {
 185         .owner          = THIS_MODULE,
 186         .llseek         = no_llseek,
 187         .write          = watchdog_write,
 188         .unlocked_ioctl = watchdog_ioctl,
 189         .open           = watchdog_open,
 190         .release        = watchdog_release,
 191 };
 192
 193 static struct miscdevice watchdog_miscdev = {
 194         .minor          = WATCHDOG_MINOR,
 195         .name           = "watchdog",
 196         .fops           = &watchdog_fops,
 197 };
 198
 199 static int __init footbridge_watchdog_init(void)
 200 {
 201         int retval;
 202
 203         if (machine_is_netwinder())
 204                 return -ENODEV;
 205
 206         retval = misc_register(&watchdog_miscdev);
 207         if (retval < 0)
 208                 return retval;
 209
 210         pr_info("Footbridge Watchdog Timer: 0.01, timer margin: %d sec\n",
 211                 soft_margin);
 212
 213         if (machine_is_cats())
 214                 pr_warn("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);