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