drivers/watchdog/sbc_epx_c3.c

   1 /*
   2  *      SBC EPX C3 0.1  A Hardware Watchdog Device for the Winsystems EPX-C3
   3  *      single board computer
   4  *
   5  *      (c) Copyright 2006 Calin A. Culianu <calin@ajvar.org>, All Rights
   6  *      Reserved.
   7  *
   8  *      This program is free software; you can redistribute it and/or
   9  *      modify it under the terms of the GNU General Public License
  10  *      as published by the Free Software Foundation; either version
  11  *      2 of the License, or (at your option) any later version.
  12  *
  13  *      based on softdog.c by Alan Cox <alan@lxorguk.ukuu.org.uk>
  14  */
  15
  16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  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/notifier.h>
  27 #include <linux/reboot.h>
  28 #include <linux/init.h>
  29 #include <linux/ioport.h>
  30 #include <linux/uaccess.h>
  31 #include <linux/io.h>
  32
  33 static int epx_c3_alive;
  34
  35 #define WATCHDOG_TIMEOUT 1              /* 1 sec default timeout */
  36
  37 static bool nowayout = WATCHDOG_NOWAYOUT;
  38 module_param(nowayout, bool, 0);
  39 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  40                                         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  41
  42 #define EPXC3_WATCHDOG_CTL_REG 0x1ee /* write 1 to enable, 0 to disable */
  43 #define EPXC3_WATCHDOG_PET_REG 0x1ef /* write anything to pet once enabled */
  44
  45 static void epx_c3_start(void)
  46 {
  47         outb(1, EPXC3_WATCHDOG_CTL_REG);
  48 }
  49
  50 static void epx_c3_stop(void)
  51 {
  52
  53         outb(0, EPXC3_WATCHDOG_CTL_REG);
  54
  55         pr_info("Stopped watchdog timer\n");
  56 }
  57
  58 static void epx_c3_pet(void)
  59 {
  60         outb(1, EPXC3_WATCHDOG_PET_REG);
  61 }
  62
  63 /*
  64  *      Allow only one person to hold it open
  65  */
  66 static int epx_c3_open(struct inode *inode, struct file *file)
  67 {
  68         if (epx_c3_alive)
  69                 return -EBUSY;
  70
  71         if (nowayout)
  72                 __module_get(THIS_MODULE);
  73
  74         /* Activate timer */
  75         epx_c3_start();
  76         epx_c3_pet();
  77
  78         epx_c3_alive = 1;
  79         pr_info("Started watchdog timer\n");
  80
  81         return nonseekable_open(inode, file);
  82 }
  83
  84 static int epx_c3_release(struct inode *inode, struct file *file)
  85 {
  86         /* Shut off the timer.
  87          * Lock it in if it's a module and we defined ...NOWAYOUT */
  88         if (!nowayout)
  89                 epx_c3_stop();          /* Turn the WDT off */
  90
  91         epx_c3_alive = 0;
  92
  93         return 0;
  94 }
  95
  96 static ssize_t epx_c3_write(struct file *file, const char __user *data,
  97                         size_t len, loff_t *ppos)
  98 {
  99         /* Refresh the timer. */
 100         if (len)
 101                 epx_c3_pet();
 102         return len;
 103 }
 104
 105 static long epx_c3_ioctl(struct file *file, unsigned int cmd,
 106                                                 unsigned long arg)
 107 {
 108         int options, retval = -EINVAL;
 109         int __user *argp = (void __user *)arg;
 110         static const struct watchdog_info ident = {
 111                 .options                = WDIOF_KEEPALIVEPING,
 112                 .firmware_version       = 0,
 113                 .identity               = "Winsystems EPX-C3 H/W Watchdog",
 114         };
 115
 116         switch (cmd) {
 117         case WDIOC_GETSUPPORT:
 118                 if (copy_to_user(argp, &ident, sizeof(ident)))
 119                         return -EFAULT;
 120                 return 0;
 121         case WDIOC_GETSTATUS:
 122         case WDIOC_GETBOOTSTATUS:
 123                 return put_user(0, argp);
 124         case WDIOC_SETOPTIONS:
 125                 if (get_user(options, argp))
 126                         return -EFAULT;
 127
 128                 if (options & WDIOS_DISABLECARD) {
 129                         epx_c3_stop();
 130                         retval = 0;
 131                 }
 132
 133                 if (options & WDIOS_ENABLECARD) {
 134                         epx_c3_start();
 135                         retval = 0;
 136                 }
 137
 138                 return retval;
 139         case WDIOC_KEEPALIVE:
 140                 epx_c3_pet();
 141                 return 0;
 142         case WDIOC_GETTIMEOUT:
 143                 return put_user(WATCHDOG_TIMEOUT, argp);
 144         default:
 145                 return -ENOTTY;
 146         }
 147 }
 148
 149 static int epx_c3_notify_sys(struct notifier_block *this, unsigned long code,
 150                                 void *unused)
 151 {
 152         if (code == SYS_DOWN || code == SYS_HALT)
 153                 epx_c3_stop();          /* Turn the WDT off */
 154
 155         return NOTIFY_DONE;
 156 }
 157
 158 static const struct file_operations epx_c3_fops = {
 159         .owner          = THIS_MODULE,
 160         .llseek         = no_llseek,
 161         .write          = epx_c3_write,
 162         .unlocked_ioctl = epx_c3_ioctl,
 163         .open           = epx_c3_open,
 164         .release        = epx_c3_release,
 165 };
 166
 167 static struct miscdevice epx_c3_miscdev = {
 168         .minor          = WATCHDOG_MINOR,
 169         .name           = "watchdog",
 170         .fops           = &epx_c3_fops,
 171 };
 172
 173 static struct notifier_block epx_c3_notifier = {
 174         .notifier_call = epx_c3_notify_sys,
 175 };
 176
 177 static int __init watchdog_init(void)
 178 {
 179         int ret;
 180
 181         if (!request_region(EPXC3_WATCHDOG_CTL_REG, 2, "epxc3_watchdog"))
 182                 return -EBUSY;
 183
 184         ret = register_reboot_notifier(&epx_c3_notifier);
 185         if (ret) {
 186                 pr_err("cannot register reboot notifier (err=%d)\n", ret);
 187                 goto out;
 188         }
 189
 190         ret = misc_register(&epx_c3_miscdev);
 191         if (ret) {
 192                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
 193                        WATCHDOG_MINOR, ret);
 194                 unregister_reboot_notifier(&epx_c3_notifier);
 195                 goto out;
 196         }
 197
 198         pr_info("Hardware Watchdog Timer for Winsystems EPX-C3 SBC: 0.1\n");
 199
 200         return 0;
 201
 202 out:
 203         release_region(EPXC3_WATCHDOG_CTL_REG, 2);
 204         return ret;
 205 }
 206
 207 static void __exit watchdog_exit(void)
 208 {
 209         misc_deregister(&epx_c3_miscdev);
 210         unregister_reboot_notifier(&epx_c3_notifier);
 211         release_region(EPXC3_WATCHDOG_CTL_REG, 2);
 212 }
 213
 214 module_init(watchdog_init);
 215 module_exit(watchdog_exit);
 216
 217 MODULE_AUTHOR("Calin A. Culianu <calin@ajvar.org>");
 218 MODULE_DESCRIPTION("Hardware Watchdog Device for Winsystems EPX-C3 SBC.  "
 219         "Note that there is no way to probe for this device -- "
 220         "so only use it if you are *sure* you are running on this specific "
 221         "SBC system from Winsystems!  It writes to IO ports 0x1ee and 0x1ef!");
 222 MODULE_LICENSE("GPL");