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 #include <linux/module.h>
  17 #include <linux/moduleparam.h>
  18 #include <linux/types.h>
  19 #include <linux/kernel.h>
  20 #include <linux/fs.h>
  21 #include <linux/mm.h>
  22 #include <linux/miscdevice.h>
  23 #include <linux/watchdog.h>
  24 #include <linux/notifier.h>
  25 #include <linux/reboot.h>
  26 #include <linux/init.h>
  27 #include <linux/ioport.h>
  28 #include <linux/uaccess.h>
  29 #include <linux/io.h>
  30
  31 #define PFX "epx_c3: "
  32 static int epx_c3_alive;
  33
  34 #define WATCHDOG_TIMEOUT 1              /* 1 sec default timeout */
  35
  36 static int nowayout = WATCHDOG_NOWAYOUT;
  37 module_param(nowayout, int, 0);
  38 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  39                                         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  40
  41 #define EPXC3_WATCHDOG_CTL_REG 0x1ee /* write 1 to enable, 0 to disable */
  42 #define EPXC3_WATCHDOG_PET_REG 0x1ef /* write anything to pet once enabled */
  43
  44 static void epx_c3_start(void)
  45 {
  46         outb(1, EPXC3_WATCHDOG_CTL_REG);
  47 }
  48
  49 static void epx_c3_stop(void)
  50 {
  51
  52         outb(0, EPXC3_WATCHDOG_CTL_REG);
  53
  54         printk(KERN_INFO PFX "Stopped watchdog timer.\n");
  55 }
  56
  57 static void epx_c3_pet(void)
  58 {
  59         outb(1, EPXC3_WATCHDOG_PET_REG);
  60 }
  61
  62 /*
  63  *      Allow only one person to hold it open
  64  */
  65 static int epx_c3_open(struct inode *inode, struct file *file)
  66 {
  67         if (epx_c3_alive)
  68                 return -EBUSY;
  69
  70         if (nowayout)
  71                 __module_get(THIS_MODULE);
  72
  73         /* Activate timer */
  74         epx_c3_start();
  75         epx_c3_pet();
  76
  77         epx_c3_alive = 1;
  78         printk(KERN_INFO "Started watchdog timer.\n");
  79
  80         return nonseekable_open(inode, file);
  81 }
  82
  83 static int epx_c3_release(struct inode *inode, struct file *file)
  84 {
  85         /* Shut off the timer.
  86          * Lock it in if it's a module and we defined ...NOWAYOUT */
  87         if (!nowayout)
  88                 epx_c3_stop();          /* Turn the WDT off */
  89
  90         epx_c3_alive = 0;
  91
  92         return 0;
  93 }
  94
  95 static ssize_t epx_c3_write(struct file *file, const char __user *data,
  96                         size_t len, loff_t *ppos)
  97 {
  98         /* Refresh the timer. */
  99         if (len)
 100                 epx_c3_pet();
 101         return len;
 102 }
 103
 104 static long epx_c3_ioctl(struct file *file, unsigned int cmd,
 105                                                 unsigned long arg)
 106 {
 107         int options, retval = -EINVAL;
 108         int __user *argp = (void __user *)arg;
 109         static const struct watchdog_info ident = {
 110                 .options                = WDIOF_KEEPALIVEPING,
 111                 .firmware_version       = 0,
 112                 .identity               = "Winsystems EPX-C3 H/W Watchdog",
 113         };
 114
 115         switch (cmd) {
 116         case WDIOC_GETSUPPORT:
 117                 if (copy_to_user(argp, &ident, sizeof(ident)))
 118                         return -EFAULT;
 119                 return 0;
 120         case WDIOC_GETSTATUS:
 121         case WDIOC_GETBOOTSTATUS:
 122                 return put_user(0, argp);
 123         case WDIOC_SETOPTIONS:
 124                 if (get_user(options, argp))
 125                         return -EFAULT;
 126
 127                 if (options & WDIOS_DISABLECARD) {
 128                         epx_c3_stop();
 129                         retval = 0;
 130                 }
 131
 132                 if (options & WDIOS_ENABLECARD) {
 133                         epx_c3_start();
 134                         retval = 0;
 135                 }
 136
 137                 return retval;
 138         case WDIOC_KEEPALIVE:
 139                 epx_c3_pet();
 140                 return 0;
 141         case WDIOC_GETTIMEOUT:
 142                 return put_user(WATCHDOG_TIMEOUT, argp);
 143         default:
 144                 return -ENOTTY;
 145         }
 146 }
 147
 148 static int epx_c3_notify_sys(struct notifier_block *this, unsigned long code,
 149                                 void *unused)
 150 {
 151         if (code == SYS_DOWN || code == SYS_HALT)
 152                 epx_c3_stop();          /* Turn the WDT off */
 153
 154         return NOTIFY_DONE;
 155 }
 156
 157 static const struct file_operations epx_c3_fops = {
 158         .owner          = THIS_MODULE,
 159         .llseek         = no_llseek,
 160         .write          = epx_c3_write,
 161         .unlocked_ioctl = epx_c3_ioctl,
 162         .open           = epx_c3_open,
 163         .release        = epx_c3_release,
 164 };
 165
 166 static struct miscdevice epx_c3_miscdev = {
 167         .minor          = WATCHDOG_MINOR,
 168         .name           = "watchdog",
 169         .fops           = &epx_c3_fops,
 170 };
 171
 172 static struct notifier_block epx_c3_notifier = {
 173         .notifier_call = epx_c3_notify_sys,
 174 };
 175
 176 static const char banner[] __initconst = KERN_INFO PFX
 177         "Hardware Watchdog Timer for Winsystems EPX-C3 SBC: 0.1\n";
 178
 179 static int __init watchdog_init(void)
 180 {
 181         int ret;
 182
 183         if (!request_region(EPXC3_WATCHDOG_CTL_REG, 2, "epxc3_watchdog"))
 184                 return -EBUSY;
 185
 186         ret = register_reboot_notifier(&epx_c3_notifier);
 187         if (ret) {
 188                 printk(KERN_ERR PFX "cannot register reboot notifier "
 189                         "(err=%d)\n", ret);
 190                 goto out;
 191         }
 192
 193         ret = misc_register(&epx_c3_miscdev);
 194         if (ret) {
 195                 printk(KERN_ERR PFX "cannot register miscdev on minor=%d "
 196                         "(err=%d)\n", WATCHDOG_MINOR, ret);
 197                 unregister_reboot_notifier(&epx_c3_notifier);
 198                 goto out;
 199         }
 200
 201         printk(banner);
 202
 203         return 0;
 204
 205 out:
 206         release_region(EPXC3_WATCHDOG_CTL_REG, 2);
 207         return ret;
 208 }
 209
 210 static void __exit watchdog_exit(void)
 211 {
 212         misc_deregister(&epx_c3_miscdev);
 213         unregister_reboot_notifier(&epx_c3_notifier);
 214         release_region(EPXC3_WATCHDOG_CTL_REG, 2);
 215 }
 216
 217 module_init(watchdog_init);
 218 module_exit(watchdog_exit);
 219
 220 MODULE_AUTHOR("Calin A. Culianu <calin@ajvar.org>");
 221 MODULE_DESCRIPTION("Hardware Watchdog Device for Winsystems EPX-C3 SBC.  "
 222         "Note that there is no way to probe for this device -- "
 223         "so only use it if you are *sure* you are running on this specific "
 224         "SBC system from Winsystems!  It writes to IO ports 0x1ee and 0x1ef!");
 225 MODULE_LICENSE("GPL");
 226 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);