drivers/watchdog/scx200_wdt.c

   1 /* drivers/char/watchdog/scx200_wdt.c
   2
   3    National Semiconductor SCx200 Watchdog support
   4
   5    Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
   6
   7    Some code taken from:
   8    National Semiconductor PC87307/PC97307 (ala SC1200) WDT driver
   9    (c) Copyright 2002 Zwane Mwaikambo <zwane@commfireservices.com>
  10
  11    This program is free software; you can redistribute it and/or
  12    modify it under the terms of the GNU General Public License as
  13    published by the Free Software Foundation; either version 2 of the
  14    License, or (at your option) any later version.
  15
  16    The author(s) of this software shall not be held liable for damages
  17    of any nature resulting due to the use of this software. This
  18    software is provided AS-IS with no warranties. */
  19
  20 #include <linux/module.h>
  21 #include <linux/moduleparam.h>
  22 #include <linux/init.h>
  23 #include <linux/miscdevice.h>
  24 #include <linux/watchdog.h>
  25 #include <linux/notifier.h>
  26 #include <linux/reboot.h>
  27 #include <linux/fs.h>
  28 #include <linux/ioport.h>
  29 #include <linux/scx200.h>
  30
  31 #include <asm/uaccess.h>
  32 #include <asm/io.h>
  33
  34 #define NAME "scx200_wdt"
  35
  36 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
  37 MODULE_DESCRIPTION("NatSemi SCx200 Watchdog Driver");
  38 MODULE_LICENSE("GPL");
  39 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  40
  41 static int margin = 60;         /* in seconds */
  42 module_param(margin, int, 0);
  43 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
  44
  45 static int nowayout = WATCHDOG_NOWAYOUT;
  46 module_param(nowayout, int, 0);
  47 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
  48
  49 static u16 wdto_restart;
  50 static struct semaphore open_semaphore;
  51 static char expect_close;
  52
  53 /* Bits of the WDCNFG register */
  54 #define W_ENABLE 0x00fa         /* Enable watchdog */
  55 #define W_DISABLE 0x0000        /* Disable watchdog */
  56
  57 /* The scaling factor for the timer, this depends on the value of W_ENABLE */
  58 #define W_SCALE (32768/1024)
  59
  60 static void scx200_wdt_ping(void)
  61 {
  62         outw(wdto_restart, scx200_cb_base + SCx200_WDT_WDTO);
  63 }
  64
  65 static void scx200_wdt_update_margin(void)
  66 {
  67         printk(KERN_INFO NAME ": timer margin %d seconds\n", margin);
  68         wdto_restart = margin * W_SCALE;
  69 }
  70
  71 static void scx200_wdt_enable(void)
  72 {
  73         printk(KERN_DEBUG NAME ": enabling watchdog timer, wdto_restart = %d\n",
  74                wdto_restart);
  75
  76         outw(0, scx200_cb_base + SCx200_WDT_WDTO);
  77         outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
  78         outw(W_ENABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
  79
  80         scx200_wdt_ping();
  81 }
  82
  83 static void scx200_wdt_disable(void)
  84 {
  85         printk(KERN_DEBUG NAME ": disabling watchdog timer\n");
  86
  87         outw(0, scx200_cb_base + SCx200_WDT_WDTO);
  88         outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
  89         outw(W_DISABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
  90 }
  91
  92 static int scx200_wdt_open(struct inode *inode, struct file *file)
  93 {
  94         /* only allow one at a time */
  95         if (down_trylock(&open_semaphore))
  96                 return -EBUSY;
  97         scx200_wdt_enable();
  98
  99         return nonseekable_open(inode, file);
 100 }
 101
 102 static int scx200_wdt_release(struct inode *inode, struct file *file)
 103 {
 104         if (expect_close != 42) {
 105                 printk(KERN_WARNING NAME ": watchdog device closed unexpectedly, will not disable the watchdog timer\n");
 106         } else if (!nowayout) {
 107                 scx200_wdt_disable();
 108         }
 109         expect_close = 0;
 110         up(&open_semaphore);
 111
 112         return 0;
 113 }
 114
 115 static int scx200_wdt_notify_sys(struct notifier_block *this,
 116                                       unsigned long code, void *unused)
 117 {
 118         if (code == SYS_HALT || code == SYS_POWER_OFF)
 119                 if (!nowayout)
 120                         scx200_wdt_disable();
 121
 122         return NOTIFY_DONE;
 123 }
 124
 125 static struct notifier_block scx200_wdt_notifier =
 126 {
 127         .notifier_call = scx200_wdt_notify_sys,
 128 };
 129
 130 static ssize_t scx200_wdt_write(struct file *file, const char __user *data,
 131                                      size_t len, loff_t *ppos)
 132 {
 133         /* check for a magic close character */
 134         if (len)
 135         {
 136                 size_t i;
 137
 138                 scx200_wdt_ping();
 139
 140                 expect_close = 0;
 141                 for (i = 0; i < len; ++i) {
 142                         char c;
 143                         if (get_user(c, data+i))
 144                                 return -EFAULT;
 145                         if (c == 'V')
 146                                 expect_close = 42;
 147                 }
 148
 149                 return len;
 150         }
 151
 152         return 0;
 153 }
 154
 155 static int scx200_wdt_ioctl(struct inode *inode, struct file *file,
 156         unsigned int cmd, unsigned long arg)
 157 {
 158         void __user *argp = (void __user *)arg;
 159         int __user *p = argp;
 160         static struct watchdog_info ident = {
 161                 .identity = "NatSemi SCx200 Watchdog",
 162                 .firmware_version = 1,
 163                 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING),
 164         };
 165         int new_margin;
 166
 167         switch (cmd) {
 168         default:
 169                 return -ENOTTY;
 170         case WDIOC_GETSUPPORT:
 171                 if(copy_to_user(argp, &ident, sizeof(ident)))
 172                         return -EFAULT;
 173                 return 0;
 174         case WDIOC_GETSTATUS:
 175         case WDIOC_GETBOOTSTATUS:
 176                 if (put_user(0, p))
 177                         return -EFAULT;
 178                 return 0;
 179         case WDIOC_KEEPALIVE:
 180                 scx200_wdt_ping();
 181                 return 0;
 182         case WDIOC_SETTIMEOUT:
 183                 if (get_user(new_margin, p))
 184                         return -EFAULT;
 185                 if (new_margin < 1)
 186                         return -EINVAL;
 187                 margin = new_margin;
 188                 scx200_wdt_update_margin();
 189                 scx200_wdt_ping();
 190         case WDIOC_GETTIMEOUT:
 191                 if (put_user(margin, p))
 192                         return -EFAULT;
 193                 return 0;
 194         }
 195 }
 196
 197 static const struct file_operations scx200_wdt_fops = {
 198         .owner   = THIS_MODULE,
 199         .llseek  = no_llseek,
 200         .write   = scx200_wdt_write,
 201         .ioctl   = scx200_wdt_ioctl,
 202         .open    = scx200_wdt_open,
 203         .release = scx200_wdt_release,
 204 };
 205
 206 static struct miscdevice scx200_wdt_miscdev = {
 207         .minor = WATCHDOG_MINOR,
 208         .name  = "watchdog",
 209         .fops  = &scx200_wdt_fops,
 210 };
 211
 212 static int __init scx200_wdt_init(void)
 213 {
 214         int r;
 215
 216         printk(KERN_DEBUG NAME ": NatSemi SCx200 Watchdog Driver\n");
 217
 218         /* check that we have found the configuration block */
 219         if (!scx200_cb_present())
 220                 return -ENODEV;
 221
 222         if (!request_region(scx200_cb_base + SCx200_WDT_OFFSET,
 223                             SCx200_WDT_SIZE,
 224                             "NatSemi SCx200 Watchdog")) {
 225                 printk(KERN_WARNING NAME ": watchdog I/O region busy\n");
 226                 return -EBUSY;
 227         }
 228
 229         scx200_wdt_update_margin();
 230         scx200_wdt_disable();
 231
 232         sema_init(&open_semaphore, 1);
 233
 234         r = misc_register(&scx200_wdt_miscdev);
 235         if (r) {
 236                 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
 237                                 SCx200_WDT_SIZE);
 238                 return r;
 239         }
 240
 241         r = register_reboot_notifier(&scx200_wdt_notifier);
 242         if (r) {
 243                 printk(KERN_ERR NAME ": unable to register reboot notifier");
 244                 misc_deregister(&scx200_wdt_miscdev);
 245                 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
 246                                 SCx200_WDT_SIZE);
 247                 return r;
 248         }
 249
 250         return 0;
 251 }
 252
 253 static void __exit scx200_wdt_cleanup(void)
 254 {
 255         unregister_reboot_notifier(&scx200_wdt_notifier);
 256         misc_deregister(&scx200_wdt_miscdev);
 257         release_region(scx200_cb_base + SCx200_WDT_OFFSET,
 258                        SCx200_WDT_SIZE);
 259 }
 260
 261 module_init(scx200_wdt_init);
 262 module_exit(scx200_wdt_cleanup);
 263
 264 /*
 265     Local variables:
 266         compile-command: "make -k -C ../.. SUBDIRS=drivers/char modules"
 267         c-basic-offset: 8
 268     End:
 269 */