drivers/char/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/config.h>
  21 #include <linux/module.h>
  22 #include <linux/moduleparam.h>
  23 #include <linux/init.h>
  24 #include <linux/miscdevice.h>
  25 #include <linux/watchdog.h>
  26 #include <linux/notifier.h>
  27 #include <linux/reboot.h>
  28 #include <linux/fs.h>
  29 #include <linux/pci.h>
  30 #include <linux/scx200.h>
  31
  32 #include <asm/uaccess.h>
  33 #include <asm/io.h>
  34
  35 #define NAME "scx200_wdt"
  36
  37 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
  38 MODULE_DESCRIPTION("NatSemi SCx200 Watchdog Driver");
  39 MODULE_LICENSE("GPL");
  40 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  41
  42 #ifndef CONFIG_WATCHDOG_NOWAYOUT
  43 #define CONFIG_WATCHDOG_NOWAYOUT 0
  44 #endif
  45
  46 static int margin = 60;         /* in seconds */
  47 module_param(margin, int, 0);
  48 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
  49
  50 static int nowayout = CONFIG_WATCHDOG_NOWAYOUT;
  51 module_param(nowayout, int, 0);
  52 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
  53
  54 static u16 wdto_restart;
  55 static struct semaphore open_semaphore;
  56 static char expect_close;
  57
  58 /* Bits of the WDCNFG register */
  59 #define W_ENABLE 0x00fa         /* Enable watchdog */
  60 #define W_DISABLE 0x0000        /* Disable watchdog */
  61
  62 /* The scaling factor for the timer, this depends on the value of W_ENABLE */
  63 #define W_SCALE (32768/1024)
  64
  65 static void scx200_wdt_ping(void)
  66 {
  67         outw(wdto_restart, scx200_cb_base + SCx200_WDT_WDTO);
  68 }
  69
  70 static void scx200_wdt_update_margin(void)
  71 {
  72         printk(KERN_INFO NAME ": timer margin %d seconds\n", margin);
  73         wdto_restart = margin * W_SCALE;
  74 }
  75
  76 static void scx200_wdt_enable(void)
  77 {
  78         printk(KERN_DEBUG NAME ": enabling watchdog timer, wdto_restart = %d\n",
  79                wdto_restart);
  80
  81         outw(0, scx200_cb_base + SCx200_WDT_WDTO);
  82         outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
  83         outw(W_ENABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
  84
  85         scx200_wdt_ping();
  86 }
  87
  88 static void scx200_wdt_disable(void)
  89 {
  90         printk(KERN_DEBUG NAME ": disabling watchdog timer\n");
  91
  92         outw(0, scx200_cb_base + SCx200_WDT_WDTO);
  93         outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
  94         outw(W_DISABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
  95 }
  96
  97 static int scx200_wdt_open(struct inode *inode, struct file *file)
  98 {
  99         /* only allow one at a time */
 100         if (down_trylock(&open_semaphore))
 101                 return -EBUSY;
 102         scx200_wdt_enable();
 103
 104         return nonseekable_open(inode, file);
 105 }
 106
 107 static int scx200_wdt_release(struct inode *inode, struct file *file)
 108 {
 109         if (expect_close != 42) {
 110                 printk(KERN_WARNING NAME ": watchdog device closed unexpectedly, will not disable the watchdog timer\n");
 111         } else if (!nowayout) {
 112                 scx200_wdt_disable();
 113         }
 114         expect_close = 0;
 115         up(&open_semaphore);
 116
 117         return 0;
 118 }
 119
 120 static int scx200_wdt_notify_sys(struct notifier_block *this,
 121                                       unsigned long code, void *unused)
 122 {
 123         if (code == SYS_HALT || code == SYS_POWER_OFF)
 124                 if (!nowayout)
 125                         scx200_wdt_disable();
 126
 127         return NOTIFY_DONE;
 128 }
 129
 130 static struct notifier_block scx200_wdt_notifier =
 131 {
 132         .notifier_call = scx200_wdt_notify_sys,
 133 };
 134
 135 static ssize_t scx200_wdt_write(struct file *file, const char __user *data,
 136                                      size_t len, loff_t *ppos)
 137 {
 138         /* check for a magic close character */
 139         if (len)
 140         {
 141                 size_t i;
 142
 143                 scx200_wdt_ping();
 144
 145                 expect_close = 0;
 146                 for (i = 0; i < len; ++i) {
 147                         char c;
 148                         if (get_user(c, data+i))
 149                                 return -EFAULT;
 150                         if (c == 'V')
 151                                 expect_close = 42;
 152                 }
 153
 154                 return len;
 155         }
 156
 157         return 0;
 158 }
 159
 160 static int scx200_wdt_ioctl(struct inode *inode, struct file *file,
 161         unsigned int cmd, unsigned long arg)
 162 {
 163         void __user *argp = (void __user *)arg;
 164         int __user *p = argp;
 165         static struct watchdog_info ident = {
 166                 .identity = "NatSemi SCx200 Watchdog",
 167                 .firmware_version = 1,
 168                 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING),
 169         };
 170         int new_margin;
 171
 172         switch (cmd) {
 173         default:
 174                 return -ENOIOCTLCMD;
 175         case WDIOC_GETSUPPORT:
 176                 if(copy_to_user(argp, &ident, sizeof(ident)))
 177                         return -EFAULT;
 178                 return 0;
 179         case WDIOC_GETSTATUS:
 180         case WDIOC_GETBOOTSTATUS:
 181                 if (put_user(0, p))
 182                         return -EFAULT;
 183                 return 0;
 184         case WDIOC_KEEPALIVE:
 185                 scx200_wdt_ping();
 186                 return 0;
 187         case WDIOC_SETTIMEOUT:
 188                 if (get_user(new_margin, p))
 189                         return -EFAULT;
 190                 if (new_margin < 1)
 191                         return -EINVAL;
 192                 margin = new_margin;
 193                 scx200_wdt_update_margin();
 194                 scx200_wdt_ping();
 195         case WDIOC_GETTIMEOUT:
 196                 if (put_user(margin, p))
 197                         return -EFAULT;
 198                 return 0;
 199         }
 200 }
 201
 202 static struct file_operations scx200_wdt_fops = {
 203         .owner   = THIS_MODULE,
 204         .llseek  = no_llseek,
 205         .write   = scx200_wdt_write,
 206         .ioctl   = scx200_wdt_ioctl,
 207         .open    = scx200_wdt_open,
 208         .release = scx200_wdt_release,
 209 };
 210
 211 static struct miscdevice scx200_wdt_miscdev = {
 212         .minor = WATCHDOG_MINOR,
 213         .name  = NAME,
 214         .fops  = &scx200_wdt_fops,
 215 };
 216
 217 static int __init scx200_wdt_init(void)
 218 {
 219         int r;
 220
 221         printk(KERN_DEBUG NAME ": NatSemi SCx200 Watchdog Driver\n");
 222
 223         /* check that we have found the configuration block */
 224         if (!scx200_cb_present())
 225                 return -ENODEV;
 226
 227         if (!request_region(scx200_cb_base + SCx200_WDT_OFFSET,
 228                             SCx200_WDT_SIZE,
 229                             "NatSemi SCx200 Watchdog")) {
 230                 printk(KERN_WARNING NAME ": watchdog I/O region busy\n");
 231                 return -EBUSY;
 232         }
 233
 234         scx200_wdt_update_margin();
 235         scx200_wdt_disable();
 236
 237         sema_init(&open_semaphore, 1);
 238
 239         r = misc_register(&scx200_wdt_miscdev);
 240         if (r) {
 241                 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
 242                                 SCx200_WDT_SIZE);
 243                 return r;
 244         }
 245
 246         r = register_reboot_notifier(&scx200_wdt_notifier);
 247         if (r) {
 248                 printk(KERN_ERR NAME ": unable to register reboot notifier");
 249                 misc_deregister(&scx200_wdt_miscdev);
 250                 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
 251                                 SCx200_WDT_SIZE);
 252                 return r;
 253         }
 254
 255         return 0;
 256 }
 257
 258 static void __exit scx200_wdt_cleanup(void)
 259 {
 260         unregister_reboot_notifier(&scx200_wdt_notifier);
 261         misc_deregister(&scx200_wdt_miscdev);
 262         release_region(scx200_cb_base + SCx200_WDT_OFFSET,
 263                        SCx200_WDT_SIZE);
 264 }
 265
 266 module_init(scx200_wdt_init);
 267 module_exit(scx200_wdt_cleanup);
 268
 269 /*
 270     Local variables:
 271         compile-command: "make -k -C ../.. SUBDIRS=drivers/char modules"
 272         c-basic-offset: 8
 273     End:
 274 */