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