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
 112                         ": watchdog device closed unexpectedly, "
 113                         "will not disable the watchdog timer\n");
 114         else if (!nowayout)
 115                 scx200_wdt_disable();
 116         expect_close = 0;
 117         clear_bit(0, &open_lock);
 118
 119         return 0;
 120 }
 121
 122 static int scx200_wdt_notify_sys(struct notifier_block *this,
 123                                       unsigned long code, void *unused)
 124 {
 125         if (code == SYS_HALT || code == SYS_POWER_OFF)
 126                 if (!nowayout)
 127                         scx200_wdt_disable();
 128
 129         return NOTIFY_DONE;
 130 }
 131
 132 static struct notifier_block scx200_wdt_notifier = {
 133         .notifier_call = scx200_wdt_notify_sys,
 134 };
 135
 136 static ssize_t scx200_wdt_write(struct file *file, const char __user *data,
 137                                      size_t len, loff_t *ppos)
 138 {
 139         /* check for a magic close character */
 140         if (len) {
 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 long scx200_wdt_ioctl(struct file *file, unsigned int cmd,
 161                                                         unsigned long arg)
 162 {
 163         void __user *argp = (void __user *)arg;
 164         int __user *p = argp;
 165         static const struct watchdog_info ident = {
 166                 .identity = "NatSemi SCx200 Watchdog",
 167                 .firmware_version = 1,
 168                 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 169                                                 WDIOF_MAGICCLOSE,
 170         };
 171         int new_margin;
 172
 173         switch (cmd) {
 174         case WDIOC_GETSUPPORT:
 175                 if (copy_to_user(argp, &ident, sizeof(ident)))
 176                         return -EFAULT;
 177                 return 0;
 178         case WDIOC_GETSTATUS:
 179         case WDIOC_GETBOOTSTATUS:
 180                 if (put_user(0, p))
 181                         return -EFAULT;
 182                 return 0;
 183         case WDIOC_KEEPALIVE:
 184                 scx200_wdt_ping();
 185                 return 0;
 186         case WDIOC_SETTIMEOUT:
 187                 if (get_user(new_margin, p))
 188                         return -EFAULT;
 189                 if (new_margin < 1)
 190                         return -EINVAL;
 191                 margin = new_margin;
 192                 scx200_wdt_update_margin();
 193                 scx200_wdt_ping();
 194         case WDIOC_GETTIMEOUT:
 195                 if (put_user(margin, p))
 196                         return -EFAULT;
 197                 return 0;
 198         default:
 199                 return -ENOTTY;
 200         }
 201 }
 202
 203 static const struct file_operations scx200_wdt_fops = {
 204         .owner = THIS_MODULE,
 205         .llseek = no_llseek,
 206         .write = scx200_wdt_write,
 207         .unlocked_ioctl = scx200_wdt_ioctl,
 208         .open = scx200_wdt_open,
 209         .release = scx200_wdt_release,
 210 };
 211
 212 static struct miscdevice scx200_wdt_miscdev = {
 213         .minor = WATCHDOG_MINOR,
 214         .name = "watchdog",
 215         .fops = &scx200_wdt_fops,
 216 };
 217
 218 static int __init scx200_wdt_init(void)
 219 {
 220         int r;
 221
 222         printk(KERN_DEBUG NAME ": NatSemi SCx200 Watchdog Driver\n");
 223
 224         /* check that we have found the configuration block */
 225         if (!scx200_cb_present())
 226                 return -ENODEV;
 227
 228         if (!request_region(scx200_cb_base + SCx200_WDT_OFFSET,
 229                             SCx200_WDT_SIZE,
 230                             "NatSemi SCx200 Watchdog")) {
 231                 printk(KERN_WARNING NAME ": watchdog I/O region busy\n");
 232                 return -EBUSY;
 233         }
 234
 235         scx200_wdt_update_margin();
 236         scx200_wdt_disable();
 237
 238         r = register_reboot_notifier(&scx200_wdt_notifier);
 239         if (r) {
 240                 printk(KERN_ERR NAME ": unable to register reboot notifier");
 241                 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
 242                                 SCx200_WDT_SIZE);
 243                 return r;
 244         }
 245
 246         r = misc_register(&scx200_wdt_miscdev);
 247         if (r) {
 248                 unregister_reboot_notifier(&scx200_wdt_notifier);
 249                 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
 250                                 SCx200_WDT_SIZE);
 251                 return r;
 252         }
 253
 254         return 0;
 255 }
 256
 257 static void __exit scx200_wdt_cleanup(void)
 258 {
 259         misc_deregister(&scx200_wdt_miscdev);
 260         unregister_reboot_notifier(&scx200_wdt_notifier);
 261         release_region(scx200_cb_base + SCx200_WDT_OFFSET,
 262                        SCx200_WDT_SIZE);
 263 }
 264
 265 module_init(scx200_wdt_init);
 266 module_exit(scx200_wdt_cleanup);
 267
 268 /*
 269     Local variables:
 270         compile-command: "make -k -C ../.. SUBDIRS=drivers/char modules"
 271         c-basic-offset: 8
 272     End:
 273 */