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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  21
  22 #include <linux/module.h>
  23 #include <linux/moduleparam.h>
  24 #include <linux/init.h>
  25 #include <linux/miscdevice.h>
  26 #include <linux/watchdog.h>
  27 #include <linux/notifier.h>
  28 #include <linux/reboot.h>
  29 #include <linux/fs.h>
  30 #include <linux/ioport.h>
  31 #include <linux/scx200.h>
  32 #include <linux/uaccess.h>
  33 #include <linux/io.h>
  34
  35 #define DEBUG
  36
  37 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
  38 MODULE_DESCRIPTION("NatSemi SCx200 Watchdog Driver");
  39 MODULE_LICENSE("GPL");
  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 bool nowayout = WATCHDOG_NOWAYOUT;
  46 module_param(nowayout, bool, 0);
  47 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
  48
  49 static u16 wdto_restart;
  50 static char expect_close;
  51 static unsigned long open_lock;
  52 static DEFINE_SPINLOCK(scx_lock);
  53
  54 /* Bits of the WDCNFG register */
  55 #define W_ENABLE 0x00fa         /* Enable watchdog */
  56 #define W_DISABLE 0x0000        /* Disable watchdog */
  57
  58 /* The scaling factor for the timer, this depends on the value of W_ENABLE */
  59 #define W_SCALE (32768/1024)
  60
  61 static void scx200_wdt_ping(void)
  62 {
  63         spin_lock(&scx_lock);
  64         outw(wdto_restart, scx200_cb_base + SCx200_WDT_WDTO);
  65         spin_unlock(&scx_lock);
  66 }
  67
  68 static void scx200_wdt_update_margin(void)
  69 {
  70         pr_info("timer margin %d seconds\n", margin);
  71         wdto_restart = margin * W_SCALE;
  72 }
  73
  74 static void scx200_wdt_enable(void)
  75 {
  76         pr_debug("enabling watchdog timer, wdto_restart = %d\n", 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         pr_debug("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                 pr_warn("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                                                 WDIOF_MAGICCLOSE,
 168         };
 169         int new_margin;
 170
 171         switch (cmd) {
 172         case WDIOC_GETSUPPORT:
 173                 if (copy_to_user(argp, &ident, sizeof(ident)))
 174                         return -EFAULT;
 175                 return 0;
 176         case WDIOC_GETSTATUS:
 177         case WDIOC_GETBOOTSTATUS:
 178                 if (put_user(0, p))
 179                         return -EFAULT;
 180                 return 0;
 181         case WDIOC_KEEPALIVE:
 182                 scx200_wdt_ping();
 183                 return 0;
 184         case WDIOC_SETTIMEOUT:
 185                 if (get_user(new_margin, p))
 186                         return -EFAULT;
 187                 if (new_margin < 1)
 188                         return -EINVAL;
 189                 margin = new_margin;
 190                 scx200_wdt_update_margin();
 191                 scx200_wdt_ping();
 192         case WDIOC_GETTIMEOUT:
 193                 if (put_user(margin, p))
 194                         return -EFAULT;
 195                 return 0;
 196         default:
 197                 return -ENOTTY;
 198         }
 199 }
 200
 201 static const struct file_operations scx200_wdt_fops = {
 202         .owner = THIS_MODULE,
 203         .llseek = no_llseek,
 204         .write = scx200_wdt_write,
 205         .unlocked_ioctl = scx200_wdt_ioctl,
 206         .open = scx200_wdt_open,
 207         .release = scx200_wdt_release,
 208 };
 209
 210 static struct miscdevice scx200_wdt_miscdev = {
 211         .minor = WATCHDOG_MINOR,
 212         .name = "watchdog",
 213         .fops = &scx200_wdt_fops,
 214 };
 215
 216 static int __init scx200_wdt_init(void)
 217 {
 218         int r;
 219
 220         pr_debug("NatSemi SCx200 Watchdog Driver\n");
 221
 222         /* check that we have found the configuration block */
 223         if (!scx200_cb_present())
 224                 return -ENODEV;
 225
 226         if (!request_region(scx200_cb_base + SCx200_WDT_OFFSET,
 227                             SCx200_WDT_SIZE,
 228                             "NatSemi SCx200 Watchdog")) {
 229                 pr_warn("watchdog I/O region busy\n");
 230                 return -EBUSY;
 231         }
 232
 233         scx200_wdt_update_margin();
 234         scx200_wdt_disable();
 235
 236         r = register_reboot_notifier(&scx200_wdt_notifier);
 237         if (r) {
 238                 pr_err("unable to register reboot notifier\n");
 239                 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
 240                                 SCx200_WDT_SIZE);
 241                 return r;
 242         }
 243
 244         r = misc_register(&scx200_wdt_miscdev);
 245         if (r) {
 246                 unregister_reboot_notifier(&scx200_wdt_notifier);
 247                 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
 248                                 SCx200_WDT_SIZE);
 249                 return r;
 250         }
 251
 252         return 0;
 253 }
 254
 255 static void __exit scx200_wdt_cleanup(void)
 256 {
 257         misc_deregister(&scx200_wdt_miscdev);
 258         unregister_reboot_notifier(&scx200_wdt_notifier);
 259         release_region(scx200_cb_base + SCx200_WDT_OFFSET,
 260                        SCx200_WDT_SIZE);
 261 }
 262
 263 module_init(scx200_wdt_init);
 264 module_exit(scx200_wdt_cleanup);
 265
 266 /*
 267     Local variables:
 268         compile-command: "make -k -C ../.. SUBDIRS=drivers/char modules"
 269         c-basic-offset: 8
 270     End:
 271 */