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 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
  41
  42 static int margin = 60;         /* in seconds */
  43 module_param(margin, int, 0);
  44 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
  45
  46 static bool nowayout = WATCHDOG_NOWAYOUT;
  47 module_param(nowayout, bool, 0);
  48 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
  49
  50 static u16 wdto_restart;
  51 static char expect_close;
  52 static unsigned long open_lock;
  53 static DEFINE_SPINLOCK(scx_lock);
  54
  55 /* Bits of the WDCNFG register */
  56 #define W_ENABLE 0x00fa         /* Enable watchdog */
  57 #define W_DISABLE 0x0000        /* Disable watchdog */
  58
  59 /* The scaling factor for the timer, this depends on the value of W_ENABLE */
  60 #define W_SCALE (32768/1024)
  61
  62 static void scx200_wdt_ping(void)
  63 {
  64         spin_lock(&scx_lock);
  65         outw(wdto_restart, scx200_cb_base + SCx200_WDT_WDTO);
  66         spin_unlock(&scx_lock);
  67 }
  68
  69 static void scx200_wdt_update_margin(void)
  70 {
  71         pr_info("timer margin %d seconds\n", margin);
  72         wdto_restart = margin * W_SCALE;
  73 }
  74
  75 static void scx200_wdt_enable(void)
  76 {
  77         pr_debug("enabling watchdog timer, wdto_restart = %d\n", wdto_restart);
  78
  79         spin_lock(&scx_lock);
  80         outw(0, scx200_cb_base + SCx200_WDT_WDTO);
  81         outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
  82         outw(W_ENABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
  83         spin_unlock(&scx_lock);
  84
  85         scx200_wdt_ping();
  86 }
  87
  88 static void scx200_wdt_disable(void)
  89 {
  90         pr_debug("disabling watchdog timer\n");
  91
  92         spin_lock(&scx_lock);
  93         outw(0, scx200_cb_base + SCx200_WDT_WDTO);
  94         outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
  95         outw(W_DISABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
  96         spin_unlock(&scx_lock);
  97 }
  98
  99 static int scx200_wdt_open(struct inode *inode, struct file *file)
 100 {
 101         /* only allow one at a time */
 102         if (test_and_set_bit(0, &open_lock))
 103                 return -EBUSY;
 104         scx200_wdt_enable();
 105
 106         return nonseekable_open(inode, file);
 107 }
 108
 109 static int scx200_wdt_release(struct inode *inode, struct file *file)
 110 {
 111         if (expect_close != 42)
 112                 pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
 113         else if (!nowayout)
 114                 scx200_wdt_disable();
 115         expect_close = 0;
 116         clear_bit(0, &open_lock);
 117
 118         return 0;
 119 }
 120
 121 static int scx200_wdt_notify_sys(struct notifier_block *this,
 122                                       unsigned long code, void *unused)
 123 {
 124         if (code == SYS_HALT || code == SYS_POWER_OFF)
 125                 if (!nowayout)
 126                         scx200_wdt_disable();
 127
 128         return NOTIFY_DONE;
 129 }
 130
 131 static struct notifier_block scx200_wdt_notifier = {
 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                 size_t i;
 141
 142                 scx200_wdt_ping();
 143
 144                 expect_close = 0;
 145                 for (i = 0; i < len; ++i) {
 146                         char c;
 147                         if (get_user(c, data + i))
 148                                 return -EFAULT;
 149                         if (c == 'V')
 150                                 expect_close = 42;
 151                 }
 152
 153                 return len;
 154         }
 155
 156         return 0;
 157 }
 158
 159 static long scx200_wdt_ioctl(struct file *file, unsigned int cmd,
 160                                                         unsigned long arg)
 161 {
 162         void __user *argp = (void __user *)arg;
 163         int __user *p = argp;
 164         static const struct watchdog_info ident = {
 165                 .identity = "NatSemi SCx200 Watchdog",
 166                 .firmware_version = 1,
 167                 .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 168                                                 WDIOF_MAGICCLOSE,
 169         };
 170         int new_margin;
 171
 172         switch (cmd) {
 173         case WDIOC_GETSUPPORT:
 174                 if (copy_to_user(argp, &ident, sizeof(ident)))
 175                         return -EFAULT;
 176                 return 0;
 177         case WDIOC_GETSTATUS:
 178         case WDIOC_GETBOOTSTATUS:
 179                 if (put_user(0, p))
 180                         return -EFAULT;
 181                 return 0;
 182         case WDIOC_KEEPALIVE:
 183                 scx200_wdt_ping();
 184                 return 0;
 185         case WDIOC_SETTIMEOUT:
 186                 if (get_user(new_margin, p))
 187                         return -EFAULT;
 188                 if (new_margin < 1)
 189                         return -EINVAL;
 190                 margin = new_margin;
 191                 scx200_wdt_update_margin();
 192                 scx200_wdt_ping();
 193         case WDIOC_GETTIMEOUT:
 194                 if (put_user(margin, p))
 195                         return -EFAULT;
 196                 return 0;
 197         default:
 198                 return -ENOTTY;
 199         }
 200 }
 201
 202 static const struct file_operations scx200_wdt_fops = {
 203         .owner = THIS_MODULE,
 204         .llseek = no_llseek,
 205         .write = scx200_wdt_write,
 206         .unlocked_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 = "watchdog",
 214         .fops = &scx200_wdt_fops,
 215 };
 216
 217 static int __init scx200_wdt_init(void)
 218 {
 219         int r;
 220
 221         pr_debug("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                 pr_warn("watchdog I/O region busy\n");
 231                 return -EBUSY;
 232         }
 233
 234         scx200_wdt_update_margin();
 235         scx200_wdt_disable();
 236
 237         r = register_reboot_notifier(&scx200_wdt_notifier);
 238         if (r) {
 239                 pr_err("unable to register reboot notifier\n");
 240                 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
 241                                 SCx200_WDT_SIZE);
 242                 return r;
 243         }
 244
 245         r = misc_register(&scx200_wdt_miscdev);
 246         if (r) {
 247                 unregister_reboot_notifier(&scx200_wdt_notifier);
 248                 release_region(scx200_cb_base + SCx200_WDT_OFFSET,
 249                                 SCx200_WDT_SIZE);
 250                 return r;
 251         }
 252
 253         return 0;
 254 }
 255
 256 static void __exit scx200_wdt_cleanup(void)
 257 {
 258         misc_deregister(&scx200_wdt_miscdev);
 259         unregister_reboot_notifier(&scx200_wdt_notifier);
 260         release_region(scx200_cb_base + SCx200_WDT_OFFSET,
 261                        SCx200_WDT_SIZE);
 262 }
 263
 264 module_init(scx200_wdt_init);
 265 module_exit(scx200_wdt_cleanup);
 266
 267 /*
 268     Local variables:
 269         compile-command: "make -k -C ../.. SUBDIRS=drivers/char modules"
 270         c-basic-offset: 8
 271     End:
 272 */