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/* drivers/char/watchdog/scx200_wdt.c
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National Semiconductor SCx200 Watchdog support
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Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
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National Semiconductor PC87307/PC97307 (ala SC1200) WDT driver
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(c) Copyright 2002 Zwane Mwaikambo <zwane@commfireservices.com>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The author(s) of this software shall not be held liable for damages
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of any nature resulting due to the use of this software. This
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software is provided AS-IS with no warranties. */
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/init.h>
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#include <linux/miscdevice.h>
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#include <linux/watchdog.h>
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#include <linux/notifier.h>
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#include <linux/reboot.h>
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#include <linux/ioport.h>
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#include <linux/scx200.h>
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#include <linux/uaccess.h>
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#define NAME "scx200_wdt"
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MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
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MODULE_DESCRIPTION("NatSemi SCx200 Watchdog Driver");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
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static int margin = 60; /* in seconds */
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module_param(margin, int, 0);
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MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
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static int nowayout = WATCHDOG_NOWAYOUT;
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module_param(nowayout, int, 0);
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MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
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static u16 wdto_restart;
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static char expect_close;
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static unsigned long open_lock;
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static DEFINE_SPINLOCK(scx_lock);
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/* Bits of the WDCNFG register */
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#define W_ENABLE 0x00fa /* Enable watchdog */
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#define W_DISABLE 0x0000 /* Disable watchdog */
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/* The scaling factor for the timer, this depends on the value of W_ENABLE */
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#define W_SCALE (32768/1024)
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static void scx200_wdt_ping(void)
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outw(wdto_restart, scx200_cb_base + SCx200_WDT_WDTO);
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spin_unlock(&scx_lock);
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static void scx200_wdt_update_margin(void)
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printk(KERN_INFO NAME ": timer margin %d seconds\n", margin);
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wdto_restart = margin * W_SCALE;
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static void scx200_wdt_enable(void)
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printk(KERN_DEBUG NAME ": enabling watchdog timer, wdto_restart = %d\n",
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outw(0, scx200_cb_base + SCx200_WDT_WDTO);
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outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
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outw(W_ENABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
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spin_unlock(&scx_lock);
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static void scx200_wdt_disable(void)
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printk(KERN_DEBUG NAME ": disabling watchdog timer\n");
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outw(0, scx200_cb_base + SCx200_WDT_WDTO);
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outb(SCx200_WDT_WDSTS_WDOVF, scx200_cb_base + SCx200_WDT_WDSTS);
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outw(W_DISABLE, scx200_cb_base + SCx200_WDT_WDCNFG);
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spin_unlock(&scx_lock);
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static int scx200_wdt_open(struct inode *inode, struct file *file)
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/* only allow one at a time */
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if (test_and_set_bit(0, &open_lock))
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return nonseekable_open(inode, file);
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static int scx200_wdt_release(struct inode *inode, struct file *file)
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if (expect_close != 42)
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printk(KERN_WARNING NAME
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": watchdog device closed unexpectedly, "
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"will not disable the watchdog timer\n");
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scx200_wdt_disable();
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clear_bit(0, &open_lock);
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static int scx200_wdt_notify_sys(struct notifier_block *this,
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unsigned long code, void *unused)
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if (code == SYS_HALT || code == SYS_POWER_OFF)
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scx200_wdt_disable();
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static struct notifier_block scx200_wdt_notifier = {
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.notifier_call = scx200_wdt_notify_sys,
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static ssize_t scx200_wdt_write(struct file *file, const char __user *data,
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size_t len, loff_t *ppos)
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/* check for a magic close character */
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for (i = 0; i < len; ++i) {
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if (get_user(c, data + i))
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static long scx200_wdt_ioctl(struct file *file, unsigned int cmd,
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void __user *argp = (void __user *)arg;
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int __user *p = argp;
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static const struct watchdog_info ident = {
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.identity = "NatSemi SCx200 Watchdog",
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.firmware_version = 1,
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.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
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case WDIOC_GETSUPPORT:
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if (copy_to_user(argp, &ident, sizeof(ident)))
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case WDIOC_GETSTATUS:
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case WDIOC_GETBOOTSTATUS:
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case WDIOC_KEEPALIVE:
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case WDIOC_SETTIMEOUT:
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if (get_user(new_margin, p))
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scx200_wdt_update_margin();
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case WDIOC_GETTIMEOUT:
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if (put_user(margin, p))
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static const struct file_operations scx200_wdt_fops = {
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.owner = THIS_MODULE,
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.write = scx200_wdt_write,
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.unlocked_ioctl = scx200_wdt_ioctl,
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.open = scx200_wdt_open,
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.release = scx200_wdt_release,
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static struct miscdevice scx200_wdt_miscdev = {
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.minor = WATCHDOG_MINOR,
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.fops = &scx200_wdt_fops,
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static int __init scx200_wdt_init(void)
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printk(KERN_DEBUG NAME ": NatSemi SCx200 Watchdog Driver\n");
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/* check that we have found the configuration block */
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if (!scx200_cb_present())
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if (!request_region(scx200_cb_base + SCx200_WDT_OFFSET,
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"NatSemi SCx200 Watchdog")) {
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printk(KERN_WARNING NAME ": watchdog I/O region busy\n");
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scx200_wdt_update_margin();
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scx200_wdt_disable();
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r = register_reboot_notifier(&scx200_wdt_notifier);
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printk(KERN_ERR NAME ": unable to register reboot notifier");
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release_region(scx200_cb_base + SCx200_WDT_OFFSET,
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r = misc_register(&scx200_wdt_miscdev);
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unregister_reboot_notifier(&scx200_wdt_notifier);
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release_region(scx200_cb_base + SCx200_WDT_OFFSET,
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static void __exit scx200_wdt_cleanup(void)
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misc_deregister(&scx200_wdt_miscdev);
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unregister_reboot_notifier(&scx200_wdt_notifier);
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release_region(scx200_cb_base + SCx200_WDT_OFFSET,
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module_init(scx200_wdt_init);
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module_exit(scx200_wdt_cleanup);
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compile-command: "make -k -C ../.. SUBDIRS=drivers/char modules"