335 строки
8.5 KiB
C
335 строки
8.5 KiB
C
/*
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* Acquire Single Board Computer Watchdog Timer driver
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*
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* Based on wdt.c. Original copyright messages:
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*
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* (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
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* All Rights Reserved.
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*
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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
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
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* warranty for any of this software. This material is provided
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* "AS-IS" and at no charge.
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*
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* (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
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*
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* 14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>
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* Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
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* Can't add timeout - driver doesn't allow changing value
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*/
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/*
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* Theory of Operation:
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* The Watch-Dog Timer is provided to ensure that standalone
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* Systems can always recover from catastrophic conditions that
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* caused the CPU to crash. This condition may have occurred by
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* external EMI or a software bug. When the CPU stops working
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* correctly, hardware on the board will either perform a hardware
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* reset (cold boot) or a non-maskable interrupt (NMI) to bring the
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* system back to a known state.
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*
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* The Watch-Dog Timer is controlled by two I/O Ports.
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* 443 hex - Read - Enable or refresh the Watch-Dog Timer
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* 043 hex - Read - Disable the Watch-Dog Timer
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*
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* To enable the Watch-Dog Timer, a read from I/O port 443h must
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* be performed. This will enable and activate the countdown timer
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* which will eventually time out and either reset the CPU or cause
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* an NMI depending on the setting of a jumper. To ensure that this
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* reset condition does not occur, the Watch-Dog Timer must be
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* periodically refreshed by reading the same I/O port 443h.
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* The Watch-Dog Timer is disabled by reading I/O port 043h.
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*
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* The Watch-Dog Timer Time-Out Period is set via jumpers.
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* It can be 1, 2, 10, 20, 110 or 220 seconds.
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*/
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/*
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* Includes, defines, variables, module parameters, ...
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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/* Includes */
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#include <linux/module.h> /* For module specific items */
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#include <linux/moduleparam.h> /* For new moduleparam's */
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#include <linux/types.h> /* For standard types (like size_t) */
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#include <linux/errno.h> /* For the -ENODEV/... values */
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#include <linux/kernel.h> /* For printk/panic/... */
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#include <linux/miscdevice.h> /* For struct miscdevice */
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#include <linux/watchdog.h> /* For the watchdog specific items */
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#include <linux/fs.h> /* For file operations */
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#include <linux/ioport.h> /* For io-port access */
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#include <linux/platform_device.h> /* For platform_driver framework */
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#include <linux/init.h> /* For __init/__exit/... */
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#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
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#include <linux/io.h> /* For inb/outb/... */
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/* Module information */
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#define DRV_NAME "acquirewdt"
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#define WATCHDOG_NAME "Acquire WDT"
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/* There is no way to see what the correct time-out period is */
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#define WATCHDOG_HEARTBEAT 0
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/* internal variables */
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/* the watchdog platform device */
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static struct platform_device *acq_platform_device;
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static unsigned long acq_is_open;
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static char expect_close;
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/* module parameters */
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/* You must set this - there is no sane way to probe for this board. */
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static int wdt_stop = 0x43;
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module_param(wdt_stop, int, 0);
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MODULE_PARM_DESC(wdt_stop, "Acquire WDT 'stop' io port (default 0x43)");
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/* You must set this - there is no sane way to probe for this board. */
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static int wdt_start = 0x443;
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module_param(wdt_start, int, 0);
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MODULE_PARM_DESC(wdt_start, "Acquire WDT 'start' io port (default 0x443)");
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static bool nowayout = WATCHDOG_NOWAYOUT;
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module_param(nowayout, bool, 0);
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MODULE_PARM_DESC(nowayout,
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"Watchdog cannot be stopped once started (default="
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__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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/*
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* Watchdog Operations
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*/
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static void acq_keepalive(void)
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{
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/* Write a watchdog value */
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inb_p(wdt_start);
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}
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static void acq_stop(void)
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{
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/* Turn the card off */
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inb_p(wdt_stop);
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}
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/*
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* /dev/watchdog handling
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*/
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static ssize_t acq_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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/* See if we got the magic character 'V' and reload the timer */
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if (count) {
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if (!nowayout) {
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size_t i;
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/* note: just in case someone wrote the magic character
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five months ago... */
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expect_close = 0;
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/* scan to see whether or not we got the
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magic character */
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for (i = 0; i != count; i++) {
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char c;
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if (get_user(c, buf + i))
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return -EFAULT;
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if (c == 'V')
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expect_close = 42;
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}
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}
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/* Well, anyhow someone wrote to us, we should
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return that favour */
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acq_keepalive();
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}
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return count;
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}
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static long acq_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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{
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int options, retval = -EINVAL;
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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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.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
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.firmware_version = 1,
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.identity = WATCHDOG_NAME,
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};
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switch (cmd) {
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case WDIOC_GETSUPPORT:
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return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
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case WDIOC_GETSTATUS:
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case WDIOC_GETBOOTSTATUS:
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return put_user(0, p);
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case WDIOC_SETOPTIONS:
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{
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if (get_user(options, p))
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return -EFAULT;
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if (options & WDIOS_DISABLECARD) {
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acq_stop();
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retval = 0;
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}
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if (options & WDIOS_ENABLECARD) {
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acq_keepalive();
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retval = 0;
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}
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return retval;
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}
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case WDIOC_KEEPALIVE:
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acq_keepalive();
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return 0;
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case WDIOC_GETTIMEOUT:
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return put_user(WATCHDOG_HEARTBEAT, p);
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default:
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return -ENOTTY;
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}
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}
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static int acq_open(struct inode *inode, struct file *file)
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{
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if (test_and_set_bit(0, &acq_is_open))
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return -EBUSY;
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if (nowayout)
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__module_get(THIS_MODULE);
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/* Activate */
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acq_keepalive();
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return stream_open(inode, file);
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}
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static int acq_close(struct inode *inode, struct file *file)
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{
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if (expect_close == 42) {
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acq_stop();
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} else {
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pr_crit("Unexpected close, not stopping watchdog!\n");
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acq_keepalive();
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}
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clear_bit(0, &acq_is_open);
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expect_close = 0;
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return 0;
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}
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/*
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* Kernel Interfaces
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*/
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static const struct file_operations acq_fops = {
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.owner = THIS_MODULE,
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.llseek = no_llseek,
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.write = acq_write,
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.unlocked_ioctl = acq_ioctl,
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.open = acq_open,
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.release = acq_close,
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};
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static struct miscdevice acq_miscdev = {
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.minor = WATCHDOG_MINOR,
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.name = "watchdog",
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.fops = &acq_fops,
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};
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/*
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* Init & exit routines
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*/
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static int __init acq_probe(struct platform_device *dev)
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{
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int ret;
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if (wdt_stop != wdt_start) {
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if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) {
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pr_err("I/O address 0x%04x already in use\n", wdt_stop);
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ret = -EIO;
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goto out;
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}
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}
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if (!request_region(wdt_start, 1, WATCHDOG_NAME)) {
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pr_err("I/O address 0x%04x already in use\n", wdt_start);
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ret = -EIO;
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goto unreg_stop;
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}
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ret = misc_register(&acq_miscdev);
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if (ret != 0) {
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pr_err("cannot register miscdev on minor=%d (err=%d)\n",
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WATCHDOG_MINOR, ret);
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goto unreg_regions;
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}
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pr_info("initialized. (nowayout=%d)\n", nowayout);
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return 0;
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unreg_regions:
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release_region(wdt_start, 1);
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unreg_stop:
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if (wdt_stop != wdt_start)
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release_region(wdt_stop, 1);
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out:
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return ret;
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}
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static int acq_remove(struct platform_device *dev)
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{
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misc_deregister(&acq_miscdev);
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release_region(wdt_start, 1);
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if (wdt_stop != wdt_start)
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release_region(wdt_stop, 1);
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return 0;
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}
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static void acq_shutdown(struct platform_device *dev)
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{
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/* Turn the WDT off if we have a soft shutdown */
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acq_stop();
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}
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static struct platform_driver acquirewdt_driver = {
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.remove = acq_remove,
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.shutdown = acq_shutdown,
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.driver = {
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.name = DRV_NAME,
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},
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};
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static int __init acq_init(void)
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{
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int err;
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pr_info("WDT driver for Acquire single board computer initialising\n");
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acq_platform_device = platform_device_register_simple(DRV_NAME,
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-1, NULL, 0);
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if (IS_ERR(acq_platform_device))
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return PTR_ERR(acq_platform_device);
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err = platform_driver_probe(&acquirewdt_driver, acq_probe);
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if (err)
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goto unreg_platform_device;
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return 0;
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unreg_platform_device:
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platform_device_unregister(acq_platform_device);
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return err;
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}
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static void __exit acq_exit(void)
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{
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platform_device_unregister(acq_platform_device);
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platform_driver_unregister(&acquirewdt_driver);
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pr_info("Watchdog Module Unloaded\n");
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}
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module_init(acq_init);
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module_exit(acq_exit);
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MODULE_AUTHOR("David Woodhouse");
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MODULE_DESCRIPTION("Acquire Inc. Single Board Computer Watchdog Timer driver");
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MODULE_LICENSE("GPL");
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