forked from luck/tmp_suning_uos_patched
62322d2554
Mark the static struct file_operations in drivers/char as const. Making them const prevents accidental bugs, and moves them to the .rodata section so that they no longer do any false sharing; in addition with the proper debug option they are then protected against corruption.. [akpm@osdl.org: build fix] Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
328 lines
7.7 KiB
C
328 lines
7.7 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@redhat.com>, All Rights Reserved.
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* http://www.redhat.com
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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@redhat.com>
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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 occured 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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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/types.h>
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#include <linux/miscdevice.h>
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#include <linux/watchdog.h>
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#include <linux/fs.h>
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#include <linux/ioport.h>
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#include <linux/notifier.h>
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#include <linux/reboot.h>
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#include <linux/init.h>
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#include <asm/io.h>
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#include <asm/uaccess.h>
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#include <asm/system.h>
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#define WATCHDOG_NAME "Acquire WDT"
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#define PFX WATCHDOG_NAME ": "
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#define WATCHDOG_HEARTBEAT 0 /* There is no way to see what the correct time-out period is */
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static unsigned long acq_is_open;
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static char expect_close;
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/*
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* You must set these - there is no sane way to probe for this board.
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*/
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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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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 int nowayout = WATCHDOG_NOWAYOUT;
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module_param(nowayout, int, 0);
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MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
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/*
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* Kernel methods.
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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, 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 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 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 int acq_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
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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 struct watchdog_info ident =
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{
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.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
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.firmware_version = 1,
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.identity = "Acquire WDT",
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};
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switch(cmd)
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{
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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_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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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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{
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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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{
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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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default:
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return -ENOIOCTLCMD;
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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 nonseekable_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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printk(KERN_CRIT PFX "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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* Notifier for system down
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*/
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static int acq_notify_sys(struct notifier_block *this, unsigned long code,
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void *unused)
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{
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if(code==SYS_DOWN || code==SYS_HALT) {
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/* Turn the WDT off */
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acq_stop();
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}
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return NOTIFY_DONE;
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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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.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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{
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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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* The WDT card needs to learn about soft shutdowns in order to
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* turn the timebomb registers off.
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*/
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static struct notifier_block acq_notifier =
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{
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.notifier_call = acq_notify_sys,
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};
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static int __init acq_init(void)
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{
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int ret;
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printk(KERN_INFO "WDT driver for Acquire single board computer initialising.\n");
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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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printk (KERN_ERR PFX "I/O address 0x%04x already in use\n",
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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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printk (KERN_ERR PFX "I/O address 0x%04x already in use\n",
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wdt_start);
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ret = -EIO;
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goto unreg_stop;
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}
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ret = register_reboot_notifier(&acq_notifier);
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if (ret != 0) {
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printk (KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
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ret);
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goto unreg_regions;
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}
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ret = misc_register(&acq_miscdev);
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if (ret != 0) {
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printk (KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
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WATCHDOG_MINOR, ret);
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goto unreg_reboot;
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}
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printk (KERN_INFO PFX "initialized. (nowayout=%d)\n",
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nowayout);
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return 0;
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unreg_reboot:
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unregister_reboot_notifier(&acq_notifier);
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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 void __exit acq_exit(void)
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{
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misc_deregister(&acq_miscdev);
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unregister_reboot_notifier(&acq_notifier);
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if(wdt_stop != wdt_start)
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release_region(wdt_stop,1);
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release_region(wdt_start,1);
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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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MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
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