385 lines
9.9 KiB
C
385 lines
9.9 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* 60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x
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*
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* Based on acquirewdt.c by Alan Cox.
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*
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* The author does NOT admit liability nor provide warranty for
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* any of this software. This material is provided "AS-IS" in
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* the hope that it may be useful for others.
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*
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* (c) Copyright 2000 Jakob Oestergaard <jakob@unthought.net>
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*
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* 12/4 - 2000 [Initial revision]
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* 25/4 - 2000 Added /dev/watchdog support
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* 09/5 - 2001 [smj@oro.net] fixed fop_write to "return 1"
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* on success
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* 12/4 - 2002 [rob@osinvestor.com] eliminate fop_read
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* fix possible wdt_is_open race
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* add CONFIG_WATCHDOG_NOWAYOUT support
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* remove lock_kernel/unlock_kernel pairs
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* added KERN_* to printk's
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* got rid of extraneous comments
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* changed watchdog_info to correctly reflect what
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* the driver offers
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* added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,
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* WDIOC_SETTIMEOUT, WDIOC_GETTIMEOUT, and
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* WDIOC_SETOPTIONS ioctls
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* 09/8 - 2003 [wim@iguana.be] cleanup of trailing spaces
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* use module_param
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* made timeout (the emulated heartbeat) a
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* module_param
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* made the keepalive ping an internal subroutine
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* made wdt_stop and wdt_start module params
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* added extra printk's for startup problems
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* added MODULE_AUTHOR and MODULE_DESCRIPTION info
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*
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* This WDT driver is different from the other Linux WDT
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* drivers in the following ways:
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* *) The driver will ping the watchdog by itself, because this
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* particular WDT has a very short timeout (one second) and it
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* would be insane to count on any userspace daemon always
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* getting scheduled within that time frame.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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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/timer.h>
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#include <linux/jiffies.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 <linux/io.h>
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#include <linux/uaccess.h>
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#define OUR_NAME "sbc60xxwdt"
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#define PFX OUR_NAME ": "
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/*
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* You must set these - The driver cannot probe for the settings
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*/
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static int wdt_stop = 0x45;
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module_param(wdt_stop, int, 0);
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MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
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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, "SBC60xx WDT 'start' io port (default 0x443)");
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/*
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* The 60xx board can use watchdog timeout values from one second
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* to several minutes. The default is one second, so if we reset
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* the watchdog every ~250ms we should be safe.
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*/
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#define WDT_INTERVAL (HZ/4+1)
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/*
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* We must not require too good response from the userspace daemon.
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* Here we require the userspace daemon to send us a heartbeat
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* char to /dev/watchdog every 30 seconds.
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* If the daemon pulses us every 25 seconds, we can still afford
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* a 5 second scheduling delay on the (high priority) daemon. That
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* should be sufficient for a box under any load.
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*/
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#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
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static int timeout = WATCHDOG_TIMEOUT; /* in seconds, multiplied by HZ to
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get seconds to wait for a ping */
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module_param(timeout, int, 0);
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MODULE_PARM_DESC(timeout,
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"Watchdog timeout in seconds. (1<=timeout<=3600, default="
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__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
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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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static void wdt_timer_ping(struct timer_list *);
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static DEFINE_TIMER(timer, wdt_timer_ping);
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static unsigned long next_heartbeat;
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static unsigned long wdt_is_open;
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static char wdt_expect_close;
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/*
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* Whack the dog
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*/
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static void wdt_timer_ping(struct timer_list *unused)
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{
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/* If we got a heartbeat pulse within the WDT_US_INTERVAL
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* we agree to ping the WDT
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*/
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if (time_before(jiffies, next_heartbeat)) {
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/* Ping the WDT by reading from wdt_start */
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inb_p(wdt_start);
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/* Re-set the timer interval */
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mod_timer(&timer, jiffies + WDT_INTERVAL);
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} else
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pr_warn("Heartbeat lost! Will not ping the watchdog\n");
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}
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/*
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* Utility routines
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*/
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static void wdt_startup(void)
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{
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next_heartbeat = jiffies + (timeout * HZ);
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/* Start the timer */
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mod_timer(&timer, jiffies + WDT_INTERVAL);
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pr_info("Watchdog timer is now enabled\n");
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}
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static void wdt_turnoff(void)
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{
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/* Stop the timer */
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del_timer_sync(&timer);
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inb_p(wdt_stop);
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pr_info("Watchdog timer is now disabled...\n");
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}
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static void wdt_keepalive(void)
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{
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/* user land ping */
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next_heartbeat = jiffies + (timeout * HZ);
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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 fop_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 ofs;
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/* note: just in case someone wrote the
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magic character five months ago... */
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wdt_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 (ofs = 0; ofs != count; ofs++) {
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char c;
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if (get_user(c, buf + ofs))
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return -EFAULT;
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if (c == 'V')
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wdt_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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wdt_keepalive();
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}
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return count;
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}
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static int fop_open(struct inode *inode, struct file *file)
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{
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/* Just in case we're already talking to someone... */
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if (test_and_set_bit(0, &wdt_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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/* Good, fire up the show */
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wdt_startup();
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return stream_open(inode, file);
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}
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static int fop_close(struct inode *inode, struct file *file)
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{
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if (wdt_expect_close == 42)
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wdt_turnoff();
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else {
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del_timer(&timer);
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pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
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}
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clear_bit(0, &wdt_is_open);
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wdt_expect_close = 0;
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return 0;
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}
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static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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{
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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_SETTIMEOUT |
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WDIOF_MAGICCLOSE,
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.firmware_version = 1,
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.identity = "SBC60xx",
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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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int new_options, retval = -EINVAL;
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if (get_user(new_options, p))
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return -EFAULT;
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if (new_options & WDIOS_DISABLECARD) {
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wdt_turnoff();
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retval = 0;
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}
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if (new_options & WDIOS_ENABLECARD) {
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wdt_startup();
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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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wdt_keepalive();
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return 0;
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case WDIOC_SETTIMEOUT:
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{
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int new_timeout;
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if (get_user(new_timeout, p))
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return -EFAULT;
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/* arbitrary upper limit */
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if (new_timeout < 1 || new_timeout > 3600)
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return -EINVAL;
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timeout = new_timeout;
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wdt_keepalive();
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}
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fallthrough;
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case WDIOC_GETTIMEOUT:
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return put_user(timeout, 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 const struct file_operations wdt_fops = {
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.owner = THIS_MODULE,
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.llseek = no_llseek,
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.write = fop_write,
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.open = fop_open,
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.release = fop_close,
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.unlocked_ioctl = fop_ioctl,
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.compat_ioctl = compat_ptr_ioctl,
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};
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static struct miscdevice wdt_miscdev = {
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.minor = WATCHDOG_MINOR,
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.name = "watchdog",
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.fops = &wdt_fops,
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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 wdt_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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wdt_turnoff();
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return NOTIFY_DONE;
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}
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/*
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* The WDT 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 wdt_notifier = {
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.notifier_call = wdt_notify_sys,
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};
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static void __exit sbc60xxwdt_unload(void)
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{
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wdt_turnoff();
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/* Deregister */
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misc_deregister(&wdt_miscdev);
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unregister_reboot_notifier(&wdt_notifier);
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if ((wdt_stop != 0x45) && (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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static int __init sbc60xxwdt_init(void)
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{
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int rc = -EBUSY;
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if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
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timeout = WATCHDOG_TIMEOUT;
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pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
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timeout);
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}
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if (!request_region(wdt_start, 1, "SBC 60XX WDT")) {
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pr_err("I/O address 0x%04x already in use\n", wdt_start);
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rc = -EIO;
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goto err_out;
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}
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/* We cannot reserve 0x45 - the kernel already has! */
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if (wdt_stop != 0x45 && wdt_stop != wdt_start) {
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if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) {
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pr_err("I/O address 0x%04x already in use\n", wdt_stop);
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rc = -EIO;
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goto err_out_region1;
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}
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}
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rc = register_reboot_notifier(&wdt_notifier);
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if (rc) {
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pr_err("cannot register reboot notifier (err=%d)\n", rc);
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goto err_out_region2;
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}
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rc = misc_register(&wdt_miscdev);
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if (rc) {
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pr_err("cannot register miscdev on minor=%d (err=%d)\n",
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wdt_miscdev.minor, rc);
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goto err_out_reboot;
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}
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pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n",
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timeout, nowayout);
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return 0;
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err_out_reboot:
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unregister_reboot_notifier(&wdt_notifier);
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err_out_region2:
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if (wdt_stop != 0x45 && wdt_stop != wdt_start)
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release_region(wdt_stop, 1);
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err_out_region1:
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release_region(wdt_start, 1);
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err_out:
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return rc;
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}
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module_init(sbc60xxwdt_init);
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module_exit(sbc60xxwdt_unload);
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MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
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MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
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MODULE_LICENSE("GPL");
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