436 lines
11 KiB
C
436 lines
11 KiB
C
/*
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* AMD Elan SC520 processor Watchdog Timer driver
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*
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* Based on acquirewdt.c by Alan Cox,
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* and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
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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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* The authors do 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 2001 Scott Jennings <linuxdrivers@oro.net>
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* 9/27 - 2001 [Initial release]
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*
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* Additional fixes Alan Cox
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* - Fixed formatting
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* - Removed debug printks
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* - Fixed SMP built kernel deadlock
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* - Switched to private locks not lock_kernel
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* - Used ioremap/writew/readw
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* - Added NOWAYOUT support
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* 4/12 - 2002 Changes by Rob Radez <rob@osinvestor.com>
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* - Change comments
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* - Eliminate fop_llseek
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* - Change CONFIG_WATCHDOG_NOWAYOUT semantics
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* - Add KERN_* tags to printks
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* - fix possible wdt_is_open race
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* - Report proper capabilities in watchdog_info
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* - Add WDIOC_{GETSTATUS, GETBOOTSTATUS, SETTIMEOUT,
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* GETTIMEOUT, SETOPTIONS} ioctls
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* 09/8 - 2003 Changes by Wim Van Sebroeck <wim@iguana.be>
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* - cleanup of trailing spaces
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* - added extra printk's for startup problems
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* - use module_param
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* - made timeout (the emulated heartbeat) a module_param
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* - made the keepalive ping an internal subroutine
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* 3/27 - 2004 Changes by Sean Young <sean@mess.org>
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* - set MMCR_BASE to 0xfffef000
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* - CBAR does not need to be read
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* - removed debugging printks
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*
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* This WDT driver is different from most other Linux WDT
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* drivers in that the driver will ping the watchdog by itself,
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* because this particular WDT has a very short timeout (1.6
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* seconds) and it would be insane to count on any userspace
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* daemon always getting scheduled within that time frame.
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*
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* This driver uses memory mapped IO, and spinlock.
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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/timer.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/jiffies.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 OUR_NAME "sc520_wdt"
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#define PFX OUR_NAME ": "
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/*
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* The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7)
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*
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* 0: 492us 2: 1.01s 4: 4.03s 6: 16.22s
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* 1: 503ms 3: 2.01s 5: 8.05s 7: 32.21s
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*
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* We will program the SC520 watchdog for a timeout of 2.01s.
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* If we reset 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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*/
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#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
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static int timeout = WATCHDOG_TIMEOUT; /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
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module_param(timeout, int, 0);
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MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
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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=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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/*
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* AMD Elan SC520 - Watchdog Timer Registers
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*/
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#define MMCR_BASE 0xfffef000 /* The default base address */
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#define OFFS_WDTMRCTL 0xCB0 /* Watchdog Timer Control Register */
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/* WDT Control Register bit definitions */
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#define WDT_EXP_SEL_01 0x0001 /* [01] Time-out = 496 us (with 33 Mhz clk). */
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#define WDT_EXP_SEL_02 0x0002 /* [02] Time-out = 508 ms (with 33 Mhz clk). */
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#define WDT_EXP_SEL_03 0x0004 /* [03] Time-out = 1.02 s (with 33 Mhz clk). */
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#define WDT_EXP_SEL_04 0x0008 /* [04] Time-out = 2.03 s (with 33 Mhz clk). */
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#define WDT_EXP_SEL_05 0x0010 /* [05] Time-out = 4.07 s (with 33 Mhz clk). */
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#define WDT_EXP_SEL_06 0x0020 /* [06] Time-out = 8.13 s (with 33 Mhz clk). */
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#define WDT_EXP_SEL_07 0x0040 /* [07] Time-out = 16.27s (with 33 Mhz clk). */
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#define WDT_EXP_SEL_08 0x0080 /* [08] Time-out = 32.54s (with 33 Mhz clk). */
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#define WDT_IRQ_FLG 0x1000 /* [12] Interrupt Request Flag */
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#define WDT_WRST_ENB 0x4000 /* [14] Watchdog Timer Reset Enable */
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#define WDT_ENB 0x8000 /* [15] Watchdog Timer Enable */
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static __u16 __iomem *wdtmrctl;
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static void wdt_timer_ping(unsigned long);
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static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
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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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static spinlock_t wdt_spinlock;
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/*
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* Whack the dog
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*/
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static void wdt_timer_ping(unsigned long data)
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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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{
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/* Ping the WDT */
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spin_lock(&wdt_spinlock);
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writew(0xAAAA, wdtmrctl);
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writew(0x5555, wdtmrctl);
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spin_unlock(&wdt_spinlock);
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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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printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n");
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}
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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_config(int writeval)
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{
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__u16 dummy;
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unsigned long flags;
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/* buy some time (ping) */
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spin_lock_irqsave(&wdt_spinlock, flags);
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dummy=readw(wdtmrctl); /* ensure write synchronization */
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writew(0xAAAA, wdtmrctl);
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writew(0x5555, wdtmrctl);
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/* unlock WDT = make WDT configuration register writable one time */
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writew(0x3333, wdtmrctl);
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writew(0xCCCC, wdtmrctl);
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/* write WDT configuration register */
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writew(writeval, wdtmrctl);
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spin_unlock_irqrestore(&wdt_spinlock, flags);
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}
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static int 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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/* Start the watchdog */
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wdt_config(WDT_ENB | WDT_WRST_ENB | WDT_EXP_SEL_04);
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printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
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return 0;
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}
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static int wdt_turnoff(void)
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{
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/* Stop the timer */
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del_timer(&timer);
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/* Stop the watchdog */
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wdt_config(0);
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printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
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return 0;
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}
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static int 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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return 0;
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}
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static int wdt_set_heartbeat(int t)
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{
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if ((t < 1) || (t > 3600)) /* arbitrary upper limit */
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return -EINVAL;
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timeout = t;
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return 0;
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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, 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 magic character
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* five months ago... */
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wdt_expect_close = 0;
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/* now scan */
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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 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 nonseekable_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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printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
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wdt_keepalive();
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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 int fop_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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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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.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
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.firmware_version = 1,
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.identity = "SC520",
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};
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switch(cmd)
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{
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default:
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return -ENOTTY;
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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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wdt_keepalive();
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return 0;
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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_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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if(wdt_set_heartbeat(new_timeout))
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return -EINVAL;
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wdt_keepalive();
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/* Fall through */
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}
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case WDIOC_GETTIMEOUT:
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return put_user(timeout, p);
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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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.ioctl = fop_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 sc520_wdt_unload(void)
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{
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if (!nowayout)
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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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iounmap(wdtmrctl);
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}
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static int __init sc520_wdt_init(void)
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{
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int rc = -EBUSY;
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spin_lock_init(&wdt_spinlock);
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/* Check that the timeout value is within it's range ; if not reset to the default */
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if (wdt_set_heartbeat(timeout)) {
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wdt_set_heartbeat(WATCHDOG_TIMEOUT);
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printk(KERN_INFO PFX "timeout value must be 1<=timeout<=3600, using %d\n",
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WATCHDOG_TIMEOUT);
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}
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wdtmrctl = ioremap((unsigned long)(MMCR_BASE + OFFS_WDTMRCTL), 2);
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if (!wdtmrctl) {
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printk(KERN_ERR PFX "Unable to remap memory\n");
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rc = -ENOMEM;
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goto err_out_region2;
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}
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rc = register_reboot_notifier(&wdt_notifier);
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if (rc) {
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printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
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rc);
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goto err_out_ioremap;
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}
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rc = misc_register(&wdt_miscdev);
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if (rc) {
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printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
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WATCHDOG_MINOR, rc);
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goto err_out_notifier;
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}
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printk(KERN_INFO PFX "WDT driver for SC520 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_notifier:
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unregister_reboot_notifier(&wdt_notifier);
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err_out_ioremap:
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iounmap(wdtmrctl);
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err_out_region2:
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return rc;
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}
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module_init(sc520_wdt_init);
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module_exit(sc520_wdt_unload);
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MODULE_AUTHOR("Scott and Bill Jennings");
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MODULE_DESCRIPTION("Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
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