📄 watchdog.c
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//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
//
// Use of this sample source code is subject to the terms of the Microsoft
// license agreement under which you licensed this sample source code. If
// you did not accept the terms of the license agreement, you are not
// authorized to use this sample source code. For the terms of the license,
// please see the license agreement between you and Microsoft or, if applicable,
// see the LICENSE.RTF on your install media or the root of your tools installation.
// THE SAMPLE SOURCE CODE IS PROVIDED "AS IS", WITH NO WARRANTIES.
//
//------------------------------------------------------------------------------
//
// File: watchdog.c
//
// Samsung SMDK2410X watchdog timer support code.
//
#include <windows.h>
#include <ceddk.h>
#include <oal.h>
#include <s3c2410x.h>
//
// Watchdog registers
//
#define WTCON_OFFSET 0 // address of WTCON is base of WATCHDOG + 0
#define WTCNT_OFFSET 0x08 // address of WTCNT is base of WATCHDOG + 8
// WTCON - control register, bit specifications
#define WTCON_PRESCALE(x) ((x) << 8) // bit 15:8, prescale value, 0 <= (x) <= 27
#define WTCON_ENABLE 0x20 // bit 5, enable watchdog timer
#define WTCON_CLOCK_SELECT(x) ((x) << 3) // bit 4:3, clock select
// 0b00: 1/16
// 0b01: 1/32
// 0b10: 1/64
// 0b11: 1/128
#define WTCON_RESET 0x01 // bit 0, reset if timer expired
// WTCNT - watchdog counter register
#define WTCNT_MAX_VALUE 0xffff // max value for WTCNT = 0xffff
//
// The default setup value: prescale: 27+1, enable watchdog, enable reset, clock select 1/128.
// With the default setup, the watchdog timer will reset if not refreshed within ~4.6 seconds.
//
#define WTCON_DEFAULT_SETUP_VALUE (WTCON_PRESCALE(27) | WTCON_ENABLE | WTCON_CLOCK_SELECT(0x3) | WTCON_RESET)
#define WD_REFRESH_PERIOD 3000 // tell the OS to refresh watchdog every 3 second.
//
// function to refresh watchdog timer
//
void RefreshWatchdogTimer (void)
{
static DWORD dwWDBase = 0; // VA for Watchdog base
if (!dwWDBase) {
// called the 1st time, setup the watchdog timer
dwWDBase = (DWORD) OALPAtoVA (S3C2410X_BASE_REG_PA_WATCHDOG, FALSE);
if (!dwWDBase) {
OALMSG (OAL_ERROR, (L"Address of Watch Dog Base Not Defined, WatchDog not enabled!\r\n"));
} else {
WRITE_REGISTER_USHORT (dwWDBase + WTCNT_OFFSET, WTCNT_MAX_VALUE);
WRITE_REGISTER_USHORT (dwWDBase + WTCON_OFFSET, WTCON_DEFAULT_SETUP_VALUE);
}
} else {
// subsequent refresh calls, just reset the counter register to max value
WRITE_REGISTER_USHORT (dwWDBase + WTCNT_OFFSET, WTCNT_MAX_VALUE);
}
}
//------------------------------------------------------------------------------
//
// Function: SMDKInitWatchDogTimer
//
// This is the function to enable hardware watchdog timer support by kernel.
//
void SMDKInitWatchDogTimer (void)
{
OALMSG(OAL_FUNC, (L"+SMDKInitWatchDogTimer\r\n"));
pfnOEMRefreshWatchDog = RefreshWatchdogTimer;
dwOEMWatchDogPeriod = WD_REFRESH_PERIOD;
OALMSG(OAL_FUNC, (L"-SMDKInitWatchDogTimer\r\n"));
}
//------------------------------------------------------------------------------
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