oaltimer.c

老外的一个开源项目

// Copyright (c) David Vescovi.  All rights reserved.
// Part of Project DrumStix
// Windows Embedded Developers Interest Group (WE-DIG) community project.
// http://www.we-dig.org
// Copyright (c) Microsoft Corporation.  All rights reserved.
//------------------------------------------------------------------------------
//
//  File:  oaltimer.c
//
//  Timer initialization code.
//
//------------------------------------------------------------------------------

#include <windows.h>
#include <nkintr.h>
#include <oal.h>
#include <pxa255.h>

//------------------------------------------------------------------------------
// Defines 

//------------------------------------------------------------------------------
// External Variables 

//------------------------------------------------------------------------------
// Global Variables 
static volatile OST_REG_T  *g_pOSTRegs  = NULL;
static volatile INTC_REG_T *g_pINTCRegs = NULL;
 
//------------------------------------------------------------------------------
// Local Variables 

//------------------------------------------------------------------------------
// Local Functions 


BOOL OALTimerInit (UINT32 msecPerSysTick, 
                   UINT32 countsPerMSec, 
                   UINT32 countsMargin)
{

	g_pOSTRegs  = (volatile OST_REG_T *)  OALPAtoVA(PXA255_BASE_REG_PA_OST, FALSE);
	g_pINTCRegs = (volatile INTC_REG_T *) OALPAtoVA(PXA255_BASE_REG_PA_INTC, FALSE);

	
	OALMSGS(OAL_KITL&&OAL_TIMER, (
        L"+OALTimerInit(%d, %d, %d)\r\n", msecPerSysTick, countsPerMSec,countsMargin 
    ));
    // Initialize timer state global variable.
    //
    g_oalTimer.countsPerMSec          = countsPerMSec;
    g_oalTimer.msecPerSysTick         = msecPerSysTick;
    g_oalTimer.actualMSecPerSysTick   = msecPerSysTick;
    g_oalTimer.countsMargin           = countsMargin;

    g_oalTimer.countsPerSysTick       = (countsPerMSec * msecPerSysTick);
    g_oalTimer.actualCountsPerSysTick = (countsPerMSec * msecPerSysTick);
    g_oalTimer.curCounts              = 0;
    g_oalTimer.maxPeriodMSec          = (UINT32)0x7FFFFFFF/g_oalTimer.countsPerMSec;

    // Initialize kernel-exported values.
    //
    idleconv     = countsPerMSec;
    curridlehigh = 0;
    curridlehigh = 0;

    // Initialize high resolution timer function pointers
    pQueryPerformanceFrequency = OALTimerQueryPerformanceFrequency;
    pQueryPerformanceCounter   = OALTimerQueryPerformanceCounter;

    // Configure and arm the timer interrupt to interrupt every specified system tick interval.
    //
    // Disable interrupts on the specified Match register
    g_pOSTRegs->OIER &= ~(OIER_E0 | OIER_RESERVED_BITS);
    // Clear any interrupt on the specified Match register
    g_pOSTRegs->OSSR = OSSR_M0; 
	// Set up the match register to expire when the oscr reaches
    // the next match interval.
	g_pOSTRegs->OSMR0 = g_pOSTRegs->OSCR + g_oalTimer.countsPerSysTick;
    // Enable the Match register interrupt on OS timer 
    g_pOSTRegs->OIER |= OIER_E0;
    // Enable the Match interrupt at the interrupt controller
    g_pINTCRegs->ICMR |= INTC_OSMR0; 

    return(TRUE);
}


//------------------------------------------------------------------------------
//
//  Function: OALTimerCountsSinceSysTick
//
//  This function return count of hi res ticks since system tick.
//
//

INT32 OALTimerCountsSinceSysTick()
{
	UINT32 LastTimerMatch;

	LastTimerMatch = g_pOSTRegs->OSMR0 - g_oalTimer.countsPerSysTick;

    // How many ticks since the last timer interrupt?
    return (g_pOSTRegs->OSCR - LastTimerMatch);
}


//------------------------------------------------------------------------------
//
//  Function: OALTimerIntrHandler
//
//  This function implement timer interrupt handler. It is called from common
//  ARM interrupt handler.
//
UINT32 OALTimerIntrHandler()
{
    UINT32 sysIntr = SYSINTR_NOP;

    // Configure and arm the timer interrupt to interrupt every specified system tick interval.
    //
	// Disable interrupts on the specified Match register
	g_pOSTRegs->OIER &= ~(OIER_E0 | OIER_RESERVED_BITS);
	// Clear any interrupt on the specified Match register
	g_pOSTRegs->OSSR = OSSR_M0;

    if ((INT32)(g_pOSTRegs->OSCR - g_pOSTRegs->OSMR0 - g_oalTimer.countsMargin) < 0)
    {
		// Set up the match register to expire when the oscr reaches
		// the next match interval.
		g_pOSTRegs->OSMR0 = g_pOSTRegs->OSMR0 + g_oalTimer.countsPerSysTick;
    }
    else
    {
		// slip??
		// Set up the match register to expire when the oscr reaches
		// the next interval.
		g_pOSTRegs->OSMR0 = g_pOSTRegs->OSCR + g_oalTimer.countsPerSysTick;
    }
	// Enable the Match register interrupt on OS timer 
	g_pOSTRegs->OIER |= OIER_E0;
	// Enable the Match interrupt at the interrupt controller
	g_pINTCRegs->ICMR |= INTC_OSMR0; 

    // Update high resolution counter.
    //
    g_oalTimer.curCounts += g_oalTimer.countsPerSysTick;

    // Update the millisecond counter.
    //
    CurMSec += g_oalTimer.msecPerSysTick;

    // Reschedule?
    //
    if ((int)(CurMSec - dwReschedTime) >= 0)
	{
		sysIntr = SYSINTR_RESCHED;
	}


#ifdef OAL_ILTIMING
    if (g_oalILT.active) {
        if (--g_oalILT.counter == 0) {
            sysIntr = SYSINTR_TIMING;
            g_oalILT.counter = g_oalILT.counterSet;
            g_oalILT.isrTime2 = OALTimerCountsSinceSysTick();
        }
    }
#endif

    return (sysIntr);
}

//------------------------------------------------------------------------------