i8253timer.c

IXP425的BSP代码

    if (!sysAuxClkRunning)
	{
	tc = PIT_CLOCK / sysAuxClkTicksPerSecond;

	sysOutByte (PIT_CMD (PIT_BASE_ADR), 0x76);
	sysOutByte (PIT_CNT1 (PIT_BASE_ADR), LSB(tc));
	sysOutByte (PIT_CNT1 (PIT_BASE_ADR), MSB(tc));

	/* enable clock interrupt */

	sysIntEnablePIC (PIT1_INT_LVL);
	
	sysAuxClkRunning = TRUE;
	}
    }

/*******************************************************************************
*
* sysAuxClkRateGet - get the auxiliary clock rate
*
* This routine returns the interrupt rate of the auxiliary clock.
*
* RETURNS: The number of ticks per second of the auxiliary clock.
*
* SEE ALSO: sysAuxClkEnable(), sysAuxClkRateSet()
*/

int sysAuxClkRateGet (void)
    {
    return (sysAuxClkTicksPerSecond);
    }

/*******************************************************************************
*
* sysAuxClkRateSet - set the auxiliary clock rate
*
* This routine sets the interrupt rate of the auxiliary clock.  It does not
* enable auxiliary clock interrupts.
*
* RETURNS: OK, or ERROR if the tick rate is invalid or the timer cannot be set.
*
* SEE ALSO: sysAuxClkEnable(), sysAuxClkRateGet()
*/

STATUS sysAuxClkRateSet
    (
    int ticksPerSecond  /* number of clock interrupts per second */
    )
    {
    if (ticksPerSecond < AUX_CLK_RATE_MIN || ticksPerSecond > AUX_CLK_RATE_MAX)
        return (ERROR);

    sysAuxClkTicksPerSecond = ticksPerSecond;

    if (sysAuxClkRunning)
	{
	sysAuxClkDisable ();
	sysAuxClkEnable ();
	}

    return (OK);
    }

#else /*PIT1_FOR_AUX*/

/*******************************************************************************
*
* sysAuxClkInt - handle an auxiliary clock interrupt
*
* This routine handles an auxiliary clock interrupt.  It acknowledges the
* interrupt and calls the routine installed by sysAuxClkConnect().
*
* RETURNS: N/A
*/

void sysAuxClkInt (void)
    {
    int oldLevel;

    /* acknowledge the interrupt */

    oldLevel = intLock ();				/* LOCK INTERRUPT */
    sysOutByte (RTC_INDEX, MC146818_STATUS_C);
    sysInByte (RTC_DATA);
    intUnlock (oldLevel);				/* UNLOCK INTERRUPT */

    /* call auxiliary clock service routine */

    if (sysAuxClkRoutine != NULL)
	(*sysAuxClkRoutine) (sysAuxClkArg);
    }

/*******************************************************************************
*
* sysAuxClkConnect - connect a routine to the auxiliary clock interrupt
*
* This routine specifies the interrupt service routine to be called at each
* auxiliary clock interrupt.  It does not enable auxiliary clock interrupts.
*
* RETURNS: OK, or ERROR if the routine cannot be connected to the interrupt.
*
* SEE ALSO: intConnect(), sysAuxClkEnable()
*/

STATUS sysAuxClkConnect
    (
    FUNCPTR routine,    /* routine called at each aux clock interrupt */
    int arg             /* argument to auxiliary clock interrupt routine */
    )
    {
    sysAuxClkRoutine	= routine;
    sysAuxClkArg	= arg;

    return (OK);
    }

/*******************************************************************************
*
* sysAuxClkDisable - turn off auxiliary clock interrupts
*
* This routine disables auxiliary clock interrupts.
*
* RETURNS: N/A
*
* SEE ALSO: sysAuxClkEnable()
*/

void sysAuxClkDisable (void)
    {
    if (sysAuxClkRunning)
        {
	/* disable interrupts */

	sysOutByte (RTC_INDEX, MC146818_STATUS_B);
	sysOutByte (RTC_DATA, MC146818_24);

	sysIntDisablePIC (RTC_INT_LVL);

	sysAuxClkRunning = FALSE;
        }
    }

/*******************************************************************************
*
* sysAuxClkEnable - turn on auxiliary clock interrupts
*
* This routine enables auxiliary clock interrupts.
*
* RETURNS: N/A
*
* SEE ALSO: sysAuxClkConnect(), sysAuxClkDisable(), sysAuxClkRateSet()
*/

void sysAuxClkEnable (void)
    {
    int ix;
    char statusA;
    int oldLevel;

    if (!sysAuxClkRunning)
        {

	/* set an interrupt rate */

	for (ix = 0; ix < NELEMENTS (auxTable); ix++)
	    {
	    if (auxTable [ix].rate == sysAuxClkTicksPerSecond)
		{
	        sysOutByte (RTC_INDEX, MC146818_STATUS_A);
	        statusA = sysInByte (RTC_DATA) & ~MC146818_RS_BITS;
	        sysOutByte (RTC_INDEX, MC146818_STATUS_A);
	        sysOutByte (RTC_DATA, statusA | auxTable [ix].bits);
		break;
		}
	    }

	/* start the timer */

        oldLevel = intLock ();				/* LOCK INTERRUPT */

        sysOutByte (RTC_INDEX, MC146818_STATUS_C);	/* clear Int Flags */
        sysInByte (RTC_DATA);

	sysOutByte (RTC_INDEX, MC146818_STATUS_B);	/* set PIE */
	sysOutByte (RTC_DATA, MC146818_PIE | MC146818_24);

	sysIntEnablePIC (RTC_INT_LVL);

	sysAuxClkRunning = TRUE;

        intUnlock (oldLevel);				/* UNLOCK INTERRUPT */
	}
    }

/*******************************************************************************
*
* sysAuxClkRateGet - get the auxiliary clock rate
*
* This routine returns the interrupt rate of the auxiliary clock.
*
* RETURNS: The number of ticks per second of the auxiliary clock.
*
* SEE ALSO: sysAuxClkEnable(), sysAuxClkRateSet()
*/

int sysAuxClkRateGet (void)
    {
    return (sysAuxClkTicksPerSecond);
    }

/*******************************************************************************
*
* sysAuxClkRateSet - set the auxiliary clock rate
*
* This routine sets the interrupt rate of the auxiliary clock.  It does not
* enable auxiliary clock interrupts.
*
* RETURNS: OK, or ERROR if the tick rate is invalid or the timer cannot be set.
*
* SEE ALSO: sysAuxClkEnable(), sysAuxClkRateGet()
*/

STATUS sysAuxClkRateSet
    (
    int ticksPerSecond  /* number of clock interrupts per second */
    )
    {
    int		ix;	/* hold temporary variable */
    BOOL	match;	/* hold the match status */

    match = FALSE; 	/* initialize to false */

    if (ticksPerSecond < AUX_CLK_RATE_MIN || ticksPerSecond > AUX_CLK_RATE_MAX)
        return (ERROR);

    for (ix = 0; ix < NELEMENTS (auxTable); ix++)
	{
	if (auxTable [ix].rate == ticksPerSecond)
	    {
	    sysAuxClkTicksPerSecond = ticksPerSecond;
	    match = TRUE;
	    break;
	    }
	}

    if (!match)		/* ticksPerSecond not matching the values in table */
       return (ERROR);

    if (sysAuxClkRunning)
	{
	sysAuxClkDisable ();
	sysAuxClkEnable ();
	}

    return (OK);
    }

#endif	/* PIT1_FOR_AUX */

#if defined(INCLUDE_TIMESTAMP_PIT2) || defined (INCLUDE_TIMESTAMP_TSC)

/*******************************************************************************
*
* sysTimestampConnect - connect a user routine to the timestamp timer interrupt
*
* This routine specifies the user interrupt routine to be called at each
* timestamp timer interrupt.  It does not enable the timestamp timer itself.
*
* RETURNS: OK, or ERROR if sysTimestampInt() interrupt handler is not used.
*/
 
STATUS sysTimestampConnect
    (
    FUNCPTR routine,	/* routine called at each timestamp timer interrupt */
    int arg		/* argument with which to call routine */
    )
    {
    return (ERROR);
    }

/*******************************************************************************
*
* sysTimestampEnable - initialize and enable the timestamp timer
*
* This routine connects the timestamp timer interrupt and initializes the
* counter registers.  If the timestamp timer is already running, this routine
* merely resets the timer counter.
*
* The rate of the timestamp timer should be set explicitly within the BSP,
* in the sysHwInit() routine.  This routine does not intialize the timer
* rate.  
*
* RETURNS: OK, or ERROR if the timestamp timer cannot be enabled.
*/
 
STATUS sysTimestampEnable (void)
    {
    if (sysTimestampRunning)
	return (OK);
    
    sysTimestampRunning = TRUE;

    return (OK);
    }

/********************************************************************************
* sysTimestampDisable - disable the timestamp timer
*
* This routine disables the timestamp timer.  Interrupts are not disabled,
* although the tick counter will not increment after the timestamp timer
* is disabled, thus interrupts will no longer be generated.
*
* RETURNS: OK, or ERROR if the timestamp timer cannot be disabled.
*/
 
STATUS sysTimestampDisable (void)
    {
    if (sysTimestampRunning)
	{
        sysTimestampRunning = FALSE;
	}

    return (ERROR);
    }

/*******************************************************************************
*
* sysTimestampPeriod - get the timestamp timer period
*
* This routine returns the period of the timestamp timer in ticks.
* The period, or terminal count, is the number of ticks to which the timestamp
* timer will count before rolling over and restarting the counting process.
*
* RETURNS: The period of the timestamp timer in counter ticks.
*/
 
UINT32 sysTimestampPeriod (void)
    {
    sysTimestampPeriodValue = sysTimestampFreq () / sysClkTicksPerSecond;

    return (sysTimestampPeriodValue);
    }

/*******************************************************************************
*
* sysTimestampFreq - get the timestamp timer clock frequency
*
* This routine returns the frequency of the timer clock, in ticks per second.
* The rate of the timestamp timer should be set explicitly within the BSP,
* in the sysHwInit() routine.
*
* RETURNS: The timestamp timer clock frequency, in ticks per second.
*/
 
UINT32 sysTimestampFreq (void)
    {
#ifdef	INCLUDE_TIMESTAMP_TSC
    return (sysTimestampFreqValue);
#else
    return (PIT_CLOCK * 2);
#endif	/* INCLUDE_TIMESTAMP_TSC */
    }
 
#ifdef	INCLUDE_TIMESTAMP_TSC
LOCAL void sysTimestampFreqGet (void)
    {
    if (sysTimestampTickCount == sysClkTicksPerSecond)
	{
	sysTimestampFreqValue = pentiumTscGet32 ();
	sysTimestampTickCount = 0;
	}
    if (sysTimestampTickCount == 0)
	pentiumTscReset ();
    sysTimestampTickCount++;
    }
#endif	/* INCLUDE_TIMESTAMP_TSC */

/*******************************************************************************
*
* sysTimestamp - get the timestamp timer tick count
*
* This routine returns the current value of the timestamp timer tick counter.
* The tick count can be converted to seconds by dividing by the return of
* sysTimestampFreq().
*
* This routine should be called with interrupts locked.  If interrupts are
* not already locked, sysTimestampLock() should be used instead.
*
* RETURNS: The current timestamp timer tick count.
*
* SEE ALSO: sysTimestampLock()
*/
 
UINT32 sysTimestamp (void)
    {
#ifdef	INCLUDE_TIMESTAMP_TSC
    return (pentiumTscGet32 ());
#else
    union uc uc;

    sysOutByte (PIT_CMD (PIT_BASE_ADR), 0x80);
    uc.count08[0] = sysInByte (PIT_CNT2 (PIT_BASE_ADR));
    uc.count08[1] = sysInByte (PIT_CNT2 (PIT_BASE_ADR));

    return (sysTimestampPeriodValue - uc.count16);
#endif	/* INCLUDE_TIMESTAMP_TSC */
    }

/*******************************************************************************
*
* sysTimestampLock - get the timestamp timer tick count
*
* This routine returns the current value of the timestamp timer tick counter.
* The tick count can be converted to seconds by dividing by the return of
* sysTimestampFreq().
*
* This routine locks interrupts for cases where it is necessary to stop the
* tick counter in order to read it, or when two independent counters must
* be read.  If interrupts are already locked, sysTimestamp() should be
* used instead.
*
* RETURNS: The current timestamp timer tick count.
*
* SEE ALSO: sysTimestamp()
*/
 
UINT32 sysTimestampLock (void)
    {
#ifdef	INCLUDE_TIMESTAMP_TSC
    /* pentiumTscGet32() has just one instruction "rdtsc", so locking
     * the interrupt is not necessary.
     */
    return (pentiumTscGet32 ());
#else
    int oldLevel;
    union uc uc;

    oldLevel = intLock ();
    sysOutByte (PIT_CMD (PIT_BASE_ADR), 0x80);
    uc.count08[0] = sysInByte (PIT_CNT2 (PIT_BASE_ADR));
    uc.count08[1] = sysInByte (PIT_CNT2 (PIT_BASE_ADR));
    intUnlock (oldLevel);

    return (sysTimestampPeriodValue - uc.count16);
#endif	/* INCLUDE_TIMESTAMP_TSC */
    }

#endif	/* INCLUDE_TIMESTAMP_PIT2 || INCLUDE_TIMESTAMP_TSC */