xtime_l.c

自学ZedBoard：使用IP通过ARM PS访问FPGA（源代码）

/* $Id: xtime_l.c,v 1.1.4.1 2011/10/24 09:35:17 sadanan Exp $ */
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/**
* @file xtime_l.c
*
* This file contains low level functions to get/set time from the Global Timer
* register in the ARM Cortex A9 MP core.
*
* <pre>
* MODIFICATION HISTORY:
*
* Ver   Who    Date     Changes
* ----- ------ -------- ---------------------------------------------------
* 1.00a rp/sdm 11/03/09 Initial release.
* 3.06a sgd    05/15/12 Upadted get/set time functions to make use Global Timer
* 3.06a asa    06/17/12 Reverted back the changes to make use Global Timer.
* </pre>
*
* @note		None.
*
******************************************************************************/
/***************************** Include Files *********************************/

#include "xtime_l.h"
#include "xpseudo_asm.h"
#include "xil_types.h"
#include "xil_assert.h"

/***************** Macros (Inline Functions) Definitions *********************/

/**************************** Type Definitions *******************************/

/************************** Constant Definitions *****************************/

#define CYCLE_COUNTER_MASK			0x80000000

/************************** Variable Definitions *****************************/

static u32 high=0;

/************************** Function Prototypes ******************************/

/****************************************************************************
*
* Set the time in the Cycle Counter Register.
*
* @param	Value to be written to the Cycle Counter Register.
*
* @return	None.
*
* @note		None.
*
****************************************************************************/
void XTime_SetTime(XTime Xtime)
{
	u32 reg;

#ifdef __GNUC__
	/* disable the cycle counter before updating */
	reg = mfcp(XREG_CP15_COUNT_ENABLE_CLR);
#else
	{ register unsigned int Reg __asm(XREG_CP15_COUNT_ENABLE_CLR);
	  reg = Reg; }
#endif

	mtcp(XREG_CP15_COUNT_ENABLE_CLR, reg | CYCLE_COUNTER_MASK);

	/* clear the cycle counter overflow flag */
#ifdef __GNUC__
	reg = mfcp(XREG_CP15_V_FLAG_STATUS);
#else
	{ register unsigned int Reg __asm(XREG_CP15_V_FLAG_STATUS);
	  reg = Reg; }
#endif
	mtcp(XREG_CP15_V_FLAG_STATUS, reg & CYCLE_COUNTER_MASK);

	/* set the time in cyle counter reg */
	mtcp(XREG_CP15_PERF_CYCLE_COUNTER, (u32) Xtime);
	high = Xtime >> 32;

	/* enable the cycle counter */
#ifdef __GNUC__
	reg = mfcp(XREG_CP15_COUNT_ENABLE_SET);
#else
	{ register unsigned int Reg __asm(XREG_CP15_COUNT_ENABLE_SET);
	  reg = Reg; }
#endif
	mtcp(XREG_CP15_COUNT_ENABLE_SET, reg | CYCLE_COUNTER_MASK);
}

/****************************************************************************
*
* Get the time from the Cycle Counter Register.
*
* @param	Pointer to the location to be updated with the time.
*
* @return	None.
*
* @note		None.
*
****************************************************************************/
void XTime_GetTime(XTime *Xtime)
{
	u32 reg;
	u32 low;

	/* loop until we got a consistent result */
	do {
#ifdef __GNUC__
		low = mfcp(XREG_CP15_PERF_CYCLE_COUNTER);
		reg = mfcp(XREG_CP15_V_FLAG_STATUS);
#else
		{ register unsigned int Reg __asm(XREG_CP15_PERF_CYCLE_COUNTER);
		  low = Reg; }
		{ register unsigned int Reg __asm(XREG_CP15_V_FLAG_STATUS);
		  reg = Reg; }
#endif
		if (reg & CYCLE_COUNTER_MASK) {
			/* clear overflow */
			mtcp(XREG_CP15_V_FLAG_STATUS, CYCLE_COUNTER_MASK);
			high++;
		}
	} while (reg & CYCLE_COUNTER_MASK);

	*Xtime = (((XTime) high) << 32) | (XTime) low;
}