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******************************************************************************/
/******************************************************************************/
/**
* @file  xspi_low_level_example.c
*
* This file contains a design example using the low-level driver of the
* SPI driver (XSpi). These macros are found in xspi_l.h.  A simple loopback
* test is done within an SPI device in polled mode. This example works only with
* 8-bit wide data transfers.
*
* @note
* This example works only with 8-bit wide data transfers in standard SPI mode.
* This example will not work if the axi_qspi device is confiured in dual/quad
* modes.
*
* To make this example work for 16 bit transfers change u8 Buffer[BUFFER_SIZE]
* to u16 Buffer[BUFFER_SIZE]. The SPI Core should aslo be configured for 16 bit
* access during the build time.
*
* To make this example work for 32 bit transfers change u8 Buffer[BUFFER_SIZE]
* to u32 Buffer[BUFFER_SIZE]. The SPI Core should aslo be configured for 32 bit
* access during the build time.
*
*
*<pre>
* MODIFICATION HISTORY:
*
* Ver   Who  Date     Changes
* ----- ---- -------- ----------------------------------------------------------
* 1.00b rpm  04/24/02 First release
* 1.00b jhl  09/10/02 Added code to ensure it works with a fast processor.
* 1.00b sv   05/16/05 Minor changes to comply to Doxygen and coding guidelines
* 3.00a ktn  10/28/09 Converted all register accesses to 32 bit access.
* 3.02a sdm  05/04/11 Added a note about dual/quad modes in axi_qspi.
*
*</pre>
*******************************************************************************/

/***************************** Include Files **********************************/

#include "xparameters.h"
#include "xstatus.h"
#include "xspi_l.h"

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

/*
 * The following constants map to the XPAR parameters created in the
 * xparameters.h file. They are defined here such that a user can easily
 * change all the needed parameters in one place.
 */
#define SPI_BASEADDR		XPAR_SPI_0_BASEADDR

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


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


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

int XSpi_LowLevelExample(u32 BaseAddress);

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


/*
 *  This is the size of the buffer to be transmitted/received in this example.
 */
#define BUFFER_SIZE			 32

/*
 * The buffer used for Transmission/Reception of the SPI test data
 */
u16 Buffer[BUFFER_SIZE];

/******************************************************************************/
/**
* This function is the main function of the SPI Low Level example.
*
* @param	None
*
* @return	XST_SUCCESS to indicate success, else XST_FAILURE to indicate
*		Failure.
*
* @note		None
*
*******************************************************************************/
int main(void)
{
	int Status;

	/*
	 * Run the example, specify the Base Address that is generated in
	 * xparameters.h
	 */
	Status = XSpi_LowLevelExample(SPI_BASEADDR);
	if (Status != XST_SUCCESS) {
		return XST_FAILURE;
	}

	return XST_SUCCESS;
}

/******************************************************************************/
/**
*
* This function does a simple loopback test within an SPI device.
*
* @param	BaseAddress is the BaseAddress of the SPI device
*
* @return	XST_SUCCESS if successful, XST_FAILURE if unsuccessful
*
* @note		None
*
*******************************************************************************/
int XSpi_LowLevelExample(u32 BaseAddress)
{
	u32 Control;
	int NumBytesSent = 0;
	int NumBytesRcvd = 0;
	u32 Count;

	/*
	 * Set up the device in loopback mode and enable master mode.
	 */
	Control = XSpi_ReadReg(BaseAddress, XSP_CR_OFFSET);
	Control |= (XSP_CR_LOOPBACK_MASK | XSP_CR_MASTER_MODE_MASK);
	XSpi_WriteReg(BaseAddress, XSP_CR_OFFSET, Control);


	/*
	 * Initialize the buffer with some data.
	 */
	for (Count = 0; Count < BUFFER_SIZE; Count++) {
		Buffer[Count] = Count;
	}

	/*
	 * Fill up the transmitter with data, assuming the receiver can hold
	 * the same amount of data.
	 */
	while ((XSpi_ReadReg(BaseAddress, XSP_SR_OFFSET) &
			XSP_SR_TX_FULL_MASK) == 0) {
		XSpi_WriteReg((BaseAddress), XSP_DTR_OFFSET,
				Buffer[NumBytesSent++]);
	}

	/*
	 * Enable the device.
	 */
	Control = XSpi_ReadReg(BaseAddress, XSP_CR_OFFSET);
	Control |= XSP_CR_ENABLE_MASK;
	Control &= ~XSP_CR_TRANS_INHIBIT_MASK;
	XSpi_WriteReg(BaseAddress, XSP_CR_OFFSET, Control);

	/*
	 * Initialize the buffer with zeroes so that it can be used to receive
	 * data.
	 */
	for (Count = 0; Count < BUFFER_SIZE; Count++) {
		Buffer[Count] = 0x0;
	}

	/*
	 * Wait for the transmit FIFO to transition to empty before checking
	 * the receive FIFO, this prevents a fast processor from seeing the
	 * receive FIFO as empty
	 */
	while (!(XSpi_ReadReg(BaseAddress, XSP_SR_OFFSET) &
					XSP_SR_TX_EMPTY_MASK));

	/*
	 * Transmitter is full, now receive the data just looped back until
	 * the receiver is empty.
	 */
	while ((XSpi_ReadReg(BaseAddress, XSP_SR_OFFSET) &
			XSP_SR_RX_EMPTY_MASK) == 0) {
		Buffer[NumBytesRcvd++] = XSpi_ReadReg((BaseAddress),
						XSP_DRR_OFFSET);
	}

	/*
	 * If no data was sent or the data that was sent was not received,
	 * then return an error
	 */
	if ((NumBytesSent != NumBytesRcvd) || (NumBytesSent == 0)) {
		return XST_FAILURE;
	}

	return XST_SUCCESS;
}