spi.c

武汉创维特公司的2410arm9开发办的can linux源代码

	
	//----- 4. Delay a little bit so the byte finishes clocking out before the chip select line is deasserted -----
	if(SPI_WaitTxRxReady()==FALSE) return FALSE;
	
//	printk("after the 2nd wait in SPI_SendByte.\n");

	*pData = *(unsigned char *)rSPRDAT0;

	//----- 5. Deselect the slave device (active low) -----
	//rGPGDAT |= CHIP_DESELECT_nSS0;

   // StopSPIClock();

	return TRUE;
}

BOOL SPI_ReadByte(BYTE *pData)
{
    BOOL    bRet = TRUE;
    
    //----- 0. Start clock
    //StartSPIClock();

	//----- 1. Chip select the slave device (active low) -----
	//rGPGDAT &= CHIP_SELECT_nSS0;

	//----- 2. Wait until the controller is ready to transfer -----
	if(SPI_WaitTxRxReady()==FALSE) return FALSE;

	//----- 3. Put the byte out onto the SPI bus -----
	*pData = *(unsigned char *)rSPRDAT0;
	
	//----- 4. Delay a little bit so the byte finishes clocking out before the chip select line is deasserted -----
	//if(SPI_WaitTxRxReady()==FALSE) return FALSE;

	//----- 5. Deselect the slave device (active low) -----
	//rGPGDAT |= CHIP_DESELECT_nSS0;

   // StopSPIClock();

	return bRet;	
}

BOOL SPI_WaitTxRxReady(VOID)
{
	int waitCount;
//	int reg;
	
	//----- 1. Wait until the controller is ready to transfer -----
	waitCount = 1000;
	while(!((*(unsigned int *)rSPSTA0) & SPI_TRANSFER_READY))
	{
		if(--waitCount == 0)
		{
//			reg = *(unsigned int *)rSPSTA0;
//			printk("rSPSTA0 = %d\n",reg);
//			printk("WaitTxRxReady return FALSE.\n");			

//			ssleep(1);
//			msleep(1);

			mdelay(10);
		//	udelay(1);
//			ndelay(1);

			return FALSE;
		}
	}
	
	return TRUE;
	
}

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Function:		SPI_SendWord()

Description:	Sends the specified word out onto the SPI bus.

Returns:		Boolean indicating success.
-------------------------------------------------------------------*/
/*BOOL SPI_SendWord(WORD wData)
{
    BOOL    bRet = TRUE;
	DWORD   waitCount = 0;

    StartSPIClock();

	//----- 1. Chip select the slave device (active low) -----
	rGPGDAT &= CHIP_SELECT_nSS0;

	//----- 2. Wait until the controller is ready to transfer -----
	waitCount = 1000;
	while(!(rSPSTA0 & SPI_TRANSFER_READY))
	{
		if(--waitCount == 0)
		{
            bRet = FALSE;
			goto SEND_ERROR;
		}
	}

	//----- 3. Send first half of word -----
	rSPTDAT0 = (wData & 0xFF00) >> 8;

	//----- 4. Wait until the controller is ready to transfer -----
	waitCount = 1000;
	while(!(rSPSTA0 & SPI_TRANSFER_READY))
	{
		if(--waitCount == 0)
		{
			//RETAILMSG(1, (TEXT("WAVEDEV.DLL: SPI_SendWord() - timeout occurred while waiting to transfer byte\r\n")));
            bRet = FALSE;
			goto SEND_ERROR;
		}
	}

	//----- 5. Send second half of word -----
	rSPTDAT0 = (wData & 0x00FF);

	//----- 6. Delay a little bit so the byte finishes clocking out before the chip select line is deasserted -----
	WAIT(10000);

	//----- 7. Deselect the slave device (active low) -----
	rGPGDAT |= CHIP_DESELECT_nSS0;

SEND_ERROR:

    StopSPIClock();

	return bRet;
}
*/

//------------------------------------ Helper Routines ------------------------------------

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Function:		StartSPIClock()

Description:	Enables the SPI clock.

Returns:		N/A
-------------------------------------------------------------------*/
VOID StartSPIClock(VOID)
{
	*(unsigned int *)rCLKCON = (*(unsigned int *)rCLKCON)|SPI_INTERNAL_CLOCK_ENABLE;// Enable the CPU clock to the SPI controller

	*(unsigned int *)rSPCON0 = (*(unsigned int *)rSPCON0)|SPI_CLOCK_ENABLE|SPI_SELECT_MASTER;// Enable the SPI clock
	
	return;
}


/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Function:		StopSPIClock()

Description:	Disables the SPI clock.

Returns:		N/A
-------------------------------------------------------------------*/
VOID StopSPIClock(VOID)
{
	*(unsigned int *)rCLKCON = (*(unsigned int *)rCLKCON) & ~SPI_INTERNAL_CLOCK_ENABLE;	// Disable the CPU clock to the SPI controller

	*(unsigned int *)rSPCON0 = (*(unsigned int *)rCLKCON) & ~SPI_CLOCK_ENABLE;				// Disable the SPI clock
	
	return;
}


/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Function:		SetSPIClockRate()

Description:	Sets the SPI clock (a.k.a. baud) rate:

Params:			ClockRate       0x00 =      25Mhz
								0x01 = 1/2  25Mhz
								0x02 = 1/4  25Mhz
								0x03 = 1/8  25Mhz
								0x04 = 1/16 25Mhz
								0x05 = 1/32 25Mhz
								0x06 = 1/64 25Mhz
								0x07 = 99.121Khz

Returns:		N/A
-------------------------------------------------------------------*/
VOID SetSPIClockRate(DWORD ClockRate)
{
	UINT16 prescale;

    //----- 1. Set the clock rate  -----
	//		   NOTE: Using the prescale value, the clock's baud rate is
	//				 determined as follows: baud_rate = (PCLK / 2 / (prescale + 1))
	//
	//				 Hence, the prescale value can be computed as follows:
	//				 prescale = ((PCLK / 2) / baud_rate) - 1
	switch(ClockRate)
	{
		case CLK_RATE_FULL:						// 25 Mhz			
		prescale = (PCLK / 40000000) - 1;
		break;

		case CLK_RATE_HALF:						// 1/2  25 Mhz						
		prescale = (PCLK / 30000000) - 1;
		break;

		case CLK_RATE_FOUR:						// 1/4  25 Mhz						
		prescale = (PCLK / 10000000) - 1;
		break;

		case CLK_RATE_EIGHT:					// 1/8  25 Mhz						
		prescale = (PCLK / 500000) - 1;
		break;

		case CLK_RATE_SIXTEEN:					// 1/16 25 Mhz						
		prescale = (PCLK / 2500000) - 1;
		break;

		case CLK_RATE_THIRTY2:					// 1/32 25 Mhz						
		prescale = (PCLK / 1250000) - 1;
		break;

		case CLK_RATE_SIXTY4:					// 1/64 25 Mhz						
		prescale = (PCLK / 625000) - 1;
		break;

		case CLK_RATE_SLOW:						// 99.121 kHz (i.e. ~1/256 25Mhz)
		prescale = 255;
		break;

		default:
		return;
		break;
	}

	*(unsigned int *)rSPPRE0 = prescale;


    return;
}