xuartps.c

自学ZedBoard：使用IP通过ARM PS访问FPGA（源代码）

	 */
	Xil_AssertNonvoid(InstancePtr != NULL);
	Xil_AssertNonvoid(BufferPtr != NULL);
	Xil_AssertNonvoid(InstancePtr->IsReady == XIL_COMPONENT_IS_READY);

	/*
	 * Disable all the interrupts.
	 * This stops a previous operation that may be interrupt driven
	 */
	ImrRegister = XUartPs_ReadReg(InstancePtr->Config.BaseAddress,
				  XUARTPS_IMR_OFFSET);
	XUartPs_WriteReg(InstancePtr->Config.BaseAddress, XUARTPS_IDR_OFFSET,
		XUARTPS_IXR_MASK);

	/*
	 * Setup the buffer parameters
	 */
	InstancePtr->ReceiveBuffer.RequestedBytes = NumBytes;
	InstancePtr->ReceiveBuffer.RemainingBytes = NumBytes;
	InstancePtr->ReceiveBuffer.NextBytePtr = BufferPtr;

	/*
	 * Receive the data from the device
	 */
	ReceivedCount = XUartPs_ReceiveBuffer(InstancePtr);

	/*
	 * Restore the interrupt state
	 */
	XUartPs_WriteReg(InstancePtr->Config.BaseAddress, XUARTPS_IER_OFFSET,
		ImrRegister);

	return ReceivedCount;
}

/****************************************************************************/
/*
*
* This function sends a buffer that has been previously specified by setting
* up the instance variables of the instance. This function is an internal
* function for the XUartPs driver such that it may be called from a shell
* function that sets up the buffer or from an interrupt handler.
*
* This function sends the specified buffer in either polled or interrupt
* driven modes. This function is non-blocking.
*
* In a polled mode, this function only sends as much data as the TX FIFO
* can buffer. The application may need to call it repeatedly to send the
* entire buffer.
*
* In interrupt mode, this function starts the sending of the buffer, if not
* the entire buffer has been sent, then the interrupt handler continues the
* sending until the entire buffer has been sent. A callback function, as
* specified by the application, will be called to indicate the completion of
* sending.
*
* @param	InstancePtr is a pointer to the XUartPs instance
*
* @return	The number of bytes actually sent
*
* @note		None.
*
*****************************************************************************/
unsigned int XUartPs_SendBuffer(XUartPs *InstancePtr)
{
	unsigned int SentCount = 0;
	u32 ImrRegister;

	/*
	 * If the TX FIFO is full, send nothing.
	 * Otherwise put bytes into the TX FIFO unil it is full, or all of the
	 * data has been put into the FIFO.
	 */
	while ((!XUartPs_IsTransmitFull(InstancePtr->Config.BaseAddress)) &&
		   (InstancePtr->SendBuffer.RemainingBytes > SentCount)) {

		/*
		 * Fill the FIFO from the buffer
		 */
		XUartPs_WriteReg(InstancePtr->Config.BaseAddress,
				   XUARTPS_FIFO_OFFSET,
				   InstancePtr->SendBuffer.
				   NextBytePtr[SentCount]);

		/*
		 * Incriment the send count.
		 */
		SentCount++;
	}

	/*
	 * Update the buffer to reflect the bytes that were sent from it
	 */
	InstancePtr->SendBuffer.NextBytePtr += SentCount;
	InstancePtr->SendBuffer.RemainingBytes -= SentCount;

	/*
	 * If interrupts are enabled as indicated by the receive interrupt, then
	 * enable the TX FIFO empty interrupt, so further action can be taken
	 * for this sending.
	 */
	ImrRegister =
		XUartPs_ReadReg(InstancePtr->Config.BaseAddress,
				  XUARTPS_IMR_OFFSET);
	if ((ImrRegister & XUARTPS_IXR_RXFULL) ||
		(ImrRegister & XUARTPS_IXR_RXEMPTY) ||
		(ImrRegister & XUARTPS_IXR_RXOVR)) {

	XUartPs_WriteReg(InstancePtr->Config.BaseAddress,
				   XUARTPS_IER_OFFSET,
				   ImrRegister | XUARTPS_IXR_TXEMPTY);
	}

	return SentCount;
}

/****************************************************************************/
/*
*
* This function receives a buffer that has been previously specified by setting
* up the instance variables of the instance. This function is an internal
* function, and it may be called from a shell function that sets up the buffer
* or from an interrupt handler.
*
* This function attempts to receive a specified number of bytes from the
* device and store it into the specified buffer. This function works for
* either polled or interrupt driven modes. It is non-blocking.
*
* In polled mode, this function only receives as much data as in the RX FIFO.
* The application may need to call it repeatedly to receive the entire buffer.
* Polled mode is the default mode for the driver.
*
* In interrupt mode, this function starts the receiving, if not the entire
* buffer has been received, the interrupt handler will continue until the
* entire buffer has been received. A callback function, as specified by the
* application, will be called to indicate the completion of the receiving or
* error conditions.
*
* @param	InstancePtr is a pointer to the XUartPs instance
*
* @return	The number of bytes received.
*
* @note		None.
*
*****************************************************************************/
unsigned int XUartPs_ReceiveBuffer(XUartPs *InstancePtr)
{
	u32 CsrRegister;
	unsigned int ReceivedCount = 0;

	/*
 	 * Read the Channel Status Register to determine if there is any data in
	 * the RX FIFO
	 */
	CsrRegister = XUartPs_ReadReg(InstancePtr->Config.BaseAddress,
				XUARTPS_SR_OFFSET);

	/*
	 * Loop until there is no more data in RX FIFO or the specified
	 * number of bytes has been received
	 */
	while((ReceivedCount < InstancePtr->ReceiveBuffer.RemainingBytes)&&
		(0 == (CsrRegister & XUARTPS_SR_RXEMPTY))){

		InstancePtr->ReceiveBuffer.NextBytePtr[ReceivedCount] =
			XUartPs_ReadReg(InstancePtr->Config.
				  BaseAddress,
				  XUARTPS_FIFO_OFFSET);

		ReceivedCount++;

		CsrRegister = XUartPs_ReadReg(InstancePtr->Config.BaseAddress,
								XUARTPS_SR_OFFSET);
	}

	/*
	 * Update the receive buffer to reflect the number of bytes just
	 * received
	 */
	InstancePtr->ReceiveBuffer.NextBytePtr += ReceivedCount;
	InstancePtr->ReceiveBuffer.RemainingBytes -= ReceivedCount;

	return ReceivedCount;
}

/*****************************************************************************/
/**
*
* Sets the baud rate for the device. Checks the input value for
* validity and also verifies that the requested rate can be configured to
* within the maximum error range specified by XUARTPS_MAX_BAUD_ERROR_RATE.
* If the provided rate is not possible, the current setting is unchanged.
*
* @param	InstancePtr is a pointer to the XUartPs instance
* @param	BaudRate to be set
*
* @return
*		- XST_SUCCESS if everything configured as expected
*		- XST_UART_BAUD_ERROR if the requested rate is not available
*		  because there was too much error
*
* @note		None.
*
*****************************************************************************/
int XUartPs_SetBaudRate(XUartPs *InstancePtr, u32 BaudRate)
{
	u8 IterBAUDDIV;		/* Iterator for available baud divisor values */
	u32 BRGR_Value;		/* Calculated value for baud rate generator */
	u32 CalcBaudRate;	/* Calculated baud rate */
	u32 BaudError;		/* Diff between calculated and requested baud rate */
	u32 Best_BRGR = 0;	/* Best value for baud rate generator */
	u8 Best_BAUDDIV = 0;	/* Best value for baud divisor */
	u32 Best_Error = 0xFFFFFFFF;
	u32 PercentError;
	u32 ModeReg;
	u32 InputClk;

	/*
	 * Asserts validate the input arguments
	 */
	Xil_AssertNonvoid(InstancePtr != NULL);
	Xil_AssertNonvoid(InstancePtr->IsReady == XIL_COMPONENT_IS_READY);
	Xil_AssertNonvoid(BaudRate <= XUARTPS_MAX_RATE);
	Xil_AssertNonvoid(BaudRate >= XUARTPS_MIN_RATE);

	/*
	 * Make sure the baud rate is not impossilby large.
	 * Fastest possible baud rate is Input Clock / 2.
	 */
	if ((BaudRate * 2) > InstancePtr->Config.InputClockHz) {
		return XST_UART_BAUD_ERROR;
	}
	/*
	 * Check whether the input clock is divided by 8
	 */
	ModeReg = XUartPs_ReadReg( InstancePtr->Config.BaseAddress,
				 XUARTPS_MR_OFFSET);

	InputClk = InstancePtr->Config.InputClockHz;
	if(ModeReg & XUARTPS_MR_CLKSEL) {
		InputClk = InstancePtr->Config.InputClockHz / 8;
	}

	/*
	 * Determine the Baud divider. It can be 4to 254.
	 * Loop through all possible combinations
	 */
	for (IterBAUDDIV = 4; IterBAUDDIV < 255; IterBAUDDIV++) {

		/*
		 * Calculate the value for BRGR register
		 */
		BRGR_Value = InputClk / (BaudRate * (IterBAUDDIV + 1));

		/*
		 * Calculate the baud rate from the BRGR value
		 */
		CalcBaudRate = InputClk/ (BRGR_Value * (IterBAUDDIV + 1));

		/*
		 * Avoid unsigned integer underflow
		 */
		if (BaudRate > CalcBaudRate) {
			BaudError = BaudRate - CalcBaudRate;
		}
		else {
			BaudError = CalcBaudRate - BaudRate;
		}

		/*
		 * Find the calculated baud rate closest to requested baud rate.
		 */
		if (Best_Error > BaudError) {

			Best_BRGR = BRGR_Value;
			Best_BAUDDIV = IterBAUDDIV;
			Best_Error = BaudError;
		}
	}

	/*
	 * Make sure the best error is not too large.
	 */
	PercentError = (Best_Error * 100) / BaudRate;
	if (XUARTPS_MAX_BAUD_ERROR_RATE < PercentError) {
		return XST_UART_BAUD_ERROR;
	}

	/*
	 * Disable TX and RX to avoid glitches when setting the baud rate.
	 */
	XUartPs_DisableUart(InstancePtr);

	XUartPs_WriteReg(InstancePtr->Config.BaseAddress,
			   XUARTPS_BAUDGEN_OFFSET, Best_BRGR);
	XUartPs_WriteReg(InstancePtr->Config.BaseAddress,
			   XUARTPS_BAUDDIV_OFFSET, Best_BAUDDIV);

	/*
	 * Enable device
	 */
	XUartPs_EnableUart(InstancePtr);

	InstancePtr->BaudRate = BaudRate;

	return XST_SUCCESS;

}

/****************************************************************************/
/**
*
* This function is a stub handler that is the default handler such that if the
* application has not set the handler when interrupts are enabled, this
* function will be called.
*
* @param	CallBackRef is unused by this function.
* @param	Event is unused by this function.
* @param	ByteCount is unused by this function.
*
* @return	None.
*
* @note		None.
*
*****************************************************************************/
static void XUartPs_StubHandler(void *CallBackRef, u32 Event,
				 unsigned int ByteCount)
{
	(void) CallBackRef;
	(void) Event;
	(void) ByteCount;
	/*
	 * Assert occurs always since this is a stub and should never be called
	 */
	Xil_AssertVoidAlways();
}