xemac_intr_dma.c

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			 * be serviced.
			 */
			if (Result != XST_SUCCESS) {
				break;
			}

			InstancePtr->Stats.RecvFrames++;
			InstancePtr->Stats.RecvBytes += NumBytes;

			/*
			 * Make the callback to the upper layers, passing it the first
			 * descriptor in the packet and the number of descriptors in the
			 * packet.
			 */
			InstancePtr->SgRecvHandler(InstancePtr->SgRecvRef,
						   FirstBdPtr, NumBuffers);

			/*
			 * Decrement the packet count register to reflect the fact we
			 * just processed a packet
			 */
			XDmaChannel_DecrementPktCount(&InstancePtr->
						      RecvChannel);

		}		/* end for loop */

		/*
		 * If the interrupt was an end-ack, check the descriptor list again to
		 * see if it is empty. If not, go ahead and restart the scatter-gather
		 * channel. This is to fix a possible race condition where, on receive,
		 * the driver attempted to start a scatter-gather channel that was
		 * already started, which resulted in no action from the XDmaChannel
		 * component. But, just after the XDmaChannel component saw that the
		 * hardware was already started, the hardware stopped because it
		 * reached the end of the list.  In that case, this interrupt is
		 * generated and we can restart the hardware here.
		 */
		if (IntrStatus & XDC_IXR_SG_END_MASK) {
			/*
			 * Ignore the return status since we know the list exists and we
			 * don't care if the list is empty or the channel is already started.
			 */
			(void) XDmaChannel_SgStart(&InstancePtr->RecvChannel);
		}
	}

	/*
	 * All interrupts are handled (except the error below) so acknowledge
	 * (clear) the interrupts by writing the value read above back to the status
	 * register. The packet count interrupt must be acknowledged after the
	 * decrement, otherwise it will come right back. We clear the interrupts
	 * before we handle the error interrupt because the ErrorHandler should
	 * result in a reset, which clears the interrupt status register. So we
	 * don't want to toggle the interrupt back on by writing the interrupt
	 * status register with an old value after a reset.
	 */
	XDmaChannel_SetIntrStatus(&InstancePtr->RecvChannel, IntrStatus);

	/*
	 * Check for DMA errors and call the error callback function if an error
	 * occurred (DMA bus or timeout error), which should result in a reset of
	 * the device by the upper layer software.
	 */
	if (IntrStatus & XDC_IXR_DMA_ERROR_MASK) {
		InstancePtr->Stats.DmaErrors++;
		InstancePtr->ErrorHandler(InstancePtr->ErrorRef, XST_DMA_ERROR);
	}
}

/*****************************************************************************/
/*
*
* Handle an interrupt from the DMA send channel. DMA interrupts are:
*
* - DMA error. DMA encountered a bus error or timeout. This is a fatal error
*   that requires reset of the channel.  The driver calls the error handler
*   of the upper layer software with an error code indicating the device should
*   be reset.
* - Packet count threshold reached.  For scatter-gather operations, indicates
*   the threshold for the number of packets not serviced by software has been
*   reached. The driver behaves as follows:
*       - Get the value of the packet counter, which tells us how many packets
*         are ready to be serviced
*       - For each packet
*           - For each descriptor, remove it from the scatter-gather list
*           - Check for the last descriptor in the frame, and if set
*               - Bump frame statistics
*               - Call the scatter-gather receive callback function
*               - Decrement the packet counter by one
*       Note that there are no receive errors reported in the status word of
*       the buffer descriptor.  If receive errors occur, the MAC drops the
*       packet, and we only find out about the errors through various error
*       count registers.
* - Packet wait bound reached.  For scatter-gather, indicates the time to wait
*   for the next packet has expired.  The driver follows the same logic as when
*   the packet count threshold interrupt is received.
* - Scatter-gather end acknowledge.  Hardware has reached the end of the
*   descriptor list.  The driver follows the same logic as when the packet count
*   threshold interrupt is received. In addition, the driver restarts the DMA
*   scatter-gather channel in case there are newly inserted descriptors.
*
* @param InstancePtr is a pointer to the XEmac instance to be worked on.
*
* @return
*
* Although the function returns void, there are asynchronous errors
* that can be generated from this function.  These are:
* - XST_DMA_SG_LIST_EMPTY indicates we tried to get a buffer descriptor from
*   the DMA channel, but there was not one ready for software.
* - XST_DMA_ERROR indicates a DMA bus error or timeout occurred. This is a
*   fatal error that requires reset.
*
* @note
*
* None.
*
******************************************************************************/
static void
HandleDmaSendIntr(XEmac * InstancePtr)
{
	u32 IntrStatus;

	/*
	 * Read the interrupt status
	 */
	IntrStatus = XDmaChannel_GetIntrStatus(&InstancePtr->SendChannel);

	/*
	 * For packet threshold or wait bound interrupt, process descriptors. Also
	 * process descriptors on a SG end acknowledgement, which means the end of
	 * the descriptor list has been reached by the hardware. For transmit,
	 * this is a normal condition during times of light traffic.  In fact, the
	 * wait bound interrupt may be masked for transmit since the end-ack would
	 * always occur before the wait bound expires.
	 */
	if (IntrStatus & (XDC_IXR_PKT_THRESHOLD_MASK |
			  XDC_IXR_PKT_WAIT_BOUND_MASK | XDC_IXR_SG_END_MASK)) {
		XStatus Result = XST_SUCCESS;
		u32 NumFrames;
		u32 NumProcessed;
		u32 NumBuffers;
		u32 NumBytes;
		u32 IsLast;
		XBufDescriptor *FirstBdPtr;
		XBufDescriptor *BdPtr;

		/*
		 * Get the number of unserviced packets
		 */
		NumFrames = XDmaChannel_GetPktCount(&InstancePtr->SendChannel);

		for (NumProcessed = 0; NumProcessed < NumFrames; NumProcessed++) {
			IsLast = FALSE;
			FirstBdPtr = NULL;
			NumBuffers = 0;
			NumBytes = 0;

			/*
			 * For each frame, traverse the descriptor list and look for
			 * errors. On the last one in the frame, make the callback.
			 */
			while (!IsLast) {
				Result =
				    XDmaChannel_GetDescriptor(&InstancePtr->
							      SendChannel,
							      &BdPtr);
				if (Result != XST_SUCCESS) {
					/*
					 * An error getting a buffer descriptor from the list.
					 * This should not happen, but if it does, report it to
					 * the error callback and break out of the loops to service
					 * other interrupts
					 */
					InstancePtr->ErrorHandler(InstancePtr->
								  ErrorRef,
								  Result);
					break;
				}

				/*
				 * Keep a pointer to the first descriptor in the list and
				 * check the device status for errors. The device status is
				 * only available in the first descriptor of a packet.
				 */
				if (FirstBdPtr == NULL) {
					u32 XmitStatus;

					FirstBdPtr = BdPtr;

					XmitStatus =
					    XBufDescriptor_GetDeviceStatus
					    (BdPtr);
					if (XmitStatus &
					    XEM_TSR_EXCESS_DEFERRAL_MASK) {
						InstancePtr->Stats.
						    XmitExcessDeferral++;
					}

					if (XmitStatus &
					    XEM_TSR_LATE_COLLISION_MASK) {
						InstancePtr->Stats.
						    XmitLateCollisionErrors++;
					}
				}

				NumBytes += XBufDescriptor_GetLength(BdPtr);

				/*
				 * Check to see if this is the last descriptor in the frame,
				 * and if so, set the IsLast flag to get out of the loop. The
				 * transmit channel must check the last bit in the control
				 * word, not the status word (the DMA engine does not update
				 * the last bit in the status word for the transmit direction).
				 */
				if (XBufDescriptor_IsLastControl(BdPtr)) {
					IsLast = TRUE;
				}

				/*
				 * Bump the number of buffers in this packet
				 */
				NumBuffers++;

			}	/* end while loop */

			/*
			 * Check for error that occurred inside the while loop, and break
			 * out of the for loop if there was one so other interrupts can
			 * be serviced.
			 */
			if (Result != XST_SUCCESS) {
				break;
			}

			InstancePtr->Stats.XmitFrames++;
			InstancePtr->Stats.XmitBytes += NumBytes;

			/*
			 * Make the callback to the upper layers, passing it the first
			 * descriptor in the packet and the number of descriptors in the
			 * packet.
			 */
			InstancePtr->SgSendHandler(InstancePtr->SgSendRef,
						   FirstBdPtr, NumBuffers);

			/*
			 * Decrement the packet count register to reflect the fact we
			 * just processed a packet
			 */
			XDmaChannel_DecrementPktCount(&InstancePtr->
						      SendChannel);

		}		/* end for loop */

		/*
		 * If the interrupt was an end-ack, check the descriptor list again to
		 * see if it is empty. If not, go ahead and restart the scatter-gather
		 * channel. This is to fix a possible race condition where, on transmit,
		 * the driver attempted to start a scatter-gather channel that was
		 * already started, which resulted in no action from the XDmaChannel
		 * component. But, just after the XDmaChannel component saw that the
		 * hardware was already started, the hardware stopped because it
		 * reached the end of the list.  In that case, this interrupt is
		 * generated and we can restart the hardware here.
		 */
		if (IntrStatus & XDC_IXR_SG_END_MASK) {
			/*
			 * Ignore the return status since we know the list exists and we
			 * don't care if the list is empty or the channel is already started.
			 */
			(void) XDmaChannel_SgStart(&InstancePtr->SendChannel);
		}
	}

	/*
	 * All interrupts are handled (except the error below) so acknowledge
	 * (clear) the interrupts by writing the value read above back to the status
	 * register. The packet count interrupt must be acknowledged after the
	 * decrement, otherwise it will come right back. We clear the interrupts
	 * before we handle the error interrupt because the ErrorHandler should
	 * result in a reset, which clears the interrupt status register. So we
	 * don't want to toggle the interrupt back on by writing the interrupt
	 * status register with an old value after a reset.
	 */
	XDmaChannel_SetIntrStatus(&InstancePtr->SendChannel, IntrStatus);

	/*
	 * Check for DMA errors and call the error callback function if an error
	 * occurred (DMA bus or timeout error), which should result in a reset of
	 * the device by the upper layer software.
	 */
	if (IntrStatus & XDC_IXR_DMA_ERROR_MASK) {
		InstancePtr->Stats.DmaErrors++;
		InstancePtr->ErrorHandler(InstancePtr->ErrorRef, XST_DMA_ERROR);
	}
}

/*****************************************************************************/
/*
*
* Handle an interrupt from the Ethernet MAC when configured with scatter-gather
* DMA. The only interrupts handled in this case are errors.
*
* @param InstancePtr is a pointer to the XEmac instance to be worked on.
*
* @return
*
* None.
*
* @note
*
* None.
*
******************************************************************************/
static void
HandleEmacDmaIntr(XEmac * InstancePtr)
{
	u32 IntrStatus;

	/*
	 * When configured with DMA, the EMAC generates interrupts only when errors
	 * occur. We clear the interrupts immediately so that any latched status
	 * interrupt bits will reflect the true status of the device, and so any
	 * pulsed interrupts (non-status) generated during the Isr will not be lost.
	 */
	IntrStatus = XIIF_V123B_READ_IISR(InstancePtr->BaseAddress);
	XIIF_V123B_WRITE_IISR(InstancePtr->BaseAddress, IntrStatus);

	/*
	 * Check the MAC for errors
	 */
	XEmac_CheckEmacError(InstancePtr, IntrStatus);
}