-/* $Id: xdma_channel_sg.c,v 1.6 2003/02/03 19:50:33 moleres Exp $ */
-/******************************************************************************
-*
-* Author: Xilinx, Inc.
-*
-*
-* This program is free software; you can redistribute it and/or modify it
-* under the terms of the GNU General Public License as published by the
-* Free Software Foundation; either version 2 of the License, or (at your
-* option) any later version.
-*
-*
-* XILINX IS PROVIDING THIS DESIGN, CODE, OR INFORMATION "AS IS" AS A
-* COURTESY TO YOU. BY PROVIDING THIS DESIGN, CODE, OR INFORMATION AS
-* ONE POSSIBLE IMPLEMENTATION OF THIS FEATURE, APPLICATION OR STANDARD,
-* XILINX IS MAKING NO REPRESENTATION THAT THIS IMPLEMENTATION IS FREE
-* FROM ANY CLAIMS OF INFRINGEMENT, AND YOU ARE RESPONSIBLE FOR OBTAINING
-* ANY THIRD PARTY RIGHTS YOU MAY REQUIRE FOR YOUR IMPLEMENTATION.
-* XILINX EXPRESSLY DISCLAIMS ANY WARRANTY WHATSOEVER WITH RESPECT TO
-* THE ADEQUACY OF THE IMPLEMENTATION, INCLUDING BUT NOT LIMITED TO ANY
-* WARRANTIES OR REPRESENTATIONS THAT THIS IMPLEMENTATION IS FREE FROM
-* CLAIMS OF INFRINGEMENT, IMPLIED WARRANTIES OF MERCHANTABILITY AND
-* FITNESS FOR A PARTICULAR PURPOSE.
-*
-*
-* Xilinx hardware products are not intended for use in life support
-* appliances, devices, or systems. Use in such applications is
-* expressly prohibited.
-*
-*
-* (c) Copyright 2002-2004 Xilinx Inc.
-* All rights reserved.
-*
-*
-* You should have received a copy of the GNU General Public License along
-* with this program; if not, write to the Free Software Foundation, Inc.,
-* 675 Mass Ave, Cambridge, MA 02139, USA.
-*
-* FILENAME:
-*
-* xdma_channel_sg.c
-*
-* DESCRIPTION:
-*
-* This file contains the implementation of the XDmaChannel component which is
-* related to scatter gather operations.
-*
-* Scatter Gather Operations
-*
-* The DMA channel may support scatter gather operations. A scatter gather
-* operation automates the DMA channel such that multiple buffers can be
-* sent or received with minimal software interaction with the hardware. Buffer
-* descriptors, contained in the XBufDescriptor component, are used by the
-* scatter gather operations of the DMA channel to describe the buffers to be
-* processed.
-*
-* Scatter Gather List Operations
-*
-* A scatter gather list may be supported by each DMA channel. The scatter
-* gather list allows buffer descriptors to be put into the list by a device
-* driver which requires scatter gather. The hardware processes the buffer
-* descriptors which are contained in the list and modifies the buffer
-* descriptors to reflect the status of the DMA operations. The device driver
-* is notified by interrupt that specific DMA events occur including scatter
-* gather events. The device driver removes the completed buffer descriptors
-* from the scatter gather list to evaluate the status of each DMA operation.
-*
-* The scatter gather list is created and buffer descriptors are inserted into
-* the list. Buffer descriptors are never removed from the list after it's
-* creation such that a put operation copies from a temporary buffer descriptor
-* to a buffer descriptor in the list. Get operations don't copy from the list
-* to a temporary, but return a pointer to the buffer descriptor in the list.
-* A buffer descriptor in the list may be locked to prevent it from being
-* overwritten by a put operation. This allows the device driver to get a
-* descriptor from a scatter gather list and prevent it from being overwritten
-* until the buffer associated with the buffer descriptor has been processed.
-*
-* The get and put functions only operate on the list and are asynchronous from
-* the hardware which may be using the list of descriptors. This is important
-* because there are no checks in the get and put functions to ensure that the
-* hardware has processed the descriptors. This must be handled by the driver
-* using the DMA scatter gather channel through the use of the other functions.
-* When a scatter gather operation is started, the start function does ensure
-* that the descriptor to start has not already been processed by the hardware
-* and is not the first of a series of descriptors that have not been committed
-* yet.
-*
-* Descriptors are put into the list but not marked as ready to use by the
-* hardware until a commit operation is done. This allows multiple descriptors
-* which may contain a single packet of information for a protocol to be
-* guaranteed not to cause any underflow conditions during transmission. The
-* hardware design only allows descriptors to cause it to stop after a descriptor
-* has been processed rather than before it is processed. A series of
-* descriptors are put into the list followed by a commit operation, or each
-* descriptor may be commited. A commit operation is performed by changing a
-* single descriptor, the first of the series of puts, to indicate that the
-* hardware may now use all descriptors after it. The last descriptor in the
-* list is always set to cause the hardware to stop after it is processed.
-*
-* Typical Scatter Gather Processing
-*
-* The following steps illustrate the typical processing to use the
-* scatter gather features of a DMA channel.
-*
-* 1. Create a scatter gather list for the DMA channel which puts empty buffer
-* descriptors into the list.
-* 2. Create buffer descriptors which describe the buffers to be filled with
-* receive data or the buffers which contain data to be sent.
-* 3. Put buffer descriptors into the DMA channel scatter list such that scatter
-* gather operations are requested.
-* 4. Commit the buffer descriptors in the list such that they are ready to be
-* used by the DMA channel hardware.
-* 5. Start the scatter gather operations of the DMA channel.
-* 6. Process any interrupts which occur as a result of the scatter gather
-* operations or poll the DMA channel to determine the status. This may
-* be accomplished by getting the packet count for the channel and then
-* getting the appropriate number of descriptors from the list for that
-* number of packets.
-*
-* Minimizing Interrupts
-*
-* The Scatter Gather operating mode is designed to reduce the amount of CPU
-* throughput necessary to manage the hardware for devices. A key to the CPU
-* throughput is the number and rate of interrupts that the CPU must service.
-* Devices with higher data rates can cause larger numbers of interrupts and
-* higher frequency interrupts. Ideally the number of interrupts can be reduced
-* by only generating an interrupt when a specific amount of data has been
-* received from the interface. This design suffers from a lack of interrupts
-* when the amount of data received is less than the specified amount of data
-* to generate an interrupt. In order to help minimize the number of interrupts
-* which the CPU must service, an algorithm referred to as "interrupt coalescing"
-* is utilized.
-*
-* Interrupt Coalescing
-*
-* The principle of interrupt coalescing is to wait before generating an
-* interrupt until a certain number of packets have been received or sent. An
-* interrupt is also generated if a smaller number of packets have been received
-* followed by a certain period of time with no packet reception. This is a
-* trade-off of latency for bandwidth and is accomplished using several
-* mechanisms of the hardware including a counter for packets received or
-* transmitted and a packet timer. These two hardware mechanisms work in
-* combination to allow a reduction in the number of interrupts processed by the
-* CPU for packet reception.
-*
-* Unserviced Packet Count
-*
-* The purpose of the packet counter is to count the number of packets received
-* or transmitted and provide an interrupt when a specific number of packets
-* have been processed by the hardware. An interrupt is generated whenever the
-* counter is greater than or equal to the Packet Count Threshold. This counter
-* contains an accurate count of the number of packets that the hardware has
-* processed, either received or transmitted, and the software has not serviced.
-*
-* The packet counter allows the number of interrupts to be reduced by waiting
-* to generate an interrupt until enough packets are received. For packet
-* reception, packet counts of less than the number to generate an interrupt
-* would not be serviced without the addition of a packet timer. This counter is
-* continuously updated by the hardware, not latched to the value at the time
-* the interrupt occurred.
-*
-* The packet counter can be used within the interrupt service routine for the
-* device to reduce the number of interrupts. The interrupt service routine
-* loops while performing processing for each packet which has been received or
-* transmitted and decrements the counter by a specified value. At the same time,
-* the hardware is possibly continuing to receive or transmit more packets such
-* that the software may choose, based upon the value in the packet counter, to
-* remain in the interrupt service routine rather than exiting and immediately
-* returning. This feature should be used with caution as reducing the number of
-* interrupts is beneficial, but unbounded interrupt processing is not desirable.
-*
-* Since the hardware may be incrementing the packet counter simultaneously
-* with the software decrementing the counter, there is a need for atomic
-* operations. The hardware ensures that the operation is atomic such that
-* simultaneous accesses are properly handled.
-*
-* Packet Wait Bound
-*
-* The purpose of the packet wait bound is to augment the unserviced packet
-* count. Whenever there is no pending interrupt for the channel and the
-* unserviced packet count is non-zero, a timer starts counting timeout at the
-* value contained the the packet wait bound register. If the timeout is
-* reached, an interrupt is generated such that the software may service the
-* data which was buffered.
-*
-* NOTES:
-*
-* Special Test Conditions:
-*
-* The scatter gather list processing must be thoroughly tested if changes are
-* made. Testing should include putting and committing single descriptors and
-* putting multiple descriptors followed by a single commit. There are some
-* conditions in the code which handle the exception conditions.
-*
-* The Put Pointer points to the next location in the descriptor list to copy
-* in a new descriptor. The Get Pointer points to the next location in the
-* list to get a descriptor from. The Get Pointer only allows software to
-* have a traverse the list after the hardware has finished processing some
-* number of descriptors. The Commit Pointer points to the descriptor in the
-* list which is to be committed. It is also used to determine that no
-* descriptor is waiting to be commited (NULL). The Last Pointer points to
-* the last descriptor that was put into the list. It typically points
-* to the previous descriptor to the one pointed to by the Put Pointer.
-* Comparisons are done between these pointers to determine when the following
-* special conditions exist.
-
-* Single Put And Commit
-*
-* The buffer descriptor is ready to be used by the hardware so it is important
-* for the descriptor to not appear to be waiting to be committed. The commit
-* pointer is reset when a commit is done indicating there are no descriptors
-* waiting to be committed. In all cases but this one, the descriptor is
-* changed to cause the hardware to go to the next descriptor after processing
-* this one. But in this case, this is the last descriptor in the list such
-* that it must not be changed.
-*
-* 3 Or More Puts And Commit
-*
-* A series of 3 or more puts followed by a single commit is different in that
-* only the 1st descriptor put into the list is changed when the commit is done.
-* This requires each put starting on the 3rd to change the previous descriptor
-* so that it allows the hardware to continue to the next descriptor in the list.
-*
-* The 1st Put Following A Commit
-*
-* The commit caused the commit pointer to be NULL indicating that there are no
-* descriptors waiting to be committed. It is necessary for the next put to set
-* the commit pointer so that a commit must follow the put for the hardware to
-* use the descriptor.
-*
-* <pre>
-* MODIFICATION HISTORY:
-*
-* Ver Who Date Changes
-* ----- ---- -------- ------------------------------------------------------
-* 1.00a rpm 02/03/03 Removed the XST_DMA_SG_COUNT_EXCEEDED return code
-* from SetPktThreshold.
-* </pre>
-*
-******************************************************************************/
-
-/***************************** Include Files *********************************/
-
-#include "xdma_channel.h"
-#include "xbasic_types.h"
-#include "xio.h"
-#include "xbuf_descriptor.h"
-#include "xstatus.h"
-
-/************************** Constant Definitions *****************************/
-
-#define XDC_SWCR_SG_ENABLE_MASK 0x80000000UL /* scatter gather enable */
-
-/**************************** Type Definitions *******************************/
-
-/***************** Macros (Inline Functions) Definitions *********************/
-
-/* the following macro copies selected fields of a buffer descriptor to another
- * buffer descriptor, this was provided by the buffer descriptor component but
- * was moved here since it is only used internally to this component and since
- * it does not copy all fields
- */
-#define CopyBufferDescriptor(InstancePtr, DestinationPtr) \
-{ \
- *((u32 *)DestinationPtr + XBD_CONTROL_OFFSET) = \
- *((u32 *)InstancePtr + XBD_CONTROL_OFFSET); \
- *((u32 *)DestinationPtr + XBD_SOURCE_OFFSET) = \
- *((u32 *)InstancePtr + XBD_SOURCE_OFFSET); \
- *((u32 *)DestinationPtr + XBD_DESTINATION_OFFSET) = \
- *((u32 *)InstancePtr + XBD_DESTINATION_OFFSET); \
- *((u32 *)DestinationPtr + XBD_LENGTH_OFFSET) = \
- *((u32 *)InstancePtr + XBD_LENGTH_OFFSET); \
- *((u32 *)DestinationPtr + XBD_STATUS_OFFSET) = \
- *((u32 *)InstancePtr + XBD_STATUS_OFFSET); \
- *((u32 *)DestinationPtr + XBD_DEVICE_STATUS_OFFSET) = \
- *((u32 *)InstancePtr + XBD_DEVICE_STATUS_OFFSET); \
- *((u32 *)DestinationPtr + XBD_ID_OFFSET) = \
- *((u32 *)InstancePtr + XBD_ID_OFFSET); \
- *((u32 *)DestinationPtr + XBD_FLAGS_OFFSET) = \
- *((u32 *)InstancePtr + XBD_FLAGS_OFFSET); \
- *((u32 *)DestinationPtr + XBD_RQSTED_LENGTH_OFFSET) = \
- *((u32 *)InstancePtr + XBD_RQSTED_LENGTH_OFFSET); \
-}
-
-/************************** Variable Definitions *****************************/
-
-/************************** Function Prototypes ******************************/
-
-/******************************************************************************
-*
-* FUNCTION:
-*
-* XDmaChannel_SgStart
-*
-* DESCRIPTION:
-*
-* This function starts a scatter gather operation for a scatter gather
-* DMA channel. The first buffer descriptor in the buffer descriptor list
-* will be started with the scatter gather operation. A scatter gather list
-* should have previously been created for the DMA channel and buffer
-* descriptors put into the scatter gather list such that there are scatter
-* operations ready to be performed.
-*
-* ARGUMENTS:
-*
-* InstancePtr contains a pointer to the DMA channel to operate on. The DMA
-* channel should be configured to use scatter gather in order for this function
-* to be called.
-*
-* RETURN VALUE:
-*
-* A status containing XST_SUCCESS if scatter gather was started successfully
-* for the DMA channel.
-*
-* A value of XST_DMA_SG_NO_LIST indicates the scatter gather list has not
-* been created.
-*
-* A value of XST_DMA_SG_LIST_EMPTY indicates scatter gather was not started
-* because the scatter gather list of the DMA channel does not contain any
-* buffer descriptors that are ready to be processed by the hardware.
-*
-* A value of XST_DMA_SG_IS_STARTED indicates scatter gather was not started
-* because the scatter gather was not stopped, but was already started.
-*
-* A value of XST_DMA_SG_BD_NOT_COMMITTED indicates the buffer descriptor of
-* scatter gather list which was to be started is not committed to the list.
-* This status is more likely if this function is being called from an ISR
-* and non-ISR processing is putting descriptors into the list.
-*
-* A value of XST_DMA_SG_NO_DATA indicates that the buffer descriptor of the
-* scatter gather list which was to be started had already been used by the
-* hardware for a DMA transfer that has been completed.
-*
-* NOTES:
-*
-* It is the responsibility of the caller to get all the buffer descriptors
-* after performing a stop operation and before performing a start operation.
-* If buffer descriptors are not retrieved between stop and start operations,
-* buffer descriptors may be processed by the hardware more than once.
-*
-******************************************************************************/
-XStatus
-XDmaChannel_SgStart(XDmaChannel * InstancePtr)
-{
- u32 Register;
- XBufDescriptor *LastDescriptorPtr;
-
- /* assert to verify input arguments */
-
- XASSERT_NONVOID(InstancePtr != NULL);
- XASSERT_NONVOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);
-
- /* if a scatter gather list has not been created yet, return a status */
-
- if (InstancePtr->TotalDescriptorCount == 0) {
- return XST_DMA_SG_NO_LIST;
- }
-
- /* if the scatter gather list exists but is empty then return a status */
-
- if (XDmaChannel_IsSgListEmpty(InstancePtr)) {
- return XST_DMA_SG_LIST_EMPTY;
- }
-
- /* if scatter gather is busy for the DMA channel, return a status because
- * restarting it could lose data
- */
-
- Register = XIo_In32(InstancePtr->RegBaseAddress + XDC_DMAS_REG_OFFSET);
- if (Register & XDC_DMASR_SG_BUSY_MASK) {
- return XST_DMA_SG_IS_STARTED;
- }
-
- /* get the address of the last buffer descriptor which the DMA hardware
- * finished processing
- */
- LastDescriptorPtr =
- (XBufDescriptor *) XIo_In32(InstancePtr->RegBaseAddress +
- XDC_BDA_REG_OFFSET);
-
- /* setup the first buffer descriptor that will be sent when the scatter
- * gather channel is enabled, this is only necessary one time since
- * the BDA register of the channel maintains the last buffer descriptor
- * processed
- */
- if (LastDescriptorPtr == NULL) {
- XIo_Out32(InstancePtr->RegBaseAddress + XDC_BDA_REG_OFFSET,
- (u32) InstancePtr->GetPtr);
- } else {
- XBufDescriptor *NextDescriptorPtr;
-
- /* get the next descriptor to be started, if the status indicates it
- * hasn't already been used by the h/w, then it's OK to start it,
- * s/w sets the status of each descriptor to busy and then h/w clears
- * the busy when it is complete
- */
- NextDescriptorPtr =
- XBufDescriptor_GetNextPtr(LastDescriptorPtr);
-
- if ((XBufDescriptor_GetStatus(NextDescriptorPtr) &
- XDC_DMASR_BUSY_MASK) == 0) {
- return XST_DMA_SG_NO_DATA;
- }
- /* don't start the DMA SG channel if the descriptor to be processed
- * by h/w is to be committed by the s/w, this function can be called
- * such that it interrupts a thread that was putting into the list
- */
- if (NextDescriptorPtr == InstancePtr->CommitPtr) {
- return XST_DMA_SG_BD_NOT_COMMITTED;
- }
- }
-
- /* start the scatter gather operation by clearing the stop bit in the
- * control register and setting the enable bit in the s/w control register,
- * both of these are necessary to cause it to start, right now the order of
- * these statements is important, the software control register should be
- * set 1st. The other order can cause the CPU to have a loss of sync
- * because it cannot read/write the register while the DMA operation is
- * running
- */
-
- Register = XIo_In32(InstancePtr->RegBaseAddress + XDC_SWCR_REG_OFFSET);
-
- XIo_Out32(InstancePtr->RegBaseAddress + XDC_SWCR_REG_OFFSET,
- Register | XDC_SWCR_SG_ENABLE_MASK);
-
- Register = XIo_In32(InstancePtr->RegBaseAddress + XDC_DMAC_REG_OFFSET);
-
- XIo_Out32(InstancePtr->RegBaseAddress + XDC_DMAC_REG_OFFSET,
- Register & ~XDC_DMACR_SG_DISABLE_MASK);
-
- /* indicate the DMA channel scatter gather operation was started
- * successfully
- */
- return XST_SUCCESS;
-}
-
-/******************************************************************************
-*
-* FUNCTION:
-*
-* XDmaChannel_SgStop
-*
-* DESCRIPTION:
-*
-* This function stops a scatter gather operation for a scatter gather
-* DMA channel. This function starts the process of stopping a scatter
-* gather operation that is in progress and waits for the stop to be completed.
-* Since it waits for the operation to stopped before returning, this function
-* could take an amount of time relative to the size of the DMA scatter gather
-* operation which is in progress. The scatter gather list of the DMA channel
-* is not modified by this function such that starting the scatter gather
-* channel after stopping it will cause it to resume. This operation is
-* considered to be a graceful stop in that the scatter gather operation
-* completes the current buffer descriptor before stopping.
-*
-* If the interrupt is enabled, an interrupt will be generated when the
-* operation is stopped and the caller is responsible for handling the
-* interrupt.
-*
-* ARGUMENTS:
-*
-* InstancePtr contains a pointer to the DMA channel to operate on. The DMA
-* channel should be configured to use scatter gather in order for this function
-* to be called.
-*
-* BufDescriptorPtr is also a return value which contains a pointer to the
-* buffer descriptor which the scatter gather operation completed when it
-* was stopped.
-*
-* RETURN VALUE:
-*
-* A status containing XST_SUCCESS if scatter gather was stopped successfully
-* for the DMA channel.
-*
-* A value of XST_DMA_SG_IS_STOPPED indicates scatter gather was not stoppped
-* because the scatter gather is not started, but was already stopped.
-*
-* BufDescriptorPtr contains a pointer to the buffer descriptor which was
-* completed when the operation was stopped.
-*
-* NOTES:
-*
-* This function implements a loop which polls the hardware for an infinite
-* amount of time. If the hardware is not operating correctly, this function
-* may never return.
-*
-******************************************************************************/
-XStatus
-XDmaChannel_SgStop(XDmaChannel * InstancePtr,
- XBufDescriptor ** BufDescriptorPtr)
-{
- u32 Register;
-
- /* assert to verify input arguments */
-
- XASSERT_NONVOID(InstancePtr != NULL);
- XASSERT_NONVOID(BufDescriptorPtr != NULL);
- XASSERT_NONVOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);
-
- /* get the contents of the software control register, if scatter gather is not
- * enabled (started), then return a status because the disable acknowledge
- * would not be generated
- */
- Register = XIo_In32(InstancePtr->RegBaseAddress + XDC_SWCR_REG_OFFSET);
-
- if ((Register & XDC_SWCR_SG_ENABLE_MASK) == 0) {
- return XST_DMA_SG_IS_STOPPED;
- }
-
- /* Ensure the interrupt status for the scatter gather is cleared such
- * that this function will wait til the disable has occurred, writing
- * a 1 to only that bit in the register will clear only it
- */
- XIo_Out32(InstancePtr->RegBaseAddress + XDC_IS_REG_OFFSET,
- XDC_IXR_SG_DISABLE_ACK_MASK);
-
- /* disable scatter gather by writing to the software control register
- * without modifying any other bits of the register
- */
- XIo_Out32(InstancePtr->RegBaseAddress + XDC_SWCR_REG_OFFSET,
- Register & ~XDC_SWCR_SG_ENABLE_MASK);
-
- /* scatter gather does not disable immediately, but after the current
- * buffer descriptor is complete, so wait for the DMA channel to indicate
- * the disable is complete
- */
- do {
- Register =
- XIo_In32(InstancePtr->RegBaseAddress + XDC_IS_REG_OFFSET);
- } while ((Register & XDC_IXR_SG_DISABLE_ACK_MASK) == 0);
-
- /* Ensure the interrupt status for the scatter gather disable is cleared,
- * writing a 1 to only that bit in the register will clear only it
- */
- XIo_Out32(InstancePtr->RegBaseAddress + XDC_IS_REG_OFFSET,
- XDC_IXR_SG_DISABLE_ACK_MASK);
-
- /* set the specified buffer descriptor pointer to point to the buffer
- * descriptor that the scatter gather DMA channel was processing
- */
- *BufDescriptorPtr =
- (XBufDescriptor *) XIo_In32(InstancePtr->RegBaseAddress +
- XDC_BDA_REG_OFFSET);
-
- return XST_SUCCESS;
-}
-
-/******************************************************************************
-*
-* FUNCTION:
-*
-* XDmaChannel_CreateSgList
-*
-* DESCRIPTION:
-*
-* This function creates a scatter gather list in the DMA channel. A scatter
-* gather list consists of a list of buffer descriptors that are available to
-* be used for scatter gather operations. Buffer descriptors are put into the
-* list to request a scatter gather operation to be performed.
-*
-* A number of buffer descriptors are created from the specified memory and put
-* into a buffer descriptor list as empty buffer descriptors. This function must
-* be called before non-empty buffer descriptors may be put into the DMA channel
-* to request scatter gather operations.
-*
-* ARGUMENTS:
-*
-* InstancePtr contains a pointer to the DMA channel to operate on. The DMA
-* channel should be configured to use scatter gather in order for this function
-* to be called.
-*
-* MemoryPtr contains a pointer to the memory which is to be used for buffer
-* descriptors and must not be cached.
-*
-* ByteCount contains the number of bytes for the specified memory to be used
-* for buffer descriptors.
-*
-* RETURN VALUE:
-*
-* A status contains XST_SUCCESS if the scatter gather list was successfully
-* created.
-*
-* A value of XST_DMA_SG_LIST_EXISTS indicates that the scatter gather list
-* was not created because the list has already been created.
-*
-* NOTES:
-*
-* None.
-*
-******************************************************************************/
-XStatus
-XDmaChannel_CreateSgList(XDmaChannel * InstancePtr,
- u32 * MemoryPtr, u32 ByteCount)
-{
- XBufDescriptor *BufferDescriptorPtr = (XBufDescriptor *) MemoryPtr;
- XBufDescriptor *PreviousDescriptorPtr = NULL;
- XBufDescriptor *StartOfListPtr = BufferDescriptorPtr;
- u32 UsedByteCount;
-
- /* assert to verify valid input arguments, alignment for those
- * arguments that have alignment restrictions, and at least enough
- * memory for one buffer descriptor
- */
- XASSERT_NONVOID(InstancePtr != NULL);
- XASSERT_NONVOID(MemoryPtr != NULL);
- XASSERT_NONVOID(((u32) MemoryPtr & 3) == 0);
- XASSERT_NONVOID(ByteCount != 0);
- XASSERT_NONVOID(ByteCount >= sizeof (XBufDescriptor));
- XASSERT_NONVOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);
-
- /* if the scatter gather list has already been created, then return
- * with a status
- */
- if (InstancePtr->TotalDescriptorCount != 0) {
- return XST_DMA_SG_LIST_EXISTS;
- }
-
- /* loop thru the specified memory block and create as many buffer
- * descriptors as possible putting each into the list which is
- * implemented as a ring buffer, make sure not to use any memory which
- * is not large enough for a complete buffer descriptor
- */
- UsedByteCount = 0;
- while ((UsedByteCount + sizeof (XBufDescriptor)) <= ByteCount) {
- /* setup a pointer to the next buffer descriptor in the memory and
- * update # of used bytes to know when all of memory is used
- */
- BufferDescriptorPtr = (XBufDescriptor *) ((u32) MemoryPtr +
- UsedByteCount);
-
- /* initialize the new buffer descriptor such that it doesn't contain
- * garbage which could be used by the DMA hardware
- */
- XBufDescriptor_Initialize(BufferDescriptorPtr);
-
- /* if this is not the first buffer descriptor to be created,
- * then link it to the last created buffer descriptor
- */
- if (PreviousDescriptorPtr != NULL) {
- XBufDescriptor_SetNextPtr(PreviousDescriptorPtr,
- BufferDescriptorPtr);
- }
-
- /* always keep a pointer to the last created buffer descriptor such
- * that they can be linked together in the ring buffer
- */
- PreviousDescriptorPtr = BufferDescriptorPtr;
-
- /* keep a count of the number of descriptors in the list to allow
- * error processing to be performed
- */
- InstancePtr->TotalDescriptorCount++;
-
- UsedByteCount += sizeof (XBufDescriptor);
- }
-
- /* connect the last buffer descriptor created and inserted in the list
- * to the first such that a ring buffer is created
- */
- XBufDescriptor_SetNextPtr(BufferDescriptorPtr, StartOfListPtr);
-
- /* initialize the ring buffer to indicate that there are no
- * buffer descriptors in the list which point to valid data buffers
- */
- InstancePtr->PutPtr = BufferDescriptorPtr;
- InstancePtr->GetPtr = BufferDescriptorPtr;
- InstancePtr->CommitPtr = NULL;
- InstancePtr->LastPtr = BufferDescriptorPtr;
- InstancePtr->ActiveDescriptorCount = 0;
-
- /* indicate the scatter gather list was successfully created */
-
- return XST_SUCCESS;
-}
-
-/******************************************************************************
-*
-* FUNCTION:
-*
-* XDmaChannel_IsSgListEmpty
-*
-* DESCRIPTION:
-*
-* This function determines if the scatter gather list of a DMA channel is
-* empty with regard to buffer descriptors which are pointing to buffers to be
-* used for scatter gather operations.
-*
-* ARGUMENTS:
-*
-* InstancePtr contains a pointer to the DMA channel to operate on. The DMA
-* channel should be configured to use scatter gather in order for this function
-* to be called.
-*
-* RETURN VALUE:
-*
-* A value of TRUE if the scatter gather list is empty, otherwise a value of
-* FALSE.
-*
-* NOTES:
-*
-* None.
-*
-******************************************************************************/
-u32
-XDmaChannel_IsSgListEmpty(XDmaChannel * InstancePtr)
-{
- /* assert to verify valid input arguments */
-
- XASSERT_NONVOID(InstancePtr != NULL);
- XASSERT_NONVOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);
-
- /* if the number of descriptors which are being used in the list is zero
- * then the list is empty
- */
- return (InstancePtr->ActiveDescriptorCount == 0);
-}
-
-/******************************************************************************
-*
-* FUNCTION:
-*
-* XDmaChannel_PutDescriptor
-*
-* DESCRIPTION:
-*
-* This function puts a buffer descriptor into the DMA channel scatter
-* gather list. A DMA channel maintains a list of buffer descriptors which are
-* to be processed. This function puts the specified buffer descriptor
-* at the next location in the list. Note that since the list is already intact,
-* the information in the parameter is copied into the list (rather than modify
-* list pointers on the fly).
-*
-* After buffer descriptors are put into the list, they must also be committed
-* by calling another function. This allows multiple buffer descriptors which
-* span a single packet to be put into the list while preventing the hardware
-* from starting the first buffer descriptor of the packet.
-*
-* ARGUMENTS:
-*
-* InstancePtr contains a pointer to the DMA channel to operate on. The DMA
-* channel should be configured to use scatter gather in order for this function
-* to be called.
-*
-* BufferDescriptorPtr is a pointer to the buffer descriptor to be put into
-* the next available location of the scatter gather list.
-*
-* RETURN VALUE:
-*
-* A status which indicates XST_SUCCESS if the buffer descriptor was
-* successfully put into the scatter gather list.
-*
-* A value of XST_DMA_SG_NO_LIST indicates the scatter gather list has not
-* been created.
-*
-* A value of XST_DMA_SG_LIST_FULL indicates the buffer descriptor was not
-* put into the list because the list was full.
-*
-* A value of XST_DMA_SG_BD_LOCKED indicates the buffer descriptor was not
-* put into the list because the buffer descriptor in the list which is to
-* be overwritten was locked. A locked buffer descriptor indicates the higher
-* layered software is still using the buffer descriptor.
-*
-* NOTES:
-*
-* It is necessary to create a scatter gather list for a DMA channel before
-* putting buffer descriptors into it.
-*
-******************************************************************************/
-XStatus
-XDmaChannel_PutDescriptor(XDmaChannel * InstancePtr,
- XBufDescriptor * BufferDescriptorPtr)
-{
- u32 Control;
-
- /* assert to verify valid input arguments and alignment for those
- * arguments that have alignment restrictions
- */
- XASSERT_NONVOID(InstancePtr != NULL);
- XASSERT_NONVOID(BufferDescriptorPtr != NULL);
- XASSERT_NONVOID(((u32) BufferDescriptorPtr & 3) == 0);
- XASSERT_NONVOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);
-
- /* if a scatter gather list has not been created yet, return a status */
-
- if (InstancePtr->TotalDescriptorCount == 0) {
- return XST_DMA_SG_NO_LIST;
- }
-
- /* if the list is full because all descriptors are pointing to valid
- * buffers, then indicate an error, this code assumes no list or an
- * empty list is detected above
- */
- if (InstancePtr->ActiveDescriptorCount ==
- InstancePtr->TotalDescriptorCount) {
- return XST_DMA_SG_LIST_FULL;
- }
-
- /* if the buffer descriptor in the list which is to be overwritten is
- * locked, then don't overwrite it and return a status
- */
- if (XBufDescriptor_IsLocked(InstancePtr->PutPtr)) {
- return XST_DMA_SG_BD_LOCKED;
- }
-
- /* set the scatter gather stop bit in the control word of the descriptor
- * to cause the h/w to stop after it processes this descriptor since it
- * will be the last in the list
- */
- Control = XBufDescriptor_GetControl(BufferDescriptorPtr);
- XBufDescriptor_SetControl(BufferDescriptorPtr,
- Control | XDC_DMACR_SG_DISABLE_MASK);
-
- /* set both statuses in the descriptor so we tell if they are updated with
- * the status of the transfer, the hardware should change the busy in the
- * DMA status to be false when it completes
- */
- XBufDescriptor_SetStatus(BufferDescriptorPtr, XDC_DMASR_BUSY_MASK);
- XBufDescriptor_SetDeviceStatus(BufferDescriptorPtr, 0);
-
- /* copy the descriptor into the next position in the list so it's ready to
- * be used by the h/w, this assumes the descriptor in the list prior to this
- * one still has the stop bit in the control word set such that the h/w
- * use this one yet
- */
- CopyBufferDescriptor(BufferDescriptorPtr, InstancePtr->PutPtr);
-
- /* only the last in the list and the one to be committed have scatter gather
- * disabled in the control word, a commit requires only one descriptor
- * to be changed, when # of descriptors to commit > 2 all others except the
- * 1st and last have scatter gather enabled
- */
- if ((InstancePtr->CommitPtr != InstancePtr->LastPtr) &&
- (InstancePtr->CommitPtr != NULL)) {
- Control = XBufDescriptor_GetControl(InstancePtr->LastPtr);
- XBufDescriptor_SetControl(InstancePtr->LastPtr,
- Control & ~XDC_DMACR_SG_DISABLE_MASK);
- }
-
- /* update the list data based upon putting a descriptor into the list,
- * these operations must be last
- */
- InstancePtr->ActiveDescriptorCount++;
-
- /* only update the commit pointer if it is not already active, this allows
- * it to be deactivated after every commit such that a single descriptor
- * which is committed does not appear to be waiting to be committed
- */
- if (InstancePtr->CommitPtr == NULL) {
- InstancePtr->CommitPtr = InstancePtr->LastPtr;
- }
-
- /* these updates MUST BE LAST after the commit pointer update in order for
- * the commit pointer to track the correct descriptor to be committed
- */
- InstancePtr->LastPtr = InstancePtr->PutPtr;
- InstancePtr->PutPtr = XBufDescriptor_GetNextPtr(InstancePtr->PutPtr);
-
- return XST_SUCCESS;
-}
-
-/******************************************************************************
-*
-* FUNCTION:
-*
-* XDmaChannel_CommitPuts
-*
-* DESCRIPTION:
-*
-* This function commits the buffer descriptors which have been put into the
-* scatter list for the DMA channel since the last commit operation was
-* performed. This enables the calling functions to put several buffer
-* descriptors into the list (e.g.,a packet's worth) before allowing the scatter
-* gather operations to start. This prevents the DMA channel hardware from
-* starting to use the buffer descriptors in the list before they are ready
-* to be used (multiple buffer descriptors for a single packet).
-*
-* ARGUMENTS:
-*
-* InstancePtr contains a pointer to the DMA channel to operate on. The DMA
-* channel should be configured to use scatter gather in order for this function
-* to be called.
-*
-* RETURN VALUE:
-*
-* A status indicating XST_SUCCESS if the buffer descriptors of the list were
-* successfully committed.
-*
-* A value of XST_DMA_SG_NOTHING_TO_COMMIT indicates that the buffer descriptors
-* were not committed because there was nothing to commit in the list. All the
-* buffer descriptors which are in the list are commited.
-*
-* NOTES:
-*
-* None.
-*
-******************************************************************************/
-XStatus
-XDmaChannel_CommitPuts(XDmaChannel * InstancePtr)
-{
- /* assert to verify input arguments */
-
- XASSERT_NONVOID(InstancePtr != NULL);
- XASSERT_NONVOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);
-
- /* if the buffer descriptor to be committed is already committed or
- * the list is empty (none have been put in), then indicate an error
- */
- if ((InstancePtr->CommitPtr == NULL) ||
- XDmaChannel_IsSgListEmpty(InstancePtr)) {
- return XST_DMA_SG_NOTHING_TO_COMMIT;
- }
-
- /* last descriptor in the list must have scatter gather disabled so the end
- * of the list is hit by h/w, if descriptor to commit is not last in list,
- * commit descriptors by enabling scatter gather in the descriptor
- */
- if (InstancePtr->CommitPtr != InstancePtr->LastPtr) {
- u32 Control;
-
- Control = XBufDescriptor_GetControl(InstancePtr->CommitPtr);
- XBufDescriptor_SetControl(InstancePtr->CommitPtr, Control &
- ~XDC_DMACR_SG_DISABLE_MASK);
- }
- /* Update the commit pointer to indicate that there is nothing to be
- * committed, this state is used by start processing to know that the
- * buffer descriptor to start is not waiting to be committed
- */
- InstancePtr->CommitPtr = NULL;
-
- return XST_SUCCESS;
-}
-
-/******************************************************************************
-*
-* FUNCTION:
-*
-* XDmaChannel_GetDescriptor
-*
-* DESCRIPTION:
-*
-* This function gets a buffer descriptor from the scatter gather list of the
-* DMA channel. The buffer descriptor is retrieved from the scatter gather list
-* and the scatter gather list is updated to not include the retrieved buffer
-* descriptor. This is typically done after a scatter gather operation
-* completes indicating that a data buffer has been successfully sent or data
-* has been received into the data buffer. The purpose of this function is to
-* allow the device using the scatter gather operation to get the results of the
-* operation.
-*
-* ARGUMENTS:
-*
-* InstancePtr contains a pointer to the DMA channel to operate on. The DMA
-* channel should be configured to use scatter gather in order for this function
-* to be called.
-*
-* BufDescriptorPtr is a pointer to a pointer to the buffer descriptor which
-* was retrieved from the list. The buffer descriptor is not really removed
-* from the list, but it is changed to a state such that the hardware will not
-* use it again until it is put into the scatter gather list of the DMA channel.
-*
-* RETURN VALUE:
-*
-* A status indicating XST_SUCCESS if a buffer descriptor was retrieved from
-* the scatter gather list of the DMA channel.
-*
-* A value of XST_DMA_SG_NO_LIST indicates the scatter gather list has not
-* been created.
-*
-* A value of XST_DMA_SG_LIST_EMPTY indicates no buffer descriptor was
-* retrieved from the list because there are no buffer descriptors to be
-* processed in the list.
-*
-* BufDescriptorPtr is updated to point to the buffer descriptor which was
-* retrieved from the list if the status indicates success.
-*
-* NOTES:
-*
-* None.
-*
-******************************************************************************/
-XStatus
-XDmaChannel_GetDescriptor(XDmaChannel * InstancePtr,
- XBufDescriptor ** BufDescriptorPtr)
-{
- u32 Control;
-
- /* assert to verify input arguments */
-
- XASSERT_NONVOID(InstancePtr != NULL);
- XASSERT_NONVOID(BufDescriptorPtr != NULL);
- XASSERT_NONVOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);
-
- /* if a scatter gather list has not been created yet, return a status */
-
- if (InstancePtr->TotalDescriptorCount == 0) {
- return XST_DMA_SG_NO_LIST;
- }
-
- /* if the buffer descriptor list is empty, then indicate an error */
-
- if (XDmaChannel_IsSgListEmpty(InstancePtr)) {
- return XST_DMA_SG_LIST_EMPTY;
- }
-
- /* retrieve the next buffer descriptor which is ready to be processed from
- * the buffer descriptor list for the DMA channel, set the control word
- * such that hardware will stop after the descriptor has been processed
- */
- Control = XBufDescriptor_GetControl(InstancePtr->GetPtr);
- XBufDescriptor_SetControl(InstancePtr->GetPtr,
- Control | XDC_DMACR_SG_DISABLE_MASK);
-
- /* set the input argument, which is also an output, to point to the
- * buffer descriptor which is to be retrieved from the list
- */
- *BufDescriptorPtr = InstancePtr->GetPtr;
-
- /* update the pointer of the DMA channel to reflect the buffer descriptor
- * was retrieved from the list by setting it to the next buffer descriptor
- * in the list and indicate one less descriptor in the list now
- */
- InstancePtr->GetPtr = XBufDescriptor_GetNextPtr(InstancePtr->GetPtr);
- InstancePtr->ActiveDescriptorCount--;
-
- return XST_SUCCESS;
-}
-
-/*********************** Interrupt Collescing Functions **********************/
-
-/******************************************************************************
-*
-* FUNCTION:
-*
-* XDmaChannel_GetPktCount
-*
-* DESCRIPTION:
-*
-* This function returns the value of the unserviced packet count register of
-* the DMA channel. This count represents the number of packets that have been
-* sent or received by the hardware, but not processed by software.
-*
-* ARGUMENTS:
-*
-* InstancePtr contains a pointer to the DMA channel to operate on. The DMA
-* channel should be configured to use scatter gather in order for this function
-* to be called.
-*
-* RETURN VALUE:
-*
-* The unserviced packet counter register contents for the DMA channel.
-*
-* NOTES:
-*
-* None.
-*
-******************************************************************************/
-u32
-XDmaChannel_GetPktCount(XDmaChannel * InstancePtr)
-{
- /* assert to verify input arguments */
-
- XASSERT_NONVOID(InstancePtr != NULL);
- XASSERT_NONVOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);
-
- /* get the unserviced packet count from the register and return it */
-
- return XIo_In32(InstancePtr->RegBaseAddress + XDC_UPC_REG_OFFSET);
-}
-
-/******************************************************************************
-*
-* FUNCTION:
-*
-* XDmaChannel_DecrementPktCount
-*
-* DESCRIPTION:
-*
-* This function decrements the value of the unserviced packet count register.
-* This informs the hardware that the software has processed a packet. The
-* unserviced packet count register may only be decremented by one in the
-* hardware.
-*
-* ARGUMENTS:
-*
-* InstancePtr contains a pointer to the DMA channel to operate on. The DMA
-* channel should be configured to use scatter gather in order for this function
-* to be called.
-*
-* RETURN VALUE:
-*
-* None.
-*
-* NOTES:
-*
-* None.
-*
-******************************************************************************/
-void
-XDmaChannel_DecrementPktCount(XDmaChannel * InstancePtr)
-{
- u32 Register;
-
- /* assert to verify input arguments */
-
- XASSERT_VOID(InstancePtr != NULL);
- XASSERT_VOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);
-
- /* if the unserviced packet count register can be decremented (rather
- * than rolling over) decrement it by writing a 1 to the register,
- * this is the only valid write to the register as it serves as an
- * acknowledge that a packet was handled by the software
- */
- Register = XIo_In32(InstancePtr->RegBaseAddress + XDC_UPC_REG_OFFSET);
- if (Register > 0) {
- XIo_Out32(InstancePtr->RegBaseAddress + XDC_UPC_REG_OFFSET,
- 1UL);
- }
-}
-
-/******************************************************************************
-*
-* FUNCTION:
-*
-* XDmaChannel_SetPktThreshold
-*
-* DESCRIPTION:
-*
-* This function sets the value of the packet count threshold register of the
-* DMA channel. It reflects the number of packets that must be sent or
-* received before generating an interrupt. This value helps implement
-* a concept called "interrupt coalescing", which is used to reduce the number
-* of interrupts from devices with high data rates.
-*
-* ARGUMENTS:
-*
-* InstancePtr contains a pointer to the DMA channel to operate on. The DMA
-* channel should be configured to use scatter gather in order for this function
-* to be called.
-*
-* Threshold is the value that is written to the threshold register of the
-* DMA channel.
-*
-* RETURN VALUE:
-*
-* A status containing XST_SUCCESS if the packet count threshold was
-* successfully set.
-*
-* NOTES:
-*
-* The packet threshold could be set to larger than the number of descriptors
-* allocated to the DMA channel. In this case, the wait bound will take over
-* and always indicate data arrival. There was a check in this function that
-* returned an error if the treshold was larger than the number of descriptors,
-* but that was removed because users would then have to set the threshold
-* only after they set descriptor space, which is an order dependency that
-* caused confustion.
-*
-******************************************************************************/
-XStatus
-XDmaChannel_SetPktThreshold(XDmaChannel * InstancePtr, u8 Threshold)
-{
- /* assert to verify input arguments, don't assert the threshold since
- * it's range is unknown
- */
- XASSERT_NONVOID(InstancePtr != NULL);
- XASSERT_NONVOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);
-
- /* set the packet count threshold in the register such that an interrupt
- * may be generated, if enabled, when the packet count threshold is
- * reached or exceeded
- */
- XIo_Out32(InstancePtr->RegBaseAddress + XDC_PCT_REG_OFFSET,
- (u32) Threshold);
-
- /* indicate the packet count threshold was successfully set */
-
- return XST_SUCCESS;
-}
-
-/******************************************************************************
-*
-* FUNCTION:
-*
-* XDmaChannel_GetPktThreshold
-*
-* DESCRIPTION:
-*
-* This function gets the value of the packet count threshold register of the
-* DMA channel. This value reflects the number of packets that must be sent or
-* received before generating an interrupt. This value helps implement a concept
-* called "interrupt coalescing", which is used to reduce the number of
-* interrupts from devices with high data rates.
-*
-* ARGUMENTS:
-*
-* InstancePtr contains a pointer to the DMA channel to operate on. The DMA
-* channel should be configured to use scatter gather in order for this function
-* to be called.
-*
-* RETURN VALUE:
-*
-* The packet threshold register contents for the DMA channel and is a value in
-* the range 0 - 1023. A value of 0 indicates the packet wait bound timer is
-* disabled.
-*
-* NOTES:
-*
-* None.
-*
-******************************************************************************/
-u8
-XDmaChannel_GetPktThreshold(XDmaChannel * InstancePtr)
-{
- /* assert to verify input arguments */
-
- XASSERT_NONVOID(InstancePtr != NULL);
- XASSERT_NONVOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);
-
- /* get the packet count threshold from the register and return it,
- * since only 8 bits are used, cast it to return only those bits */
-
- return (u8) XIo_In32(InstancePtr->RegBaseAddress + XDC_PCT_REG_OFFSET);
-}
-
-/******************************************************************************
-*
-* FUNCTION:
-*
-* XDmaChannel_SetPktWaitBound
-*
-* DESCRIPTION:
-*
-* This function sets the value of the packet wait bound register of the
-* DMA channel. This value reflects the timer value used to trigger an
-* interrupt when not enough packets have been received to reach the packet
-* count threshold.
-*
-* The timer is in millisecond units with +/- 33% accuracy.
-*
-* ARGUMENTS:
-*
-* InstancePtr contains a pointer to the DMA channel to operate on. The DMA
-* channel should be configured to use scatter gather in order for this function
-* to be called.
-*
-* WaitBound is the value, in milliseconds, to be stored in the wait bound
-* register of the DMA channel and is a value in the range 0 - 1023. A value
-* of 0 disables the packet wait bound timer.
-*
-* RETURN VALUE:
-*
-* None.
-*
-* NOTES:
-*
-* None.
-*
-******************************************************************************/
-void
-XDmaChannel_SetPktWaitBound(XDmaChannel * InstancePtr, u32 WaitBound)
-{
- /* assert to verify input arguments */
-
- XASSERT_VOID(InstancePtr != NULL);
- XASSERT_VOID(WaitBound < 1024);
- XASSERT_VOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);
-
- /* set the packet wait bound in the register such that interrupt may be
- * generated, if enabled, when packets have not been handled for a specific
- * amount of time
- */
- XIo_Out32(InstancePtr->RegBaseAddress + XDC_PWB_REG_OFFSET, WaitBound);
-}
-
-/******************************************************************************
-*
-* FUNCTION:
-*
-* XDmaChannel_GetPktWaitBound
-*
-* DESCRIPTION:
-*
-* This function gets the value of the packet wait bound register of the
-* DMA channel. This value contains the timer value used to trigger an
-* interrupt when not enough packets have been received to reach the packet
-* count threshold.
-*
-* The timer is in millisecond units with +/- 33% accuracy.
-*
-* ARGUMENTS:
-*
-* InstancePtr contains a pointer to the DMA channel to operate on. The DMA
-* channel should be configured to use scatter gather in order for this function
-* to be called.
-*
-* RETURN VALUE:
-*
-* The packet wait bound register contents for the DMA channel.
-*
-* NOTES:
-*
-* None.
-*
-******************************************************************************/
-u32
-XDmaChannel_GetPktWaitBound(XDmaChannel * InstancePtr)
-{
- /* assert to verify input arguments */
-
- XASSERT_NONVOID(InstancePtr != NULL);
- XASSERT_NONVOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);
-
- /* get the packet wait bound from the register and return it */
-
- return XIo_In32(InstancePtr->RegBaseAddress + XDC_PWB_REG_OFFSET);
-}
projects / karo-tx-uboot.git / commitdiff