xdma_channel.c

linux嵌入式系统的dma方式的实现代码

/* $Id: xdma_channel.c,v 1.3 2006/07/18 17:56:33 xduan Exp $ */
/******************************************************************************
*
*       XILINX IS PROVIDING THIS DESIGN, CODE, OR INFORMATION "AS IS"
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*       FOR A PARTICULAR PURPOSE.
*
*       (c) Copyright 2001-2004 Xilinx Inc.
*       All rights reserved.
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******************************************************************************/
/*****************************************************************************/
/**
*
* @file xdma_channel.c
*
* <b>Description</b>
*
* This file contains the DMA channel component. This component supports
* a distributed DMA design in which each device can have it's own dedicated
* DMA channel, as opposed to a centralized DMA design. This component
* performs processing for DMA on all devices.
*
* See xdma_channel.h for more information about this component.
*
* @note
*
* None.
*
* <pre>
* MODIFICATION HISTORY:
*
* Ver   Who  Date     Changes
* ----- ---- -------- -----------------------------------------------
* 1.00a xd  10/27/04  Doxygenated for inclusion in API documentation
* 1.00b ecm 10/31/05  Updated for the check sum offload changes.
* 1.00b xd  03/22/06  Fixed a multi-descriptor packet related bug that sgdma
*                     engine is restarted in case no scatter gather disabled
*                     bit is set yet
* </pre>
*
******************************************************************************/

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

#include "xdma_channel.h"
#include "xbasic_types.h"
#include "xio.h"

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


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


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


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


/*****************************************************************************/
/**
*
* This function initializes a DMA channel.  This function must be called
* prior to using a DMA channel.  Initialization of a channel includes setting
* up the registers base address, and resetting the channel such that it's in a
* known state.  Interrupts for the channel are disabled when the channel is
* reset.
*
* @param
*
* InstancePtr contains a pointer to the DMA channel to operate on.
*
* @param
*
* BaseAddress contains the base address of the registers for the DMA channel.
*
* @return
*
* XST_SUCCESS indicating initialization was successful.
*
* @note
*
* None.
*
******************************************************************************/
XStatus XDmaChannel_Initialize(XDmaChannel *InstancePtr,
                                    Xuint32 BaseAddress)
{
    /* assert to verify input arguments, don't assert base address */

    XASSERT_NONVOID(InstancePtr != XNULL);

    /* setup the base address of the registers for the DMA channel such
     * that register accesses can be done
     */
    InstancePtr->RegBaseAddress = BaseAddress;

    /* initialize the scatter gather list such that it indicates it has not
     * been created yet and the DMA channel is ready to use (initialized)
     */
    InstancePtr->GetPtr = XNULL;
    InstancePtr->PutPtr = XNULL;
    InstancePtr->CommitPtr = XNULL;
    InstancePtr->LastPtr = XNULL;

    InstancePtr->TotalDescriptorCount = 0;
    InstancePtr->ActiveDescriptorCount = 0;

    InstancePtr->ActivePacketCount = 0;
    InstancePtr->Committed = XFALSE;

    InstancePtr->IsReady = XCOMPONENT_IS_READY;

    /* initialize the version of the component
     */
    XVersion_FromString(&InstancePtr->Version, "1.00a");

    /* reset the DMA channel such that it's in a known state and ready
     * and indicate the initialization occurred with no errors, note that
     * the is ready variable must be set before this call or reset will assert
     */
    XDmaChannel_Reset(InstancePtr);

    return XST_SUCCESS;
}

/*****************************************************************************/
/**
*
* This function determines if a DMA channel component has been successfully
* initialized such that it's ready to use.
*
* @param
*
* InstancePtr contains a pointer to the DMA channel to operate on.
*
* @return
*
* XTRUE if the DMA channel component is ready, XFALSE otherwise.
*
* @note
*
* None.
*
******************************************************************************/
Xboolean XDmaChannel_IsReady(XDmaChannel *InstancePtr)
{
    /* assert to verify input arguments used by the base component */

    XASSERT_NONVOID(InstancePtr != XNULL);

    return InstancePtr->IsReady == XCOMPONENT_IS_READY;
}

/*****************************************************************************/
/**
*
* This function gets the software version for the specified DMA channel
* component.
*
* @param
*
* InstancePtr contains a pointer to the DMA channel to operate on.
*
* @return
*
* A pointer to the software version of the specified DMA channel.
*
* @note
*
* None.
*
******************************************************************************/
XVersion *XDmaChannel_GetVersion(XDmaChannel *InstancePtr)
{
    /* assert to verify input arguments */

    XASSERT_NONVOID(InstancePtr != XNULL);
    XASSERT_NONVOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);

    /* return a pointer to the version of the DMA channel */

    return &InstancePtr->Version;
}

/*****************************************************************************/
/**
*
* This function performs a self test on the specified DMA channel.  This self
* test is destructive as the DMA channel is reset and a register default is
* verified.
*
* @param
*
* InstancePtr is a pointer to the DMA channel to be operated on.
*
* @return
*
* XST_SUCCESS is returned if the self test is successful, or one of the
* following errors.
*                                       <br><br>
* - XST_DMA_RESET_REGISTER_ERROR        Indicates the control register value
*                                       after a reset was not correct
*
* @note
*
* This test does not performs a DMA transfer to test the channel because the
* DMA hardware will not currently allow a non-local memory transfer to non-local
* memory (memory copy), but only allows a non-local memory to or from the device
* memory (typically a FIFO).
*
******************************************************************************/

#define XDC_CONTROL_REG_RESET_MASK  0x98000000UL /* control reg reset value */

XStatus XDmaChannel_SelfTest(XDmaChannel *InstancePtr)
{
    Xuint32 ControlReg;

    /* assert to verify input arguments */

    XASSERT_NONVOID(InstancePtr != XNULL);
    XASSERT_NONVOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);

    /* reset the DMA channel such that it's in a known state before the test
     * it resets to no interrupts enabled, the desired state for the test
     */
    XDmaChannel_Reset(InstancePtr);

    /* this should be the first test to help prevent a lock up with the polling
     * loop that occurs later in the test, check the reset value of the DMA
     * control register to make sure it's correct, return with an error if not
     */
    ControlReg = XDmaChannel_GetControl(InstancePtr);
    if (ControlReg != XDC_CONTROL_REG_RESET_MASK)
    {
        return XST_DMA_RESET_REGISTER_ERROR;
    }

    return XST_SUCCESS;
}

/*****************************************************************************/
/**
*
* This function resets the DMA channel. This is a destructive operation such
* that it should not be done while a channel is being used.  If the DMA channel
* is transferring data into other blocks, such as a FIFO, it may be necessary
* to reset other blocks.  This function does not modify the contents of a
* scatter gather list for a DMA channel such that the user is responsible for
* getting buffer descriptors from the list if necessary.
*
* @param
*
* InstancePtr contains a pointer to the DMA channel to operate on.
*
* @return
*
* None.
*
* @note
*
* None.
*
******************************************************************************/
void XDmaChannel_Reset(XDmaChannel *InstancePtr)
{
    /* assert to verify input arguments */

    XASSERT_VOID(InstancePtr != XNULL);
    XASSERT_VOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);

    /* reset the DMA channel such that it's in a known state, the reset
     * register is self clearing such that it only has to be set
     */
    XIo_Out32(InstancePtr->RegBaseAddress + XDC_RST_REG_OFFSET, XDC_RESET_MASK);
}

/*****************************************************************************/
/**
*
* This function gets the control register contents of the DMA channel.
*
* @param
*
* InstancePtr contains a pointer to the DMA channel to operate on.
*
* @return
*
* The control register contents of the DMA channel. One or more of the
* following values may be contained the register.  Each of the values are
* unique bit masks.
*                               <br><br>
* - XDC_DMACR_SOURCE_INCR_MASK  Increment the source address
*                               <br><br>
* - XDC_DMACR_DEST_INCR_MASK    Increment the destination address
*                               <br><br>
* - XDC_DMACR_SOURCE_LOCAL_MASK Local source address
*                               <br><br>
* - XDC_DMACR_DEST_LOCAL_MASK   Local destination address
*                               <br><br>
* - XDC_DMACR_SG_ENABLE_MASK    Scatter gather enable
*                               <br><br>
* - XDC_DMACR_GEN_BD_INTR_MASK  Individual buffer descriptor interrupt
*                               <br><br>
* - XDC_DMACR_LAST_BD_MASK      Last buffer descriptor in a packet
*
* @note
*
* None.
*
******************************************************************************/
Xuint32 XDmaChannel_GetControl(XDmaChannel *InstancePtr)
{
    /* assert to verify input arguments */

    XASSERT_NONVOID(InstancePtr != XNULL);
    XASSERT_NONVOID(InstancePtr->IsReady == XCOMPONENT_IS_READY);

    /* return the contents of the DMA control register */

    return XIo_In32(InstancePtr->RegBaseAddress + XDC_DMAC_REG_OFFSET);
}

/*****************************************************************************/
/**
*
* This function sets the control register of the specified DMA channel.
*
* @param
*
* InstancePtr contains a pointer to the DMA channel to operate on.
*
* @param
*
* Control contains the value to be written to the control register of the DMA
* channel. One or more of the following values may be contained the register.
* Each of the values are unique bit masks such that they may be ORed together
* to enable multiple bits or inverted and ANDed to disable multiple bits.
* - XDC_DMACR_SOURCE_INCR_MASK  Increment the source address
* - XDC_DMACR_DEST_INCR_MASK    Increment the destination address
* - XDC_DMACR_SOURCE_LOCAL_MASK Local source address
* - XDC_DMACR_DEST_LOCAL_MASK   Local destination address