wiki:Component/VciDma

Version 5 (modified by wahid, 16 years ago) (diff)

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SocLib Components General Index

VciDma Functional Description

This VCI component is both a target and an initiator.

  • Addressing as a target allows to configure it for a transfer.
  • Initiator will do the transfer

There is only one DMA context handled at a time

An IRQ is optionally asserted when transfer is finished.

This hardware component cheks for segmentation violation, and can be used as a default target.

Memory region layout

  • DMA_SRC

The source of memory copy.

  • DMA_DST

The destination of memory copy

  • DMA_LEN

Length of transfer, in bytes. Writing to this register initiates the transfer, you should write to it after src and dst. This register gets back to 0 when transfer is finished.

  • DMA_IRQ_ENABLED
    • Written to: A boolean enabling the IRQ line (0 is disabling)
    • Read from: A boolean indicating the completion of the transfer, (0 is completed)

Component usage

For extensibility issues, you should access the DMA using globally-defined offsets.

You should include file source:trunk/soclib/soclib/module/infrastructure_component/dma_infrastructure/vci_dma/include/dma.h from your software, it defines DMA_SRC, DMA_DST, DMA_LEN, DMA_IRQ_ENABLED.

Sample code: 

#include "soclib/dma.h"

static const volatile void* dma = 0xc0000000;

void * memcpy(void *dst, const void *src, const size_t len)
{
    soclib_io_set( dma, DMA_DST, dst );
    soclib_io_set( dma, DMA_SRC, src );
    soclib_io_set( dma, DMA_LEN, len );
    while( soclib_io_get( dma, DMA_LEN ) )
        ;
    return dst;
}

(add -I/path/to/soclib/include to your compilation command-line)

Component definition

Available in source:trunk/soclib/soclib/module/infrastructure_component/dma_infrastructure/vci_dma/caba/metadata/vci_dma.sd​

Usage

VciDma has no other parameter than VCI ones, it may be used like others, see SoclibCc/VciParameters 

Uses( 'vci_dma', **vci_parameters )

VciDma CABA Implementation

The caba implementation is in

Template parameters:

  • The VCI parameters

Constructor parameters

VciDma(
     sc_module_name name,   //  Component Name
     const soclib::common::IntTab & index,  // Target index
     const soclib::common::MappingTable &mt,   // MappingTable
     const size_t burst_size );   //  Number of bytes transfered in a burst

Ports

  • sc_in<bool> p_resetn : Global system reset
  • sc_in<bool> p_clk : Global system clock
  • soclib::caba::VciTarget<vci_param> p_vci_target : The VCI target port
  • soclib::caba::VciInitiator<vci_param> p_vci_initiator : The VCI initiator port
  • sc_out<bool> p_irq : Interrupt port