ZYNQ基礎(chǔ)---AXI DMA使用

前言

在ZYNQ中進(jìn)行PL-PS數(shù)據(jù)交互的時候，經(jīng)常會使用到DMA，其實在前面的ZYNQ學(xué)習(xí)當(dāng)中，也有學(xué)習(xí)過DMA的使用，那就是通過使用自定義的IP，完成HP接口向內(nèi)存寫入和讀取數(shù)據(jù)的方式。同樣Xilinx官方也提供有一些DMA的IP，通過調(diào)用API函數(shù)能夠更加靈活地使用DMA。

1. AXI DMA的基本接口

axi dma IP的基本結(jié)構(gòu)如下，主要分為三個部分，分別是控制axi dma寄存器通道，從ddr讀出數(shù)據(jù)通道和向ddr寫入數(shù)據(jù)通道。其IP結(jié)構(gòu)的兩邊分別對應(yīng)著用于訪問內(nèi)存的AXI總線和用于用戶簡單操作的axis stream總線。axi stream總線相較于axi總線來說要簡單很多，它沒有地址，靠主機(jī)和從機(jī)之間進(jìn)行握手來傳遞數(shù)據(jù)。

2 Block design搭建

做一個簡單的例子來測試一下axi dma。先自定義一個IP，用于緩存從zynq通過axi dma發(fā)來的數(shù)據(jù)，一次突發(fā)傳輸結(jié)束之后，將接收到的數(shù)據(jù)寫回到內(nèi)存中。

2.1 自定義一個IP

時序設(shè)計如下，將接收到的數(shù)據(jù)緩存到FIFO中，當(dāng)zynq一次axi stream 傳輸結(jié)束的時候，開始將數(shù)據(jù)從FIFO中讀出，并將數(shù)據(jù)寫入到內(nèi)存中。

module dma_loop(

//====================================================

//clock and reset

//====================================================

input wire axis_clk ,

input wire rst_n ,

//====================================================

//input axis port

//====================================================

input wire [7:0] axis_in_tdata ,

input wire axis_in_tvalid ,

output wire axis_in_tready ,

input wire axis_in_tlast ,

//====================================================

//output axis port

//====================================================

output wire [7:0] axis_out_tdata ,

output reg axis_out_tvalid ,

input wire axis_out_tready ,

output wire axis_out_tlast

);

//====================================================

//input axis port

//====================================================

wire wr_fifo_en ;

wire rd_fifo_en ;

wire full,empty ;

reg rd_start ;

reg [9:0] cnt_data_in ;

wire add_cnt_data_in ;

wire end_cnt_data_in ;

reg [9:0] data_len ;

reg [9:0] cnt_data_out ;

wire add_cnt_data_out;

wire end_cnt_data_out;

assign wr_fifo_en = axis_in_tvalid & axis_in_tready;

assign axis_in_tready = ~full;

always @(posedge axis_clk or negedge rst_n) begin

if (rst_n==1'b0) begin

rd_start <= 1'b0;

end

else if (axis_in_tvalid & axis_in_tready & axis_in_tlast) begin

rd_start <= 1'b1;

end

else begin

rd_start <= 1'b0;

end

end

//----------------cnt_data------------------

always @(posedge axis_clk or negedge rst_n) begin

if (rst_n == 1'b0) begin

cnt_data_in <= 'd0;

end

else if (add_cnt_data_in) begin

if(end_cnt_data_in)

cnt_data_in <= 'd0;

else

cnt_data_in <= cnt_data_in + 1'b1;

end

end

assign add_cnt_data_in = axis_in_tvalid & axis_in_tready;

assign end_cnt_data_in = add_cnt_data_in && axis_in_tlast;

//----------------data_len------------------

always @(posedge axis_clk or negedge rst_n) begin

if (rst_n==1'b0) begin

data_len <= 'd0;

end

else if (end_cnt_data_in) begin

data_len <= cnt_data_in + 1'b1;

end

end

sfifo_wr1024x8_rd1024x8 inst_sfifo (

.clk(axis_clk), // input wire clk

.din(axis_in_tdata), // input wire [7 : 0] din

.wr_en(wr_fifo_en), // input wire wr_en

.rd_en(rd_fifo_en), // input wire rd_en

.dout(axis_out_tdata), // output wire [7 : 0] dout

.full(full), // output wire full

.empty(empty) // output wire empty

);

//----------------axis_out_tvalid------------------

always @(posedge axis_clk or negedge rst_n) begin

if (rst_n==1'b0) begin

axis_out_tvalid <= 1'b0;

end

else if (end_cnt_data_out) begin

axis_out_tvalid <= 1'b0;

end

else if (rd_start == 1'b1) begin

axis_out_tvalid <= 1'b1;

end

end

//----------------cnt_data_out------------------

always @(posedge axis_clk or negedge rst_n) begin

if (rst_n == 1'b0) begin

cnt_data_out <= 'd0;

end

else if (add_cnt_data_out) begin

if(end_cnt_data_out)

cnt_data_out <= 'd0;

else

cnt_data_out <= cnt_data_out + 1'b1;

end

end

assign add_cnt_data_out = axis_out_tvalid & axis_out_tready;

assign end_cnt_data_out = add_cnt_data_out && cnt_data_out == data_len - 1;

assign axis_out_tlast = end_cnt_data_out;

assign rd_fifo_en = axis_out_tvalid & axis_out_tready;

wire [63:0] probe0;

assign probe0 = {

cnt_data_in ,

cnt_data_out ,

rd_start ,

data_len ,

axis_in_tdata ,

axis_in_tvalid ,

axis_in_tready ,

axis_in_tlast ,

axis_out_tdata ,

axis_out_tvalid ,

axis_out_tready ,

axis_out_tlast

};

ila_0 inst_ila (

.clk(axis_clk), // input wire clk

.probe0(probe0) // input wire [63:0] probe0

);

endmodule

搭建block design

3. vitis

xilinx的東西就有這點優(yōu)點，基本上fpga里面有的資源，都有一個示例工程，把它導(dǎo)入進(jìn)來就可以參考一下具體這個外設(shè)改怎么來使用了。這個demo里面使用到了串口。串口在前面的串口中斷中已經(jīng)使用到，本次實驗需要使用到串口的中斷和DMA的中斷。

PC的串口向FPGA發(fā)送數(shù)據(jù)，一幀數(shù)據(jù)發(fā)送完成之后，會觸發(fā)串口的中斷。串口中斷函數(shù)會接收數(shù)據(jù)，并且記錄數(shù)據(jù)長度。然后將通過DMA將數(shù)據(jù)寫入到自定義的IP當(dāng)中，自定義IP接收完數(shù)據(jù)之后，將把數(shù)據(jù)寫回到內(nèi)存中。

#include

#include "platform.h"

#include "xil_printf.h"

#include "xparameters.h"

#include "xaxidma.h"

#include "xuartps.h"

#include "xscugic.h"

#include "sleep.h"

#define GIC_DEVICE_IDXPAR_PS7_SCUGIC_0_DEVICE_ID

#define UART_DEV_ID XPAR_PS7_UART_1_DEVICE_ID

#define DMA_DEVICE_ID XPAR_AXI_DMA_0_DEVICE_ID

#define UART_INTR_ID XPAR_PS7_UART_1_INTR

#define MM2S_INTR_ID XPAR_FABRIC_AXIDMA_0_MM2S_INTROUT_VEC_ID

#define S2MM_INTR_ID XPAR_FABRIC_AXIDMA_0_S2MM_INTROUT_VEC_ID

XUartPs UartInst;

XScuGic GicInst;

XAxiDma DmaInst;

volatile int TxDone;

volatile int RxDone;

volatile int Error;

u32 UartRxLen = 0;

int UartRxFlag = 0;

u8 * UartRxBuf = (u8 *)(0x2000000);

u8 * UartTxBuf = (u8 *)(0x4000000);

/***********************************

* Uart Init function

**********************************/

int Uart_Init();

/********************************

* DMA initialize function

********************************/

int Dma_Init();

int Setup_Interrupt_System();

void Uart_Intr_Handler(void *CallBackRef, u32 Event, unsigned int EventData);

void Mm2s_Intr_Handler();

void S2mm_Intr_Handler();

int main()

{

init_platform();

Uart_Init();

Dma_Init();

Setup_Interrupt_System();

while(1)

{

/*****************************************************************************

* Uart has receive one frame

*****************************************************************************/

if (UartRxFlag == 1) {

// clear the flag

UartRxFlag = 0;

/*****************************************************************************

* Transfer data from axidma to device

*****************************************************************************/

Xil_DCacheFlushRange((INTPTR)UartRxBuf, UartRxLen);//flush data into ddr

usleep(2);

// transfer data from axi dma to device

XAxiDma_SimpleTransfer(&DmaInst, (UINTPTR)UartRxBuf, UartRxLen, XAXIDMA_DMA_TO_DEVICE);

while(!TxDone);

TxDone=0;//reset txdone flag; complete txtransfer

/*****************************************************************************

* Transfer data from device to dma

*****************************************************************************/

Xil_DCacheInvalidateRange((INTPTR)UartTxBuf, UartRxLen);

usleep(2);

XAxiDma_SimpleTransfer(&DmaInst, (UINTPTR)UartTxBuf, UartRxLen, XAXIDMA_DEVICE_TO_DMA);

while(!RxDone);

RxDone = 0;

XUartPs_Send(&UartInst, UartTxBuf, UartRxLen);

XUartPs_Recv(&UartInst, UartRxBuf, 4096);//reset conter and start recv from uart

}

}

cleanup_platform();

return 0;

}

/*****************************************************************************

* @ function : init uart and set the callback fuction

*****************************************************************************/

int Uart_Init()

{

int Status;

u32 IntrMask;

XUartPs_Config *UartCfgPtr;

UartCfgPtr = XUartPs_LookupConfig(UART_DEV_ID);

Status = XUartPs_CfgInitialize(&UartInst, UartCfgPtr, UartCfgPtr->BaseAddress);

if(Status != XST_SUCCESS)

{

printf("initialize UART failed ");

return XST_FAILURE;

}

/****************************************

* Set uart interrput mask

****************************************/

IntrMask =

XUARTPS_IXR_TOUT | XUARTPS_IXR_PARITY | XUARTPS_IXR_FRAMING |

XUARTPS_IXR_OVER | XUARTPS_IXR_TXEMPTY | XUARTPS_IXR_RXFULL |

XUARTPS_IXR_RXOVR;

XUartPs_SetInterruptMask(&UartInst, IntrMask);

/*****************************************************************************

* Set Uart interrput callback function

*****************************************************************************/

XUartPs_SetHandler(&UartInst, (XUartPs_Handler)Uart_Intr_Handler, &UartInst);

/*****************************************************************************

* Set Uart baud rate

*****************************************************************************/

XUartPs_SetBaudRate(&UartInst, 115200);

/*****************************************************************************

* Set Uart opertion mode

*****************************************************************************/

XUartPs_SetOperMode(&UartInst, XUARTPS_OPER_MODE_NORMAL);

/*****************************************************************************

* Set Uart Receive timeout

*****************************************************************************/

XUartPs_SetRecvTimeout(&UartInst, 8);

/*****************************************************************************

* Start to listen

*****************************************************************************/

XUartPs_Recv(&UartInst, UartRxBuf, 4096);

return Status;

}

void Uart_Intr_Handler(void *CallBackRef, u32 Event, unsigned int EventData)

{

if (Event == XUARTPS_EVENT_RECV_TOUT) {

if(EventData == 0)

{

XUartPs_Recv(&UartInst, UartRxBuf, 4096);

}

else if(EventData > 0) {

UartRxLen = EventData;

UartRxFlag = 1;

}

}

}

/*****************************************************************************

* @ function : init Axi DMA

*****************************************************************************/

int Dma_Init()

{

int Status;

XAxiDma_Config * DmaCfgPtr;

DmaCfgPtr = XAxiDma_LookupConfig(DMA_DEVICE_ID);

Status = XAxiDma_CfgInitialize(&DmaInst, DmaCfgPtr);

if(Status != XST_SUCCESS)

{

printf("initialize AXI DMA failed ");

return XST_FAILURE;

}

/*****************************************************************************

* Disable all the interrupt before setup

*****************************************************************************/

XAxiDma_IntrDisable(&DmaInst, XAXIDMA_IRQ_ALL_MASK, XAXIDMA_DEVICE_TO_DMA);

XAxiDma_IntrDisable(&DmaInst, XAXIDMA_IRQ_ALL_MASK, XAXIDMA_DMA_TO_DEVICE);

/*****************************************************************************

*Enable all the interrput

*****************************************************************************/

XAxiDma_IntrEnable(&DmaInst, XAXIDMA_IRQ_ALL_MASK, XAXIDMA_DEVICE_TO_DMA);

XAxiDma_IntrEnable(&DmaInst, XAXIDMA_IRQ_ALL_MASK, XAXIDMA_DMA_TO_DEVICE);

return Status;

}

/*****************************************************************************/

/*

*

* This is the DMA TX Interrupt handler function.

*

* It gets the interrupt status from the hardware, acknowledges it, and if any

* error happens, it resets the hardware. Otherwise, if a completion interrupt

* is present, then sets the TxDone.flag

*

* @paramCallback is a pointer to TX channel of the DMA engine.

*

* @returnNone.

*

* @noteNone.

*

******************************************************************************/

void Mm2s_Intr_Handler(void *Callback)

{

u32 IrqStatus;

int TimeOut;

XAxiDma *AxiDmaInst = (XAxiDma *)Callback;

/* Read pending interrupts */

IrqStatus = XAxiDma_IntrGetIrq(AxiDmaInst, XAXIDMA_DMA_TO_DEVICE);

/* Acknowledge pending interrupts */

XAxiDma_IntrAckIrq(AxiDmaInst, IrqStatus, XAXIDMA_DMA_TO_DEVICE);

/*

* If no interrupt is asserted, we do not do anything

*/

if (!(IrqStatus & XAXIDMA_IRQ_ALL_MASK)) {

return;

}

/*

* If error interrupt is asserted, raise error flag, reset the

* hardware to recover from the error, and return with no further

* processing.

*/

if ((IrqStatus & XAXIDMA_IRQ_ERROR_MASK)) {

Error = 1;

/*

* Reset should never fail for transmit channel

*/

XAxiDma_Reset(AxiDmaInst);

TimeOut = 10000;

while (TimeOut) {

if (XAxiDma_ResetIsDone(AxiDmaInst)) {

break;

}

TimeOut -= 1;

}

return;

}

/*

* If Completion interrupt is asserted, then set the TxDone flag

*/

if ((IrqStatus & XAXIDMA_IRQ_IOC_MASK)) {

TxDone = 1;

}

}

/*****************************************************************************/

/*

*

* This is the DMA RX interrupt handler function

*

* It gets the interrupt status from the hardware, acknowledges it, and if any

* error happens, it resets the hardware. Otherwise, if a completion interrupt

* is present, then it sets the RxDone flag.

*

* @paramCallback is a pointer to RX channel of the DMA engine.

*

* @returnNone.

*

* @noteNone.

*

******************************************************************************/

void S2mm_Intr_Handler(void *Callback)

{

u32 IrqStatus;

int TimeOut;

XAxiDma *AxiDmaInst = (XAxiDma *)Callback;

/* Read pending interrupts */

IrqStatus = XAxiDma_IntrGetIrq(AxiDmaInst, XAXIDMA_DEVICE_TO_DMA);

/* Acknowledge pending interrupts */

XAxiDma_IntrAckIrq(AxiDmaInst, IrqStatus, XAXIDMA_DEVICE_TO_DMA);

/*

* If no interrupt is asserted, we do not do anything

*/

if (!(IrqStatus & XAXIDMA_IRQ_ALL_MASK)) {

return;

}

/*

* If error interrupt is asserted, raise error flag, reset the

* hardware to recover from the error, and return with no further

* processing.

*/

if ((IrqStatus & XAXIDMA_IRQ_ERROR_MASK)) {

Error = 1;

/* Reset could fail and hang

* NEED a way to handle this or do not call it??

*/

XAxiDma_Reset(AxiDmaInst);

TimeOut = 10000;

while (TimeOut) {

if(XAxiDma_ResetIsDone(AxiDmaInst)) {

break;

}

TimeOut -= 1;

}

return;

}

/*

* If completion interrupt is asserted, then set RxDone flag

*/

if ((IrqStatus & XAXIDMA_IRQ_IOC_MASK)) {

RxDone = 1;

}

}

/*****************************************************************************

* @ function : Set up the interrupt system

*****************************************************************************/

int Setup_Interrupt_System()

{

int Status;

XScuGic_Config * GicCfgPtr;

GicCfgPtr = XScuGic_LookupConfig(GIC_DEVICE_ID);

Status = XScuGic_CfgInitialize(&GicInst, GicCfgPtr, GicCfgPtr->CpuBaseAddress);

if(Status != XST_SUCCESS)

{

printf("initialize GIC failed ");

return XST_FAILURE;

}

/*****************************************************************************

* initialize exception system

*****************************************************************************/

Xil_ExceptionInit();

/*****************************************************************************

* register interrput type exception

*****************************************************************************/

Xil_ExceptionRegisterHandler(XIL_EXCEPTION_ID_INT,(Xil_ExceptionHandler)XScuGic_InterruptHandler, &GicInst);

/*****************************************************************************

* connect interrput to scugic controller

*****************************************************************************/

Status = XScuGic_Connect(&GicInst, UART_INTR_ID, (Xil_ExceptionHandler) XUartPs_InterruptHandler, &UartInst);

if(Status != XST_SUCCESS)

{

printf("Connect Uart interrput to GIC failed ");

return XST_FAILURE;

}

Status = XScuGic_Connect(&GicInst, MM2S_INTR_ID, (Xil_ExceptionHandler) Mm2s_Intr_Handler, &DmaInst);

if(Status != XST_SUCCESS)

{

printf("Connect DMA tx interrput to GIC failed ");

return XST_FAILURE;

}

Status = XScuGic_Connect(&GicInst, S2MM_INTR_ID, (Xil_ExceptionHandler) S2mm_Intr_Handler, &DmaInst);

if(Status != XST_SUCCESS)

{

printf("Connect DMA tx interrput to GIC failed ");

return XST_FAILURE;

}

/*****************************************************************************

* Enable the interrput

*****************************************************************************/

XScuGic_Enable(&GicInst, UART_INTR_ID);

XScuGic_Enable(&GicInst, S2MM_INTR_ID);

XScuGic_Enable(&GicInst, MM2S_INTR_ID);

/*****************************************************************************

* Enable the exception system

*****************************************************************************/

Xil_ExceptionEnable();

return Status;

}

測試結(jié)果

從串口發(fā)出的數(shù)據(jù)被成功的接收。再看看ila抓取到的波形。

輸入到自定義IP的數(shù)據(jù)：

從自定義IP輸出的數(shù)據(jù)。一次傳輸之間隔了較長的時間。

原文鏈接：

https://openatomworkshop.csdn.net/67401f383a01316874d6e783.html