ZYNQ基础---AXI DMA使用

前言

在ZYNQ中进行PL-PS数据交互的时候，经常会使用到DMA，其实在前面的ZYNQ学习当中，也有学习过DMA的使用，那就是通过使用自定义的IP，完成HP接口向内存写入和读取数据的方式。同样Xilinx官方也提供有一些DMA的IP，通过调用API函数能够更加灵活地使用DMA。

1. AXI DMA的基本接口

axi dma IP的基本结构如下，主要分为三个部分，分别是控制axi dma寄存器通道，从ddr读出数据通道和向ddr写入数据通道。其IP结构的两边分别对应着用于访问内存的AXI总线和用于用户简单操作的axis stream总线。axi stream总线相较于axi总线来说要简单很多，它没有地址，靠主机和从机之间进行握手来传递数据。

2 Block design搭建

做一个简单的例子来测试一下axi dma。先自定义一个IP，用于缓存从zynq通过axi dma发来的数据，一次突发传输结束之后，将接收到的数据写回到内存中。

2.1 自定义一个IP

时序设计如下，将接收到的数据缓存到FIFO中，当zynq一次axi stream 传输结束的时候，开始将数据从FIFO中读出，并将数据写入到内存中。

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) beginif (rst_n==1'b0) beginrd_start <= 1'b0;endelse if (axis_in_tvalid & axis_in_tready & axis_in_tlast) beginrd_start <= 1'b1;endelse beginrd_start <= 1'b0;endend//----------------cnt_data------------------always @(posedge axis_clk or negedge rst_n) beginif (rst_n == 1'b0) begincnt_data_in <= 'd0;endelse if (add_cnt_data_in) beginif(end_cnt_data_in)cnt_data_in <= 'd0;elsecnt_data_in <= cnt_data_in + 1'b1;endendassign 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) beginif (rst_n==1'b0) begindata_len <= 'd0;endelse if (end_cnt_data_in) begindata_len <= cnt_data_in + 1'b1;endendsfifo_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) beginif (rst_n==1'b0) beginaxis_out_tvalid <= 1'b0;endelse if (end_cnt_data_out) beginaxis_out_tvalid <= 1'b0;endelse if (rd_start == 1'b1) beginaxis_out_tvalid <= 1'b1;endend//----------------cnt_data_out------------------always @(posedge axis_clk or negedge rst_n) beginif (rst_n == 1'b0) begincnt_data_out <= 'd0;endelse if (add_cnt_data_out) beginif(end_cnt_data_out)cnt_data_out <= 'd0;elsecnt_data_out <= cnt_data_out + 1'b1;endendassign 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的东西就有这点优点，基本上fpga里面有的资源，都有一个示例工程，把它导入进来就可以参考一下具体这个外设改怎么来使用了。这个demo里面使用到了串口。串口在前面的串口中断中已经使用到，本次实验需要使用到串口的中断和DMA的中断。

PC的串口向FPGA发送数据，一帧数据发送完成之后，会触发串口的中断。串口中断函数会接收数据，并且记录数据长度。然后将通过DMA将数据写入到自定义的IP当中，自定义IP接收完数据之后，将把数据写回到内存中。

#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_ID	XPAR_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_IDXUartPs 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\n"); 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\n"); 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** @param	Callback is a pointer to TX channel of the DMA engine.** @return	None.** @note		None.*******************************************************************************/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.** @param	Callback is a pointer to RX channel of the DMA engine.** @return	None.** @note		None.*******************************************************************************/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\n"); 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\n"); 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\n"); 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\n"); 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;}