ZYNQ linux下AXI_BRAM的使用方法，PS与PL端数据交互

1、AXI总线、AXI接口、AXI协议
总线是一组传输通道，是各种逻辑器件构成的传输数据的通道；接口是一种连接标准，又常被称为物理接口；协议是数据传输的规则。

PS与PL连接方式主要是通过AXI总线进行的。ZYNQ上的总线协议有AXI4, AXI4-Lite, AXI4-Stream三种总线协议。而PS与PL之间的接口（AXI-GP、AXI-HP、AXI-ACP）只支持AXI4与AXI4-Lite这两种总线协议。

2、BRAM简介
Block RAM是PL部分的存储器阵列，就相当于在PL中开辟一片空间来存储数据，通过端口来进行读写。
BRAM设置模式：
1、单端口：通过一个端口对BRAM进行读写。
2、简单双端口：有两个端口连接到BRAM，一个端口只读，一个端口只写
3、真双端口：两个端口都可以对BRAM进行读写。

3、vivado设计
前提：创建好了工程并导入了ZYNQ核

打开AXI GP0 和 AXI GP1的接口

将M_AXI_GP0_ACLK连接到FCLK_CLK0

导入两个BRAM 控制器

设置为单端口

导入一个BRAM

设置为真双端口模式

进行设计连接

进行1的时候需要修改主机从GP0 改为GP1

最终的生成图

可以在address editor中查看自动分配的BRAM控制器的地址，不要随意更改地址，因为其他地址可能被其他设备占用了。
axi_bram_ctrl_0 0x40000000
axi_bram_ctrl_1 0x80000000

接下来生成bit流，将硬件资源导入petlainux中，生成BOOT.BIN 和image.ub

将生成的BOOT.BIN和内核放到板子上，启动系统。

进行编程：

#include 
#include 
#include 
#include 
#include 
#include 

#define BRAM_CTRL_0 0x40000000
#define BRAM_CTRL_1 0x80000000
#define DATA_LEN    10

int main(int argc, char **argv)
{
    unsigned int *map_base0;
    unsigned int *map_base1;

    int fd = open("/dev/mem", O_RDWR | O_SYNC);
    if (fd < 0) {
        printf("can not open /dev/mem \n");
        return (-1);
    }   
    printf("/dev/mem is open \n");

    map_base0 = mmap(NULL, DATA_LEN * 4, PROT_READ | PROT_WRITE, MAP_SHARED, fd, BRAM_CTRL_0);
    map_base1 = mmap(NULL, DATA_LEN * 4, PROT_READ | PROT_WRITE, MAP_SHARED, fd, BRAM_CTRL_1);
    if (map_base0 == 0 || map_base1 == 0 ) { 
        printf("NULL pointer\n");
    }   
    else {
        printf("mmap successful\n");
    }   

    unsigned long addr;
    unsigned int content;
    int i = 0;

    printf("\nwrite data to bram\n");
    for (i = 0; i < DATA_LEN; i++) {
        addr = (unsigned long)(map_base0 + i); 
        content = i + 2;
        map_base0[i] = content;
        printf("%2dth data, address: 0x%lx data_write: 0x%x\t\t\n", i, addr, content);

    }   

    printf("\nread data from bram\n");
    for (i = 0; i< DATA_LEN; i++) {
        addr = (unsigned long)(map_base1 + i); 
        content = map_base1[i];
        printf("%2dth data, address: 0x%lx data_read: 0x%x\t\t\n", i, addr, content);
    }   

    close(fd);
    munmap(map_base0, DATA_LEN);
       munmap(map_base1, DATA_LEN);

    return 0;
}

运行效果

也可以将BRAM与socket进行联合使用，将PC端的数据发到PS端，PS端放在PL端，PL端再发给PS端，PS端发回PC端。

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#define PORT 3333

#define BRAM_CTRL0 0x40000000
#define BRAM_CTRL1 0x80000000
#define DATA_LEN   100

unsigned int *map_base0;
unsigned int *map_base1;


void udp_server(int sockfd)
{
    
    socklen_t len;

    struct sockaddr_in server_addr;
    int n;
    int opt = 1;

    
    len = sizeof(server_addr);
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    server_addr.sin_port = htons(PORT);

    setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));

    if (bind(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
        printf("can not bind\n");
        exit(1);
    }   
    
    while (1) {
        printf("\n========wait for client's request========\n");
        n = recvfrom(sockfd, map_base0, 1024, 0, (struct sockaddr *)&server_addr, &len);
        char buf[1024];
        memcpy(buf, map_base0, 1024);
        printf("\nreceive client's data: %s\n", buf);
        sendto(sockfd, map_base0, n, 0, (struct sockaddr *)&server_addr, len);
        memcpy(buf, map_base1, 1024);
        printf("\nsend data to client: %s\n", buf);
    }

    close(sockfd);
}

int main(int argc, char **argv)
{
    int sockfd, devfd;

    if ((sockfd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) {
        printf("create socket false\n");
        exit(1);
    }
    if ((devfd = open("/dev/mem", O_RDWR | O_SYNC)) < 0) {
        printf("can not open /dev/mem \n");
        return (-1);
    }
    printf("\nopen /dev/mem successful\n");

    map_base0 = mmap(NULL, DATA_LEN * 4, PROT_READ | PROT_WRITE, MAP_SHARED, devfd, BRAM_CTRL0);
    map_base1 = mmap(NULL, DATA_LEN * 4, PROT_READ | PROT_WRITE, MAP_SHARED, devfd, BRAM_CTRL1);
    if (map_base0 ==0 || map_base1 == 0) {
        printf("NULL pointer \n");
    }
    else {
        printf("mmap successful\n");
    }

    udp_server(sockfd);

    exit(0);
}

最终实现相关效果