pcie接口编程案例
时间: 2023-08-14 22:07:28 浏览: 52
下面是一个基本的PCIe接口编程案例,用于读取PCIe设备的配置空间信息:
```c
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/mman.h>
// 定义PCIe设备的基本信息
#define VENDOR_ID 0x1234
#define DEVICE_ID 0x5678
// 定义PCIe设备的配置空间偏移量
#define CONFIG_VENDOR_ID 0x00
#define CONFIG_DEVICE_ID 0x02
#define CONFIG_COMMAND 0x04
#define CONFIG_STATUS 0x06
#define CONFIG_REVISION 0x08
#define CONFIG_CLASS 0x0b
int main(void)
{
int fd;
void *map_base, *virt_addr;
unsigned long read_result, writeval;
off_t target;
unsigned short vendor_id, device_id, command, status, revision, class;
// 打开/dev/mem设备文件,用于访问物理内存
if((fd = open("/dev/mem", O_RDWR | O_SYNC)) == -1) {
printf("Could not open /dev/mem\n");
return -1;
}
// 映射PCIe设备的配置空间
target = 0x12345678; // PCIe设备的地址
map_base = mmap(0, getpagesize(), PROT_READ | PROT_WRITE, MAP_SHARED, fd, target & ~getpagesize());
if(map_base == (void *) -1) {
printf("Could not map memory\n");
return -1;
}
// 计算PCIe设备的配置空间偏移量
virt_addr = map_base + (target & getpagesize());
vendor_id = *((unsigned short *) (virt_addr + CONFIG_VENDOR_ID));
device_id = *((unsigned short *) (virt_addr + CONFIG_DEVICE_ID));
command = *((unsigned short *) (virt_addr + CONFIG_COMMAND));
status = *((unsigned short *) (virt_addr + CONFIG_STATUS));
revision = *((unsigned char *) (virt_addr + CONFIG_REVISION));
class = *((unsigned char *) (virt_addr + CONFIG_CLASS));
// 输出PCIe设备的配置空间信息
printf("Vendor ID: 0x%x\n", vendor_id);
printf("Device ID: 0x%x\n", device_id);
printf("Command: 0x%x\n", command);
printf("Status: 0x%x\n", status);
printf("Revision: 0x%x\n", revision);
printf("Class: 0x%x\n", class);
// 解除PCIe设备的配置空间映射
if(munmap(map_base, getpagesize()) == -1) {
printf("Could not unmap memory\n");
return -1;
}
// 关闭/dev/mem设备文件
close(fd);
return 0;
}
```
该程序通过打开/dev/mem设备文件,映射PCIe设备的配置空间,读取设备的基本信息,并输出到终端。程序中需要根据实际情况修改PCIe设备的地址、设备ID和配置空间偏移量等参数。同时需要注意权限和安全问题,防止程序对系统造成不可逆的损害。