linux mmap从用户空间应用程序访问PCI内存区域

作为我的PCI驱动程序的第一级测试,我希望我可以通过/sys/bus/pci/devices/0000:01:00.0/resource0访问pci_iomap区域
来自我的用户应用程序的文mmap的手册页,我找到的示例程序以及其他帖子似乎表明用户进程访问应该有效.但是有些文章似乎表明mmap调用需要通过ioctl访问器在内核中完成.

我的问题是PCI sysfs资源文件的mmap()应该来自应用程序空间吗？

当我运行我的代码时,mmap返回看起来像有效地址的内容但是当我尝试访问虚拟地址时出现Bus错误.
我相信我的终端设备是一个PCI到Xilinx AXI桥接器,它在FPGA上运行正常,因为我可以通过Windows PCIe实用程序(Win驱动程序)进行R / W操作
我使用的是Linux版本3.12.37的NXP LS1021A ARM7处理器.

谢谢
法案

并不是说我希望任何人调试我的代码,但我正在做的事情最好用代码来解释,所以我也把它包括在内.如果粘贴的代码无法正确显示,我深表歉意.希望它能做到.

我运行下面的代码并得到
root @ ls1021aiot：?#pcimem /sys/bus/pci/devices/0000:01:00.0/resource0 0 w

/sys/bus/pci/devices/0000:01:00.0/resource0已打开.
目标偏移量为0x0,页面大小为4096,映射掩码为0xFFF
mmap(0,4096,0×3,0x1,3,0×0)
mmap(0,0×0)
PCI内存将4096字节区域映射到map_base 0x76fb5000.
PCI内存映射访问0x 76FB5000.
总线错误

/*
 * pcimem.c: Simple program to read/write from/to a pci device from userspace.
 *
 *  Copyright (C) 2010,Bill Farrow (bfarrow@beyondelectronics.us)
 *
 *  Based on the devmem2.c code
 *  Copyright (C) 2000,Jan-Derk Bakker (J.D.Bakker@its.tudelft.nl)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License,or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,* but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not,write to the Free Software
 * Foundation,Inc.,59 Temple Place,Suite 330,Boston,MA  02111-1307  USA
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <signal.h>
#include <fcntl.h>
#include <ctype.h>
#include <termios.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <linux/pci.h>


#define PRINT_ERROR 
    do { 
        fprintf(stderr,"Error at line %d,file %s (%d) [%s]n",
        __LINE__,__FILE__,errno,strerror(errno)); exit(1); 
    } while(0)

#define MAP_SIZE 4096UL
#define MAP_MASK (MAP_SIZE - 1)

int main(int argc,char **argv) {
    int fd; 
    void *map_base,*virt_addr;
    uint32_t read_result,writeval;
    char *filename;
    off_t target;
    int access_type = 'w';

    if(argc < 3) {
        // pcimem /sys/bus/pci/devices/0001:00:07.0/resource0 0x100 w 0x00
        // argv[0]  [1]                                         [2]   [3] [4]
        fprintf(stderr,"nUsage:t%s { sys file } { offset } [ type [ data ] ]n"
                "tsys file: sysfs file for the pci resource to act onn"
                "toffset  : offset into pci memory region to act uponn"
                "ttype    : access operation type : [b]yte,[h]alfword,[w]ordn"
                "tdata    : data to be writtennn",argv[0]);
        exit(1);
    }   
    filename = argv[1];
    target = strtoul(argv[2],0); 

    if(argc > 3)
        access_type = tolower(argv[3][0]);

    if((fd = open(filename,O_RDWR | O_SYNC)) == -1){
        PRINT_ERROR;
    }
    printf("%s opened.n",filename);
    printf("Target offset is 0x%x,page size is %ld map mask is 0x%lXn",(int) target,sysconf(_SC_PAGE_SIZE),MAP_MASK);
    fflush(stdout);

    /* Map one page */
#if 0
    //map_base = mmap(0,MAP_SIZE,PROT_READ | PROT_WRITE,MAP_SHARED,fd,(off_t) (target & ~MAP_MASK));
    //map_base = mmap(0,target & ~MAP_MASK);
#endif
    printf("mmap(%d,%ld,0x%x,%d,0x%x)n",(int) (target & ~MAP_MASK));
    map_base = mmap(0,(target & ~MAP_MASK));
    if(map_base == (void *) -1){
       printf("PCI Memory mapped ERROR.n");
        PRINT_ERROR;
        close(fd);
        return 1;
    }

    printf("mmap(%d,(int) (target & ~MAP_MASK));
    printf("PCI Memory mapped %ld byte region to map_base 0x%08lx.n",(unsigned long) map_base);
    fflush(stdout);

    virt_addr = map_base + (target & MAP_MASK);
    printf("PCI Memory mapped access 0x %08X.n",(uint32_t ) virt_addr);
   switch(access_type) {
        case 'b':
                read_result = *((uint8_t *) virt_addr);
                break;  
        case 'h':
                read_result = *((uint16_t *) virt_addr);
                break;  
        case 'w':
                read_result = *((uint32_t *) virt_addr);
                        printf("READ Value at offset 0x%X (%p): 0x%Xn",virt_addr,read_result);
                break;
        default:
                fprintf(stderr,"Illegal data type '%c'.n",access_type);
                exit(2);
    }
    fflush(stdout);

    if(argc > 4) {
        writeval = strtoul(argv[4],0);
        switch(access_type) {
                case 'b':
                        *((uint8_t *) virt_addr) = writeval;
                        read_result = *((uint8_t *) virt_addr);
                        break;
                case 'h':
                        *((uint16_t *) virt_addr) = writeval;
                        read_result = *((uint16_t *) virt_addr);
                        break;
                case 'w':
                        *((uint32_t *) virt_addr) = writeval;
                        read_result = *((uint32_t *) virt_addr);
                        break;
        }
        printf("Written 0x%X; readback 0x%Xn",writeval,read_result);
        fflush(stdout);
    }

    if(munmap(map_base,MAP_SIZE) == -1) { PRINT_ERROR;}
    close(fd);
    return 0;
}