Zynq-Linux移植学习笔记之15-用户APP直接访问PL物理地址

1、  背景介绍

在zynq中，由于有PL部分的存在，操作系统需要对PL部分的物理地址进行操作，也就是对操作相关IP核的寄存器。除了在驱动中进行映射外（参看前一篇文章点击打开链接），也可以直接在用户态进行地址映射访问。

 

2、  IO接口头文件

如果做过裸奔的应用程序，可以看到用户app最终调用的接口无非是下面以下这一类函数：

u8 Xil_In8(INTPTR Addr);u16 Xil_In16(INTPTR Addr);u32 Xil_In32(INTPTR Addr);void Xil_Out8(INTPTR Addr, u8 Value);void Xil_Out16(INTPTR Addr, u16 Value);void Xil_Out32(INTPTR Addr, u32 Value);u16 Xil_In16BE(INTPTR Addr);u32 Xil_In32BE(INTPTR Addr);void Xil_Out16BE(INTPTR Addr, u16 Value);void Xil_Out32BE(INTPTR Addr, u32 Value);

在访问物理地址方面，没有比这一类函数更底层的了。当在linux下对这一类函数加以实现，用户app便可直接访问PL部分物理地址。实现这一类函数需要进行物理映射，不过由于不是驱动，这种映射可以直接放在应用层实现。

下面是xil_in32()和xil_out32()的具体实现，映射时只需要对/dev/mem映射即可。

#include <stdio.h>#include <stdlib.h>#include <stdint.h>#include <string.h>#include <sys/types.h>#include <sys/stat.h>#include <sys/mman.h>#include <unistd.h>#include <fcntl.h>#define PAGE_SIZE  ((size_t)getpagesize())#define PAGE_MASK ((uint64_t) (long)~(PAGE_SIZE - 1))void Xil_Out32(uint64_t phyaddr, uint32_t val){int fd;volatile uint8_t *map_base;uint64_t base = phyaddr & PAGE_MASK;uint64_t pgoffset = phyaddr & (~PAGE_MASK);if((fd = open("/dev/mem", O_RDWR | O_SYNC)) == -1){perror("open /dev/mem:");}map_base = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED,fd, base);if(map_base == MAP_FAILED){perror("mmap:");}*(volatile uint32_t *)(map_base + pgoffset) = val; close(fd);munmap((void *)map_base, PAGE_SIZE);}int Xil_In32(uint64_t phyaddr){int fd;uint32_t val;volatile uint8_t *map_base;uint64_t base = phyaddr & PAGE_MASK;uint64_t pgoffset = phyaddr & (~PAGE_MASK);//open /dev/memif((fd = open("/dev/mem", O_RDWR | O_SYNC)) == -1){perror("open /dev/mem:");}//mmapmap_base = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED,fd, base);if(map_base == MAP_FAILED){perror("mmap:");}val = *(volatile uint32_t *)(map_base + pgoffset);close(fd);munmap((void *)map_base, PAGE_SIZE);return val;}

 

 

3、  应用层实现

应用层中只需要指定起始物理地址，然后调用xil_in32()和xil_out32()进行操作，为了调用方便，可以封装一层。

 

#ifndef SMARTCARMOVE_H#define SMARTCARMOVE_H#include <stdio.h>#include <fcntl.h>#include <unistd.h>#include <string.h>#include <sys/time.h>#include <sys/stat.h>#include <sys/types.h>#include <syslog.h>#include <memory.h>#include "move.h"static int fd;#define MODE (O_WRONLY | O_TRUNC)/*static char *gpio_addr[] = {"/sys/class/gpio/export","/sys/class/gpio/gpio61/direction/","/sys/class/gpio/gpio61/value/","/sys/class/gpio/gpio62/direction/","/sys/class/gpio/gpio62/value/","/sys/class/gpio/gpio63/direction/","/sys/class/gpio/gpio63/value/","/sys/class/gpio/gpio64/direction/","/sys/class/gpio/gpio64/value/"};*/extern void rio_setreg32(unsigned int addrBase,unsigned int addrOffset,unsigned int value);extern int rio_getreg32(unsigned int addrBase,unsigned int addrOffset);extern int hlMaintWrite(unsigned int dstId,unsigned short hopcount, unsigned int offset, unsigned int writedata);extern int hlMaintRead(unsigned int dstId,unsigned short hopcount, unsigned int offset, int mrdataAdr);#endif

 

#include "xil_io.h"#include "move.h"#define AXI_RIO_BASEADDR 0x40000000#define AXI_RIO_NODE_BASEADDR0x10100#define AXI_RIO_MAX_HOPCOUNT13/**read and write phy mem * */void rio_setreg32(unsigned int addrBase,unsigned int addrOffset,unsigned int value){Xil_Out32(addrBase+addrOffset, value);}int rio_getreg32(unsigned int addrBase,unsigned int addrOffset){int ans=0;ans=Xil_In32(addrBase+addrOffset);return ans;}int hlMaintWrite(unsigned int dstId,unsigned short hopcount, unsigned int offset, unsigned int writedata){unsigned int reg_addr;if( hopcount > AXI_RIO_MAX_HOPCOUNT ){printf("!!!error, hopcount = %d,  > %d\n",hopcount,AXI_RIO_MAX_HOPCOUNT);return -1;}rio_setreg32(AXI_RIO_BASEADDR,AXI_RIO_NODE_BASEADDR,dstId);reg_addr = (((hopcount+1)<<24)|offset);rio_setreg32(AXI_RIO_BASEADDR,reg_addr,writedata);return 0;  }int hlMaintRead(unsigned int dstId,unsigned short hopcount, unsigned int offset, int mrdataAdr){unsigned int reg_addr;if( hopcount > AXI_RIO_MAX_HOPCOUNT ){printf("!!!error, hopcount = %d,  > %d\n",hopcount,AXI_RIO_MAX_HOPCOUNT);return -1;}rio_setreg32(AXI_RIO_BASEADDR,AXI_RIO_NODE_BASEADDR,dstId);reg_addr = (((hopcount+1)<<24)|offset);mrdataAdr = rio_getreg32(AXI_RIO_BASEADDR,reg_addr);printf("M_SRIO_MAINT_REG_READ: hopcount = %d, offset = 0x%x, value = 0x%x\n",hopcount,offset,mrdataAdr);return 0;  }int main(int argc, char *argv[]){int mtRdata=0;printf("get 1848 device id through rio\n");hlMaintRead(0xFF,0, 0, mtRdata);printf("ok\n");return 0;}

运行结果如下，可以看到和在驱动中实现一样

4、  总结

出于安全考虑，在用户态中直接访问物理地址，这种做法在linux中不常见，不过对于zynq来说这种方法要比实现驱动后再通过app调用驱动接口间接明了的多。也可以这样说，是把驱动移植到了用户态中，在用户态下实现地址映射。考虑到这一点，上面给出的例子可以作为用户态中提供给更上一层app的接口，这样就能避免真正的用户直接接触物理地址。