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/mem
if((fd = open("/dev/mem", O_RDWR | O_SYNC)) == -1)
{
perror("open /dev/mem:");
}
//mmap
map_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_BASEADDR 0x10100
#define AXI_RIO_MAX_HOPCOUNT 13

/**
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。