mmap操作荔枝派gpio v3s Linux

1.预备知识

https://baike.baidu.com/item/mmap/1322217?fr=aladdin 大家直接看百度百科，比较清楚了。

2.代码

gpio.c

#include "gpio.h"

unsigned int fd;
PIO_Map *PIO = NULL;
unsigned int *gpio_map;
unsigned int addr_start, addr_offset;
unsigned int PageSize, PageMask;
void GPIO_Init(void)
{

    if ((fd = open("/dev/mem", O_RDWR)) == -1)
    {
        printf("open error
");
        return;
    }

    PageSize = sysconf(_SC_PAGESIZE); //使用sysconf查询系统页面大小
    PageMask = (~(PageSize - 1));     //页掩码
    printf("PageSize:%d,PageMask:0x%.8X
", PageSize, PageMask);

    addr_start = PIO_BASE_ADDRESS & PageMask;   //0x01C20800 & 0xfffff000 =  0x1C20000
    addr_offset = PIO_BASE_ADDRESS & ~PageMask; //0x01C20800 & 0x00000100 = 0x800
    printf("addr_start:%.8X,addr_offset:0x%.8X
", addr_start, addr_offset);
    //mmap(系统自动分配内存地址，映射区长度“内存页的整数倍”，选择可读可写，MAP_SHARED=与其他所有映射到这个对象的进程共享空间，文件句柄，被映射内容的起点)
    //offest 映射物理内存的话，必须页对其!!!   所以这个起始地址应该是0x1000的整数倍，那么明显0x01C20800需要减去0x800才是整数倍！
    if ((gpio_map = mmap(NULL, PageSize * 2, PROT_READ | PROT_WRITE, MAP_SHARED, fd, addr_start)) == NULL)
    {
        printf("mmap error
");
        close(fd);
        return;
    }
    printf("gpio_map:%.8X
", gpio_map);
    //这里已经将0x1c20000的地址映射到了内存中，但是我们需要的地址是0x01C20800，所以要再加上地址偏移量～
    PIO = (PIO_Map *)((unsigned int)gpio_map + addr_offset);
    printf("PIO:0x%.8X
", PIO);

    close(fd); //映射好之后就可以关闭文件？
}

void GPIO_ConfigPin(PORT port, unsigned int pin, PIN_MODE mode)
{
    if (gpio_map == NULL)
        return;
    PIO->Pn[port].CFG[pin / 8] &= ~((unsigned int)0x07 << pin % 8 * 4);
    PIO->Pn[port].CFG[pin / 8] |= ((unsigned int)mode << pin % 8 * 4);
    printf("struct PIO_Struct size : %d",sizeof(PIO->Pn[port]));
}

void GPIO_SetPin(PORT port, unsigned int pin, unsigned int level)
{
    if (gpio_map == NULL)
        return;
    if (level)
        PIO->Pn[port].DAT |= (1 << pin);
    else
        PIO->Pn[port].DAT &= ~(1 << pin);
}

int GPIO_Free(void)
{
    if ((munmap(gpio_map, PageSize * 2)) == 0)//取消映射
    {
        printf("unmap success!
");
    }
    else
    {
        printf("unmap failed!
");
    }
    return 0;
}

gpio.h

#ifndef __GPIO_H__
#define __GPIO_H__
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#define PIO_BASE_ADDRESS 0x01C20800


//unsigned int 4字节 一个PIO_Struct占36字节,对应十六进制就是0x24，正好是一个offset值。
typedef struct
{
    unsigned int CFG[4];
    unsigned int DAT;
    unsigned int DRV0;
    unsigned int DRV1;
    unsigned int PUL0;
    unsigned int PUL1;
} PIO_Struct;

typedef struct
{
    PIO_Struct Pn[7];
} PIO_Map;

typedef enum {
    PA = 0,
    PB = 1,
    PC = 2,
    PD = 3,
    PE = 4,
    PF = 5,
    PG = 6,
} PORT;

typedef enum {
    IN = 0x00,
    OUT = 0x01,
    AUX = 0x02,
    INT = 0x06,
    DISABLE = 0x07,
} PIN_MODE;

extern PIO_Map *PIO;

void GPIO_Init(void);
void GPIO_ConfigPin(PORT port, unsigned int pin, PIN_MODE mode);
void GPIO_SetPin(PORT port, unsigned int pin, unsigned int level);
unsigned int GPIO_GetPin(PORT port, unsigned int pin);
int GPIO_Free(void);
#endif

main.c

#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "gpio.h"
#include <stdbool.h>
int main()
{
    int a=0,b=-1,i;
    GPIO_Init();
    GPIO_ConfigPin(PB,4,OUT);
    GPIO_ConfigPin(PB,5,OUT);
    for(i=0;i<20;i++)
    {
        GPIO_SetPin(PB,4,a=~a);//！！-1的取反是0 1的取反是-2....
        GPIO_SetPin(PB,5,b=~b);
        //usleep(100000);
        sleep(1);
    }
    GPIO_Free();
}

makefile

TARGET        = myGPIO    #可执行文件名称

########################编译参数############################
CC            = arm-linux-gnueabihf-gcc 
CXX           = arm-linux-gnueabihf-g++ 
DEFINES       = 
CFLAGS        = -pipe -g -Wall -W -fPIE $(DEFINES)
CXXFLAGS      = -pipe -g -Wall -W -fPIE $(DEFINES)
INCPATH       = -I. 


########################编译文件############################
SOURCES       = ./main.c ./gpio.c
OBJECTS       = main.o gpio.o

$(TARGET) : $(OBJECTS)
        $(CC) -o $(TARGET) $(OBJECTS)
main.o : main.c gpio.h
        $(CC) $(include) $(CFLAGS) -c main.c 
gpio.o : gpio.c gpio.h 
        $(CC) $(include) $(CFLAGS) -c gpio.c 
clean :
        rm  $(OBJECTS) $(TARGET)

3.运行

将程序编译出来放到v3s上运行，那么pb4 pb5 会交替高低电平。