I2c.h

#pragma once
 
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <linux/i2c-dev.h>
// heuristic to guess what version of i2c-dev.h we have:
// the one installed with `apt-get install libi2c-dev`
// would conflict with linux/i2c.h, while the stock
// one requires linus/i2c.h
#ifndef I2C_SMBUS_BLOCK_MAX
// If this is not defined, we have the "stock" i2c-dev.h
// so we include linux/i2c.h
#include <linux/i2c.h>
typedef unsigned char i2c_char_t;
#else
typedef char i2c_char_t;
#endif
#include <sys/ioctl.h>
 
#define MAX_BUF_NAME 64
 
class I2c
{
 
protected:
        int i2C_bus;
        int i2C_address;
        int i2C_file;
public:
        ssize_t readBytes(void* buf, size_t count);
        ssize_t writeBytes(const void* buf, size_t count);
        I2c(){};
        I2c(I2c&&) = delete;
        int initI2C_RW(int bus, int address, int file);
        int closeI2C();
 
        virtual ~I2c();
};
 
 
inline int I2c::initI2C_RW(int bus, int address, int fileHnd)
{
        i2C_bus         = bus;
        i2C_address = address;
        i2C_file        = fileHnd;
 
        // open I2C device as a file
        char namebuf[MAX_BUF_NAME];
        snprintf(namebuf, sizeof(namebuf), "/dev/i2c-%d", i2C_bus);
 
        if ((i2C_file = open(namebuf, O_RDWR)) < 0)
        {
                fprintf(stderr, "Failed to open %s I2C Bus\n", namebuf);
                return(1);
        }
 
        // target device as slave
        if (ioctl(i2C_file, I2C_SLAVE, i2C_address) < 0){
                fprintf(stderr, "I2C_SLAVE address %#x failed...", i2C_address);
                return(2);
        }
 
        return 0;
}
 
 
 
inline int I2c::closeI2C()
{
        if(i2C_file > 0) {
                if(close(i2C_file) > 0)
                        return 1;
                else
                        i2C_file = -1;
        }
        return 0;
}
 
inline ssize_t I2c::readBytes(void *buf, size_t count)
{
        return read(i2C_file, buf, count);
}
 
inline ssize_t I2c::writeBytes(const void *buf, size_t count)
{
        return write(i2C_file, buf, count);
}
 
inline I2c::~I2c(){}