【海思应用篇】-（8）GPIO模拟I2C

xclshwd 2020-08-30 09:57:38 3262
海思
【海思应用篇】-（8）GPIO模拟I2C
1.前言

有时候芯片上i2c数量不多，我们可以通过gpio模拟i2c时序，达到通过i2c与芯片交互目的。
gpio_i2c.h


#ifndef _GPIO_I2C_H
#define _GPIO_I2C_H

#if 1
#define GPIO_I2C_MAGIC_BASE 'I'
#define GPIO_I2C_READ_BYTE   _IOR(GPIO_I2C_MAGIC_BASE,0x01,int)
#define GPIO_I2C_WRITE_BYTE  _IOW(GPIO_I2C_MAGIC_BASE,0x02,int)

#define GPIO_I2C_READ_DWORD   _IOR(GPIO_I2C_MAGIC_BASE,0x03,int)
#define GPIO_I2C_WRITE_DWORD  _IOR(GPIO_I2C_MAGIC_BASE,0x04,int)
#else
#define GPIO_I2C_READ_BYTE    0x01
#define GPIO_I2C_WRITE_BYTE   0x02

#define GPIO_I2C_READ_DWORD   0x03
#define GPIO_I2C_WRITE_DWORD  0x04
#endif

typedef struct _cx25838_regs_data
{
    unsigned int chip;  //0x88 or 0x8a
    unsigned int addr;  //reg address
    unsigned int hibit;
    unsigned int lobit;
    unsigned int data;
} cx25838_regs_data;

unsigned char gpio_i2c_read(unsigned char devaddress, unsigned char address);
void          gpio_i2c_write(unsigned char devaddress, unsigned char address, unsigned char value);
unsigned int  gpio_i2c2_read(unsigned char devaddress, unsigned short address, int num_bytes);
void          gpio_i2c2_write(unsigned char devaddress, unsigned short address, unsigned int data, int num_bytes);

unsigned int  gpio_i2c2_read_1bytesubaddr(unsigned char devaddress, unsigned char address, int num_bytes);
void          gpio_i2c2_write_1bytesubaddr(unsigned char devaddress, unsigned char address, unsigned int data, int num_bytes);

#endif

gpio_i2c.c


#include <linux/module.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/fcntl.h>

#include <linux/init.h>
#include <linux/delay.h>
#include <linux/proc_fs.h>
#include <linux/workqueue.h>

#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>

#include "gpio_i2c.h" 

#define GPIO_0_BASE 0x12210000
#define SCL                 (1 << 7)    /* GPIO 12_7 */
#define SDA                 (1 << 6)    /* GPIO 12_6 */
#define GPIO_I2C_SCL_REG    IO_ADDRESS(GPIO_0_BASE + 0x200)
#define GPIO_I2C_SDA_REG    IO_ADDRESS(GPIO_0_BASE + 0x100)
#define GPIO_I2C_SCLSDA_REG IO_ADDRESS(GPIO_0_BASE + 0x300)

#define GPIO_0_DIR IO_ADDRESS(GPIO_0_BASE + 0x400)

#define HW_REG(reg)         *((volatile unsigned int *)(reg))
#define DELAY(us)           time_delay_us(us)

/* 
 * I2C by GPIO simulated  clear 0 routine.
 *
 * @param whichline: GPIO control line
 *
 */
static void i2c_clr(unsigned char whichline)
{
    unsigned char regvalue;

    if(whichline == SCL)
    {
        regvalue = HW_REG(GPIO_0_DIR);
        regvalue |= SCL;
        HW_REG(GPIO_0_DIR) = regvalue;

        HW_REG(GPIO_I2C_SCL_REG) = 0;
        return;
    }
    else if(whichline == SDA)
    {
        regvalue = HW_REG(GPIO_0_DIR);
        regvalue |= SDA;
        HW_REG(GPIO_0_DIR) = regvalue;

        HW_REG(GPIO_I2C_SDA_REG) = 0;
        return;
    }
    else if(whichline == (SDA|SCL))
    {
        regvalue = HW_REG(GPIO_0_DIR);
        regvalue |= (SDA|SCL);
        HW_REG(GPIO_0_DIR) = regvalue;

        HW_REG(GPIO_I2C_SCLSDA_REG) = 0;
        return;
    }
    else
    {
        printk("Error input.\n");
        return;
    }

}

/* 
 * I2C by GPIO simulated  set 1 routine.
 *
 * @param whichline: GPIO control line
 *
 */
static void  i2c_set(unsigned char whichline)
{
    unsigned char regvalue;

    if(whichline == SCL)
    {
        regvalue = HW_REG(GPIO_0_DIR);
        regvalue |= SCL;
        HW_REG(GPIO_0_DIR) = regvalue;

        HW_REG(GPIO_I2C_SCL_REG) = SCL;
        return;
    }
    else if(whichline == SDA)
    {
        regvalue = HW_REG(GPIO_0_DIR);
        regvalue |= SDA;
        HW_REG(GPIO_0_DIR) = regvalue;

        HW_REG(GPIO_I2C_SDA_REG) = SDA;
        return;
    }
    else if(whichline == (SDA|SCL))
    {
        regvalue = HW_REG(GPIO_0_DIR);
        regvalue |= (SDA|SCL);
        HW_REG(GPIO_0_DIR) = regvalue;

        HW_REG(GPIO_I2C_SCLSDA_REG) = (SDA|SCL);
        return;
    }
    else
    {
        printk("Error input.\n");
        return;
    }
}

/*
 *  delays for a specified number of micro seconds rountine.
 *
 *  @param usec: number of micro seconds to pause for
 *
 */
void time_delay_us(unsigned int usec)
{
    //int i,j;

    udelay(1);
    /*
    for(i=0;i<usec * 50;i++)
    {
        for(j=0;j<4700;j++)
        {;}
    }*/
}

/* 
 * I2C by GPIO simulated  read data routine.
 *
 * @return value: a bit for read 
 *
 */

static unsigned char i2c_data_read(void)
{
    unsigned char regvalue;

    regvalue = HW_REG(GPIO_0_DIR);
    regvalue &= (~SDA);
    HW_REG(GPIO_0_DIR) = regvalue;
    DELAY(1);

    regvalue = HW_REG(GPIO_I2C_SDA_REG);
    if((regvalue&SDA) != 0)
        return 1;
    else
        return 0;
}

/*
 * sends a start bit via I2C rountine.
 *
 */
static void i2c_start_bit(void)
{
        DELAY(1);
        i2c_set(SDA | SCL);
        DELAY(1);
        i2c_clr(SDA);
        DELAY(1);
}

/*
 * sends a stop bit via I2C rountine.
 *
 */
static void i2c_stop_bit(void)
{
        /* clock the ack */
        DELAY(1);
        i2c_set(SCL);
        DELAY(1); 
        i2c_clr(SCL);  

        /* actual stop bit */
        DELAY(1);
        i2c_clr(SDA);
        DELAY(1);
        i2c_set(SCL);
        DELAY(1);
        i2c_set(SDA);
        DELAY(1);
}

/*
 * sends a character over I2C rountine.
 *
 * @param  c: character to send
 *
 */
static void i2c_send_byte(unsigned char c)
{
    int i;
    local_irq_disable();
    for (i=0; i<8; i++)
    {
        DELAY(1);
        i2c_clr(SCL);
        DELAY(1);

        if (c & (1<<(7-i)))
            i2c_set(SDA);
        else
            i2c_clr(SDA);

        DELAY(1);
        i2c_set(SCL);
        DELAY(1);
        i2c_clr(SCL);
    }
    DELAY(1);
   // i2c_set(SDA);
    local_irq_enable();
}

/*  receives a character from I2C rountine.
 *
 *  @return value: character received
 *
 */
static unsigned char i2c_receive_byte(void)
{
    int j=0;
    int i;
    unsigned char regvalue;

    local_irq_disable();
    for (i=0; i<8; i++)
    {
        DELAY(1);
        i2c_clr(SCL);
        DELAY(1);
        i2c_set(SCL);

        regvalue = HW_REG(GPIO_0_DIR);
        regvalue &= (~SDA);
        HW_REG(GPIO_0_DIR) = regvalue;
        DELAY(1);

        if (i2c_data_read())
            j+=(1<<(7-i));

        DELAY(1);
        i2c_clr(SCL);
    }
    local_irq_enable();
    DELAY(1);
   // i2c_clr(SDA);
   // DELAY(1);

    return j;
}

/*  receives an acknowledge from I2C rountine.
 *
 *  @return value: 0--Ack received; 1--Nack received
 *          
 */
static int i2c_receive_ack(void)
{
    int nack;
    unsigned char regvalue;

    DELAY(1);

    regvalue = HW_REG(GPIO_0_DIR);
    regvalue &= (~SDA);
    HW_REG(GPIO_0_DIR) = regvalue;

    DELAY(1);
    i2c_clr(SCL);
    DELAY(1);
    i2c_set(SCL);
    DELAY(1);

    nack = i2c_data_read();

    DELAY(1);
    i2c_clr(SCL);
    DELAY(1);
  //  i2c_set(SDA);
  //  DELAY(1);

    if (nack == 0)
        return 1; 

    return 0;
}

#if 0
static void i2c_send_ack(void)
{
    DELAY(1);
    i2c_clr(SCL);
    DELAY(1);
    i2c_set(SDA);
    DELAY(1);
    i2c_set(SCL);
    DELAY(1);
    i2c_clr(SCL);
    DELAY(1);
    i2c_clr(SDA);
    DELAY(1);
}
#endif

EXPORT_SYMBOL(gpio_i2c_read);
unsigned char gpio_i2c_read(unsigned char devaddress, unsigned char address)
{
    int rxdata;

    i2c_start_bit();
    i2c_send_byte((unsigned char)(devaddress));
    i2c_receive_ack();
    i2c_send_byte(address);
    i2c_receive_ack();   
    i2c_start_bit();
    i2c_send_byte((unsigned char)(devaddress) | 1);
    i2c_receive_ack();
    rxdata = i2c_receive_byte();
    //i2c_send_ack();
    i2c_stop_bit();

    return rxdata;
}

EXPORT_SYMBOL(gpio_i2c_write);
void gpio_i2c_write(unsigned char devaddress, unsigned char address, unsigned char data)
{
    i2c_start_bit();
    i2c_send_byte((unsigned char)(devaddress));
    i2c_receive_ack();
    i2c_send_byte(address);
    i2c_receive_ack();
    i2c_send_byte(data); 
   // i2c_receive_ack();//add by hyping for tw2815
    i2c_stop_bit();
}

EXPORT_SYMBOL(gpio_i2c2_read);
unsigned int gpio_i2c2_read(unsigned char devaddress, unsigned short address, int num_bytes)
{
    unsigned char rxdata;
    unsigned int  ret = 0x00;
    int i;

#if 1
    for (i=0; i<num_bytes; i++) {
        i2c_start_bit();
        i2c_send_byte((unsigned char)(devaddress));
        i2c_receive_ack();
        i2c_send_byte((unsigned char)((address >> 8) & 0xff));
        i2c_receive_ack();
        i2c_send_byte((unsigned char)(address & 0xff));
        i2c_receive_ack();   

        i2c_start_bit();
        i2c_send_byte((unsigned char)(devaddress) | 1);
        i2c_receive_ack();
        rxdata = i2c_receive_byte();
        //      i2c_send_nack();
        i2c_stop_bit();

        ret |= (rxdata << (i * 8));

        address ++;
    }
#else
    i2c_start_bit();
    i2c_send_byte((unsigned char)(devaddress));
    i2c_receive_ack();
    i2c_send_byte((unsigned char)((address >> 8) & 0xff));
    i2c_receive_ack();
    i2c_send_byte((unsigned char)(address & 0xff));
    i2c_receive_ack();   

    i2c_start_bit();
    i2c_send_byte((unsigned char)(devaddress) | 1);
    i2c_receive_ack();
    for (i=0; i<num_bytes-1; i++) {
        rxdata = i2c_receive_byte();
        i2c_send_ack();
        ret |= rxdata;
        ret <<= 8;
    }
    rxdata = i2c_receive_byte();
    //  i2c_send_ack();
    i2c_stop_bit(ACK);
    ret |= rxdata;
#endif

    //  printk("dev=%x, reg =%x, rxd=%x\n", devaddress, address, ret);

    return ret;
}

EXPORT_SYMBOL(gpio_i2c2_write);
void gpio_i2c2_write(unsigned char devaddress, unsigned short address, unsigned int data, int num_bytes)
{
    int i;

    //  printk("wr: %x %x %x %x\n", devaddress, address, data, num_bytes);
#if 1
    for (i=0; i<num_bytes; i++) {
        i2c_start_bit();
        i2c_send_byte((unsigned char)(devaddress));
        i2c_receive_ack();
        i2c_send_byte((unsigned char)((address >> 8) & 0xff));
        i2c_receive_ack();
        i2c_send_byte((unsigned char)(address & 0xff));
        i2c_receive_ack();   

        i2c_send_byte((unsigned char)((data >> (i*8)) & 0xff)); 
        i2c_receive_ack();
        i2c_stop_bit();
        address++;
        //  DELAY(100);
    }
#else
    i2c_start_bit();
    i2c_send_byte((unsigned char)(devaddress));
    i2c_receive_ack();
    i2c_send_byte((unsigned char)((address >> 8) & 0xff));
    i2c_receive_ack();
    i2c_send_byte((unsigned char)(address & 0xff));
    i2c_receive_ack();
    for (i=0; i<num_bytes; i++) {
        i2c_send_byte((unsigned char)((data >> (i*8)) & 0xff)); 
        i2c_receive_ack();
    }
    //  i2c_send_byte((unsigned char)((data >> (i*8)) & 0xff)); 
    i2c_stop_bit(ACK);
#endif
}
//在发布版本时注释

#if 1
void RegMaskWrite(unsigned char chip_addr, unsigned short addr, int lo_bit, int hi_bit, int data)
{
    int i, num_bytes;
    unsigned int value = 0;

    num_bytes = 4;

    value = gpio_i2c2_read(chip_addr, addr, num_bytes);

    for (i=lo_bit; i<=hi_bit; i++) {
        value &= ~(1<<i);
    }

    value |= (data << lo_bit);

    gpio_i2c2_write(chip_addr, addr, value, num_bytes);
}

#endif

unsigned int gpio_i2c2_read_1bytesubaddr(unsigned char devaddress, unsigned char address, int num_bytes)
{
    unsigned int value = 0;
    value = gpio_i2c2_read(devaddress, address, num_bytes);

    return value;

}

void gpio_i2c2_write_1bytesubaddr(unsigned char devaddress, unsigned char address, unsigned int data, int num_bytes)
{
    gpio_i2c2_write(devaddress, address, data, num_bytes);

}

long gpioi2c_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    unsigned int val;

    char device_addr;
    int reg_val,reg_addr;
    cx25838_regs_data val1;
    unsigned char chip_addr;
    int addr;
    int lo_bit;
    int hi_bit;
    int data;

    switch(cmd)
    {
        case GPIO_I2C_READ_BYTE:
            val = *(unsigned int *)arg;
            device_addr = (val&0xff000000)>>24;
            reg_addr = (val&0xff0000)>>16;

            reg_val = gpio_i2c_read(device_addr, reg_addr);
            *(unsigned int *)arg = (val&0xffff0000)|reg_val;    
            //printk("Func:%s, line:%d  dev_addr=0x%x, reg_addr=0x%x, value=0x%x\n", 
            //    __FUNCTION__, __LINE__, device_addr, reg_addr, reg_val);
            break;

        case GPIO_I2C_WRITE_BYTE:
            val = *(unsigned int *)arg;
            device_addr = (val&0xff000000)>>24;
            reg_addr = (val&0xff0000)>>16;

            reg_val = val&0xffff;
            gpio_i2c_write(device_addr, reg_addr, reg_val);
            break;  

        case GPIO_I2C_READ_DWORD:
            val = *(unsigned int *)arg;
            device_addr = (val&0xff000000)>>24;
            reg_addr = (val&0xffff00)>>8;

            reg_val = gpio_i2c2_read(device_addr, reg_addr, 4);
            *(unsigned int *)arg = reg_val;         
            //printk("Func:%s, line:%d  dev_addr=0x%x, reg_addr=0x%x, value=0x%x\n", 
            //    __FUNCTION__, __LINE__, device_addr, reg_addr, reg_val);
            break;

        case GPIO_I2C_WRITE_DWORD:
            val1 = *(cx25838_regs_data *)arg;

            chip_addr=val1.chip&0xff;
            addr=val1.addr;
            lo_bit=val1.lobit;
            hi_bit=val1.hibit;
            data=val1.data;
            //printk("Func:%s, line:%d  dev_addr=0x%x, reg_addr=0x%x, lo_bit=0x%x, hi_bit=0x%x, data=0x%x\n", 
            //__FUNCTION__, __LINE__, chip_addr, addr, lo_bit, hi_bit, data);

            RegMaskWrite(chip_addr, addr, lo_bit, hi_bit, data);
            break;      

        default:
            return -1;
    }
    return 0;
}

int gpioi2c_open(struct inode * inode, struct file * file)
{
    return 0;
}
int gpioi2c_close(struct inode * inode, struct file * file)
{
    return 0;
}

static struct file_operations gpioi2c_fops = {
    .owner          = THIS_MODULE,
    //.ioctl          = gpioi2c_ioctl,
    .unlocked_ioctl = gpioi2c_ioctl,
    .open           = gpioi2c_open,
    .release        = gpioi2c_close
};

static struct miscdevice gpioi2c_dev = {
   .minor       = MISC_DYNAMIC_MINOR,
   .name        = "gpioi2c",
   .fops        = &gpioi2c_fops,
};

static int __init gpio_i2c_init(void)
{
    int ret;
    //unsigned int reg;

    ret = misc_register(&gpioi2c_dev);
    if(0 != ret)
    {
        return -1;
    }

#if 1         
    //printk(KERN_INFO OSDRV_MODULE_VERSION_STRING "\n");            
    //reg = HW_REG(SC_PERCTRL1);
    //reg |= 0x00004000;
    //HW_REG(SC_PERCTRL1) = reg;
    i2c_set(SCL|SDA);
#endif              
    return 0;    
}

static void __exit gpio_i2c_exit(void)
{
    misc_deregister(&gpioi2c_dev);
}

module_init(gpio_i2c_init);
module_exit(gpio_i2c_exit);

#ifdef MODULE
//#include <linux/compile.h>
#endif
//MODULE_INFO(build, UTS_VERSION);
MODULE_LICENSE("GPL");
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    消失 2022-03-02 10:08:37
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    最近也在调 2字节寄存器地址和两字节数据返回的 写设备地址有ACK 其他的都没有 不知道为啥
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