【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
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#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
{
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
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
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
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
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<
}
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
#endif
//MODULE_INFO(build, UTS_VERSION);
MODULE_LICENSE(“GPL”);
