GPIO模拟I2C操作

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/****I2C*****I2C*****I2C*****I2C*****I2C*****I2C*****I2C*****I2C*****I2C*****I2C*****I2C****/
#define DELAY 1
#define SCL 89

#define SDA 20
#define RST 19

#define IRQ 108
void i2c_start(void)
{
gpio_direction_output(SDA, 1);
gpio_direction_output(SCL, 1);
udelay(DELAY);

gpio_set_value(SDA, 0);
udelay(DELAY);

gpio_set_value(SCL, 0);
udelay(DELAY);
}
void i2c_stop(void)
{
gpio_set_value(SCL, 0);
gpio_set_value(SDA, 0);
udelay(DELAY);

gpio_set_value(SCL, 1);
udelay(DELAY);
gpio_set_value(SDA, 1);
udelay(DELAY);
}
void i2c_send_ack(u8 ack)
{
if(ack)
gpio_direction_output(SDA, 1);
else
gpio_direction_output(SDA, 0);
udelay(DELAY);

gpio_set_value(SCL, 1);
udelay(DELAY);

gpio_set_value(SCL, 0);
udelay(DELAY);
}
u8 i2c_receive_ack(void)
{
u8 rc = 0;

gpio_direction_input(SDA);
gpio_set_value(SCL, 1);
udelay(DELAY);

if(gpio_get_value(SDA)) {
rc = 1;
}
gpio_set_value(SCL, 0);
gpio_direction_output(SDA, 1);
return rc;
}
u8 i2c_send_byte(u8 send_byte)
{
u8 rc = 0;
u8 out_mask = 0x80;
u8 value;
u8 count = 8;
while(count > 0) {
value = ((send_byte & out_mask) ? 1 : 0);
if (value == 1) {
gpio_set_value(SDA, 1);
}
else {
gpio_set_value(SDA, 0);
}
udelay(DELAY);

gpio_set_value(SCL, 1);
udelay(DELAY);

gpio_set_value(SCL, 0);
udelay(DELAY);

out_mask >>= 1;
count--;
}

gpio_set_value(SDA, 1);
rc = i2c_receive_ack();
return rc;
}
void i2c_read_byte(u8 *buffer, u8 ack)
{
u8 count = 0x08;
u8 data = 0x00;
u8 temp = 0;

gpio_direction_input(SDA);
while(count > 0) {
gpio_set_value(SCL, 1);
udelay(DELAY);
temp = gpio_get_value(SDA);
data <<= 1;
if (temp)
data |= 0x01;
gpio_set_value(SCL, 0);
udelay(DELAY);
count--;
}
i2c_send_ack(ack);//0 = ACK 1 = NACK

*buffer = data;
}
//向client的某个寄存器写入多个字节,len是要写入的数据的长度

u8 i2c_write(u8 device_id, u8 reg_address, u8* data, u8 len)
{
u8 rc = 0;
u8 i;
i2c_start();

rc |= i2c_send_byte( (device_id << 1) | 0x00 );
rc |= i2c_send_byte(reg_address);
if(data==NULL ||0==len) {
i2c_stop();
return rc;
}

for(i=0; i<len; i++) {
rc |= i2c_send_byte(*data);
data++;
}

i2c_stop();
if(rc) {
printk("ERROR! ssd2531_i2c_write failed/n");
}
return rc;
}
//从某个register中读取len个字节放在长度为len的缓冲区buffer中

u8 i2c_read(u8 device_id, u8 reg_address, u8 *buffer, u8 len)
{
u8 rc = 0;
u8 i;

i2c_start();
rc |= i2c_send_byte( (device_id << 1) | 0x00 );
rc |= i2c_send_byte(reg_address);
i2c_start();//restart I2C
rc |= i2c_send_byte( (device_id << 1) | 0x01 );

for(i=0;i<len;i++) {
i2c_read_byte(buffer++, !(len-i-1));// !(len-i-1) 这个用来保证在读到每个字节后发送一个ACK并能在最后一个字节读完后发送一个NACK

}

i2c_stop();
if(rc) {
printk("ERROR! ssd2531_i2c_read failed/n");
return rc;
}
return rc;
}
/****I2C*****I2C*****I2C*****I2C*****I2C*****I2C*****I2C*****I2C*****I2C*****I2C*****I2C****/