I2C_PCF_START
set_pcf(adap, 1, I2C_PCF_START);
writeb(I2C_PCF_START, bp->i2c_control_regs + 0x0);
writeb(I2C_PCF_START, bp->i2c_control_regs + 0x0);
writeb(I2C_PCF_START, bp->i2c_control_regs + 0x0);