i2c-0 i2c Radeon i2c bit bus 0xc0 I2C adapter i2c-1 i2c Radeon i2c bit bus 0x90 I2C adapter i2c-2 i2c Radeon i2c bit bus 0x91 I2C adapter i2c-3 i2c Radeon i2c bit bus 0x92 I2C adapter i2c-4 smbus SMBus PIIX4 adapter at 0b00 SMBus adapter