MPC8308 I2C bus complies to I2C specifications. SMBus is generally compatible with I2C devices, though not in all respects. SMBus Specification Version 2.0 includes an Appendix B that discusses differences in electrical specifications between I2C and SMBushttp://www.smbus.org/specs/smbus20.pdf
Normally devices, both masters and slaves, are freely interchangeable between I2C and SMBus. The MPC8308 I2C operates at 3.3V which is suitable for the SMBus devices. It supports clock from the SMBus clock ranges (10kHz to 100kHz) too. So it should support the TI device. By the way there is also TI app. note “SMBus Compatibility With an I2C Device” https://www.ti.com/lit/an/sloa132/sloa132.pdf which consider I2C-SMBus connection and exchange protocol in details.
