I'd like to port FreeRTOS to Freescale Kinetis K64 (ARM Cortex-M4). As far as I know, there is no example code to this part, and the best way to do this port is to use an existing port closest to mine. If so, what is the best way to do that?
Another question, is there any I/O drivers for this chip peripherals?
yes, there is an (inofficial) port for the K64F (https://github.com/ErichStyger/mcuoneclipse/tree/master/Examples/KSDK) and multiple examples are here: https://github.com/ErichStyger/mcuoneclipse/tree/master/Examples/KDS/FRDM-K64F120M
Having said that: the K64F is an ARM Cortex-M4 with floating point unit, and from the RTOS perspective it is not different than any other M4F.