The BIOS is part of the silicon is factory programmed into the chip. You do not have to seperately load it.
There are 2 ways to communicate with the EZ-Host in co-processor mode.
Method 1 is as follows:
The external processor can send LCP commands to BIOS. The TD_list information is dumped into EZ-HOST memory which contains details about the set up phase, data phase and acknowleldgement phase of USB transactions. The LCP commands can be used by the external master to access any CPU register.
Here, triggering the BIOS through LCP and then sending TD_list information is sufficient.The OTG-Host device then transfers the data associated with this TD_List to or from USB.
This method eliminates the need of having USB Host stack (TD_list,urb,mass storage class or any class request info,File operations/FAT32 for mass storage etc) in EZ-HOST. BIOS will handle the entire function of decoding LCP commands.
Please refer to the attached appnote which explains TD_list preperation. You will also find chapter 3 of the attached document OTG-Host BIOS User Manual useful.
The Method 2 is as follows:
Download firmware from External processor to EZ-HOST memory through HPI,HSS and SPI.
Intially from GPIO[30:31] pins logic BIOS will decide to switch to any of the 3 SPI,HSS and SPI assembly routines in its ROM code . These routines have capability to understand and decode the content of LCP formatted commands.
Initially for firmware download, BIOS on EZ-HOST side will handle all relevant LCP commands . After download there is an LCP command to jump to the start of downloaded firmware sent by external processor .From this point the firmware will have control over the EZ-HOST chip.
Now user can implement the protocol of his choice (LCP or any other) in his firmware here to suit his end device connected to HOST port.