The system host communicates with 8051 via ECPCMD, ECPARG1, ECPARG2, and ECPARG3 registers in EC space offset 10h, 11h, 12h and 13h. A non-zero value of PCMD will cause the 8051 P0IE.0 interrupt to take place informing the 8051 firmware, and the 8051 firmware will take the responsibility to carry this command.
Usual legacy EC commands over 62h/64h port - widely known
Extended EC commands:
You may use EC Index IO mode to access the EC register space (F400h ~FFFFh). The EC Index IO base is set in LPC register FE92h, FE93h. The base address + 1 is index high byte address. The base address + 2 is index low byte address. The base address + 3 is data port for reading from or writing to EC internal register space.
- 01h Query Status
- 02h Idle
- 03h Power down
- 04h Init flash write - The 8051 should return OK status to grant host system to write flash. After the completion of this command, the 8051 should enter IDLE mode or reset condition (set EC_PXCFG bit 0 = 1) to prevent from 8051 fetching instruction code.
- entry : argument_1 - if 01 - update all flash content, including 8051 code region.
if 02 - update system BIOS, not including 8051 code region.
- exit cmd 00h argument_1 if 00h: OK, the host can write flash now.
if 01h: Error, no AC Adapter (the AC should be plugged during update flash). if 02h: Error, unknown condition.
There are two memory address segments that are decoded by KB38xx/39xx
- 000Y_0000h ~ 000F_FFFFh, where Y is selectable to C/E/Fh in register LFMSM(FE91h)
- FFXX_0000h~FFFF_FFFFh, where XX is selectable to FE/FC/F8/F0/E0/C0/80h in register LFMSM(FE91h).