Proposed communication protocol between Host and EC for 1.75

[John Watlington]

On May 25, 2010, at 10:38 AM, Richard A. Smith wrote:

> On 05/24/2010 11:03 PM, Mitch Bradley wrote:
>> Another protocol idea is at
>> http://wiki.laptop.org/go/Talk:XO_1.75_HOST_to_EC_Protocol
> 
> The SPI interface on the CPU is shared with the SPI boot flash.  So on 
> boot the CPU has to be master and then switch over to slave when the 
> boot it finished.  To use this setup  we will also have to negotiate a 
> master slave switch when the CPU wants to change mfg data or when it 
> wants to update the firmware.

Not quite true, as there are additional SPI interfaces available through
the SSP ports.

wad