[OLPC-devel] Embedded Controller and Serial Flash ROM

[Ray.Tseng at quantatw.com]

Carl,
	Attachment is the EC code used in A-test board, the current size is 18K. But Quanta is still working on battery management code now. The size will grow rapidly, please reserve 64K for final EC.
	The SPI ROM is 1MB in A-test board, please combine the EC code in the lowest (ie. beginning) address of flash.
	The EC  takes care 1) Event detect 2) Power on/off 3) battery management 4) Keyboard/mouse etc. 
	The EC code control the power on sequence, it run before the BIOS
	The EC code can not be compressed.
	 
Ray Tseng 5/30/06

-----Original Message-----
From: devel-bounces at laptop.org [mailto:devel-bounces at laptop.org] On Behalf Of Carl-Daniel Hailfinger
Sent: Monday, May 29, 2006 9:56 PM
To: Mark J. Foster
Cc: devel at laptop.org
Subject: Re: [OLPC-devel] Embedded Controller and Serial Flash ROM

Mark J. Foster wrote:
> Hi, Folks!
> 
> As I scanned through 'devel' this weekend, I noticed an important 
> absence in the serial ROM Flash layout.  The 512K serial Flash ROM is 
> actually shared between the system BIOS and the embedded controller.
> Upon power-up, the embedded controller reads its code from the first 
> 64K of the serial Flash - we therefore need to reserve the first 64K 
> of the serial Flash for the EC.

Can't the EC use only 32k? And when exactly does the EC read its code?
Before the BIOS is run? If so, can we load the EC code after the BIOS?
Which vital functions are performed by the EC and can we split them from non-vital functions (if any)?

Can you attach the current EC code (even if it doesn't work)? If it is possible to execute that code during or after BIOS init, we can compress it and probably save >50% of space.

Regards,
Carl-Daniel
--
http://www.hailfinger.org/
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