Re: [Ipodlinux-devel] ipod reverse engineering

[Bernard L. <le...@bo...>]

Hi Samuel,

the information on the PP5002 has been derived by reverse engineering the
Apple firmware (and much experiment!).

Some parts of the firmware are quite helpful in the reverse eng process, e.g.
in the bootloader there are "command" functions with nice useage strings that
implement things like "power down LCD", or sound piezo.  Other parts are not
so helpful and brute force is the only technique.

I have requested the development docs from PortalPlayer and although they said
they would try and get them to me (without requiring a NDA) they never got
around to it.

cheers,
bern.

Samuel Ortiz <or...@fa...> said:

> Hi guys,
> 
> I got a 2.4.24-uc0 + latest ipodlinux cvs booting on my 3G ipod this 
> weekend. This is an impressive work !
> I was even more impressed when I started to look at the code. IMHO, 
> writing this code without documentation nor JTAG interface is not a 
> piece of cake...
> Since I now would like to contribute to this project, I need some kind 
> of help. I am interested in adding some power management features to 
> this kernel. Portalplayer claims that its chipset provides many power 
> management hooks, but how can I get some informations about it, without 
> having any useful PP5002 docs ?  More generally, how did you manage to 
> reverse engineer this machine ? As an example, how did you manage to 
> understand that, in order to set the CPU speed to 75 Mhz, you'd have to 
> do this:
> 
>     outl(0x02, 0xcf005008);
>     outl(0x55, 0xcf00500c);
>     outl(0x6000, 0xcf005010);
>     outl(24, 0xcf005018);
>     outl(75, 0xcf00501c);
> 
> How did you know that you have to write to this specific ports ? Did you 
> get all this information from Apple's firmware ?
> 
> Thanks in advance for your time and answers !
> 
> Cheers,
> Samuel.
> 
> 
> 
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