[Replicant] Apple iPhone 7 - possibility of a free baseband?

[Josh Branning]

Hi Denis, Nikolaus. (I will reply to you both here as for some reason I 
didn't get Denis' email through the list.)

On 04/10/16 15:04, H. Nikolaus Schaller wrote:
> Hi,
>
>> Am 04.10.2016 um 15:43 schrieb Denis 'GNUtoo' Carikli <GNUtoo at no-log.org>:
>>
>> On Tue, 4 Oct 2016 02:19:06 +0100
>> Josh Branning <lovell.joshyyy at gmail.com> wrote:
>>
>>> Apple iPhone 7 was released and made use of an iCE5LP4K device. [1]
>> Are you sure that this FPGA is used for the baseband?

I assumed it was for baseband.

>
> Footnote 35 of the Wikipedia article
>
> 	[1] https://en.wikipedia.org/wiki/ICE_(FPGA)#iCE40_.2840_nm.29links to
>
> mentioned by Josh is
>
> 	https://web.archive.org/web/20160916230725/http://www.chipworks.com/about-chipworks/overview/blog/apple-iphone-7-teardown
>
> This says:
>
> 	The Baseband is a PMB9943 (XMM7360) from Intel.
>
> 	In the “miscellaneous” section we have;
>
> 		• Lattice Semiconductor FPGA ICE5LP4K;
>
> So it is probably used for fingerprint sensing or whatever.
>

You are probably correct.

>> If so, do we have more information on the design of this baseband:
>> - What external circuits does it require.
>> - Is it possible to design a libre baseband based on such FPGAs?

I think it's entirely possible to develop a baseband based on FPGAs. The 
company that made the USRP hosts some of it's verilog code on github. 
Not sure what the licence is on this though. [1] And you're both 
probably aware that that the OsmocomBB project have used the USRP for 
various things related to GSM. [2]

Though it'd probably take a lot of work. And need a permit. And may 
still be easier just using something like Calypso.

[1] https://github.com/EttusResearch/fpga
[2] http://osmocom.org/projects/baseband/wiki/GSMTAP

>>
>> As for the iPhone 7, I fear that it won't be realistic to expect it to
>> be ported to Replicant.
>> The iDroid project ported some Apple smartphones under Android. The
>> iPhone 3g was, in iDroid, the device with the best support.
>>
>> The amount of work required to make such devices usable seemed to be
>> huge.
>>
>> Despite that, the people involved in the port succeeded to make lot of
>> the peripherals and hardware features work, but not the power
>> management[1].
>>
>> As a result that device cannot used as a regular smartphone.
>> I recall that suspend-to-ram wasn't even working, so it was probably
>> lasting very few hours, I'd blindly guess it was something like 3/4/5 hours.
>>
>> Also I fear that the ability to run your own bootloader and so on would
>> be severely restricted. That would probably require the bootrom to have
>> some bug[2].
>>
>> [1]shttps://web.archive.org/web/20141024013316/http://www.idroidproject.org/wiki/Status
>> [2]https://www.theiphonewiki.com/wiki/Bootrom#Bootrom_Exploits
>>
>> Denis.

Ok thanks for letting me know.

>
> BR,
> Nikolaus
>

Josh