Interface between LTE devices and Linux

[noname.nuno@gmail.com (Nuno Sá)]

On 02/08/2018 06:18 PM, Greg KH wrote:
> On Thu, Feb 08, 2018 at 06:10:59PM +0100, jjDaNiMoTh wrote:
>> Hello everyone,
>>
>> There is an example of LTE netdevice in the Linux source tree?
>>
>> In particular, I would like to know if there is any device driver that
>> implements the layers required by the 3GPP standard. I imagine that it
>> should exist something since Android is communicating over LTE, but I can't
>> find any reference.
> 
> That communication happens usually through a "dumb" serial-like
> connection to the LTE modem.  All of the modem commands are handled in
> userspace, the kernel doesn't care about anything relating to this at
> all (and it really shouldn't).
> 
>> What I fear more is that everything related to LTE is inside the
>> closed device firmware, and data is sent from the TC layer into this
>> black-box firmware through a sort of API. In this case, it would be
>> wonderful to know where, exactly, this API is used, to try to
>> understand what the firmware is doing.
> 
> Look at the Android AOSP images for the location for most of this logic,
> there should be a Telephony HAL somewhere in there that handles the
> heavy-lifting of all of this logic.
> 

As far as i know in AOSP you can look into hardware/ril for the modem
integration. There is a generic RIL daemon which interacts with a RIL
library which is vendor specific and is responsible to configure the
hardware. And that can be a problem because the vendor software most
likely is not open source but you may always give a look to the daemon
which is part of the

> Good luck!
> 
> greg k-h
> 
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