Interface between LTE devices and Linux

[Greg KH]

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.

Good luck!

greg k-h