netdev - WWAN Controller Framework (was IPA [PATCH v2 00/17])

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Message-ID: <23ff4cce-1fee-98ab-3608-1fd09c2d97f1@linaro.org>
Date:   Mon, 24 Jun 2019 11:30:35 -0500
From:   Alex Elder <elder@...aro.org>
To:     davem@...emloft.net, arnd@...db.de, bjorn.andersson@...aro.org,
        ilias.apalodimas@...aro.org
Cc:     evgreen@...omium.org, benchan@...gle.com, ejcaruso@...gle.com,
        cpratapa@...eaurora.org, syadagir@...eaurora.org,
        subashab@...eaurora.org, abhishek.esse@...il.com,
        netdev@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-soc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-arm-msm@...r.kernel.org
Subject: WWAN Controller Framework (was IPA [PATCH v2 00/17])

OK I want to try to organize a little more concisely some of the
discussion on this, because there is a very large amount of volume
to date and I think we need to try to narrow the focus back down
again.

I'm going to use a few terms here.  Some of these I really don't
like, but I want to be unambiguous *and* (at least for now) I want
to avoid the very overloaded term "device".

I have lots more to say, but let's start with a top-level picture,
to make sure we're all on the same page.

         WWAN Communication
         Channel (Physical)
                 |     ------------------------
------------     v     |           :+ Control |  \
|          |-----------|           :+ Data    |  |
|    AP    |           | WWAN unit :+ Voice   |   > Functions
|          |===========|           :+ GPS     |  |
------------     ^     |           :+ ...     |  /
                 |     -------------------------
          Multiplexed WWAN
           Communication
         Channel (Physical)

- The *AP* is the main CPU complex that's running Linux on one or
  more CPU cores.
- A *WWAN unit* is an entity that shares one or more physical
  *WWAN communication channels* with the AP.
- A *WWAN communication channel* is a bidirectional means of
  carrying data between the AP and WWAN unit.
- A WWAN communication channel carries data using a *WWAN protocol*.
- A WWAN unit implements one or more *WWAN functions*, such as
  5G data, LTE voice, GPS, and so on.
- A WWAN unit shall implement a *WWAN control function*, used to
  manage the use of other WWAN functions, as well as the WWAN unit
  itself.
- The AP communicates with a WWAN function using a WWAN protocol.
- A WWAN physical channel can be *multiplexed*, in which case it
  carries the data for one or more *WWAN logical channels*.
- A multiplexed WWAN communication channel uses a *WWAN wultiplexing
  protocol*, which is used to separate independent data streams
  carrying other WWAN protocols.
- A WWAN logical channel carries a bidirectional stream of WWAN
  protocol data between an entity on the AP and a WWAN function.

Does that adequately represent a very high-level picture of what
we're trying to manage?

And if I understand it right, the purpose of the generic framework
being discussed is to define a common mechanism for managing (i.e.,
discovering, creating, destroying, querying, configuring, enabling,
disabling, etc.) WWAN units and the functions they implement, along
with the communication and logical channels used to communicate with
them.

Comments?

					-Alex