Re: [PATCH net-next v4 1/2] net: Add a WWAN subsystem

On Thu, 11 Mar 2021 at 17:48, Greg KH [off-list ref] wrote:

On Thu, Mar 11, 2021 at 05:39:05PM +0100, Loic Poulain wrote:

quoted

This change introduces initial support for a WWAN subsystem. Given the
complexity and heterogeneity of existing WWAN hardwares and interfaces,
there is no strict definition of what a WWAN device is and how it should
be represented. It's often a collection of multiple components/devices
that perform the global WWAN feature (netdev, tty, chardev, etc).

One usual way to expose modem controls and configuration is via high
level protocols such as the well known AT command protocol, MBIM or
QMI. The USB modems started to expose that as character devices, and
user daemons such as ModemManager learnt how to deal with that. This
initial version adds the concept of WWAN port, which can be registered
by any driver to expose one of these protocols. The WWAN core takes
care of the generic part, including character device creation and lets
the driver implementing access (fops) to the selected protocol.

Since the different components/devices do no necesserarly know about
each others, and can be created/removed in different orders, the
WWAN core ensures that devices being part of the same hardware are
also represented as a unique WWAN device, relying on the provided
parent device (e.g. mhi controller, USB device). It's a 'trick' I
copied from Johannes's earlier WWAN subsystem proposal.

This initial version is purposely minimalist, it's essentially moving
the generic part of the previously proposed mhi_wwan_ctrl driver inside
a common WWAN framework, but the implementation is open and flexible
enough to allow extension for further drivers.

Signed-off-by: Loic Poulain <redacted>
---
 drivers/net/Kconfig          |   2 +
 drivers/net/Makefile         |   1 +
 drivers/net/wwan/Kconfig     |  19 ++++++
 drivers/net/wwan/Makefile    |   8 +++
 drivers/net/wwan/wwan_core.c | 150 +++++++++++++++++++++++++++++++++++++++++++
 drivers/net/wwan/wwan_core.h |  20 ++++++
 drivers/net/wwan/wwan_port.c | 136 +++++++++++++++++++++++++++++++++++++++
 include/linux/wwan.h         | 121 ++++++++++++++++++++++++++++++++++
 8 files changed, 457 insertions(+)
 create mode 100644 drivers/net/wwan/Kconfig
 create mode 100644 drivers/net/wwan/Makefile
 create mode 100644 drivers/net/wwan/wwan_core.c
 create mode 100644 drivers/net/wwan/wwan_core.h
 create mode 100644 drivers/net/wwan/wwan_port.c
 create mode 100644 include/linux/wwan.h

What changed from the last version(s)?  That should be below the ---
somewhere, right?

v5?

Yes sorry, I've overwritten my changelog with my last format-patch,
going to address your comment and add that in the next series.

Regards,
Loic