Date:   Thu, 20 Dec 2018 10:19:07 +0000
From:   Ben Whitten <Ben.Whitten@...rdtech.com>
To:     Jian-Hong Pan <starnight@...cu.edu.tw>
CC:     Andreas Färber <afaerber@...e.de>,
        Jiri Pirko <jiri@...nulli.us>,
        "David S. Miller" <davem@...emloft.net>,
        Alan Cox <gnomes@...rguk.ukuu.org.uk>,
        "linux-lpwan@...ts.infradead.org" <linux-lpwan@...ts.infradead.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Marcel Holtmann <marcel@...tmann.org>,
        Dollar Chen <dollar.chen@...ec.com>,
        Ken Yu <ken.yu@...wireless.com>,
        linux-wpan - ML <linux-wpan@...r.kernel.org>
Subject: RE: [PATCH v5 5/6] net: maclorawan: Implement maclorawan class module

> > > Am 18.12.18 um 15:27 schrieb Jian-Hong Pan:
> > > >> Sun, Dec 16, 2018 at 11:18:59AM CET, starnight@...cu.edu.tw wrote:
> > > >>> LoRaWAN defined by LoRa Alliance(TM) is the MAC layer over LoRa
> > > devices.
> > > >>>
> > > >>> This patch implements part of Class A end-devices SoftMAC defined in
> > > >>> LoRaWAN(TM) Specification Ver. 1.0.2:
> > > >>> 1. End-device receive slot timing
> > > >>> 2. Only single channel and single data rate for now
> > > >>> 3. Unconfirmed data up/down message types
> > > >>>
> > > >>> On the other side, it defines the basic interface and operation
> > > >>> functions for compatible LoRa device drivers.
> > > >>>
> > > >>> Signed-off-by: Jian-Hong Pan <starnight@...cu.edu.tw>
> > > [...]
> > > >>> net/maclorawan/Kconfig  |  14 +
> > > >>> net/maclorawan/Makefile |   2 +
> > > >>> net/maclorawan/mac.c    | 555
> > > ++++++++++++++++++++++++++++++++++++
> > > >>> net/maclorawan/main.c   | 606
> > > ++++++++++++++++++++++++++++++++++++++++
> > > >>> 4 files changed, 1177 insertions(+)
> > > >>> create mode 100644 net/maclorawan/Kconfig
> > > >>> create mode 100644 net/maclorawan/Makefile
> > > >>> create mode 100644 net/maclorawan/mac.c
> > > >>> create mode 100644 net/maclorawan/main.c
> > > >>
> > > >> I don't get it. In patch "Add LoRaWAN API declaration for LoRa devices"
> > > >> you add headers for "API" and here you implement functions. That is
> just
> > > >> weird. Does it mean you can have other implementations?
> > > >
> > > > LoRaWAN defined by LoRa Alliance(TM) is the MAC layer over LoRa PHY.
> > > > This part is soft-MAC as Andreas mentioned
> > > > http://lists.infradead.org/pipermail/linux-lpwan/2018-
> > > December/000010.html
> > > >
> > > >> Also, you don't really have any user of this API in the set. Please
> > > >> introduce at least 1 driver, preferably more (I see that Andreas has
> > > >> multiple ones in his patchset). You cannot push kernel infrastructure
> > > >> without kernel user.
> > > >
> > > > The soft-MAC is suitable for the LoRa chips' device drivers, like
> > > > sx1276/77/78/79, RFM95/96/97/98W ...
> > > > Still waiting for Andreas' sx1276 version 2 patch and more discussion.
> > >
> > > sx1276 regmap conversion was pushed to my staging tree together with
> > > Ben's sx1301 final conversion last night, lightly tested.
> > >
> > > https://git.kernel.org/pub/scm/linux/kernel/git/afaerber/linux-
> > > lora.git/log/?h=lora-next
> > >
> > > TBD: rename to sx127x, implement regmap fields, only auto-detect reset
> > > when no OF node available (all low priority atm, patches welcome)
> > >
> > > (and for sx1301 I still need to update my DT overlays with the new clk)
> > >
> > > > For example, how to make PF_LORA and PF_LORAWAN like Ethernet,
> > > PF_INET
> > > > and PF_INET6 don't need separate devices either, both use eth0.
> > > > https://lkml.org/lkml/2018/8/3/266
> > >
> > > Jiri, I am expecting the maclorawan driver to lower packets from
> > > ETH_P_LORAWAN to ETH_P_LORA in a generic way, so that any of the LoRa
> > > device drivers can benefit of it, with maclorawan using the LoRa netlink
> > > commands that the individual drivers implement.
> > > Not sure what if anything is missing for that in the current revision?
> > > Still dealing with the lower-level infrastructure and my test setup ...
> > > progressing slowly.
> > >
> > > I'll probably need to queue the remaining generic LoRaWAN part 1/6 in my
> > > tree to resolve this circular dependency between Jian-Hong and me, so
> > > that only the soft-MAC implementation remains a separate patch series.
> > > The hard-MAC implementations will be on my plate mostly, as both SX1276
> > > and SX1301 need the soft-MAC.
> >
> > On the SX1301 side of things, the ability to send messages as a LoRaWAN
> > node device is a niche use case, the majority if not all people will use the
> > concentrator card as the pass through gateway to the node.
> >
> > In this mode of operation the parameters for transmission such as;
> frequency,
> > spreading factor / data rate, power, are given by a remote server and passed
> > in from the userspace application which received it.
> > Eventually in the kernel these need to be checked locally to ensure
> regulatory
> > compliance.
> > To that end I have experimented with framing, as CAN does, so that this
> > metadata can be provided on a write from userspace to the SX1301 driver.
> >
> > Sounds like we need different protocols for framing within the protocol
> family.
> > Raw in the case of nodes and framed with metadata in the case of
> concentrator
> > cards, thoughts?
> 
> Yes, I have thought the roles of node and gateway.  They may have
> different skb passing paths.
> As you mentioned, many things of the gateway is controlled by the
> remote server.  So, I only implement the path for nodes right now.
> Maybe, we can have a role flag: node, gateway which can be assigned by
> some way.  Then, the skb can be decode, checked and passed according
> to the role flag.  And module also checks the integrity (MIC, length
> ...) and filter out the bad skb before sends to next stop.

As IP have IPPROTO_TCP, IPPROTO_UDP, etc maybe we can have
LORA_PROTO_MODULE, LORA_PROTO_GATEWAY which dictates the
pathway and skb format.

> > I will send my experiment RFC to the lpwan mailing list.
> 
> Or you can send the RFC first.  Then we can have the skb passing path
> for gateway and figure out how to put them together.
> 
> Does this sound reasonable?

Sent, it's being held at mailing list for moderator approval but should be in
your inboxes currently.

Regards,
Ben

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