linux-kernel - RE: [PATCH v11 2/2] mailbox: introduce ARM SMC based mailbox

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Message-ID: <AM0PR04MB448137850D19BADD11F75B18880B0@AM0PR04MB4481.eurprd04.prod.outlook.com>
Date:   Mon, 27 Jan 2020 12:58:12 +0000
From:   Peng Fan <peng.fan@....com>
To:     Etienne Carriere <etienne.carriere@...aro.org>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>,
        "andre.przywara@....com" <andre.przywara@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        etienne carriere <etienne.carriere@...com>,
        Sudeep Holla <sudeep.holla@....com>
Subject: RE: [PATCH v11 2/2] mailbox: introduce ARM SMC based mailbox

> Subject: Re: [PATCH v11 2/2] mailbox: introduce ARM SMC based mailbox
> 
> Hello Peng and all,
> 
> 
> > From: Peng Fan <peng.fan@....com>
> >
> > This mailbox driver implements a mailbox which signals transmitted
> > data via an ARM smc (secure monitor call) instruction. The mailbox
> > receiver is implemented in firmware and can synchronously return data
> > when it returns execution to the non-secure world again.
> > An asynchronous receive path is not implemented.
> > This allows the usage of a mailbox to trigger firmware actions on SoCs
> > which either don't have a separate management processor or on which
> > such a core is not available. A user of this mailbox could be the SCP
> > interface.
> >
> > Modified from Andre Przywara's v2 patch
> > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore
> > .kernel.org%2Fpatchwork%2Fpatch%2F812999%2F&amp;data=02%7C01%7
> Cpeng.fa
> >
> n%40nxp.com%7C735cc6cd00404082bf8c08d79f67b93a%7C686ea1d3bc2b4
> c6fa92cd
> >
> 99c5c301635%7C0%7C0%7C637153140140878278&amp;sdata=m0lcAEIr0ZP
> tyPHorSW
> > NYgjfI5p0genJLlhqHMIHBg0%3D&amp;reserved=0
> >
> > Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
> > Reviewed-by: Andre Przywara <andre.przywara@....com>
> > Signed-off-by: Peng Fan <peng.fan@....com>
> 
> I've successfully tested your change on my board. It is a stm32mp1 with TZ
> secure hardening and I run an OP-TEE firmware (possibly a TF-A
> sp_min) with a SCMI server for clock and reset. Upstream in progress.
> The platform uses 2 instances of your SMC based mailbox device driver
> (2 mailboxes). Works nice with your change.
> 
> You can add my T-b tag: Tested-by: Etienne Carriere
> <etienne.carriere@...aro.org>

Thanks, but this patch has been dropped.

Per Sudeep, we all use smc transport, not smc mailbox ,
I'll post patch in a few days based on the transport split patch.

> 
> FYI, I'll (hopefully soon) post a change proposal in U-Boot ML for an equvalent
> 'SMC based mailbox' driver and SCMI agent protocol/device drivers for clock
> and reset controllers.

Great to know you did scmi agent code in U-Boot. Do you have some public repo
for access?

Thanks,
Peng.

> I'm also working on getting this SCMI server upstream in TF-A and OP-TEE.
> Your SMC based mailbox driver is a valuable notification scheme for our SCMI
> services support in Arm TZ secure world.
> 
> Regards,
> Etienne