Re: [PATCH v4 1/3] xen/arm: Add imx8q{m,x} platform glue

From: Michal Orzel <michal.orzel@amd.com>
To: John Ernberg <john.ernberg@actia.se>,
	Julien Grall <julien@xen.org>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Bertrand Marquis <bertrand.marquis@arm.com>,
	Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
	George Dunlap <george.dunlap@citrix.com>,
	Jan Beulich <jbeulich@suse.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	Peng Fan <peng.fan@nxp.com>, Jonas Blixt <jonas.blixt@actia.se>
Subject: Re: [PATCH v4 1/3] xen/arm: Add imx8q{m,x} platform glue
Date: Tue, 9 Apr 2024 08:47:00 +0200	[thread overview]
Message-ID: <d02b7de4-41bf-4bf9-8b04-e21625449f27@amd.com> (raw)
In-Reply-To: <20240408161129.900347-2-john.ernberg@actia.se>

Hi John,

On 08/04/2024 18:11, John Ernberg wrote:
> 
> 
> When using Linux for dom0 there are a bunch of drivers that need to do SMC
> SIP calls into the firmware to enable certain hardware bits like the
> watchdog.
> 
> Provide a basic platform glue that implements the needed SMC forwarding.
> 
> The format of these calls are as follows:
>  - reg 0: function ID
>  - reg 1: subfunction ID (when there's a subfunction)
>  remaining regs: args
> 
> For now we only allow Dom0 to make these calls as they are all managing
> hardware. There is no specification for these SIP calls, the IDs and names
> have been extracted from the upstream linux kernel and the vendor kernel.
> 
> Most of the SIP calls are only available for the iMX8M series of SoCs, so
> they are easy to reject and they need to be revisited when iMX8M series
> support is added.
Stale paragraph. Should be removed given that the driver targets only Q{M,XP}.

> 
> From the other calls we can reject CPUFREQ because Dom0 cannot make an
> informed decision regarding CPU frequency scaling, WAKEUP_SRC is to wake
> up from suspend, which Xen doesn't support at this time.
> 
> This leaves the TIME SIP, OTP SIPs, BUILDINFO SIP and TEMP ALARM SIP, which
> for now are allowed to Dom0.
BUILDINFO, TEMP ALARM are leftovers from previous revision.

> 
> NOTE: This code is based on code found in NXP Xen tree located here:
> https://github.com/nxp-imx/imx-xen/blob/lf-5.10.y_4.13/xen/arch/arm/platforms/imx8qm.c
> 
> Signed-off-by: Peng Fan <peng.fan@nxp.com>
> [jernberg: Add SIP call filtering]
> Signed-off-by: John Ernberg <john.ernberg@actia.se>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>

The commit msg can be fixed on commit.

~Michal