linux-kernel - Re: [PATCH] arm64: dts: ti: k3-am64-main: Add SYSFW reserved ranges in OCRAM

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Message-ID: <20210614142849.ogi4emuqgxg3m7ls@constrict>
Date:   Mon, 14 Jun 2021 09:28:49 -0500
From:   Nishanth Menon <nm@...com>
To:     Aswath Govindraju <a-govindraju@...com>
CC:     Vignesh Raghavendra <vigneshr@...com>,
        Rob Herring <robh+dt@...nel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Linux ARM Mailing List <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] arm64: dts: ti: k3-am64-main: Add SYSFW reserved ranges
 in OCRAM

On 10:18-20210614, Aswath Govindraju wrote:
> Hi Vignesh,
> 
> On 12/06/21 12:51 pm, Vignesh Raghavendra wrote:
> > +Aswath
> > 
> > On 6/12/21 12:46 AM, Nishanth Menon wrote:
> >> On 19:36-20210609, Vignesh Raghavendra wrote:
> >>> Last 256K of OCRAM (256K@...01c0000) is reserved for SYSFW usage. Hence
> >>> add an entry in DT so that its not used for generic pool memory
> >>> allocation.
> >>
> >> Are you really sure?? I know that I had set a budget for 16K in sysfw
> >> when I did the memory split up for sysfw of which 16k is actually used.
> >>
> >> Not sure where this 256K bucket started off from.. am I missing
> >> something here?
> >>
> > 
> > Per: http://software-dl.ti.com/tisci/esd/latest/5_soc_doc/am64x/firewalls.html
> > 
> > 24	dmsc	0x44060000	0x4407BFFF	dmsc,rwcd	 	 // alias for 0x701E0000
> > 24	dmsc	0x701FC000	0x701FFFFF	sproxy_private,rwcd	 	 
> > 24	dmsc	0x4407C000	0x4407FFFF	sproxy_private,rwcd	 	 
> > 24	dmsc	0x701C0000	0x701DFFFF	everyone,rwcd	 	 
> > 
> > So it looks like only 128K@...01E0000 is firewalled off. 
> > Will update the patch.
> > 
> > This makes me wonder why ATF is being moved to 0x701a0000-0x701c0000
> > leaving a hole at 0x701C0000-0x701DFFFF? 
> > 
> > 
> 
> The reason for leaving the hole at 0x701C0000-0x701DFFFF was because
> initially there was a bug in SYSFW which lead to the usage of the above
> region too by it. However, this bug was recently fixed and the the above
> region can be used for ATF.


OK. I am going to drop the TF-A update patch from my queue.

NOTE:
a) Default device configuration (if no specific API call[1]) is done
   assumes last 128K is reserved.
b) if bootloader does invoke optionally a call[1] then only 16K is
   reserved for communication and remainder of 128K is released for usage
   with the constraint that TF-A/OPTEE takes control of security resources.
c) This is only a feature in AM64x devices so, handling is device
   specific.

Hence, on AM64x: (a) should be our default configuration and (b) can
be board specific configuration OR overlay depending on bootloader
capability.

[1] http://downloads.ti.com/tisci/esd/latest/6_topic_user_guides/security_handover.html#triggering-security-handover
-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D