[U-Boot] [PATCHv2 2/3] ARMv8/layerscape: Add FSL PPA support

[Bhupesh Sharma]

> From: Scott Wood [mailto:oss at buserror.net]
> Sent: Saturday, January 23, 2016 1:48 AM
> On Fri, 2016-01-22 at 20:14 +0000, Bhupesh Sharma wrote:
> >
> > > -----Original Message-----
> > > From: Scott Wood [mailto:oss at buserror.net]
> > > Sent: Saturday, January 23, 2016 1:39 AM
> > > To: york sun; Zhiqiang Hou; u-boot at lists.denx.de;
> > > albert.u.boot at aribaud.net; Mingkai.hu at freescale.com; Stuart Yoder;
> > > leoli at freescale.com; prabhakar at freescale.com;
> > > bhupesh.sharma at freescale.com; Zhiqiang Hou
> > > Subject: Re: [PATCHv2 2/3] ARMv8/layerscape: Add FSL PPA support
> > >
> > > On Fri, 2016-01-22 at 20:05 +0000, york sun wrote:
> > > > On 01/21/2016 01:53 AM, Zhiqiang Hou wrote:
> > > > > From: Hou Zhiqiang <Zhiqiang.Hou at freescale.com>
> > > > >
> > > > > The FSL Primary Protected Application (PPA) is a software
> > > > > component loaded during boot which runs in TrustZone and remains
> > > > > resident after boot.
> > > > >
> > > > > Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou at freescale.com>
> > > > > ---
> > > > > Tested on LS1043A RDB board
> > > > >
> > > >
> > > > I presume PSCI is implemented in PPA. How does the SMP boot flow
> > > > change with PPA? U-boot has to remain functional in the absence of
> > > > PPA,
> > > right?
> > > >
> > > > Would it be possible to write a readme for PPA?
> > >
> > > Also, how does the devicetree get updated to indicate the presence
> > > of PSCI?
> > >
> >
> > One needs to add PSCI node in the DTS for the same, claiming support
> > for PSCI specification.
> 
> So then we need a different dts based on whether PPA is loaded?  No
> thanks.

For e.g the current LS2080A DTS has no separate node for PSCI, the same can be patched-up/added
by the Bootloader.

> 
> > The cpu.enable_method needs to be changed from spin-table to psci as
> well.
> 
> Right, that's part of updating the devicetree to indicate the presence of
> PSCI.

Similarly the cpu.enable-method is also empty in the LS2080A DTS to allow Bootloader to patch
it accordingly.
 
Please see: http://lxr.free-electrons.com/source/arch/arm64/boot/dts/freescale/fsl-ls2080a.dtsi#L65 

> > See
> > http://lxr.free-electrons.com/source/Documentation/devicetree/bindings
> > /a
> > rm/psci.txt for details.
> 
> I'm familiar with the binding.

Regards,
Bhupesh