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

[Scott Wood]

On Fri, 2016-01-22 at 20:18 +0000, york sun wrote:
> On 01/22/2016 12:14 PM, 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.
> > The cpu.enable_method needs to be changed from spin-table to psci as well.
> > 
> > See http://lxr.free-electrons.com/source/Documentation/devicetree/bindings
> > /arm/psci.txt for details.
> > 
> 
> Bhupesh,
> 
> Before PPA is fully adopted, u-boot has to detect the existence of PPA and
> decide to use PSCI or spin table, right? So the device tree node should also
> be
> fixed accordingly.

How would U-Boot know what version of PSCI the loaded PPA supports?  Is or
could there be any metadata on the PPA image to convey such information?

-Scott