From:   Horia Geanta <horia.geanta@nxp.com>
To:     Chris Spencer <spencercw@gmail.com>
CC:     Aymen Sghaier <aymen.sghaier@nxp.com>,
        "linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
        Chris Spencer <christopher.spencer@sea.co.uk>,
        dl-linux-imx <linux-imx@nxp.com>
Subject: Re: [RFC 4/4] crypto: caam - use job ring for RNG instantiation
 instead of DECO
Thread-Topic: [RFC 4/4] crypto: caam - use job ring for RNG instantiation
 instead of DECO
Thread-Index: AQHUypZsrSD4izM7BUuBqlVaxZEyMQ==
Date:   Mon, 4 Mar 2019 18:13:19 +0000
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References: <20190222100613.2290-1-christopher.spencer@sea.co.uk>
 <20190222100613.2290-5-christopher.spencer@sea.co.uk>
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On 2/28/2019 1:34 PM, Chris Spencer wrote:=0A=
> What I have found is that if I set virt_en =3D 1 then the RNG is able to=
=0A=
> initialise correctly via the DECO. The register values I am seeing=0A=
> are:=0A=
> =0A=
> comp_params =3D 01914201=0A=
> scfgr =3D 00000001=0A=
> =0A=
> So:=0A=
> VIRT_EN_INCL =3D 1 & VIRT_EN_POR =3D 0 & SCFGR_VIRT_EN =3D 0=0A=
> =0A=
> I don't have the i.MX8 security reference manual so there's only so=0A=
RM should be available from here:=0A=
https://www.nxp.com/webapp/sps/download/mod_download.jsp?colCode=3DIMX8MDQL=
QSRM&location=3Dnull&appType=3Dmoderated=0A=
=0A=
> much analysis I can do, but it seems that virtualisation is enabled in=0A=
> hardware without the registers reflecting that appropriately. If I=0A=
> patch the TF-A to set SCFGR_VIRT_EN =3D 1 in the same place it sets=0A=
> CAAM_JRxMID =3D 1 then everything seems to work, but I've got no idea if=
=0A=
> that is an appropriate change to make.=0A=
> =0A=
RNG initialization should work in both cases.=0A=
=0A=
The root cause for the failure in case virtualization is disabled is probab=
ly=0A=
the lack of setup of DECO DID registers (offsets A0h, A4h).=0A=
=0A=
Section "Register-based service interface" mentions:=0A=
"But before requesting a DECO, software must specify the DID and SDID value=
s=0A=
that will be used when executing descriptors under direct software control.=
 When=0A=
virtualization is disabled (SCFGR[VIRT_EN]=3D0), these values are specified=
 by=0A=
writing DID and SDID values into the appropriate DECO DID_MS and DECO DID_L=
S=0A=
registers."=0A=
=0A=
Horia=0A=