From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Sakkinen Subject: Re: [PATCH v10 8/8] tpm: TPM 2.0 FIFO Interface Date: Sun, 14 Dec 2014 17:40:03 +0200 Message-ID: <20141214154003.GA13338@intel.com> References: <1418413600-5400-1-git-send-email-jarkko.sakkinen@linux.intel.com> <1418413600-5400-9-git-send-email-jarkko.sakkinen@linux.intel.com> <548DA33A.4010300@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <548DA33A.4010300-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Stefan Berger Cc: Peter Huewe , Ashley Lai , Marcel Selhorst , tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, josh-iaAMLnmF4UmaiuxdJuQwMA@public.gmane.org, christophe.ricard-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, jason.gunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, trousers-tech-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, Will Arthur List-Id: linux-api@vger.kernel.org On Sun, Dec 14, 2014 at 09:48:26AM -0500, Stefan Berger wrote: > On 12/12/2014 02:46 PM, Jarkko Sakkinen wrote: > >Detect TPM 2.0 by sending idempotent TPM 2.x command. Ordinals for > >TPM 2.0 are higher than TPM 1.x commands so this should be fail-safe. > >Using STS3 is unreliable because some chips just report 0xff and not > >what the spec says. > > TPM TIS 1.2 can report either 0xff or 0x00 for sts3 since that part of > register was not defined for this version but only for a later version. So, > unless the TIS 1.3 for TPM 2.0 is broken, it should report a bit _pattern_ > (not plain 0x00 or 0xff) that you could apply the suggested mask to and > check then. I propose this: lets keep the bit ugly but approach for now and when there are TPM2 FIFOs available in the market move to your workaround. I think that would be the most reasonable middle road here. > Stefan /Jarkko