On Thu Mar 21, 2024 at 6:09 PM EET, Stefan Berger wrote: > > > On 3/21/24 11:51, Jarkko Sakkinen wrote: > > On Wed Mar 20, 2024 at 6:15 PM EET, Stefan Berger wrote: > >> > >> > >> On 3/20/24 04:56, Jarkko Sakkinen wrote: > >>> Based recent discussions on LKML, provide preliminary bits of tpm_tis_core > >>> dependent drivers. Includes only bare essentials but can be extended later > >>> on case by case. This way some people may even want to read it later on. > >>> > >>> Cc: Jonathan Corbet <corbet@xxxxxxx> > >>> CC: Daniel P. Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx> > >>> Cc: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx> > >>> Cc: Jason Gunthorpe <jgg@xxxxxxxx> > >>> Cc: Peter Huewe <peterhuewe@xxxxxx> > >>> Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> > >>> Cc: Alexander Steffen <Alexander.Steffen@xxxxxxxxxxxx> > >>> Cc: keyrings@xxxxxxxxxxxxxxx > >>> Cc: linux-doc@xxxxxxxxxxxxxxx > >>> Cc: linux-kernel@xxxxxxxxxxxxxxx > >>> Cc: linux-integrity@xxxxxxxxxxxxxxx > >>> Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> > >>> Signed-off-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx> > >>> --- > >>> v2: > >>> - Fixed errors reported by Randy: > >>> https://lore.kernel.org/all/aed28265-d677-491a-a045-24b351854b24@xxxxxxxxxxxxx/ > >>> - Improved the text a bit to have a better presentation. > >>> --- > >>> Documentation/security/tpm/index.rst | 1 + > >>> Documentation/security/tpm/tpm_tis.rst | 30 ++++++++++++++++++++++++++ > >>> 2 files changed, 31 insertions(+) > >>> create mode 100644 Documentation/security/tpm/tpm_tis.rst > >>> > >>> diff --git a/Documentation/security/tpm/index.rst b/Documentation/security/tpm/index.rst > >>> index fc40e9f23c85..f27a17f60a96 100644 > >>> --- a/Documentation/security/tpm/index.rst > >>> +++ b/Documentation/security/tpm/index.rst > >>> @@ -5,6 +5,7 @@ Trusted Platform Module documentation > >>> .. toctree:: > >>> > >>> tpm_event_log > >>> + tpm_tis > >>> tpm_vtpm_proxy > >>> xen-tpmfront > >>> tpm_ftpm_tee > >>> diff --git a/Documentation/security/tpm/tpm_tis.rst b/Documentation/security/tpm/tpm_tis.rst > >>> new file mode 100644 > >>> index 000000000000..b331813b3c45 > >>> --- /dev/null > >>> +++ b/Documentation/security/tpm/tpm_tis.rst > >>> @@ -0,0 +1,30 @@ > >>> +.. SPDX-License-Identifier: GPL-2.0 > >>> + > >>> +========================= > >>> +TPM FIFO interface Driver > >>> +========================= > >>> + > >>> +FIFO (First-In-First-Out) is the name of the hardware interface used by the > >> > >> FIFO is the type. I am surprised you call it a 'name'. I would say TIS > >> is the 'name'. > > > > It's what the official specification calls it [1]. > > > > > >> > >>> +tpm_tis_core dependent drivers. The prefix "tis" comes from the TPM Interface > >> > >> tis is a tla -- a three letter *acronym*. You aren't using it as a 'prefix'. > > > > I don't know what "tla" means. > > > >> > >>> +Specification, which is the hardware interface specification for TPM 1.x chips. > >> > >> It's also available for TPM2. > > > > Yes, but TIS is the name used by the legacy specification. > > > The point is that TIS is not just a TPM 1.x interface but also used for > TPM 2. FIFO interface is what is used in the spec so I'll stick to that. > > > >> > >>> + > >>> +Communication is based on a 5 KiB buffer shared by the TPM chip through a > >> > >> I thought it was typically 4 KiB. > > > > You are basing this on table 9 in [1]? > > Yes. See below. > > > > >> > >>> +hardware bus or memory map, depending on the physical wiring. The buffer is > >>> +further split into five equal-size buffers, which provide equivalent sets of > > If you are referring to the MMIO region between 0xfed4 0000 and 0xfed4 > 4fff as a buffer then you are talking about a **20kb** MMIO region > (0x5000) that is **split** into equal-sized MMIO regions, each having > 4kb (0x1000). Yes, that's the 4kb then but there that one is no 5kb > 'further split into five equal-sized buffers' of presumably 1kb each. > Each locality has a 0x1000 sized MMIO region. Oops, true! I'll fix this part thanks, had a blind spot :-) Will fix for v3. BR, Jarkko
