On Tue, Jul 25, 2017 at 10:36:11AM -0700, James Bottomley wrote: > On Tue, 2017-07-25 at 15:04 +0200, Michal Suchánek wrote: > > Hello, > > > > in commit 9754d45e9970 ("tpm: read burstcount from TPM_STS in one > > 32-bit transaction") you change reading of two 8-bit values to one > > 32bit read. This is obviously wrong wrt endianess unless the > > underlying tpm_tis_read32 does endian conversion. > > Some of the bus read primitives do do endianness conversions. The > problem is with the SPI attachment, which has unclear endianness. A > standard PCI bus attachment uses ioread32() which automatically > transforms from a little endian bus to the cpu endianness, however SPI > is forced to transfer the bytes one at a time over the serial bus and > then transform. The assumption seems to be that the TIS TPM is > replying in little endian format when SPI connected. > > We can probably get the PPC people to confirm this, I believe they have > a SPI attached TPM.
All the current OpenPOWER hardware designs I'm aware of have the TPM on I2C. Trusted Computing support in OpenPOWER firmware depends on it being on I2C. > > James > > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > tpmdd-devel mailing list > tpmdd-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/tpmdd-devel ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ tpmdd-devel mailing list tpmdd-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/tpmdd-devel