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SPI-Helper: Checking expect bit requires checking stsValid as well #2891

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AndreasFuchsTPM opened this issue Aug 20, 2024 · 0 comments · May be fixed by #2899

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AndreasFuchsTPM commented Aug 20, 2024 •

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The SPI-Helper seems to not check the expect bit nor the stsValid bit during command transmission.

The transfer should go as follows:

Write 1 byte
Check that expect and stsValid are both set (loop until stsValid)
Write the rest of the command except for the last byte (respecting burstcount and expect and stsValid along the way).
Check that expect and stsValid are set.
Write the last byte
Check that except is clear but stsValid is set.

Same applies for dataAvail during reception.

tpm2-tss/src/tss2-tcti/tcti-spi-helper.c

Line 407 in c641c77

    
           static void spi_tpm_helper_fifo_transfer(TSS2_TCTI_SPI_HELPER_CONTEXT* ctx, uint8_t* transfer_buffer, size_t transfer_size, enum TCTI_SPI_HELPER_FIFO_TRANSFER_DIRECTION direction)

wxleong linked a pull request

that will close this issue

Refactor and Update the tcti-x-helper #2899

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