Atmel I2C TPM transfer length issues

[Andrew Lunn <andrew-g2DYL2Zd6BY@public.gmane.org>]

Hi Jason

I'm hoping you can help me with an issue i have with an ATMEL I2C
TPM. I have one connected to an DLN2 USB-I2C bus controller. Initial
probe works, i can get the capabilites in /sys/class/tpm/tpm0,
tpm_version etc:

/sys/class/tpm/tpm0# cat caps 
Manufacturer: 0x41544d4c
TCG version: 1.2
Firmware version: 66.4

But i have issues with pubek and other long i2c transfers:

/sys/class/tpm/tpm0# hexdump pubek
[11621.731960] i2c i2c-11: adapter quirk: msg too long (addr 0x0029, size 314, read)
[11621.738208] tpm tpm0: tpm_transmit: tpm_recv: error -95

The dln2 i2c bus controller has a transfer limit of 256 bytes. Getting
the pubek is doing a read for 314 bytes, which is getting rejected.

Is there any way to fragment the reads/writes? Looking at
tpm_i2c_atmel i don't see any. It seems the raw TCG commands need to
be passed in a single i2c transaction. The comment in i2c_atmel_recv()
suggests that multiple reads will always start from the beginning of
the TCG response. There are no comments in the send function, but i
guess an I2C start condition indicates the start of a new command?

Or am i missing something?

Can fragmentation happen at a higher layer?

Any other ideas?

Thanks
	Andrew

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