Hi Martin,
On Mon, 18 Jun 2018 08:20:20 +0000, "Hecht, Martin (Avnet Silica)" Martin.Hecht@avnet.eu wrote:
Hi Miquel,
-----Original Message----- From: Miquel Raynal [mailto:miquel.raynal@bootlin.com] Sent: Montag, 18. Juni 2018 10:05 To: Hecht, Martin (Avnet Silica) Martin.Hecht@avnet.eu Cc: sjg@chromium.org; u-boot@lists.denx.de Subject: Re: [U-Boot] tpm TIS TPMv2.0
Hi Martin,
On Fri, 15 Jun 2018 13:34:07 +0000, "Hecht, Martin (Avnet Silica)" Martin.Hecht@avnet.eu wrote:
Hi Miquel, Simon,
Is there any specific reason why the new tpm2_tis_spi_xfer doesn't
support full duplex? It seems we did some work in parallel but you sent the patches earlier. Is that codes tested against an existing TPM v2? I have a working implementation what runs on SLB9670 including full duplex.
What do you mean exactly?
I don't think the TPM2 protocol makes real use of full-duplex unless for the wait state between the host command and the actual xfer.
You are right, TIS 1.3 FIFO doesn’t use full duplex in physical level. What I mean is that the driver you just wrote doesn't use the xfer function in that way that you can specify in and out parameters at same time. I did this in my implementation what gave me an easy chance to control the CS# of the TPM.
Do you need this CS# handling for more advanced features? Same question for the in/out xfers?
Can you tell me on what TPM did you test? For the SLB9670 the code doesn't work on my hardware.
I tested with a ST33TPHF20 SPI TPM.
I'm surprised it did not work with an SLB9670, I don't see anything in the spec explaining this CS# specificity.
For the code you wrote I'm considering to add a few lines to control the CS# in that way how my xfer is doing this for the SLB9670.
Yes please, share the patch and add me in cc so I could test it with mine.
On the other hand what about to use a xfer what can handle all three cases (in, out, in/out)?
As I did not implement any TPM command that needed it I did not care about it. Of course if there is a need for it: it should be implemented too. I contributed only basic support for essential commands (measured boot, mainly) but please feel free to enhance the code to add more features!
Regards, Miquèl