Re: [tpmdd-devel] [PATCH] Documentation: tpm: Adds the TPM device tree node documentation

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On 09/02/2016 11:27 PM, Rob Herring wrote:
On Fri, Sep 2, 2016 at 12:06 PM, Jason Gunthorpe
<jgunthorpe@xxxxxxxxxxxxxxxxxxxx> wrote:
On Fri, Sep 02, 2016 at 09:51:21AM -0500, Rob Herring wrote:
+- linux,sml-base : base address of the Event Log. It is a physical address.
+              sml stands for shared memory log.

How is it a physical address on an i2c device? Why 2 cells (which needs
to be documented also)?

To be clear, as I understand it, this mechanism is a hand off from the
boot firmware to Linux.

The boot firmware talks i2c to the device, does some stuff, writes it
to memory and then linux reads that stuff. I agree it seems crazy to
include a random physical address like that.

I'd put that in reserved-memory then if designing this from scratch...

Thanks for the review comments.

Yes, it is in reserved-memory. I modified the explanation for linux,sml-base property to be more descriptive now in my v2 version of the patch, posted just now.

Must not be completely random as somehow the kernel doesn't use that memory.

The linux,sml-* names appear to have been used by IBM for a long time
on their enterprise PPC platforms (see drivers/char/tpm/tpm_of.c), so
I've expected we have to keep them?

Yes. I wasn't aware of that.

I asked Nayna to document this stuff IBM is doing so the rest of us
in TPM land can have a hope of maintaining it...

Jason
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