[PATCH 2/3] ARM: mxs: crypto: Add Freescale MXS DCP driver

Hello Herbert,

On Mon, Oct 07, 2013 at 05:48:26PM +0200, Marek Vasut wrote:

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Hello Christoph,

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Hello Marek,

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Marek Vasut [off-list ref] hat am 28. September 2013 um 05:35
geschrieben: [...]

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3) What are those ugly new IOCTLs in the dcp.c driver?

When I firstly posted the driver in the mailinglist, there where
one person who actually used this interface (it was introduced in
Freescale's SDK) to use the OTP keys for crypto. As far as I have
seen, the crypto API does not support such keys (i.e. there seems
to be no way to tell a driver to use some kind of special keys -
which are not delivered by the user - via the API).
Therefore I added this miscdevice and adopted Freescale's
interface.

The keys are programmed into the OTP registers, correct? There is
OCOTP d

river
for the MX23/MX28 OTP hardware. This is what should have been used
then.

NOTE: This IOCTL interface seems like quite an abusive way to allow
userl

and to
access the crypto API in kernel. I understand this is used by some
Freesc ale tool, but won't it be better to fix the Freescale tool
instead ?

the IOCTL interface is used to AES encrypt a bootstream with the AES
key in OCOTP.
The idea is that only the DCP can read/access the key once it has been
programmed
into the OCOTP. If the crypto API has means to tell the DCP to use the
key from OCOTP, the tool from Freescale is a minor problem.

Ah right. I suspect the crypto API services shall not be exported into
userland at all, yes ? So there has to be some kind of workaround here
for this freescale tool, which is rather unfortunate.

These ioctls have to go.  I should have never let them through in
the first place.  Can someone cook up a patch to kill them please?

I can do that. I wonder if we can't agree to nuke the in-tree driver altogether 
instead and replace it by this one though. Does it not sound more reasonable?

Best regards,
Marek Vasut