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

Hello Christoph,

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.

Thanks for clearing this up.

Best regards,
Marek Vasut