Newer versions of ARM TrustedFirmware-A on MediaTek's ARMv8 SoCs no longer
allow accessing the TRNG from outside of the trusted firmware.
Instead, a vendor-defined custom Secure Monitor Call can be used to
acquire random bytes.
Add support for newer SoCs (MT7981, MT7987, MT7988).
As TF-A for the MT7986 may either follow the old or the new
convention, the best bet is to test if firmware blocks direct access
to the hwrng and if so, expect the SMCC interface to be usable.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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