Add support for eMMC inline encryption using the blk-crypto framework
(Documentation/block/inline-encryption.rst).

eMMC inline encryption support is specified by the upcoming JEDEC eMMC
v5.2 specification.  It is only specified for the CQ interface, not the
non-CQ interface.  Although the eMMC v5.2 specification hasn't been
officially released yet, the crypto support was already agreed on
several years ago, and it was already implemented by at least two major
hardware vendors.  Lots of hardware in the field already supports and
uses it, e.g. Snapdragon 630 to give one example.

eMMC inline encryption support is very similar to the UFS inline
encryption support which was standardized in the UFS v2.1 specification
and was already upstreamed.  The only major difference is that eMMC
limits data unit numbers to 32 bits, unlike UFS's 64 bits.

Like we did with UFS, make the crypto support opt-in by individual
drivers; don't enable it automatically whenever the hardware declares
crypto support.  This is necessary because in every case we've seen,
some extra vendor-specific logic is needed to use the crypto support.
Co-developed-by: NSatya Tangirala <satyat@google.com>
Signed-off-by: NSatya Tangirala <satyat@google.com>
Acked-by: NAdrian Hunter <adrian.hunter@intel.com>
Reviewed-by: NSatya Tangirala <satyat@google.com>
Reviewed-and-tested-by: NPeng Zhou <peng.zhou@mediatek.com>
Signed-off-by: NEric Biggers <ebiggers@google.com>
Link: https://lore.kernel.org/r/20210125183810.198008-5-ebiggers@kernel.orgSigned-off-by: NUlf Hansson <ulf.hansson@linaro.org>