Exynos850 has True Random Number Generator (TRNG) block which is very
similar to Exynos5250 for which the driver already exists
(exynos-trng.c). There are two differences though:
  1. Additional SSS PCLK clock has to be enabled to make TRNG registers
     accessible.
  2. All SSS registers (including TRNG area) are protected with
     TrustZone and can only be accessed from EL3 monitor. So the
     corresponding SMC calls have to be used instead to interact with
     TRNG block.

This patch series enables TRNG support on Exynos850 SoC. It was tested
on the E850-96 board running Debian rootfs like this:

    8<-------------------------------------------------------------->8
    # cat /sys/devices/virtual/misc/hw_random/rng_current
    exyswd_rng

    # dd if=/dev/hwrng bs=100000 count=1 > /dev/null
    ...
    122KB/s

    # apt install rng-tools5
    # rngtest -c 1000 < /dev/hwrng
    ...
    rngtest: starting FIPS tests...
    rngtest: bits received from input: 20000032
    rngtest: FIPS 140-2 successes: 1000
    rngtest: FIPS 140-2 failures: 0
    rngtest: FIPS 140-2(2001-10-10) Monobit: 0
    rngtest: FIPS 140-2(2001-10-10) Poker: 0
    rngtest: FIPS 140-2(2001-10-10) Runs: 0
    rngtest: FIPS 140-2(2001-10-10) Long run: 0
    rngtest: FIPS 140-2(2001-10-10) Continuous run: 0
    rngtest: input channel speed: (min=941.855; avg=965.515;
             max=968.236)Kibits/s
    rngtest: FIPS tests speed: (min=49.542; avg=52.886;
             max=53.577)Mibits/s
    rngtest: Program run time: 20590194 microseconds
    8<-------------------------------------------------------------->8

Sam Protsenko (7):
  dt-bindings: rng: Rename exynos5250-trng to exynos-trng
  dt-bindings: rng: Add Exynos850 support to exynos-trng
  hwrng: exynos: Improve coding style
  hwrng: exynos: Implement bus clock control
  hwrng: exynos: Add SMC based TRNG operation
  hwrng: exynos: Enable Exynos850 support
  arm64: dts: exynos850: Enable TRNG

 .../bindings/rng/samsung,exynos-trng.yaml     |  85 +++++++
 .../bindings/rng/samsung,exynos5250-trng.yaml |  44 ----
 MAINTAINERS                                   |   2 +-
 arch/arm64/boot/dts/exynos/exynos850.dtsi     |   8 +
 drivers/char/hw_random/exynos-trng.c          | 216 ++++++++++++++----
 5 files changed, 266 insertions(+), 89 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/rng/samsung,exynos-trng.yaml
 delete mode 100644 Documentation/devicetree/bindings/rng/samsung,exynos5250-trng.yaml

-- 
2.39.2