[RFC PATCH v3 0/8] scpi: Add SCPI registry to handle legacy protocol

[Neil Armstrong]

This patchset aims to support the legacy SCPI firmware implementation that was
delivered as early technology preview for the JUNO platform.

Finally a stable, maintained and public implementation for the SCPI protocol
has been upstreamed part of the JUNO support and it is the recommended way
of implementing SCP communication on ARMv8 platforms.

The Amlogic GXBB platform is using this legacy protocol, as the RK3368 & RK3399
platforms. Only the GXBB example is provided here, but it's unclear if other
Amlogic ARMv8 based SoCs uses this legacy procotol.

In order to support the legacy protocol :
 - Move the scpi_get_ops to a thin registry layer
 - Change the arm_scpi.c to use the registry layer
 - Add a separate config option to build the registry layer
 - Add the legacy SCPI driver based on the new implementation
 - For example, add the Amlogic GXBB MHU and SCPI DT cpufreq & sensors nodes

Changes since RFC v2 at https://lkml.org/lkml/2016/6/21/324 :
 - Moved MHU to a separate patchset posted at http://lkml.kernel.org/r/1470732737-18391-1-git-send-email-narmstrong@baylibre.com
 - Added a vendor send_message callback into scpi_ops to implement vendor commands
 - Implement EXT commands on arm scpi as vendor send_command
 - Added Rockchip variant mailbox handling

Initial RFC discution tread can be found at https://lkml.org/lkml/2016/5/26/111

@Sudeep: I know you wished I merged the legacy into the arm_scpi, but can you take a look at the vendor extension and how I implemented the rockchip mailbox handling ?

Neil Armstrong (8):
  firmware: Add a SCPI registry to handle multiple implementations
  firmware: scpi: Switch arm_scpi to use new registry
  scpi: Add vendor_send_message to enable access to vendor commands
  firmware: arm_scpi: Enable vendor_send_message as ext commands
  firmware: Add legacy SCPI protocol driver
  dt-bindings: arm: Update arm,scpi bindings with Meson GXBB SCPI
  ARM64: dts: meson-gxbb: Add SRAM node
  ARM64: dts: meson-gxbb: Add SCPI with cpufreq & sensors Nodes

 Documentation/devicetree/bindings/arm/arm,scpi.txt |   8 +-
 arch/arm64/boot/dts/amlogic/meson-gxbb.dtsi        |  45 ++
 drivers/firmware/Kconfig                           |  24 +
 drivers/firmware/Makefile                          |   2 +
 drivers/firmware/arm_scpi.c                        |  40 +-
 drivers/firmware/legacy_scpi.c                     | 710 +++++++++++++++++++++
 drivers/firmware/scpi.c                            |  94 +++
 include/linux/scpi_protocol.h                      |  20 +-
 8 files changed, 928 insertions(+), 15 deletions(-)
 create mode 100644 drivers/firmware/legacy_scpi.c
 create mode 100644 drivers/firmware/scpi.c

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2.7.0