[PATCH] Add eSPI device driver (flash channel)

[Rob Herring <robh@kernel.org>]

On Tue, 13 Feb 2024 20:06:08 +0530, Manojkiran Eda wrote:
> This patch adds the driver support for the eSPI controller of
> Aspeed 5/6th generation SoCs. This controller is a slave device
> communicating with a master over Enhanced Serial Peripheral
> Interface (eSPI).
> 
> eSPI supports 4 channels, namely peripheral, virtual wire,
> out-of-band, and flash, and operates at max frequency of 66MHz.
> 
> But at the moment, this patch set only supports the flash channel.
> 
> Signed-off-by: Manojkiran Eda <manojkiran.eda@gmail.com>
> ---
> Hello everyone,
> 
> I'm presenting a revised version of the eSPI device driver patch series found at the following link:
> 
> https://lore.kernel.org/openbmc/20220516005412.4844-1-chiawei_wang at aspeedtech.com/
> 
> This update addresses the issues identified during the review process.
> 
> While the previous patch series attempted to incorporate support for all four different channels of eSPI,
> this new series focuses on upstreaming the flash channel initially, ensuring that all review comments are
> duly addressed, before progressing further.
> 
> Results:
> 
> Successfully conducted a flash update via eSPI.
> 
> Note:
> 
> This marks my inaugural endeavor in contributing code to the kernel subsystem. I kindly request reviewers
> to incorporate as many details as possible in the review comments.
> ---
>  .../devicetree/bindings/soc/aspeed/espi.yaml       | 125 ++++++
>  arch/arm/boot/dts/aspeed/aspeed-g6.dtsi            |  16 +-
>  drivers/mtd/mtdcore.c                              |   2 +-
>  drivers/soc/aspeed/Kconfig                         |  10 +
>  drivers/soc/aspeed/Makefile                        |   3 +
>  drivers/soc/aspeed/aspeed-espi-ctrl.c              | 197 +++++++++
>  drivers/soc/aspeed/aspeed-espi-ctrl.h              | 169 ++++++++
>  drivers/soc/aspeed/aspeed-espi-flash.c             | 466 +++++++++++++++++++++
>  drivers/soc/aspeed/aspeed-espi-flash.h             |  45 ++
>  include/uapi/linux/espi/aspeed-espi-ioc.h          | 103 +++++
>  10 files changed, 1134 insertions(+), 2 deletions(-)
> 

My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
on your patch (DT_CHECKER_FLAGS is new in v5.13):

yamllint warnings/errors:
./Documentation/devicetree/bindings/soc/aspeed/espi.yaml:5:6: [error] string value is redundantly quoted with any quotes (quoted-strings)
./Documentation/devicetree/bindings/soc/aspeed/espi.yaml:6:10: [error] string value is redundantly quoted with any quotes (quoted-strings)

dtschema/dtc warnings/errors:

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20240213-espi_driver-v1-1-92741c812843 at gmail.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.