Re: [PATCH v6 11/17] firmware: arm_scmi: Make SCMI transports configurable

[Sudeep Holla <sudeep.holla@arm.com>]

On Mon, Jul 12, 2021 at 03:18:27PM +0100, Cristian Marussi wrote:
> Add configuration options to be able to select which SCMI transports have
> to be compiled into the SCMI stack.
> 
> Mailbox and SMC are by default enabled if their related dependencies are
> satisfied.
> 
> While doing that move all SCMI related config options in their own
> dedicated submenu.
> 
> Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
> ---
> Used a BUILD_BUG_ON() to avoid the scenario where SCMI is configured
> without any transport. Coul dnot do in any other way in Kconfig due to
> circular dependencies.
> 
> This will be neeed later on to add new Virtio based transport and
> optionally exclude other transports.
> ---
>  drivers/firmware/Kconfig           | 34 +--------------
>  drivers/firmware/arm_scmi/Kconfig  | 70 ++++++++++++++++++++++++++++++
>  drivers/firmware/arm_scmi/Makefile |  4 +-
>  drivers/firmware/arm_scmi/common.h |  4 +-
>  drivers/firmware/arm_scmi/driver.c |  6 ++-
>  5 files changed, 80 insertions(+), 38 deletions(-)
>  create mode 100644 drivers/firmware/arm_scmi/Kconfig
> 
> diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
> index 1db738d5b301..8d41f73f5395 100644
> --- a/drivers/firmware/Kconfig
> +++ b/drivers/firmware/Kconfig
> @@ -6,39 +6,7 @@
>  
>  menu "Firmware Drivers"
>  
> -config ARM_SCMI_PROTOCOL
> -	tristate "ARM System Control and Management Interface (SCMI) Message Protocol"
> -	depends on ARM || ARM64 || COMPILE_TEST
> -	depends on MAILBOX || HAVE_ARM_SMCCC_DISCOVERY
> -	help
> -	  ARM System Control and Management Interface (SCMI) protocol is a
> -	  set of operating system-independent software interfaces that are
> -	  used in system management. SCMI is extensible and currently provides
> -	  interfaces for: Discovery and self-description of the interfaces
> -	  it supports, Power domain management which is the ability to place
> -	  a given device or domain into the various power-saving states that
> -	  it supports, Performance management which is the ability to control
> -	  the performance of a domain that is composed of compute engines
> -	  such as application processors and other accelerators, Clock
> -	  management which is the ability to set and inquire rates on platform
> -	  managed clocks and Sensor management which is the ability to read
> -	  sensor data, and be notified of sensor value.
> -
> -	  This protocol library provides interface for all the client drivers
> -	  making use of the features offered by the SCMI.
> -
> -config ARM_SCMI_POWER_DOMAIN
> -	tristate "SCMI power domain driver"
> -	depends on ARM_SCMI_PROTOCOL || (COMPILE_TEST && OF)
> -	default y
> -	select PM_GENERIC_DOMAINS if PM
> -	help
> -	  This enables support for the SCMI power domains which can be
> -	  enabled or disabled via the SCP firmware
> -
> -	  This driver can also be built as a module.  If so, the module
> -	  will be called scmi_pm_domain. Note this may needed early in boot
> -	  before rootfs may be available.
> +source "drivers/firmware/arm_scmi/Kconfig"
>  
>  config ARM_SCPI_PROTOCOL
>  	tristate "ARM System Control and Power Interface (SCPI) Message Protocol"
> diff --git a/drivers/firmware/arm_scmi/Kconfig b/drivers/firmware/arm_scmi/Kconfig
> new file mode 100644
> index 000000000000..479fc8a3533e
> --- /dev/null
> +++ b/drivers/firmware/arm_scmi/Kconfig
> @@ -0,0 +1,70 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +menu "ARM System Control and Management Interface Protocol"
> +
> +config ARM_SCMI_PROTOCOL
> +	tristate "ARM System Control and Management Interface (SCMI) Message Protocol"
> +	depends on ARM || ARM64 || COMPILE_TEST
> +	help
> +	  ARM System Control and Management Interface (SCMI) protocol is a
> +	  set of operating system-independent software interfaces that are
> +	  used in system management. SCMI is extensible and currently provides
> +	  interfaces for: Discovery and self-description of the interfaces
> +	  it supports, Power domain management which is the ability to place
> +	  a given device or domain into the various power-saving states that
> +	  it supports, Performance management which is the ability to control
> +	  the performance of a domain that is composed of compute engines
> +	  such as application processors and other accelerators, Clock
> +	  management which is the ability to set and inquire rates on platform
> +	  managed clocks and Sensor management which is the ability to read
> +	  sensor data, and be notified of sensor value.
> +
> +	  This protocol library provides interface for all the client drivers
> +	  making use of the features offered by the SCMI.
> +

May be you can add if condition here to remove the depends on ARM_SCMI_PROTOCOL

if ARM_SCMI_PROTOCOL

> +config ARM_SCMI_HAVE_TRANSPORT
> +	bool
> +	help
> +	  This declares whether at least one SCMI transport has been configured.
> +	  Used to trigger a build bug when trying to build SCMI without any
> +	  configured transport.
> +
> +config ARM_SCMI_TRANSPORT_MAILBOX
> +	bool "SCMI transport based on Mailbox"
> +	depends on ARM_SCMI_PROTOCOL && MAILBOX

And drop ARM_SCMI_PROTOCOL above

> +	select ARM_SCMI_HAVE_TRANSPORT
> +	default y

Do we need a user visible choice if it is always default on ?

> +	help
> +	  Enable mailbox based transport for SCMI.
> +
> +	  If you want the ARM SCMI PROTOCOL stack to include support for a
> +	  transport based on mailboxes, answer Y.
> +	  A matching DT entry will also be needed to indicate the effective
> +	  presence of this kind of transport.
> +

I would drop the above comment on matching DT.

> +config ARM_SCMI_TRANSPORT_SMC
> +	bool "SCMI transport based on SMC"
> +	depends on ARM_SCMI_PROTOCOL && HAVE_ARM_SMCCC_DISCOVERY

Ditto

> +	select ARM_SCMI_HAVE_TRANSPORT
> +	default y
> +	help
> +	  Enable SMC based transport for SCMI.
> +
> +	  If you want the ARM SCMI PROTOCOL stack to include support for a
> +	  transport based on SMC, answer Y.
> +	  A matching DT entry will also be needed to indicate the effective
> +	  presence of this kind of transport.
> +

endif #ARM_SCMI_PROTOCOL

-- 
Regards,
Sudeep