Re: [PATCH 2/8] firmware: arm_scmi: Extend transport driver macro to support ACPI

[Jonathan Cameron <jonathan.cameron@huawei.com>]

On Fri, 17 Oct 2025 14:23:45 +0100
Sudeep Holla <sudeep.holla@arm.com> wrote:

> Extend the SCMI transport driver helper to also support ACPI-based
> systems. Introduce an internal helper macro that accepts both OF and
> ACPI match tables, and expose two wrappers:
> 
>   - DEFINE_SCMI_TRANSPORT_DRIVER(...)      -> DT/OF wrapper (unchanged ABI)
>   - DEFINE_SCMI_ACPI_TRANSPORT_DRIVER(...) -> ACPI wrapper
> 
> For ACPI, the generated platform_driver now sets .acpi_match_table via
> ACPI_PTR() so that builds without CONFIG_ACPI remain safe (becomes NULL).
In general it doesn't normally matter if ACPI_PTR() isn't used.

What specifically is this preventing?  If CONFIG_ACPI isn't set then we'll never
use those paths anyway.  Using ACPI_PTR() tends to need ifdef magic or
__maybe_unused markings that are rarely worth the effort for these tiny
tables.

> The spawned platform_device inherits the parent device’s ACPI companion
> to ensure proper firmware-node association (i.e.subsequent lookups or
> fwnode use see the correct firmware node).
> 
> This keeps existing DT users unchanged and continues to function as
> expected while allowing transports to be probed using the structure
> `acpi_device_id` tables on ACPI platforms.
> 
> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
> ---
>  drivers/firmware/arm_scmi/common.h | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
> index 911941e6885d..d038fec72360 100644
> --- a/drivers/firmware/arm_scmi/common.h
> +++ b/drivers/firmware/arm_scmi/common.h
> @@ -9,6 +9,7 @@
>  #ifndef _SCMI_COMMON_H
>  #define _SCMI_COMMON_H
>  
> +#include <linux/acpi.h>
>  #include <linux/bitfield.h>
>  #include <linux/completion.h>
>  #include <linux/device.h>
> @@ -453,7 +454,8 @@ struct scmi_transport {
>  	struct scmi_transport_core_operations **core_ops;
>  };
>  
> -#define DEFINE_SCMI_TRANSPORT_DRIVER(__tag, __drv, __desc, __match, __core_ops)\
> +#define __DEFINE_SCMI_TRANSPORT_DRIVER(__tag, __drv, __desc, __of_match,       \
> +					__acpi_match, __core_ops)	       \
>  static void __tag##_dev_free(void *data)				       \
>  {									       \
>  	struct platform_device *spdev = data;				       \
> @@ -474,6 +476,7 @@ static int __tag##_probe(struct platform_device *pdev)			       \
>  									       \
>  	device_set_of_node_from_dev(&spdev->dev, dev);			       \
>  	device_set_node(&spdev->dev, dev_fwnode(dev));			       \
> +	ACPI_COMPANION_SET(&spdev->dev, ACPI_COMPANION(dev));		       \
>  									       \
>  	strans.supplier = dev;						       \
>  	memcpy(&strans.desc, &(__desc), sizeof(strans.desc));		       \
> @@ -498,11 +501,18 @@ err:									       \
>  static struct platform_driver __drv = {					       \
>  	.driver = {							       \
>  		   .name = #__tag "_transport",				       \
> -		   .of_match_table = __match,				       \
> +		   .of_match_table = __of_match,			       \
> +		   .acpi_match_table = ACPI_PTR(__acpi_match),		       \
>  		   },							       \
>  	.probe = __tag##_probe,						       \
>  }
>  
> +#define DEFINE_SCMI_TRANSPORT_DRIVER(__tag, __drv, __desc, __match, __core_ops)\
> +	__DEFINE_SCMI_TRANSPORT_DRIVER(__tag, __drv, __desc, __match, NULL, __core_ops)
> +
> +#define DEFINE_SCMI_ACPI_TRANSPORT_DRIVER(__tag, __drv, __desc, __match, __core_ops)\
> +	__DEFINE_SCMI_TRANSPORT_DRIVER(__tag, __drv, __desc, NULL, __match, __core_ops)
> +
>  void scmi_notification_instance_data_set(const struct scmi_handle *handle,
>  					 void *priv);
>  void *scmi_notification_instance_data_get(const struct scmi_handle *handle);
>