linux-kernel - Re: [PATCH v2 1/2] firmware: arm_scmi: Add support for multiple vendors custom protocols

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Date: Wed, 17 Apr 2024 13:32:08 +0100
From: Sudeep Holla <sudeep.holla@....com>
To: Cristian Marussi <cristian.marussi@....com>
Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	james.quinlan@...adcom.com, f.fainelli@...il.com,
	vincent.guittot@...aro.org, peng.fan@....nxp.com,
	michal.simek@....com, quic_sibis@...cinc.com,
	konrad.dybcio@...aro.org, souvik.chakravarty@....com
Subject: Re: [PATCH v2 1/2] firmware: arm_scmi: Add support for multiple
 vendors custom protocols

On Mon, Apr 08, 2024 at 10:30:51AM +0100, Cristian Marussi wrote:
> Add a mechanism to be able to tag vendor protocol modules at compile-time
> with a vendor/sub_vendor string and an implementation version and then to
> choose to load, at run-time, only those vendor protocol modules matching
> as close as possible the vendor/subvendor identification advertised by
> the SCMI platform server.
> 
> In this way, any in-tree existent vendor protocol module can be build and
> shipped by default in a single kernel image, even when using the same
> clashing protocol identification numbers, since the SCMI core will take
> care at run-time to load only the ones pertinent to the running system.
> 
> Signed-off-by: Cristian Marussi <cristian.marussi@....com>
> ---
>  drivers/firmware/arm_scmi/driver.c    | 165 ++++++++++++++++++++++----
>  drivers/firmware/arm_scmi/protocols.h |  15 +++
>  2 files changed, 158 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
> index d0091459a276..aa18202054a5 100644
> --- a/drivers/firmware/arm_scmi/driver.c
> +++ b/drivers/firmware/arm_scmi/driver.c

[...]

> +static const struct scmi_protocol *
> +scmi_vendor_protocol_lookup(int protocol_id, char *vendor_id,
> +			    char *sub_vendor_id, u32 impl_ver)
> +{
> +	unsigned long key;
> +	struct scmi_protocol *proto = NULL;
> +
> +	/* Searching for closest match ...*/
> +	key = scmi_protocol_key_calculate(protocol_id, vendor_id,
> +					  sub_vendor_id, impl_ver);
> +	if (key)
> +		proto = xa_load(&scmi_protocols, key);
> +
> +	if (proto)
> +		return proto;
> +
> +	/* Any match on vendor/sub_vendor ? */
> +	if (impl_ver) {
> +		key = scmi_protocol_key_calculate(protocol_id, vendor_id,
> +						  sub_vendor_id, 0);
> +		if (key)
> +			proto = xa_load(&scmi_protocols, key);
> +
> +		if (proto)
> +			return proto;
> +	}
> +
> +	/* Any match on just the vendor ? */
> +	if (sub_vendor_id) {
> +		key = scmi_protocol_key_calculate(protocol_id, vendor_id,
> +						  NULL, 0);
> +		if (key)
> +			proto = xa_load(&scmi_protocols, key);
> +	}
>

I see a pattern here, can be simplify/compress by something like below ?

static const struct scmi_protocol *
__scmi_vendor_protocol_lookup(int protocol_id, char *vendor_id,
			      char *sub_vendor_id, u32 impl_ver)
{
	unsigned long key;
	struct scmi_protocol *proto = NULL;

	key = scmi_protocol_key_calculate(protocol_id, vendor_id,
					  sub_vendor_id, impl_ver);
	if (key)
		proto = xa_load(&scmi_protocols, key);

	return proto;
}

[...]

> diff --git a/drivers/firmware/arm_scmi/protocols.h b/drivers/firmware/arm_scmi/protocols.h
> index 317d3fb32676..45ee8b35f56d 100644
> --- a/drivers/firmware/arm_scmi/protocols.h
> +++ b/drivers/firmware/arm_scmi/protocols.h
> @@ -29,6 +29,8 @@
>  #define PROTOCOL_REV_MAJOR(x)	((u16)(FIELD_GET(PROTOCOL_REV_MAJOR_MASK, (x))))
>  #define PROTOCOL_REV_MINOR(x)	((u16)(FIELD_GET(PROTOCOL_REV_MINOR_MASK, (x))))
>  
> +#define SCMI_PROTOCOL_VENDOR	0x80
> +

s/SCMI_PROTOCOL_VENDOR/SCMI_PROTOCOL_VENDOR_BASE/

as I expect 0x80 to be used by most vendors.

-- 
Regards,
Sudeep