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

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Message-ID: <Zh_Dyi_rJGpW4qZr@pluto>
Date: Wed, 17 Apr 2024 13:42:50 +0100
From: Cristian Marussi <cristian.marussi@....com>
To: Sudeep Holla <sudeep.holla@....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 Wed, Apr 17, 2024 at 01:32:08PM +0100, Sudeep Holla wrote:
> 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;
> }

Sure...was not completely sure to proceed that way because only 2 lines
were saved for a each block....bit indeed is more clear...I'll d in V3
> 
> [...]
> 
> > 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.
> 

I'll do.

Thanks for the review.
Cristian