Re: [PATCH v6 01/37] firmware: arm_scmi: review protocol registration interface

Cristian Marussi
2021-03-08T11:25:37Z

Hi Sudeep,

thanks for reviewing this.

On Mon, Mar 08, 2021 at 04:38:30AM +0000, Sudeep Holla wrote:
> On Tue, Feb 02, 2021 at 10:15:19PM +0000, Cristian Marussi wrote:
> > Extend common protocol registration routines and provide some new generic
> > protocols get/put helpers that can track protocols usage and automatically
> > perform the proper initialization and de-initialization on demand when
> > required.
> >
> > Convert all standard protocols to use this new registration scheme while
> > keeping them all still using the usual initialization logic bound to SCMI
> > devices probing.
> >
> > Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
> > ---
> > v2 --> v3
> > - removed new Base protocol initialization, it will be re-introduced
> > later with all other protocols
> > ---
> > drivers/firmware/arm_scmi/base.c | 8 ++
> > drivers/firmware/arm_scmi/bus.c | 61 ++++++++---
> > drivers/firmware/arm_scmi/clock.c | 10 +-
> > drivers/firmware/arm_scmi/common.h | 30 +++++-
> > drivers/firmware/arm_scmi/driver.c | 159 +++++++++++++++++++++++++++-
> > drivers/firmware/arm_scmi/perf.c | 10 +-
> > drivers/firmware/arm_scmi/power.c | 10 +-
> > drivers/firmware/arm_scmi/reset.c | 10 +-
> > drivers/firmware/arm_scmi/sensors.c | 8 +-
> > drivers/firmware/arm_scmi/system.c | 8 +-
> > drivers/firmware/arm_scmi/voltage.c | 8 +-
> > include/linux/scmi_protocol.h | 6 +-
> > 12 files changed, 296 insertions(+), 32 deletions(-)
> >
> > diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
> > index 1377ec76a45d..044aa9e3ebb0 100644
> > --- a/drivers/firmware/arm_scmi/bus.c
> > +++ b/drivers/firmware/arm_scmi/bus.c
> > @@ -16,7 +16,7 @@
> > #include "common.h"
> >
> > static DEFINE_IDA(scmi_bus_id);
> > -static DEFINE_IDR(scmi_protocols);
> > +static DEFINE_IDR(scmi_available_protocols);
>
> [nit] Any particular reason for this name change ? Does it hold refer to
> something different from before ? IIRC, this is list of registered protocols ?
> Available might refer to the ones advertised to be present by the platform
> firmware ?
>

Indeed I was not completely sure to change the naming, the only
difference here is the protocol data that is kept in the IDR, which is
now a struct scmi_protocol describing a bunch of things and not just a
protocol_init function.

It contains protocols currently loaded (if module), so registered with the core
and ready to be initialized (on get_protocol) if implemented by the platform
AND once an SCMI driver user appears, so available here does NOT imply being
implemented by platform.

In fact the meaning is really as before, it's just that (I suppose I thought :D)
I wanted to stress the fact that these are the currently loaded protocols modules
which are available and differentiate a bit the naming from the struct scmi_protocol
which they hold (which really maybe does not make sense now reviewing it)

I think I can just revert to use scmi_protocols.

> > static DEFINE_SPINLOCK(protocol_lock);
> >
> > static const struct scmi_device_id *
> > @@ -51,13 +51,29 @@ static int scmi_dev_match(struct device *dev, struct device_driver *drv)
> > return 0;
> > }
> >
> > +const struct scmi_protocol *scmi_get_protocol(int protocol_id)
> > +{
> > + const struct scmi_protocol *proto;
> > +
> > + proto = idr_find(&scmi_available_protocols, protocol_id);
> > + if (!proto) {
> > + pr_warn("SCMI Protocol 0x%x not found!\n", protocol_id);
> > + return NULL;
> > + }
> > +
> > + pr_debug("GOT SCMI Protocol 0x%x\n", protocol_id);
> > +
>
> [nit] For sake of consistency, s/GOT/Found/
>
>

Sure.

> [..]
>
> > @@ -194,26 +210,45 @@ void scmi_set_handle(struct scmi_device *scmi_dev)
> > scmi_dev->handle = scmi_handle_get(&scmi_dev->dev);
> > }
> >
> > -int scmi_protocol_register(int protocol_id, scmi_prot_init_fn_t fn)
> > +int scmi_protocol_register(const struct scmi_protocol *proto)
> > {
> > int ret;
> >
> > + if (!proto) {
> > + pr_err("invalid protocol\n");
> > + return -EINVAL;
> > + }
> > +
> > + if (!proto->init && !proto->init_instance) {
> > + pr_err("missing .init() for protocol 0x%x\n", proto->id);
>
>
> s/.init()/init as it can be init_instance too ?
>

Right, in fact also because this is part of the 'transitional' code and
later on the series ("firmware: arm_scmi: cleanup legacy protocol init code")
I remove the .init method and keep only the init_instance, so much
better if I leave it generic as 'init' as you suggested.

> > diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/clock.c
> > index 4645677d86f1..e8c84cff9922 100644
> > --- a/drivers/firmware/arm_scmi/clock.c
> > +++ b/drivers/firmware/arm_scmi/clock.c
> > @@ -2,7 +2,7 @@
> > /*
> > * System Control and Management Interface (SCMI) Clock Protocol
> > *
> > - * Copyright (C) 2018 ARM Ltd.
> > + * Copyright (C) 2018-2020 ARM Ltd.
>
> 2021 perhaps ? Few instances are not updated, I prefer to be consistent
> across all modified scmi firmware driver files.
>

Ah, sorry I missed this, I'll review all the Copyrights for 2021.

>
> Other than these minor comments, the other changes looks good to me.
>

Thanks

Cristian

> --
> Regards,
> Sudeep