From: Dave Martin <Dave.Martin@arm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: lorenzo.pieralisi@arm.com, suzuki.poulose@arm.com,
marc.zyngier@arm.com, catalin.marinas@arm.com,
will.deacon@arm.com, linux@armlinux.org.uk, james.morse@arm.com,
robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCHv3 1/6] arm/arm64: smccc/psci: add arm_smccc_1_1_get_conduit()
Date: Mon, 12 Aug 2019 16:10:43 +0100 [thread overview]
Message-ID: <20190812151043.GU10425@arm.com> (raw)
In-Reply-To: <20190812150634.GB52896@lakrids.cambridge.arm.com>
On Mon, Aug 12, 2019 at 04:06:35PM +0100, Mark Rutland wrote:
> On Mon, Aug 12, 2019 at 04:03:29PM +0100, Dave Martin wrote:
> > On Fri, Aug 09, 2019 at 02:22:40PM +0100, Mark Rutland wrote:
> > > SMCCC callers are currently amassing a collection of enums for the SMCCC
> > > conduit, and are having to dig into the PSCI driver's internals in order
> > > to figure out what to do.
> > >
> > > Let's clean this up, with common SMCCC_CONDUIT_* definitions, and an
> > > arm_smccc_1_1_get_conduit() helper that abstracts the PSCI driver's
> > > internal state.
> > >
> > > We can kill off the PSCI_CONDUIT_* definitions once we've migrated users
> > > over to the new interface.
> > >
> > > Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> > > Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> > > Acked-by: Will Deacon <will.deacon@arm.com>
> > > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > > ---
> > > drivers/firmware/psci/psci.c | 15 +++++++++++++++
> > > include/linux/arm-smccc.h | 16 ++++++++++++++++
> > > 2 files changed, 31 insertions(+)
> > >
> > > diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
> > > index f82ccd39a913..5f31f1bea1af 100644
> > > --- a/drivers/firmware/psci/psci.c
> > > +++ b/drivers/firmware/psci/psci.c
> > > @@ -57,6 +57,21 @@ struct psci_operations psci_ops = {
> > > .smccc_version = SMCCC_VERSION_1_0,
> > > };
> > >
> > > +enum arm_smccc_conduit arm_smccc_1_1_get_conduit(void)
> >
> > Do we expect this to be specific to SMCCC v1.1?
>
> I intend it to be 1.1+
It seems overspecific, but I guess we can address this later if it
becomes an issue. This is an internal API for now (at worst I might
envisage it being EXPORT_SYMBOL_GPL()).
> > > +{
> > > + if (psci_ops.smccc_version < SMCCC_VERSION_1_1)
> > > + return SMCCC_CONDUIT_NONE;
> > > +
> > > + switch (psci_ops.conduit) {
> > > + case PSCI_CONDUIT_SMC:
> > > + return SMCCC_CONDUIT_SMC;
> > > + case PSCI_CONDUIT_HVC:
> > > + return SMCCC_CONDUIT_HVC;
> > > + default:
> > > + return SMCCC_CONDUIT_NONE;
> > > + }
> > > +}
> > > +
> > > typedef unsigned long (psci_fn)(unsigned long, unsigned long,
> > > unsigned long, unsigned long);
> > > static psci_fn *invoke_psci_fn;
> > > diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
> > > index 080012a6f025..df01a8579034 100644
> > > --- a/include/linux/arm-smccc.h
> > > +++ b/include/linux/arm-smccc.h
> > > @@ -80,6 +80,22 @@
> > >
> > > #include <linux/linkage.h>
> > > #include <linux/types.h>
> > > +
> > > +enum arm_smccc_conduit {
> > > + SMCCC_CONDUIT_NONE,
> >
> > If this is intended to have the value 0, is it worth making that
> > explicit? I can never remember whether enums start at 1 or 0 by
> > default...
>
> They start at 0. I intend that checks are done explicitly against an
> enum value, so I'm not sure that matters.
Not really.
It depends whether code like if (!arm_smccc_1_1_get_conduit()) { ... }
is considered sane or not.
If we don't think people should be doing this, omitting the explicit
value specifier seems fine.
Cheers
---Dave
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next prev parent reply other threads:[~2019-08-12 15:10 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-09 13:22 [PATCHv3 0/6] arm/arm64: SMCCC conduit cleanup Mark Rutland
2019-08-09 13:22 ` [PATCHv3 1/6] arm/arm64: smccc/psci: add arm_smccc_1_1_get_conduit() Mark Rutland
2019-08-12 15:03 ` Dave Martin
2019-08-12 15:06 ` Mark Rutland
2019-08-12 15:10 ` Dave Martin [this message]
2019-08-12 15:26 ` Mark Rutland
2019-08-13 11:38 ` Dave Martin
2019-08-09 13:22 ` [PATCHv3 2/6] arm64: errata: use arm_smccc_1_1_get_conduit() Mark Rutland
2019-08-09 13:22 ` [PATCHv3 3/6] arm: spectre-v2: " Mark Rutland
2019-10-11 14:02 ` Catalin Marinas
2019-08-09 13:22 ` [PATCHv3 4/6] firmware/psci: use common SMCCC_CONDUIT_* Mark Rutland
2019-08-09 13:22 ` [PATCHv3 5/6] firmware: arm_sdei: " Mark Rutland
2019-08-09 13:22 ` [PATCHv3 6/6] smccc: make 1.1 macros value-returning Mark Rutland
2019-08-15 16:42 ` Will Deacon
2019-08-19 10:44 ` Mark Rutland
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