[PATCH v1 1/2] PSCI: Use DT Function ID values only for old versions of spec

[Rob Herring]

On Thu, Mar 20, 2014 at 9:26 AM, Mark Rutland <mark.rutland at arm.com> wrote:
> On Thu, Mar 20, 2014 at 01:25:53AM +0000, Rob Herring wrote:
>> On Wed, Mar 19, 2014 at 7:54 PM, Ashwin Chaugule
>> <ashwin.chaugule at linaro.org> wrote:
>> > The PSCI v0.2+ spec mandates specific values of Function IDs
>> > for ARM32 and ARM64. Use DT bindings of Function IDs only
>> > when using older versions. Use static values otherwise.
>> > This patch also prepares the code to easily use the ACPI API
>> > which is based off of PSCI v0.2+.
>> >
>> > Signed-off-by: Ashwin Chaugule <ashwin.chaugule at linaro.org>
>> > ---
>> >  arch/arm/include/asm/psci.h   |  15 ++++++
>> >  arch/arm/kernel/psci.c        | 110 +++++++++++++++++++++++++++++++++++++-----
>> >  arch/arm64/include/asm/psci.h |  12 +++++
>> >  arch/arm64/kernel/psci.c      | 106 +++++++++++++++++++++++++++++++++++-----
>> >  4 files changed, 218 insertions(+), 25 deletions(-)
>> >
>> > diff --git a/arch/arm/include/asm/psci.h b/arch/arm/include/asm/psci.h
>> > index c4ae171..3f8ebf9 100644
>> > --- a/arch/arm/include/asm/psci.h
>> > +++ b/arch/arm/include/asm/psci.h
>> > @@ -17,6 +17,19 @@
>> >  #define PSCI_POWER_STATE_TYPE_STANDBY          0
>> >  #define PSCI_POWER_STATE_TYPE_POWER_DOWN       1
>> >
>> > +/* PSCI Function ID's for ARM32 as per PSCI spec v0.2 */
>> > +
>> > +#define PSCI_ID_VERSION                                0x84000000
>> > +#define PSCI_ID_CPU_SUSPEND                    0x84000001
>> > +#define PSCI_ID_CPU_OFF                                0x84000002
>> > +#define PSCI_ID_CPU_ON                         0x84000003
>> > +#define PSCI_ID_AFFINITY_INFO          0x84000004
>> > +#define PSCI_ID_CPU_MIGRATE                    0x84000005
>> > +#define PSCI_ID_MIGRATE_INFO_TYPE      0x84000006
>> > +#define PSCI_ID_MIGRATE_INFO_UP_CPU    0x84000007
>> > +#define PSCI_ID_SYSTEM_OFF                     0x84000008
>> > +#define PSCI_ID_SYSTEM_RESET           0x84000009
>>
>> With the KVM patches[1], this makes 4 copies of these defines in the
>> kernel (and then QEMU has more). This needs to go into a common header
>> under include/linux. Probably under uapi so QEMU can use. There is
>> some sync of headers between the kernel and QEMU I think.
>
> I agree we should have a common header, but I don't think this is uapi
> material. This is most definitely _not_ part of the user API, and it's
> from an external spec that we're not in control of -- I don't see why we
> should have to export a set of numbers forever because it happens to be
> marginally useful at this point in time.

I mention uapi only in that it is expected to be stable (in an ABI
sense) from kernel release to release, and I would assume that QEMU
would only sync ABI stable headers. Someone familiar with the QEMU
import process should comment on where this stuff should live.

Wouldn't this fall into the same category as something like
include/uapi/linux/pci_regs.h?

> Having the IDs handled by the kernel and those used by hypervisors also
> encourages people to validate the use of the correct IDs rather than
> everyone making the same mistake.

Duplicate copies seems like a poor way to validate correctness.

Rob