Hi Hanjun,
On 18/02/14 16:23, Hanjun Guo wrote:
> Get apic id from MADT or _MAT method is not implemented on arm/arm64,
> and ACPI 5.0 introduces GIC Structure for it, so this patch introduces
> map_gic_id() to get apic id followed the ACPI 5.0 spec.
>
> Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
> ---
> drivers/acpi/processor_core.c | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
> index 4dcf776..d316d9b 100644
> --- a/drivers/acpi/processor_core.c
> +++ b/drivers/acpi/processor_core.c
> @@ -71,6 +71,27 @@ static int map_lsapic_id(struct acpi_subtable_header *entry,
> return 0;
> }
>
> +static int map_gic_id(struct acpi_subtable_header *entry,
> + int device_declaration, u32 acpi_id, int *apic_id)
> +{
> + struct acpi_madt_generic_interrupt *gic =
> + (struct acpi_madt_generic_interrupt *)entry;
> +
> + if (!(gic->flags & ACPI_MADT_ENABLED))
> + return -ENODEV;
> +
> + /* In the GIC interrupt model, logical processors are
> + * required to have a Processor Device object in the DSDT,
> + * so we should check device_declaration here
> + */
> + if (device_declaration && (gic->uid == acpi_id)) {
> + *apic_id = gic->gic_id;
I have mentioned this earlier, it's not clear yet to me how does this work ?
It needs more clarity in the form of comment here at-least as the ACPIv5.0 is
also not so clear or explicit on how to handle this.
Here you are expecting gic->uid = acpi_id which is fine, while acpi_map_cpuid
matches apic_id with cpu_physical_id(which must be MPIDR in ARM{32,64}). The
latter imposes restriction that gic->gic_id has to be MPIDR. Does that mean we
are imposing restriction on GIC ID to be MPIDR ? If so please document it here
and please explain the reason behind that choice.
I would expect _UID to be MPIDR rather than GIC ID but you may have some reasons
for this choice.
Regards,
Sudeep
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