ACPI / processor: Make it possible to get APIC ID via GIC

Introduce a new function map_gic_id() to allow APIC IDs to be obtained
from the GIC Structure introduced by ACPI 5.

Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
[rjw: Subject and changelog]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
index 4d91b32423a9..f1dd404463aa 100644
--- a/drivers/acpi/processor_core.c
+++ b/drivers/acpi/processor_core.c
@@ -71,6 +71,28 @@ 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;
+                return 0;
+        }
+
+        return -EINVAL;
+}
+
 static int map_madt_entry(int type, u32 acpi_id)
 {
         unsigned long madt_end, entry;
@@ -106,6 +128,9 @@ static int map_madt_entry(int type, u32 acpi_id)
                 } else if (header->type == ACPI_MADT_TYPE_LOCAL_SAPIC) {
                         if (!map_lsapic_id(header, type, acpi_id, &apic_id))
                                 break;
+                } else if (header->type == ACPI_MADT_TYPE_GENERIC_INTERRUPT) {
+                        if (!map_gic_id(header, type, acpi_id, &apic_id))
+                                break;
                 }
                 entry += header->length;
         }
@@ -136,6 +161,8 @@ static int map_mat_entry(acpi_handle handle, int type, u32 acpi_id)
                 map_lapic_id(header, acpi_id, &apic_id);
         } else if (header->type == ACPI_MADT_TYPE_LOCAL_SAPIC) {
                 map_lsapic_id(header, type, acpi_id, &apic_id);
+        } else if (header->type == ACPI_MADT_TYPE_GENERIC_INTERRUPT) {
+                map_gic_id(header, type, acpi_id, &apic_id);
         }
 
 exit: