[PATCH v8 14/21] ACPI / processor: Make it possible to get CPU hardware ID via GICC

[Hanjun Guo]

Introduce a new function map_gicc_mpidr() to allow MPIDRs to be obtained
from the GICC Structure introduced by ACPI 5.1.

MPIDR is the CPU hardware ID as local APIC ID on x86 platform, so we use
MPIDR not the GIC CPU interface ID to identify CPUs.

Further steps would typedef a phys_id_t for in arch code(with
appropriate size and a corresponding invalid value, say ~0) and use that
instead of an int in drivers/acpi/processor_core.c to store phys_id, then
no need for mpidr packing.

CC: Rafael J. Wysocki <rjw at rjwysocki.net>
CC: Catalin Marinas <catalin.marinas at arm.com>
CC: Will Deacon <will.deacon at arm.com>
Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit at amd.com>
Tested-by: Yijing Wang <wangyijing at huawei.com>
Tested-by: Mark Langsdorf <mlangsdo at redhat.com>
Tested-by: Jon Masters <jcm at redhat.com>
Tested-by: Timur Tabi <timur at codeaurora.org>
Signed-off-by: Hanjun Guo <hanjun.guo at linaro.org>
---
 arch/arm64/include/asm/acpi.h | 30 ++++++++++++++++++++++++++++++
 drivers/acpi/processor_core.c | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+)

diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
index 8984aa5..7e825b9 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -12,6 +12,8 @@
 #ifndef _ASM_ACPI_H
 #define _ASM_ACPI_H
 
+#include <asm/smp_plat.h>
+
 /* Basic configuration for ACPI */
 #ifdef	CONFIG_ACPI
 #define acpi_strict 1	/* No out-of-spec workarounds on ARM64 */
@@ -45,6 +47,34 @@ static inline void enable_acpi(void)
 	acpi_noirq = 0;
 }
 
+/* MPIDR value provided in GICC structure is 64 bits, but the
+ * existing phys_id (CPU hardware ID) using in acpi processor
+ * driver is 32-bit, to conform to the same datatype we need
+ * to repack the GICC structure MPIDR.
+ *
+ * bits other than following 32 bits are defined as 0, so it
+ * will be no information lost after repacked.
+ *
+ * Bits [0:7] Aff0;
+ * Bits [8:15] Aff1;
+ * Bits [16:23] Aff2;
+ * Bits [32:39] Aff3;
+ */
+static inline u32 pack_mpidr(u64 mpidr)
+{
+	return (u32) ((mpidr & 0xff00000000) >> 8) | mpidr;
+}
+
+/*
+ * The ACPI processor driver for ACPI core code needs this macro
+ * to find out this cpu was already mapped (mapping from CPU hardware
+ * ID to CPU logical ID) or not.
+ *
+ * cpu_logical_map(cpu) is the mapping of MPIDR and the logical cpu,
+ * and MPIDR is the cpu hardware ID we needed to pack.
+ */
+#define cpu_physical_id(cpu) pack_mpidr(cpu_logical_map(cpu))
+
 /*
  * It's used from ACPI core in kdump to boot UP system with SMP kernel,
  * with this check the ACPI core will not override the CPU index
diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
index 02e4839..5ac12e4 100644
--- a/drivers/acpi/processor_core.c
+++ b/drivers/acpi/processor_core.c
@@ -64,6 +64,38 @@ static int map_lsapic_id(struct acpi_subtable_header *entry,
 	return 0;
 }
 
+/*
+ * On ARM platform, MPIDR value is the hardware ID as apic ID
+ * on Intel platforms
+ */
+static int map_gicc_mpidr(struct acpi_subtable_header *entry,
+		int device_declaration, u32 acpi_id, int *mpidr)
+{
+	struct acpi_madt_generic_interrupt *gicc =
+	    container_of(entry, struct acpi_madt_generic_interrupt, header);
+
+	if (!(gicc->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 && (gicc->uid == acpi_id)) {
+		/*
+		 * bits other than [0:7] Aff0, [8:15] Aff1, [16:23] Aff2 and
+		 * [32:39] Aff3 must be 0 which is defined in ACPI 5.1, so pack
+		 * the Affx fields into a single 32 bit identifier to accommodate
+		 * the acpi processor drivers.
+		 */
+		*mpidr = ((gicc->arm_mpidr & 0xff00000000) >> 8)
+			 | gicc->arm_mpidr;
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
 static int map_madt_entry(int type, u32 acpi_id)
 {
 	unsigned long madt_end, entry;
@@ -99,6 +131,9 @@ 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, &phys_id))
 				break;
+		} else if (header->type == ACPI_MADT_TYPE_GENERIC_INTERRUPT) {
+			if (!map_gicc_mpidr(header, type, acpi_id, &phys_id))
+				break;
 		}
 		entry += header->length;
 	}
@@ -131,6 +166,8 @@ static int map_mat_entry(acpi_handle handle, int type, u32 acpi_id)
 		map_lsapic_id(header, type, acpi_id, &phys_id);
 	else if (header->type == ACPI_MADT_TYPE_LOCAL_X2APIC)
 		map_x2apic_id(header, type, acpi_id, &phys_id);
+	else if (header->type == ACPI_MADT_TYPE_GENERIC_INTERRUPT)
+		map_gicc_mpidr(header, type, acpi_id, &phys_id);
 
 exit:
 	kfree(buffer.pointer);
-- 
1.9.1