ACPI: processor_core: RISC-V: Enable mapping processor to the hartid

processor_core needs arch-specific functions to map the ACPI ID
to the physical ID. In RISC-V platforms, hartid is the physical id
and RINTC structure in MADT provides this mapping. Add arch-specific
function to get this mapping from RINTC.
Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20230515054928.2079268-8-sunilvl@ventanamicro.comSigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/include/asm/acpi.h

@@ -15,6 +15,9 @@
 /* Basic configuration for ACPI */
 #ifdef CONFIG_ACPI
 
+typedef u64 phys_cpuid_t;
+#define PHYS_CPUID_INVALID INVALID_HARTID
+
 /* ACPI table mapping after acpi_permanent_mmap is set */
 void *acpi_os_ioremap(acpi_physical_address phys, acpi_size size);
 #define acpi_os_ioremap acpi_os_ioremap

drivers/acpi/processor_core.c

@@ -106,6 +106,32 @@ static int map_gicc_mpidr(struct acpi_subtable_header *entry,
 	return -EINVAL;
 }
 
+/*
+ * Retrieve the RISC-V hartid for the processor
+ */
+static int map_rintc_hartid(struct acpi_subtable_header *entry,
+			    int device_declaration, u32 acpi_id,
+			    phys_cpuid_t *hartid)
+{
+	struct acpi_madt_rintc *rintc =
+	    container_of(entry, struct acpi_madt_rintc, header);
+
+	if (!(rintc->flags & ACPI_MADT_ENABLED))
+		return -ENODEV;
+
+	/* device_declaration means Device object in DSDT, in the
+	 * RISC-V, logical processors are required to
+	 * have a Processor Device object in the DSDT, so we should
+	 * check device_declaration here
+	 */
+	if (device_declaration && rintc->uid == acpi_id) {
+		*hartid = rintc->hart_id;
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
 static phys_cpuid_t map_madt_entry(struct acpi_table_madt *madt,
 				   int type, u32 acpi_id)
 {
@@ -136,6 +162,9 @@ static phys_cpuid_t map_madt_entry(struct acpi_table_madt *madt,
 		} else if (header->type == ACPI_MADT_TYPE_GENERIC_INTERRUPT) {
 			if (!map_gicc_mpidr(header, type, acpi_id, &phys_id))
 				break;
+		} else if (header->type == ACPI_MADT_TYPE_RINTC) {
+			if (!map_rintc_hartid(header, type, acpi_id, &phys_id))
+				break;
 		}
 		entry += header->length;
 	}