ACPI / processor : add support for ACPI0010 processor container

ACPI 6.0 adds support for optional processor container device which may
contain child objects that are either processor devices or other processor
containers. This allows representing hierarchical processor topologies.

It is declared using the _HID of ACPI0010. It is an abstract container
used to represent CPU topology and should not be used to hotplug
purposes.

If no matching handler is found for a device in acpi_scan_attach_handler,
acpi_bus_attach does a default enumeration for those devices with valid
HID in the acpi namespace. This patch adds a scan handler for these ACPI
processor containers to avoid default that enumeration and ensures the
platform devices are not created for them.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpi_processor.c

@@ -514,7 +514,24 @@ static struct acpi_scan_handler processor_handler = {
 	},
 };
 
+static int acpi_processor_container_attach(struct acpi_device *dev,
+					   const struct acpi_device_id *id)
+{
+	return 1;
+}
+
+static const struct acpi_device_id processor_container_ids[] = {
+	{ ACPI_PROCESSOR_CONTAINER_HID, },
+	{ }
+};
+
+static struct acpi_scan_handler processor_container_handler = {
+	.ids = processor_container_ids,
+	.attach = acpi_processor_container_attach,
+};
+
 void __init acpi_processor_init(void)
 {
 	acpi_scan_add_handler_with_hotplug(&processor_handler, "processor");
+	acpi_scan_add_handler(&processor_container_handler);
 }

include/acpi/processor.h

@@ -9,6 +9,7 @@
 #define ACPI_PROCESSOR_CLASS		"processor"
 #define ACPI_PROCESSOR_DEVICE_NAME	"Processor"
 #define ACPI_PROCESSOR_DEVICE_HID	"ACPI0007"
+#define ACPI_PROCESSOR_CONTAINER_HID	"ACPI0010"
 
 #define ACPI_PROCESSOR_BUSY_METRIC	10