ACPI/IORT: Make iort_match_node_callback walk the ACPI namespace for NC

When the iort_match_node_callback is invoked for a named component
the match should be executed upon a device with an ACPI companion.

For devices with no ACPI companion set-up the ACPI device tree must be
walked in order to find the first parent node with a companion set and
check the parent node against the named component entry to check whether
there is a match and therefore an IORT node describing the in/out ID
translation for the device has been found.
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Link: https://lore.kernel.org/r/20200619082013.13661-2-lorenzo.pieralisi@arm.comSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

drivers/acpi/arm64/iort.c

@@ -264,15 +264,31 @@ static acpi_status iort_match_node_callback(struct acpi_iort_node *node,
 
 	if (node->type == ACPI_IORT_NODE_NAMED_COMPONENT) {
 		struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
-		struct acpi_device *adev = to_acpi_device_node(dev->fwnode);
+		struct acpi_device *adev;
 		struct acpi_iort_named_component *ncomp;
+		struct device *nc_dev = dev;
+
+		/*
+		 * Walk the device tree to find a device with an
+		 * ACPI companion; there is no point in scanning
+		 * IORT for a device matching a named component if
+		 * the device does not have an ACPI companion to
+		 * start with.
+		 */
+		do {
+			adev = ACPI_COMPANION(nc_dev);
+			if (adev)
+				break;
+
+			nc_dev = nc_dev->parent;
+		} while (nc_dev);
 
 		if (!adev)
 			goto out;
 
 		status = acpi_get_name(adev->handle, ACPI_FULL_PATHNAME, &buf);
 		if (ACPI_FAILURE(status)) {
-			dev_warn(dev, "Can't get device full path name\n");
+			dev_warn(nc_dev, "Can't get device full path name\n");
 			goto out;
 		}