ACPI/IORT: Add node match function

Device drivers (eg ARM SMMU) need to know if a specific component
is part of the IORT table, so that kernel data structures are not
initialized at initcalls time if the respective component is not
part of the IORT table.

To this end, this patch adds a trivial function that allows detecting
if a given IORT node type is present or not in the ACPI table, providing
an ACPI IORT equivalent for of_find_matching_node().

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Tomasz Nowicki <tn@semihalf.com>
Tested-by: Hanjun Guo <hanjun.guo@linaro.org>
Tested-by: Tomasz Nowicki <tn@semihalf.com>
Acked-by: Hanjun Guo <hanjun.guo@linaro.org>
Cc: Hanjun Guo <hanjun.guo@linaro.org>
Cc: Tomasz Nowicki <tn@semihalf.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index 1ac2720da96d..4bb6acbf881f 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -227,6 +227,21 @@ static struct acpi_iort_node *iort_scan_node(enum acpi_iort_node_type type,
         return NULL;
 }
 
+static acpi_status
+iort_match_type_callback(struct acpi_iort_node *node, void *context)
+{
+        return AE_OK;
+}
+
+bool iort_node_match(u8 type)
+{
+        struct acpi_iort_node *node;
+
+        node = iort_scan_node(type, iort_match_type_callback, NULL);
+
+        return node != NULL;
+}
+
 static acpi_status iort_match_node_callback(struct acpi_iort_node *node,
                                             void *context)
 {