[PATCH v3] ACPI/IORT: Fix PMCG node always look for a single ID mapping.

[Tuan Phan]

PMCG node can have zero ID mapping if its overflow interrupt
is wire based. The code to parse PMCG node can not assume it will
have a single ID mapping.

Fixes: 24e516049360 ("ACPI/IORT: Add support for PMCG")
Reviewed-by: Hanjun Guo <guoahanjun@xxxxxxxxxx>
Signed-off-by: Tuan Phan <tuanphan@xxxxxxxxxxxxxxxxxxxxxx>
---
v1 -> v2:
- Use pmcg node to detect wired base overflow interrupt.

v2 -> v3:
- Address Hanjun and Robin's comments.

 drivers/acpi/arm64/iort.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index ed3d2d1..12bb70e 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -414,6 +414,7 @@ static struct acpi_iort_node *iort_node_get_id(struct acpi_iort_node *node,
 static int iort_get_id_mapping_index(struct acpi_iort_node *node)
 {
 	struct acpi_iort_smmu_v3 *smmu;
+	struct acpi_iort_pmcg *pmcg;
 
 	switch (node->type) {
 	case ACPI_IORT_NODE_SMMU_V3:
@@ -441,6 +442,10 @@ static int iort_get_id_mapping_index(struct acpi_iort_node *node)
 
 		return smmu->id_mapping_index;
 	case ACPI_IORT_NODE_PMCG:
+		pmcg = (struct acpi_iort_pmcg *)node->node_data;
+		if (pmcg->overflow_gsiv || node->mapping_count == 0)
+			return -EINVAL;
+
 		return 0;
 	default:
 		return -EINVAL;
-- 
2.7.4