iommu/io-pgtable: Rationalise quirk handling

As the number of io-pgtable implementations grows beyond 1, it's time
to rationalise the quirks mechanism before things have a chance to
start getting really ugly and out-of-hand.

To that end:
- Indicate exactly which quirks each format can/does support.
- Fail creating a table if a caller wants unsupported quirks.
- Properly document where each quirk applies and why.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index b2bbc8427579..f433b516098a 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -659,8 +659,12 @@ static struct io_pgtable *
 arm_64_lpae_alloc_pgtable_s1(struct io_pgtable_cfg *cfg, void *cookie)
 {
 	u64 reg;
-	struct arm_lpae_io_pgtable *data = arm_lpae_alloc_pgtable(cfg);
+	struct arm_lpae_io_pgtable *data;
+
+	if (cfg->quirks & ~IO_PGTABLE_QUIRK_ARM_NS)
+		return NULL;
 
+	data = arm_lpae_alloc_pgtable(cfg);
 	if (!data)
 		return NULL;
 
@@ -743,8 +747,13 @@ static struct io_pgtable *
 arm_64_lpae_alloc_pgtable_s2(struct io_pgtable_cfg *cfg, void *cookie)
 {
 	u64 reg, sl;
-	struct arm_lpae_io_pgtable *data = arm_lpae_alloc_pgtable(cfg);
+	struct arm_lpae_io_pgtable *data;
+
+	/* The NS quirk doesn't apply at stage 2 */
+	if (cfg->quirks)
+		return NULL;
 
+	data = arm_lpae_alloc_pgtable(cfg);
 	if (!data)
 		return NULL;