[PATCH 3/4] iommu/exynos: fix TLB invalidation for no-block SysMMUs

[Markuss Broks via B4 Relay <devnull+markuss.broks.gmail.com@kernel.org>]

From: Markuss Broks <markuss.broks@gmail.com>

sysmmu_block() polls MMU_STATUS for the blocked state, which no-block
hardware never reports, so on such SysMMUs it always fails, and both
sysmmu_tlb_invalidate_entry() and sysmmu_tlb_invalidate_flpdcache()
skip the invalidation entirely when blocking fails.

On no-block hardware the invalidation registers are written with the
MMU running; the vendor driver never blocks around invalidation. Do
the same and write the invalidation directly. In the FLPD cache path
no-block implies a v7+ SysMMU, hence the unconditional flush-all.

Signed-off-by: Markuss Broks <markuss.broks@gmail.com>
---
 drivers/iommu/exynos-iommu.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
index a3a59d8a4cf1..29b27c7e400a 100644
--- a/drivers/iommu/exynos-iommu.c
+++ b/drivers/iommu/exynos-iommu.c
@@ -685,7 +685,14 @@ static void sysmmu_tlb_invalidate_flpdcache(struct sysmmu_drvdata *data,
 	spin_lock_irqsave(&data->lock, flags);
 	if (data->active && data->version >= MAKE_MMU_VER(3, 3)) {
 		clk_enable(data->clk_master);
-		if (sysmmu_block(data)) {
+		/*
+		 * No-block hardware accepts invalidation writes while the
+		 * MMU is running; it is also v7+, so flush-all covers the
+		 * FLPD cache.
+		 */
+		if (data->no_block) {
+			__sysmmu_tlb_invalidate(data);
+		} else if (sysmmu_block(data)) {
 			if (data->version >= MAKE_MMU_VER(5, 0))
 				__sysmmu_tlb_invalidate(data);
 			else
@@ -721,7 +728,9 @@ static void sysmmu_tlb_invalidate_entry(struct sysmmu_drvdata *data,
 		if (MMU_MAJ_VER(data->version) == 2)
 			num_inv = min_t(unsigned int, size / SPAGE_SIZE, 64);
 
-		if (sysmmu_block(data)) {
+		if (data->no_block) {
+			__sysmmu_tlb_invalidate_entry(data, iova, num_inv);
+		} else if (sysmmu_block(data)) {
 			__sysmmu_tlb_invalidate_entry(data, iova, num_inv);
 			sysmmu_unblock(data);
 		}

-- 
2.55.0