[PATCH AUTOSEL 4.18 82/88] iommu/ipmmu-vmsa: IMUCTRn.TTSEL needs a special usage on R-Car Gen3

[Sasha Levin]

From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>

[ Upstream commit 2ae86955703e9e6a119af4bbe27f6b6dd7a43131 ]

The TTSEL bit of IMUCTRn register of R-Car Gen3 needs to be set
unused MMU context number even if uTLBs are disabled
(The MMUEN bit of IMUCTRn register = 0).
Since initial values of IMUCTRn.TTSEL on all IPMMU-domains are 0,
this patch adds a new feature "reserved_context" to reserve IPMMU
context number 0 as the unused MMU context.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 drivers/iommu/ipmmu-vmsa.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
index 40ae6e87cb88..559ecdf84729 100644
--- a/drivers/iommu/ipmmu-vmsa.c
+++ b/drivers/iommu/ipmmu-vmsa.c
@@ -47,6 +47,7 @@ struct ipmmu_features {
 	unsigned int number_of_contexts;
 	bool setup_imbuscr;
 	bool twobit_imttbcr_sl0;
+	bool reserved_context;
 };
 
 struct ipmmu_vmsa_device {
@@ -917,6 +918,7 @@ static const struct ipmmu_features ipmmu_features_default = {
 	.number_of_contexts = 1, /* software only tested with one context */
 	.setup_imbuscr = true,
 	.twobit_imttbcr_sl0 = false,
+	.reserved_context = false,
 };
 
 static const struct ipmmu_features ipmmu_features_r8a7795 = {
@@ -925,6 +927,7 @@ static const struct ipmmu_features ipmmu_features_r8a7795 = {
 	.number_of_contexts = 8,
 	.setup_imbuscr = false,
 	.twobit_imttbcr_sl0 = true,
+	.reserved_context = true,
 };
 
 static const struct of_device_id ipmmu_of_ids[] = {
@@ -1018,6 +1021,11 @@ static int ipmmu_probe(struct platform_device *pdev)
 		}
 
 		ipmmu_device_reset(mmu);
+
+		if (mmu->features->reserved_context) {
+			dev_info(&pdev->dev, "IPMMU context 0 is reserved\n");
+			set_bit(0, mmu->ctx);
+		}
 	}
 
 	/*
-- 
2.17.1