[PATCH v3 4/7] iommu/qcom: Properly reset the IOMMU context

[kholk11 at gmail.com]

From: AngeloGioacchino Del Regno <kholk11 at gmail.com>

To avoid context faults reset the context entirely on detach and
to ensure a fresh clean start also do a complete reset before
programming the context for domain initialization.

Signed-off-by: AngeloGioacchino Del Regno <kholk11 at gmail.com>
---
 drivers/iommu/qcom_iommu.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/qcom_iommu.c b/drivers/iommu/qcom_iommu.c
index c8957ec83b92..b4a38ef129e3 100644
--- a/drivers/iommu/qcom_iommu.c
+++ b/drivers/iommu/qcom_iommu.c
@@ -220,6 +220,23 @@ static irqreturn_t qcom_iommu_fault(int irq, void *dev)
 	return IRQ_HANDLED;
 }
 
+static void qcom_iommu_reset_ctx(struct qcom_iommu_ctx *ctx)
+{
+	iommu_writel(ctx, ARM_SMMU_CB_FAR, 0);
+	iommu_writel(ctx, ARM_SMMU_CB_FSR, 0);
+	iommu_writel(ctx, ARM_SMMU_CB_S1_MAIR1, 0);
+	iommu_writel(ctx, ARM_SMMU_CB_PAR, 0);
+	iommu_writel(ctx, ARM_SMMU_CB_S1_MAIR0, 0);
+	iommu_writel(ctx, ARM_SMMU_CB_SCTLR, 0);
+	iommu_writel(ctx, ARM_SMMU_CB_TCR2, 0);
+	iommu_writel(ctx, ARM_SMMU_CB_TCR, 0);
+	iommu_writeq(ctx, ARM_SMMU_CB_TTBR0, 0);
+	iommu_writeq(ctx, ARM_SMMU_CB_TTBR1, 0);
+
+	/* Should we issue a TLBSYNC there instead? */
+	mb();
+}
+
 static int qcom_iommu_init_domain(struct iommu_domain *domain,
 				  struct qcom_iommu_dev *qcom_iommu,
 				  struct iommu_fwspec *fwspec)
@@ -267,6 +284,8 @@ static int qcom_iommu_init_domain(struct iommu_domain *domain,
 			ctx->secure_init = true;
 		}
 
+		qcom_iommu_reset_ctx(ctx);
+
 		/* TCR */
 		iommu_writel(ctx, ARM_SMMU_CB_TCR2,
 				(pgtbl_cfg.arm_lpae_s1_cfg.tcr >> 32) |
@@ -412,8 +431,8 @@ static void qcom_iommu_detach_dev(struct iommu_domain *domain, struct device *de
 	for (i = 0; i < fwspec->num_ids; i++) {
 		struct qcom_iommu_ctx *ctx = to_ctx(fwspec, fwspec->ids[i]);
 
-		/* Disable the context bank: */
-		iommu_writel(ctx, ARM_SMMU_CB_SCTLR, 0);
+		/* Disable and reset the context bank */
+		qcom_iommu_reset_ctx(ctx);
 
 		ctx->domain = NULL;
 	}
-- 
2.21.0