[PATCH] iommu/arm-smmu: Clear global and context bank fault status registers

[Andreas Herrmann <andreas.herrmann-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>]

After reset these registers have unknown values.
This might cause problems when evaluating SMMU_GFSR and/or SMMU_CB_FSR
in handlers for combined interrupts.

Signed-off-by: Andreas Herrmann <andreas.herrmann-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org>
---
 drivers/iommu/arm-smmu.c |   27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 579b6f8..cbbf597 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -631,6 +631,12 @@ static irqreturn_t arm_smmu_global_fault(int irq, void *dev)
 	return IRQ_HANDLED;
 }
 
+static void arm_smmu_clear_cb_fsr(struct arm_smmu_device *smmu, u8 cbndx)
+{
+	void __iomem *cb_base = ARM_SMMU_CB_BASE(smmu) + ARM_SMMU_CB(smmu, cbndx);
+	writel_relaxed(FSR_FAULT, cb_base + ARM_SMMU_CB_FSR);
+}
+
 static void arm_smmu_init_context_bank(struct arm_smmu_domain *smmu_domain)
 {
 	u32 reg;
@@ -838,6 +844,7 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
 		root_cfg->irptndx = root_cfg->cbndx;
 	}
 
+	arm_smmu_clear_cb_fsr(smmu, root_cfg->cbndx);
 	irq = smmu->irqs[smmu->num_global_irqs + root_cfg->irptndx];
 	ret = request_irq(irq, arm_smmu_context_fault, IRQF_SHARED,
 			  "arm-smmu-context-fault", domain);
@@ -1564,7 +1571,11 @@ static void arm_smmu_device_reset(struct arm_smmu_device *smmu)
 	void __iomem *gr0_base = ARM_SMMU_GR0(smmu);
 	void __iomem *sctlr_base = ARM_SMMU_CB_BASE(smmu) + ARM_SMMU_CB_SCTLR;
 	int i = 0;
-	u32 scr0 = readl_relaxed(gr0_base + ARM_SMMU_GR0_sCR0);
+	u32 val;
+
+	/* clear global FSR */
+	val = readl_relaxed(gr0_base + ARM_SMMU_GR0_sGFSR);
+	writel(val, gr0_base + ARM_SMMU_GR0_sGFSR);
 
 	/* Mark all SMRn as invalid and all S2CRn as bypass */
 	for (i = 0; i < smmu->num_mapping_groups; ++i) {
@@ -1581,24 +1592,26 @@ static void arm_smmu_device_reset(struct arm_smmu_device *smmu)
 	writel_relaxed(0, gr0_base + ARM_SMMU_GR0_TLBIALLH);
 	writel_relaxed(0, gr0_base + ARM_SMMU_GR0_TLBIALLNSNH);
 
+	val = readl_relaxed(gr0_base + ARM_SMMU_GR0_sCR0);
+
 	/* Enable fault reporting */
-	scr0 |= (sCR0_GFRE | sCR0_GFIE | sCR0_GCFGFRE | sCR0_GCFGFIE);
+	val |= (sCR0_GFRE | sCR0_GFIE | sCR0_GCFGFRE | sCR0_GCFGFIE);
 
 	/* Disable TLB broadcasting. */
-	scr0 |= (sCR0_VMIDPNE | sCR0_PTM);
+	val |= (sCR0_VMIDPNE | sCR0_PTM);
 
 	/* Enable client access, but bypass when no mapping is found */
-	scr0 &= ~(sCR0_CLIENTPD | sCR0_USFCFG);
+	val &= ~(sCR0_CLIENTPD | sCR0_USFCFG);
 
 	/* Disable forced broadcasting */
-	scr0 &= ~sCR0_FB;
+	val &= ~sCR0_FB;
 
 	/* Don't upgrade barriers */
-	scr0 &= ~(sCR0_BSU_MASK << sCR0_BSU_SHIFT);
+	val &= ~(sCR0_BSU_MASK << sCR0_BSU_SHIFT);
 
 	/* Push the button */
 	arm_smmu_tlb_sync(smmu);
-	writel(scr0, gr0_base + ARM_SMMU_GR0_sCR0);
+	writel(val, gr0_base + ARM_SMMU_GR0_sCR0);
 }
 
 static int arm_smmu_id_size_to_bits(int size)
-- 
1.7.9.5