linux-kernel - [PATCH 1/1] iommu/arm-smmu: Log CBFRSYNRA register on context fault

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Message-Id: <20190415173758.22112-1-vivek.gautam@codeaurora.org>
Date:   Mon, 15 Apr 2019 23:07:58 +0530
From:   Vivek Gautam <vivek.gautam@...eaurora.org>
To:     joro@...tes.org, will.deacon@....com, robin.murphy@....com,
        iommu@...ts.linux-foundation.org
Cc:     vivek.gautam@...eaurora.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-arm-msm@...r.kernel.org
Subject: [PATCH 1/1] iommu/arm-smmu: Log CBFRSYNRA register on context fault

Bits[15:0] in CBFRSYNRA register contain information about
StreamID of the incoming transaction that generated the
fault. Dump CBFRSYNRA register to get this info.
This is specially useful in a distributed SMMU architecture
where multiple masters are connected to the SMMU.
SID information helps to quickly identify the faulting
master device.

Signed-off-by: Vivek Gautam <vivek.gautam@...eaurora.org>
---

V1 of the patch available @
https://lore.kernel.org/patchwork/patch/1061615/

Changes from v1:
 - Dump the raw register value of CBFRSYNRA register in the
   context fault log rather than extracting the SID inforamtion
   and dumping that.

 drivers/iommu/arm-smmu-regs.h | 2 ++
 drivers/iommu/arm-smmu.c      | 8 ++++++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/arm-smmu-regs.h b/drivers/iommu/arm-smmu-regs.h
index a1226e4ab5f8..e9132a926761 100644
--- a/drivers/iommu/arm-smmu-regs.h
+++ b/drivers/iommu/arm-smmu-regs.h
@@ -147,6 +147,8 @@ enum arm_smmu_s2cr_privcfg {
 #define CBAR_IRPTNDX_SHIFT		24
 #define CBAR_IRPTNDX_MASK		0xff
 
+#define ARM_SMMU_GR1_CBFRSYNRA(n)	(0x400 + ((n) << 2))
+
 #define ARM_SMMU_GR1_CBA2R(n)		(0x800 + ((n) << 2))
 #define CBA2R_RW64_32BIT		(0 << 0)
 #define CBA2R_RW64_64BIT		(1 << 0)
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 045d93884164..a4773e8c6b0e 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -575,7 +575,9 @@ static irqreturn_t arm_smmu_context_fault(int irq, void *dev)
 	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
 	struct arm_smmu_cfg *cfg = &smmu_domain->cfg;
 	struct arm_smmu_device *smmu = smmu_domain->smmu;
+	void __iomem *gr1_base = ARM_SMMU_GR1(smmu);
 	void __iomem *cb_base;
+	u32 cbfrsynra;
 
 	cb_base = ARM_SMMU_CB(smmu, cfg->cbndx);
 	fsr = readl_relaxed(cb_base + ARM_SMMU_CB_FSR);
@@ -585,10 +587,12 @@ static irqreturn_t arm_smmu_context_fault(int irq, void *dev)
 
 	fsynr = readl_relaxed(cb_base + ARM_SMMU_CB_FSYNR0);
 	iova = readq_relaxed(cb_base + ARM_SMMU_CB_FAR);
+	cbfrsynra = readl_relaxed(gr1_base +
+				  ARM_SMMU_GR1_CBFRSYNRA(cfg->cbndx));
 
 	dev_err_ratelimited(smmu->dev,
-	"Unhandled context fault: fsr=0x%x, iova=0x%08lx, fsynr=0x%x, cb=%d\n",
-			    fsr, iova, fsynr, cfg->cbndx);
+	"Unhandled context fault: fsr=0x%x, iova=0x%08lx, fsynr=0x%x, cbfrsynra = 0x%x, cb=%d\n",
+			    fsr, iova, fsynr, cbfrsynra, cfg->cbndx);
 
 	writel(fsr, cb_base + ARM_SMMU_CB_FSR);
 	return IRQ_HANDLED;
-- 
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