[PATCH v7 3/3] iommu/arm-smmu-v3: Add workaround for Cavium ThunderX2 erratum #126

From: Geetha Sowjanya <redacted>

Cavium ThunderX2 SMMU doesn't support MSI and also doesn't have unique irq
lines for gerror, eventq and cmdq-sync.

This patch addresses the issue by checking if any interrupt sources are
using same irq number, then they are registered as shared irqs.

Signed-off-by: Geetha Sowjanya <redacted>
---
 Documentation/arm64/silicon-errata.txt |    1 +
 drivers/iommu/arm-smmu-v3.c            |   29 +++++++++++++++++++++++++----
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
index 4693a32..42422f6 100644
--- a/Documentation/arm64/silicon-errata.txt
+++ b/Documentation/arm64/silicon-errata.txt

@@ -63,6 +63,7 @@ stable kernels.
 | Cavium         | ThunderX Core   | #27456          | CAVIUM_ERRATUM_27456        |
 | Cavium         | ThunderX SMMUv2 | #27704          | N/A                         |
 | Cavium         | ThunderX2 SMMUv3| #74             | N/A                         |
+| Cavium         | ThunderX2 SMMUv3| #126            | N/A                         |
 |                |                 |                 |                             |
 | Freescale/NXP  | LS2080A/LS1043A | A-008585        | FSL_ERRATUM_A008585         |
 |                |                 |                 |                             |

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 4e80205..d2db01f 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c

@@ -2232,6 +2232,25 @@ static void arm_smmu_setup_msis(struct arm_smmu_device *smmu)
 	devm_add_action(dev, arm_smmu_free_msis, dev);
 }
 
+static int get_irq_flags(struct arm_smmu_device *smmu, int irq)
+{
+	int match_count = 0;
+
+	if (irq == smmu->evtq.q.irq)
+		match_count++;
+	if (irq == smmu->cmdq.q.irq)
+		match_count++;
+	if (irq == smmu->gerr_irq)
+		match_count++;
+	if (irq == smmu->priq.q.irq)
+		match_count++;
+
+	if (match_count > 1)
+		return IRQF_SHARED | IRQF_ONESHOT;
+
+	return IRQF_ONESHOT;
+}