linux-kernel - [PATCH v3 2/4] iommu/arm-smmu: Workaround for Marvell Armada-AP806 SoC erratum #582743

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Message-Id: <20200702201633.22693-3-tn@semihalf.com>
Date:   Thu,  2 Jul 2020 22:16:31 +0200
From:   Tomasz Nowicki <tn@...ihalf.com>
To:     will@...nel.org, robin.murphy@....com, joro@...tes.org,
        gregory.clement@...tlin.com, robh+dt@...nel.org, hannah@...vell.com
Cc:     linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org,
        devicetree@...r.kernel.org, catalin.marinas@....com,
        nadavh@...vell.com, linux-arm-kernel@...ts.infradead.org,
        mw@...ihalf.com, Tomasz Nowicki <tn@...ihalf.com>
Subject: [PATCH v3 2/4] iommu/arm-smmu: Workaround for Marvell Armada-AP806 SoC erratum #582743

From: Hanna Hawa <hannah@...vell.com>

Due to erratum #582743, the Marvell Armada-AP806 can't access 64bit to
ARM SMMUv2 registers.

Provide implementation relevant hooks:
- split the writeq/readq to two accesses of writel/readl.
- mask the MMU_IDR2.PTFSv8 fields to not use AArch64 format (but
only AARCH32_L) since with AArch64 format 32 bits access is not supported.

Note that separate writes/reads to 2 is not problem regards to
atomicity, because the driver use the readq/writeq while initialize
the SMMU, report for SMMU fault, and use spinlock in one
case (iova_to_phys).

Signed-off-by: Hanna Hawa <hannah@...vell.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@...tlin.com>
Signed-off-by: Tomasz Nowicki <tn@...ihalf.com>
---
 Documentation/arm64/silicon-errata.rst |  3 ++
 drivers/iommu/arm-smmu-impl.c          | 52 ++++++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/Documentation/arm64/silicon-errata.rst b/Documentation/arm64/silicon-errata.rst
index 936cf2a59ca4..157214d3abe1 100644
--- a/Documentation/arm64/silicon-errata.rst
+++ b/Documentation/arm64/silicon-errata.rst
@@ -125,6 +125,9 @@ stable kernels.
 | Cavium         | ThunderX2 Core  | #219            | CAVIUM_TX2_ERRATUM_219      |
 +----------------+-----------------+-----------------+-----------------------------+
 +----------------+-----------------+-----------------+-----------------------------+
+| Marvell        | ARM-MMU-500     | #582743         | N/A                         |
++----------------+-----------------+-----------------+-----------------------------+
++----------------+-----------------+-----------------+-----------------------------+
 | Freescale/NXP  | LS2080A/LS1043A | A-008585        | FSL_ERRATUM_A008585         |
 +----------------+-----------------+-----------------+-----------------------------+
 +----------------+-----------------+-----------------+-----------------------------+
diff --git a/drivers/iommu/arm-smmu-impl.c b/drivers/iommu/arm-smmu-impl.c
index c75b9d957b70..c1fc5e1b8193 100644
--- a/drivers/iommu/arm-smmu-impl.c
+++ b/drivers/iommu/arm-smmu-impl.c
@@ -147,6 +147,53 @@ static const struct arm_smmu_impl arm_mmu500_impl = {
 	.reset = arm_mmu500_reset,
 };
 
+static u64 mrvl_mmu500_readq(struct arm_smmu_device *smmu, int page, int off)
+{
+	u64 val;
+
+	/*
+	 * Marvell Armada-AP806 erratum #582743.
+	 * Split all the readq to double readl
+	 */
+	val = (u64)readl_relaxed(arm_smmu_page(smmu, page) + off + 4) << 32;
+	val |= readl_relaxed(arm_smmu_page(smmu, page) + off);
+
+	return val;
+}
+
+static void mrvl_mmu500_writeq(struct arm_smmu_device *smmu, int page, int off,
+			       u64 val)
+{
+	/*
+	 * Marvell Armada-AP806 erratum #582743.
+	 * Split all the writeq to double writel
+	 */
+	writel_relaxed(upper_32_bits(val), arm_smmu_page(smmu, page) + off + 4);
+	writel_relaxed(lower_32_bits(val), arm_smmu_page(smmu, page) + off);
+}
+
+static u32 mrvl_mmu500_cfg_id2_fixup(u32 id)
+{
+
+	/*
+	 * Armada-AP806 erratum #582743.
+	 * Hide the SMMU_IDR2.PTFSv8 fields to sidestep the AArch64
+	 * formats altogether and allow using 32 bits access on the
+	 * interconnect.
+	 */
+	id &= ~(ARM_SMMU_ID2_PTFS_4K | ARM_SMMU_ID2_PTFS_16K |
+		ARM_SMMU_ID2_PTFS_64K);
+
+	return id;
+}
+
+static const struct arm_smmu_impl mrvl_mmu500_impl = {
+	.read_reg64 = mrvl_mmu500_readq,
+	.write_reg64 = mrvl_mmu500_writeq,
+	.cfg_id2_fixup = mrvl_mmu500_cfg_id2_fixup,
+	.reset = arm_mmu500_reset,
+};
+
 
 struct arm_smmu_device *arm_smmu_impl_init(struct arm_smmu_device *smmu)
 {
@@ -160,6 +207,11 @@ struct arm_smmu_device *arm_smmu_impl_init(struct arm_smmu_device *smmu)
 	 */
 	switch (smmu->model) {
 	case ARM_MMU500:
+		if (of_device_is_compatible(smmu->dev->of_node,
+					    "marvell,ap806-smmu-500")) {
+			smmu->impl = &mrvl_mmu500_impl;
+			return smmu;
+		}
 		smmu->impl = &arm_mmu500_impl;
 		break;
 	case CAVIUM_SMMUV2:
-- 
2.17.1