iommu/arm-smmu: Workaround for Marvell Armada-AP806 SoC erratum #582743

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 most 64-bit registers like TTBRn can be accessed as two 32-bit
halves without issue, and AArch32 format ensures that the register writes
which must be atomic (for TLBI etc.) need only be 32-bit.
Signed-off-by: Hanna Hawa <hannah@marvell.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20200715070649.18733-3-tn@semihalf.comSigned-off-by: Will Deacon <will@kernel.org>

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         |
 +----------------+-----------------+-----------------+-----------------------------+
 +----------------+-----------------+-----------------+-----------------------------+

drivers/iommu/arm-smmu-impl.c

@@ -147,6 +147,48 @@ 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)
+{
+	/*
+	 * Marvell Armada-AP806 erratum #582743.
+	 * Split all the readq to double readl
+	 */
+	return hi_lo_readq_relaxed(arm_smmu_page(smmu, page) + off);
+}
+
+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
+	 */
+	hi_lo_writeq_relaxed(val, arm_smmu_page(smmu, page) + off);
+}
+
+static int mrvl_mmu500_cfg_probe(struct arm_smmu_device *smmu)
+{
+
+	/*
+	 * 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.
+	 */
+	smmu->features &= ~(ARM_SMMU_FEAT_FMT_AARCH64_4K |
+			    ARM_SMMU_FEAT_FMT_AARCH64_16K |
+			    ARM_SMMU_FEAT_FMT_AARCH64_64K);
+
+	return 0;
+}
+
+static const struct arm_smmu_impl mrvl_mmu500_impl = {
+	.read_reg64 = mrvl_mmu500_readq,
+	.write_reg64 = mrvl_mmu500_writeq,
+	.cfg_probe = mrvl_mmu500_cfg_probe,
+	.reset = arm_mmu500_reset,
+};
+
 
 struct arm_smmu_device *arm_smmu_impl_init(struct arm_smmu_device *smmu)
 {
@@ -177,5 +219,8 @@ struct arm_smmu_device *arm_smmu_impl_init(struct arm_smmu_device *smmu)
 	    of_device_is_compatible(np, "qcom,sm8250-smmu-500"))
 		return qcom_smmu_impl_init(smmu);
 
+	if (of_device_is_compatible(np, "marvell,ap806-smmu-500"))
+		smmu->impl = &mrvl_mmu500_impl;
+
 	return smmu;
 }