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

[hannah]

From: Hanna Hawa <hannah@xxxxxxxxxxx>

Due to erratum #582743, the Marvell Armada-AP806 can't access 64bit
to ARM SMMUv2 registers.
This patch split the writeq/readq to two accesses of writel/readl.

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@xxxxxxxxxxx>
---
 Documentation/arm64/silicon-errata.txt |  2 ++
 drivers/iommu/arm-smmu.c               | 33 +++++++++++++++++++++++++++++----
 2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/Documentation/arm64/silicon-errata.txt b/Documentation/arm64/silicon-errata.txt
index 3b2f2dd..fc3f2a0 100644
--- a/Documentation/arm64/silicon-errata.txt
+++ b/Documentation/arm64/silicon-errata.txt
@@ -67,6 +67,8 @@ stable kernels.
 | Cavium         | ThunderX2 SMMUv3| #74             | N/A                         |
 | Cavium         | ThunderX2 SMMUv3| #126            | N/A                         |
 |                |                 |                 |                             |
+| Marvell        | ARM-MMU-500     | #582743         | N/A                         |
+|                |                 |                 |                             |
 | Freescale/NXP  | LS2080A/LS1043A | A-008585        | FSL_ERRATUM_A008585         |
 |                |                 |                 |                             |
 | Hisilicon      | Hip0{5,6,7}     | #161010101      | HISILICON_ERRATUM_161010101 |
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index fccb1d4..d64f892 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -119,6 +119,7 @@ enum arm_smmu_arch_version {
 enum arm_smmu_implementation {
 	GENERIC_SMMU,
 	ARM_MMU500,
+	MRVL_MMU500,
 	CAVIUM_SMMUV2,
 };
 
@@ -276,13 +277,35 @@ static inline void smmu_writeq_relaxed(struct arm_smmu_device *smmu,
 				       u64 val,
 				       void __iomem *addr)
 {
-	writeq_relaxed(val, addr);
+	/*
+	 * Marvell Armada-AP806 erratum #582743.
+	 * Split all the writeq to double writel
+	 */
+	if (smmu->model != MRVL_MMU500) {
+		writeq_relaxed(val, addr);
+		return;
+	}
+
+	writel_relaxed(upper_32_bits(val), addr + 4);
+	writel_relaxed(lower_32_bits(val), addr);
 }
 
 static inline u64 smmu_readq_relaxed(struct arm_smmu_device *smmu,
 				     void __iomem *addr)
 {
-	return readq_relaxed(addr);
+	u64 val;
+
+	/*
+	 * Marvell Armada-AP806 erratum #582743.
+	 * Split all the readq to double readl
+	 */
+	if (smmu->model != MRVL_MMU500)
+		return readq_relaxed(addr);
+
+	val = (u64)readl_relaxed(addr + 4) << 32;
+	val |= readl_relaxed(addr);
+
+	return val;
 }
 
 static void parse_driver_options(struct arm_smmu_device *smmu)
@@ -1611,7 +1634,7 @@ static void arm_smmu_device_reset(struct arm_smmu_device *smmu)
 	for (i = 0; i < smmu->num_mapping_groups; ++i)
 		arm_smmu_write_sme(smmu, i);
 
-	if (smmu->model == ARM_MMU500) {
+	if (smmu->model == ARM_MMU500 || smmu->model == MRVL_MMU500) {
 		/*
 		 * Before clearing ARM_MMU500_ACTLR_CPRE, need to
 		 * clear CACHE_LOCK bit of ACR first. And, CACHE_LOCK
@@ -1640,7 +1663,7 @@ static void arm_smmu_device_reset(struct arm_smmu_device *smmu)
 		 * Disable MMU-500's not-particularly-beneficial next-page
 		 * prefetcher for the sake of errata #841119 and #826419.
 		 */
-		if (smmu->model == ARM_MMU500) {
+		if (smmu->model == ARM_MMU500 || smmu->model == MRVL_MMU500) {
 			reg = readl_relaxed(cb_base + ARM_SMMU_CB_ACTLR);
 			reg &= ~ARM_MMU500_ACTLR_CPRE;
 			writel_relaxed(reg, cb_base + ARM_SMMU_CB_ACTLR);
@@ -1923,6 +1946,7 @@ struct arm_smmu_match_data {
 ARM_SMMU_MATCH_DATA(smmu_generic_v2, ARM_SMMU_V2, GENERIC_SMMU);
 ARM_SMMU_MATCH_DATA(arm_mmu401, ARM_SMMU_V1_64K, GENERIC_SMMU);
 ARM_SMMU_MATCH_DATA(arm_mmu500, ARM_SMMU_V2, ARM_MMU500);
+ARM_SMMU_MATCH_DATA(mrvl_mmu500, ARM_SMMU_V2, MRVL_MMU500);
 ARM_SMMU_MATCH_DATA(cavium_smmuv2, ARM_SMMU_V2, CAVIUM_SMMUV2);
 
 static const struct of_device_id arm_smmu_of_match[] = {
@@ -1931,6 +1955,7 @@ struct arm_smmu_match_data {
 	{ .compatible = "arm,mmu-400", .data = &smmu_generic_v1 },
 	{ .compatible = "arm,mmu-401", .data = &arm_mmu401 },
 	{ .compatible = "arm,mmu-500", .data = &arm_mmu500 },
+	{ .compatible = "marvell,mmu-500", .data = &mrvl_mmu500 },
 	{ .compatible = "cavium,smmu-v2", .data = &cavium_smmuv2 },
 	{ },
 };
-- 
1.9.1