iommu/arm-smmu-v3: Add feature detection for HTTU

If the SMMU supports it and the kernel was built with HTTU support,
Probe support for Hardware Translation Table Update (HTTU) which is
essentially to enable hardware update of access and dirty flags.

Probe and set the smmu::features for Hardware Dirty and Hardware Access
bits. This is in preparation, to enable it on the context descriptors of
stage 1 format.

Signed-off-by: Jean-Philippe Brucker <[email protected]>
Signed-off-by: Joao Martins <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Reviewed-by: Ryan Roberts <[email protected]>
Reviewed-by: Kevin Tian <[email protected]>
Reviewed-by: Nicolin Chen <[email protected]>
Signed-off-by: Shameer Kolothum <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>

Author: jpbrucker

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -4014,6 +4014,28 @@ static void arm_smmu_device_iidr_probe(struct arm_smmu_device *smmu)
 	}
 }
 
+static void arm_smmu_get_httu(struct arm_smmu_device *smmu, u32 reg)
+{
+	u32 fw_features = smmu->features & (ARM_SMMU_FEAT_HA | ARM_SMMU_FEAT_HD);
+	u32 hw_features = 0;
+
+	switch (FIELD_GET(IDR0_HTTU, reg)) {
+	case IDR0_HTTU_ACCESS_DIRTY:
+		hw_features |= ARM_SMMU_FEAT_HD;
+		fallthrough;
+	case IDR0_HTTU_ACCESS:
+		hw_features |= ARM_SMMU_FEAT_HA;
+	}
+
+	if (smmu->dev->of_node)
+		smmu->features |= hw_features;
+	else if (hw_features != fw_features)
+		/* ACPI IORT sets the HTTU bits */
+		dev_warn(smmu->dev,
+			 "IDR0.HTTU features(0x%x) overridden by FW configuration (0x%x)\n",
+			  hw_features, fw_features);
+}
+
 static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)
 {
 	u32 reg;
@@ -4074,6 +4096,8 @@ static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)
 			smmu->features |= ARM_SMMU_FEAT_E2H;
 	}
 
+	arm_smmu_get_httu(smmu, reg);
+
 	/*
 	 * The coherency feature as set by FW is used in preference to the ID
 	 * register, but warn on mismatch.
@@ -4269,6 +4293,14 @@ static int arm_smmu_device_acpi_probe(struct platform_device *pdev,
 	if (iort_smmu->flags & ACPI_IORT_SMMU_V3_COHACC_OVERRIDE)
 		smmu->features |= ARM_SMMU_FEAT_COHERENCY;
 
+	switch (FIELD_GET(ACPI_IORT_SMMU_V3_HTTU_OVERRIDE, iort_smmu->flags)) {
+	case IDR0_HTTU_ACCESS_DIRTY:
+		smmu->features |= ARM_SMMU_FEAT_HD;
+		fallthrough;
+	case IDR0_HTTU_ACCESS:
+		smmu->features |= ARM_SMMU_FEAT_HA;
+	}
+
 	return 0;
 }
 #else

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h

@@ -33,6 +33,9 @@
 #define IDR0_ASID16			(1 << 12)
 #define IDR0_ATS			(1 << 10)
 #define IDR0_HYP			(1 << 9)
+#define IDR0_HTTU			GENMASK(7, 6)
+#define IDR0_HTTU_ACCESS		1
+#define IDR0_HTTU_ACCESS_DIRTY		2
 #define IDR0_COHACC			(1 << 4)
 #define IDR0_TTF			GENMASK(3, 2)
 #define IDR0_TTF_AARCH64		2
@@ -650,6 +653,8 @@ struct arm_smmu_device {
 #define ARM_SMMU_FEAT_E2H		(1 << 18)
 #define ARM_SMMU_FEAT_NESTING		(1 << 19)
 #define ARM_SMMU_FEAT_ATTR_TYPES_OVR	(1 << 20)
+#define ARM_SMMU_FEAT_HA		(1 << 21)
+#define ARM_SMMU_FEAT_HD		(1 << 22)
 	u32				features;
 
 #define ARM_SMMU_OPT_SKIP_PREFETCH	(1 << 0)