[PATCH RFC 12/19] iommu/arm-smmu-v3: Add feature detection for HTTU

Joao Martins
2022-04-28T21:12:04Z

From: Jean-Philippe Brucker <jean-philippe@linaro.org>

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 <jean-philippe@linaro.org>
[joaomart: Change commit message to reflect the underlying changes]
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
---
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 32 +++++++++++++++++++++
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 5 ++++
2 files changed, 37 insertions(+)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index fd49282c03a3..14609ece4e33 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -3424,6 +3424,28 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass)
return 0;
}

+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 features = 0;
+
+ switch (FIELD_GET(IDR0_HTTU, reg)) {
+ case IDR0_HTTU_ACCESS_DIRTY:
+ features |= ARM_SMMU_FEAT_HD;
+ fallthrough;
+ case IDR0_HTTU_ACCESS:
+ features |= ARM_SMMU_FEAT_HA;
+ }
+
+ if (smmu->dev->of_node)
+ smmu->features |= features;
+ else if (features != fw_features)
+ /* ACPI IORT sets the HTTU bits */
+ dev_warn(smmu->dev,
+ "IDR0.HTTU overridden by FW configuration (0x%x)\n",
+ fw_features);
+}
+
static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)
{
u32 reg;
@@ -3484,6 +3506,8 @@ 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.
@@ -3669,6 +3693,14 @@ 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
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
index cd48590ada30..1487a80fdf1b 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/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
@@ -639,6 +642,8 @@ struct arm_smmu_device {
#define ARM_SMMU_FEAT_BTM (1 << 16)
#define ARM_SMMU_FEAT_SVA (1 << 17)
#define ARM_SMMU_FEAT_E2H (1 << 18)
+#define ARM_SMMU_FEAT_HA (1 << 19)
+#define ARM_SMMU_FEAT_HD (1 << 20)
u32 features;

#define ARM_SMMU_OPT_SKIP_PREFETCH (1 << 0)
--
2.17.2