[PATCH v3 06/12] iommu/arm-smmu-v3: Add feature detection for BBML

[Keqian Zhu]

From: Kunkun Jiang <jiangkunkun@xxxxxxxxxx>

When altering a translation table descriptor of some specific reasons,
we require break-before-make procedure. But it might cause problems when
the TTD is alive. The I/O streams might not tolerate translation faults.

If the SMMU supports BBM level 1 or BBM level 2, we can change the block
size without using break-before-make sequence.

This adds feature detection for BBML, none functional change expected.

Co-developed-by: Keqian Zhu <zhukeqian1@xxxxxxxxxx>
Signed-off-by: Kunkun Jiang <jiangkunkun@xxxxxxxxxx>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 19 +++++++++++++++++++
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |  6 ++++++
 include/linux/io-pgtable.h                  |  8 ++++++++
 3 files changed, 33 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 369c0ea7a104..443ac19c6da9 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2030,6 +2030,11 @@ static int arm_smmu_domain_finalise(struct iommu_domain *domain,
 	if (smmu->features & ARM_SMMU_FEAT_HD)
 		pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_ARM_HD;
 
+	if (smmu->features & ARM_SMMU_FEAT_BBML1)
+		pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_ARM_BBML1;
+	else if (smmu->features & ARM_SMMU_FEAT_BBML2)
+		pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_ARM_BBML2;
+
 	pgtbl_ops = alloc_io_pgtable_ops(fmt, &pgtbl_cfg, smmu_domain);
 	if (!pgtbl_ops)
 		return -ENOMEM;
@@ -3373,6 +3378,20 @@ static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)
 
 	/* IDR3 */
 	reg = readl_relaxed(smmu->base + ARM_SMMU_IDR3);
+	switch (FIELD_GET(IDR3_BBML, reg)) {
+	case IDR3_BBML0:
+		break;
+	case IDR3_BBML1:
+		smmu->features |= ARM_SMMU_FEAT_BBML1;
+		break;
+	case IDR3_BBML2:
+		smmu->features |= ARM_SMMU_FEAT_BBML2;
+		break;
+	default:
+		dev_err(smmu->dev, "unknown/unsupported BBM behavior level\n");
+		return -ENXIO;
+	}
+
 	if (FIELD_GET(IDR3_RIL, reg))
 		smmu->features |= ARM_SMMU_FEAT_RANGE_INV;
 
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 26d6b935b383..a74125675544 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -54,6 +54,10 @@
 #define IDR1_SIDSIZE			GENMASK(5, 0)
 
 #define ARM_SMMU_IDR3			0xc
+#define IDR3_BBML			GENMASK(12, 11)
+#define IDR3_BBML0			0
+#define IDR3_BBML1			1
+#define IDR3_BBML2			2
 #define IDR3_RIL			(1 << 10)
 
 #define ARM_SMMU_IDR5			0x14
@@ -615,6 +619,8 @@ struct arm_smmu_device {
 #define ARM_SMMU_FEAT_E2H		(1 << 18)
 #define ARM_SMMU_FEAT_HA		(1 << 19)
 #define ARM_SMMU_FEAT_HD		(1 << 20)
+#define ARM_SMMU_FEAT_BBML1		(1 << 21)
+#define ARM_SMMU_FEAT_BBML2		(1 << 22)
 	u32				features;
 
 #define ARM_SMMU_OPT_SKIP_PREFETCH	(1 << 0)
diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h
index 64cee6831c97..9e7163ec9447 100644
--- a/include/linux/io-pgtable.h
+++ b/include/linux/io-pgtable.h
@@ -84,6 +84,12 @@ struct io_pgtable_cfg {
 	 *	attributes set in the TCR for a non-coherent page-table walker.
 	 *
 	 * IO_PGTABLE_QUIRK_ARM_HD: Support hardware management of dirty status.
+	 *
+	 * IO_PGTABLE_QUIRK_ARM_BBML1: ARM SMMU supports BBM Level 1 behavior
+	 *	when changing block size.
+	 *
+	 * IO_PGTABLE_QUIRK_ARM_BBML2: ARM SMMU supports BBM Level 2 behavior
+	 *	when changing block size.
 	 */
 	#define IO_PGTABLE_QUIRK_ARM_NS		BIT(0)
 	#define IO_PGTABLE_QUIRK_NO_PERMS	BIT(1)
@@ -92,6 +98,8 @@ struct io_pgtable_cfg {
 	#define IO_PGTABLE_QUIRK_ARM_TTBR1	BIT(5)
 	#define IO_PGTABLE_QUIRK_ARM_OUTER_WBWA	BIT(6)
 	#define IO_PGTABLE_QUIRK_ARM_HD		BIT(7)
+	#define IO_PGTABLE_QUIRK_ARM_BBML1	BIT(8)
+	#define IO_PGTABLE_QUIRK_ARM_BBML2	BIT(9)
 	unsigned long			quirks;
 	unsigned long			pgsize_bitmap;
 	unsigned int			ias;
-- 
2.19.1