[PATCHv6 2/6] iommu/arm-smmu: Add domain attribute for system cache

[Sai Prakash Ranjan]

Add iommu domain attribute for using system cache aka last level
cache by client drivers like GPU to set right attributes for caching
the hardware pagetables into the system cache.

Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
---
 drivers/iommu/arm/arm-smmu/arm-smmu.c | 17 +++++++++++++++++
 drivers/iommu/arm/arm-smmu/arm-smmu.h |  1 +
 include/linux/iommu.h                 |  1 +
 3 files changed, 19 insertions(+)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index 1f06ab219819..d449c895ba16 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -789,6 +789,9 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
 	if (smmu_domain->non_strict)
 		pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_NON_STRICT;
 
+	if (smmu_domain->sys_cache)
+		pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_SYS_CACHE;
+
 	pgtbl_ops = alloc_io_pgtable_ops(fmt, &pgtbl_cfg, smmu_domain);
 	if (!pgtbl_ops) {
 		ret = -ENOMEM;
@@ -1513,6 +1516,9 @@ static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
 		case DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE:
 			*(int *)data = smmu_domain->non_strict;
 			return 0;
+		case DOMAIN_ATTR_SYS_CACHE:
+			*((int *)data) = smmu_domain->sys_cache;
+			return 0;
 		default:
 			return -ENODEV;
 		}
@@ -1544,6 +1550,17 @@ static int arm_smmu_domain_set_attr(struct iommu_domain *domain,
 			else
 				smmu_domain->stage = ARM_SMMU_DOMAIN_S1;
 			break;
+		case DOMAIN_ATTR_SYS_CACHE:
+			if (smmu_domain->smmu) {
+				ret = -EPERM;
+				goto out_unlock;
+			}
+
+			if (*((int *)data))
+				smmu_domain->sys_cache = true;
+			else
+				smmu_domain->sys_cache = false;
+			break;
 		default:
 			ret = -ENODEV;
 		}
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h b/drivers/iommu/arm/arm-smmu/arm-smmu.h
index ddf2ca4c923d..93593e164e44 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h
@@ -373,6 +373,7 @@ struct arm_smmu_domain {
 	struct mutex			init_mutex; /* Protects smmu pointer */
 	spinlock_t			cb_lock; /* Serialises ATS1* ops and TLB syncs */
 	struct iommu_domain		domain;
+	bool				sys_cache;
 };
 
 struct arm_smmu_master_cfg {
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index fee209efb756..a580dfe9c68d 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -118,6 +118,7 @@ enum iommu_attr {
 	DOMAIN_ATTR_FSL_PAMUV1,
 	DOMAIN_ATTR_NESTING,	/* two stages of translation */
 	DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE,
+	DOMAIN_ATTR_SYS_CACHE,
 	DOMAIN_ATTR_MAX,
 };
 
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