[PATCH v4 18/23] iommu/arm-smmu-v3-iommufd: Support implementation-defined hw_info

[Nicolin Chen <nicolinc@nvidia.com>]

Repurpose the @__reserved field in the struct iommu_hw_info_arm_smmuv3,
to an HW implementation-defined field @impl.

This will be used by Tegra241 CMDQV implementation on top of a standard
ARM SMMUv3 IOMMU. The @impl will be only valid if @flags is set with an
implementation-defined flag.

Thus in the driver-level, add an hw_info impl op that will return such
a flag and fill the impl field.

Reviewed-by: Pranjal Shrivastava <praan@google.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h     |  1 +
 include/uapi/linux/iommufd.h                    |  4 ++--
 .../iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c | 17 ++++++++++++++---
 3 files changed, 17 insertions(+), 5 deletions(-)

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 a5835af72417..bab7a9ce1283 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -726,6 +726,7 @@ struct arm_smmu_impl_ops {
 		struct arm_smmu_domain *smmu_domain, struct iommufd_ctx *ictx,
 		unsigned int viommu_type,
 		const struct iommu_user_data *user_data);
+	u32 (*hw_info)(struct arm_smmu_device *smmu, u32 *impl);
 };
 
 /* An SMMUv3 instance */
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 001e2deb5a2d..28ab42a85268 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -554,7 +554,7 @@ struct iommu_hw_info_vtd {
  *                                   (IOMMU_HW_INFO_TYPE_ARM_SMMUV3)
  *
  * @flags: Must be set to 0
- * @__reserved: Must be 0
+ * @impl: Must be 0
  * @idr: Implemented features for ARM SMMU Non-secure programming interface
  * @iidr: Information about the implementation and implementer of ARM SMMU,
  *        and architecture version supported
@@ -585,7 +585,7 @@ struct iommu_hw_info_vtd {
  */
 struct iommu_hw_info_arm_smmuv3 {
 	__u32 flags;
-	__u32 __reserved;
+	__u32 impl;
 	__u32 idr[6];
 	__u32 iidr;
 	__u32 aidr;
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
index b316d1df043f..8ea9a022e444 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c
@@ -10,6 +10,7 @@
 void *arm_smmu_hw_info(struct device *dev, u32 *length, u32 *type)
 {
 	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+	struct arm_smmu_device *smmu = master->smmu;
 	struct iommu_hw_info_arm_smmuv3 *info;
 	u32 __iomem *base_idr;
 	unsigned int i;
@@ -18,15 +19,25 @@ void *arm_smmu_hw_info(struct device *dev, u32 *length, u32 *type)
 	if (!info)
 		return ERR_PTR(-ENOMEM);
 
-	base_idr = master->smmu->base + ARM_SMMU_IDR0;
+	base_idr = smmu->base + ARM_SMMU_IDR0;
 	for (i = 0; i <= 5; i++)
 		info->idr[i] = readl_relaxed(base_idr + i);
-	info->iidr = readl_relaxed(master->smmu->base + ARM_SMMU_IIDR);
-	info->aidr = readl_relaxed(master->smmu->base + ARM_SMMU_AIDR);
+	info->iidr = readl_relaxed(smmu->base + ARM_SMMU_IIDR);
+	info->aidr = readl_relaxed(smmu->base + ARM_SMMU_AIDR);
 
 	*length = sizeof(*info);
 	*type = IOMMU_HW_INFO_TYPE_ARM_SMMUV3;
 
+	if (smmu->impl_ops && smmu->impl_ops->hw_info) {
+		u32 flags, impl;
+
+		flags = smmu->impl_ops->hw_info(smmu, &impl);
+		if (flags) {
+			info->impl = impl;
+			info->flags |= flags;
+		}
+	}
+
 	return info;
 }
 
-- 
2.43.0