[PATCH v2 2/6] iommu/arm-smmu-qcom: Add support for TBUs

[Georgi Djakov]

The ARM MMU-500 implements a Translation Buffer Unit (TBU) for each
connected master besides a single TCU which controls and manages the
address translations.

Allow the Qualcomm SMMU driver to probe for any TBU devices that can
provide additional debug features like triggering transactions, logging
outstanding transactions, snapshot capture etc. The primary use-case
would be to get information from a TBU and print it during a context
fault.

Signed-off-by: Georgi Djakov <quic_c_gdjako@xxxxxxxxxxx>
---
 drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 8 ++++++++
 drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h | 4 +++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
index 549ae4dba3a6..1622abace484 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
@@ -1,12 +1,14 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (c) 2019, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2023 Qualcomm Innovation Center, Inc. All rights reserved
  */
 
 #include <linux/acpi.h>
 #include <linux/adreno-smmu-priv.h>
 #include <linux/delay.h>
 #include <linux/of_device.h>
+#include <linux/of_platform.h>
 #include <linux/firmware/qcom/qcom_scm.h>
 
 #include "arm-smmu.h"
@@ -444,6 +446,7 @@ static struct arm_smmu_device *qcom_smmu_create(struct arm_smmu_device *smmu,
 	const struct device_node *np = smmu->dev->of_node;
 	const struct arm_smmu_impl *impl;
 	struct qcom_smmu *qsmmu;
+	int ret;
 
 	if (!data)
 		return ERR_PTR(-EINVAL);
@@ -467,6 +470,11 @@ static struct arm_smmu_device *qcom_smmu_create(struct arm_smmu_device *smmu,
 	qsmmu->smmu.impl = impl;
 	qsmmu->cfg = data->cfg;
 
+	INIT_LIST_HEAD(&qsmmu->tbu_list);
+	ret = devm_of_platform_populate(smmu->dev);
+	if (ret)
+		return ERR_PTR(ret);
+
 	return &qsmmu->smmu;
 }
 
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h
index 593910567b88..2164a9cf3dde 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.h
@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * Copyright (c) 2022, Qualcomm Innovation Center, Inc. All rights reserved.
+ * Copyright (c) 2022-2023, Qualcomm Innovation Center, Inc. All rights reserved.
  */
 
 #ifndef _ARM_SMMU_QCOM_H
@@ -12,6 +12,8 @@ struct qcom_smmu {
 	bool bypass_quirk;
 	u8 bypass_cbndx;
 	u32 stall_enabled;
+	struct mutex tbu_list_lock;  /* protects tbu_list */
+	struct list_head tbu_list;
 };
 
 enum qcom_smmu_impl_reg_offset {