Add interrconnect voting implementation in driver and related dt-bindings

Documentation/devicetree/bindings/iommu/arm,smmu.yaml

@@ -241,6 +241,13 @@ properties:
     minItems: 1
     maxItems: 3
 
+  interconnects:
+    maxItems: 1
+    description:
+      Interconnect path to the SMMU register space. Required on SoCs
+      where the SMMU registers are only accessible after a bandwidth
+      vote has been placed on the interconnect fabric.
+
   nvidia,memory-controller:
     description: |
       A phandle to the memory controller on NVIDIA Tegra186 and later SoCs.
@@ -600,6 +607,26 @@ allOf:
         clock-names: false
         clocks: false
 
+  - if:
+      properties:
+        compatible:
+          items:
+            - enum:
+                - qcom,qcs615-smmu-500
+                - qcom,qcs8300-smmu-500
+                - qcom,sa8775p-smmu-500
+                - qcom,sc7280-smmu-500
+            - const: qcom,adreno-smmu
+            - const: qcom,smmu-500
+            - const: arm,mmu-500
+    then:
+      properties:
+        interconnects:
+          maxItems: 1
+    else:
+      properties:
+        interconnects: false
+
   - if:
       properties:
         compatible:

drivers/iommu/arm/arm-smmu/arm-smmu.c

@@ -53,6 +53,11 @@
 #define MSI_IOVA_BASE			0x8000000
 #define MSI_IOVA_LENGTH			0x100000
 
+/* Interconnect bandwidth vote values for the SMMU register access path */
+#define ARM_SMMU_ICC_AVG_BW		0
+#define ARM_SMMU_ICC_PEAK_BW_HIGH	1000
+#define ARM_SMMU_ICC_PEAK_BW_LOW	0
+
 static int force_stage;
 module_param(force_stage, int, S_IRUGO);
 MODULE_PARM_DESC(force_stage,
@@ -86,6 +91,36 @@ static inline void arm_smmu_rpm_put(struct arm_smmu_device *smmu)
 	}
 }
 
+static int arm_smmu_icc_get(struct arm_smmu_device *smmu)
+{
+	smmu->icc_path = devm_of_icc_get(smmu->dev, NULL);
+	if (IS_ERR(smmu->icc_path)) {
+		int err = PTR_ERR(smmu->icc_path);
+
+		if (err == -ENODEV) {
+			smmu->icc_path = NULL;
+			return 0;
+		}
+		return dev_err_probe(smmu->dev, err,
+				     "failed to get interconnect path\n");
+	}
+	return 0;
+}
+
+static void arm_smmu_icc_enable(struct arm_smmu_device *smmu)
+{
+	if (smmu->icc_path)
+		WARN_ON(icc_set_bw(smmu->icc_path, ARM_SMMU_ICC_AVG_BW,
+				   ARM_SMMU_ICC_PEAK_BW_HIGH));
+}
+
+static void arm_smmu_icc_disable(struct arm_smmu_device *smmu)
+{
+	if (smmu->icc_path)
+		WARN_ON(icc_set_bw(smmu->icc_path, ARM_SMMU_ICC_AVG_BW,
+				   ARM_SMMU_ICC_PEAK_BW_LOW));
+}
+
 static void arm_smmu_rpm_use_autosuspend(struct arm_smmu_device *smmu)
 {
 	/*
@@ -2212,6 +2247,17 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
 	if (err)
 		return err;
 
+	/*
+	 * Acquire and vote the interconnect path before accessing any SMMU
+	 * registers (including ARM_SMMU_GR0_ID0 in arm_smmu_device_cfg_probe).
+	 */
+	err = arm_smmu_icc_get(smmu);
+	if (err) {
+		clk_bulk_disable_unprepare(smmu->num_clks, smmu->clks);
+		return err;
+	}
+	arm_smmu_icc_enable(smmu);
+
 	err = arm_smmu_device_cfg_probe(smmu);
 	if (err)
 		return err;
@@ -2291,8 +2337,10 @@ static void arm_smmu_device_shutdown(struct platform_device *pdev)
 
 	if (pm_runtime_enabled(smmu->dev))
 		pm_runtime_force_suspend(smmu->dev);
-	else
+	else {
 		clk_bulk_disable(smmu->num_clks, smmu->clks);
+		arm_smmu_icc_disable(smmu);
+	}
 
 	clk_bulk_unprepare(smmu->num_clks, smmu->clks);
 }
@@ -2312,9 +2360,13 @@ static int __maybe_unused arm_smmu_runtime_resume(struct device *dev)
 	struct arm_smmu_device *smmu = dev_get_drvdata(dev);
 	int ret;
 
+	arm_smmu_icc_enable(smmu);
+
 	ret = clk_bulk_enable(smmu->num_clks, smmu->clks);
-	if (ret)
+	if (ret) {
+		arm_smmu_icc_disable(smmu);
 		return ret;
+	}
 
 	arm_smmu_device_reset(smmu);
 
@@ -2326,6 +2378,7 @@ static int __maybe_unused arm_smmu_runtime_suspend(struct device *dev)
 	struct arm_smmu_device *smmu = dev_get_drvdata(dev);
 
 	clk_bulk_disable(smmu->num_clks, smmu->clks);
+	arm_smmu_icc_disable(smmu);
 
 	return 0;
 }

drivers/iommu/arm/arm-smmu/arm-smmu.h

@@ -15,6 +15,7 @@
 #include <linux/bits.h>
 #include <linux/clk.h>
 #include <linux/device.h>
+#include <linux/interconnect.h>
 #include <linux/io-64-nonatomic-hi-lo.h>
 #include <linux/io-pgtable.h>
 #include <linux/iommu.h>
@@ -335,6 +336,7 @@ struct arm_smmu_device {
 	int				num_clks;
 	unsigned int			*irqs;
 	struct clk_bulk_data		*clks;
+	struct icc_path			*icc_path;
 
 	spinlock_t			global_sync_lock;