[RFC PATCH v3 7/8] iommu/arm-smmu-v3: Enable pm_runtime and setup devlinks

[Pranjal Shrivastava <praan@google.com>]

Enable PM runtime for SMMUs having a power-domain during smmu probe.
Add a devlink between the clients and SMMU device. The absence of a
power domain effectively disables runtime power management.

Signed-off-by: Pranjal Shrivastava <praan@google.com>
Reviewed-by: Mostafa Saleh <smostafa@google.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

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 5736f08e3af7..80928e5a2d60 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -3568,6 +3568,9 @@ static struct iommu_device *arm_smmu_probe_device(struct device *dev)
 		pci_prepare_ats(to_pci_dev(dev), stu);
 	}
 
+	device_link_add(dev, smmu->dev,
+			DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_SUPPLIER);
+
 	return &smmu->iommu;
 
 err_free_master:
@@ -4927,11 +4930,18 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_disable;
 
+	if (dev->pm_domain) {
+		pm_runtime_set_active(dev);
+		pm_runtime_use_autosuspend(dev);
+		pm_runtime_set_autosuspend_delay(dev, RPM_AUTOSUSPEND_DELAY_MS);
+		pm_runtime_enable(dev);
+	}
+
 	/* And we're up. Go go go! */
 	ret = iommu_device_sysfs_add(&smmu->iommu, dev, NULL,
 				     "smmu3.%pa", &ioaddr);
 	if (ret)
-		goto err_disable;
+		goto err_rpm_disable;
 
 	ret = iommu_device_register(&smmu->iommu, &arm_smmu_ops, dev);
 	if (ret) {
@@ -4943,6 +4953,8 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
 
 err_free_sysfs:
 	iommu_device_sysfs_remove(&smmu->iommu);
+err_rpm_disable:
+	pm_runtime_disable(dev);
 err_disable:
 	arm_smmu_device_disable(smmu);
 err_free_iopf:
-- 
2.50.0.rc2.692.g299adb8693-goog