linux-kernel - [PATCH 3/3] coresight-tnoc: Add runtime PM support for Interconnect TNOC

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Message-Id: <20250815-itnoc-v1-3-62c8e4f7ad32@oss.qualcomm.com>
Date: Fri, 15 Aug 2025 06:18:14 -0700
From: Yuanfang Zhang <yuanfang.zhang@....qualcomm.com>
To: Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        James Clark <james.clark@...aro.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: kernel@....qualcomm.com, coresight@...ts.linaro.org,
        linux-arm-kernel@...ts.infradead.org, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Yuanfang Zhang <yuanfang.zhang@....qualcomm.com>
Subject: [PATCH 3/3] coresight-tnoc: Add runtime PM support for
 Interconnect TNOC

This patch adds runtime power management support for platform-based
CoreSight Interconnect TNOC (ITNOC) devices. It introduces suspend and
resume callbacks to manage the APB clock (`pclk`) during device runtime
transitions.

Signed-off-by: Yuanfang Zhang <yuanfang.zhang@....qualcomm.com>
---
 drivers/hwtracing/coresight/coresight-tnoc.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-tnoc.c b/drivers/hwtracing/coresight/coresight-tnoc.c
index aa6f48d838c00d71eff22c18e34e00b93755fd82..f12a1698824bc678545319a3f482fd27e67a7352 100644
--- a/drivers/hwtracing/coresight/coresight-tnoc.c
+++ b/drivers/hwtracing/coresight/coresight-tnoc.c
@@ -270,6 +270,31 @@ static void itnoc_remove(struct platform_device *pdev)
 	pm_runtime_disable(&pdev->dev);
 }
 
+#ifdef CONFIG_PM
+static int itnoc_runtime_suspend(struct device *dev)
+{
+	struct trace_noc_drvdata *drvdata = dev_get_drvdata(dev);
+
+	clk_disable_unprepare(drvdata->pclk);
+
+	return 0;
+}
+
+static int itnoc_runtime_resume(struct device *dev)
+{
+	struct trace_noc_drvdata *drvdata = dev_get_drvdata(dev);
+	int ret;
+
+	ret = clk_prepare_enable(drvdata->pclk);
+
+	return ret;
+}
+#endif
+
+static const struct dev_pm_ops itnoc_dev_pm_ops = {
+	SET_RUNTIME_PM_OPS(itnoc_runtime_suspend, itnoc_runtime_resume, NULL)
+};
+
 static const struct of_device_id itnoc_of_match[] = {
 	{ .compatible = "qcom,coresight-itnoc" },
 	{}
@@ -282,6 +307,7 @@ static struct platform_driver itnoc_driver = {
 	.driver = {
 		.name = "coresight-itnoc",
 		.of_match_table = itnoc_of_match,
+		.pm = &itnoc_dev_pm_ops,
 	},
 };
 

-- 
2.34.1