linux-kernel - [PATCH] coresight-tpdm: add trace

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Message-ID: <20250530-showtraceid-v1-1-2761352cf7b4@quicinc.com>
Date: Fri, 30 May 2025 15:29:14 +0800
From: Yuanfang Zhang <quic_yuanfang@...cinc.com>
To: Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach
	<mike.leach@...aro.org>,
        James Clark <james.clark@...aro.org>,
        "Alexander
 Shishkin" <alexander.shishkin@...ux.intel.com>
CC: <kernel@....qualcomm.com>, <coresight@...ts.linaro.org>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        Yuanfang Zhang <quic_yuanfang@...cinc.com>
Subject: [PATCH] coresight-tpdm: add trace_id sysfs node

The trace ID of TPMD is the trace ID of the TPDA or TNOC
which it is connected to, this change adds trace_id sysfs
node to expose this trace id to userspace.

Signed-off-by: Yuanfang Zhang <quic_yuanfang@...cinc.com>
---
 drivers/hwtracing/coresight/coresight-tpdm.c | 16 ++++++++++++++++
 drivers/hwtracing/coresight/coresight-tpdm.h |  2 ++
 2 files changed, 18 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-tpdm.c b/drivers/hwtracing/coresight/coresight-tpdm.c
index 7214e65097ec9ac69f6c7c9278bcd28d25945c9e..8a5d115157924f39b09f8e3005827d7d64aa376c 100644
--- a/drivers/hwtracing/coresight/coresight-tpdm.c
+++ b/drivers/hwtracing/coresight/coresight-tpdm.c
@@ -497,6 +497,9 @@ static int tpdm_enable(struct coresight_device *csdev, struct perf_event *event,
 
 	__tpdm_enable(drvdata);
 	drvdata->enable = true;
+
+	if (path)
+		drvdata->traceid = path->trace_id;
 	spin_unlock(&drvdata->spinlock);
 
 	dev_dbg(drvdata->dev, "TPDM tracing enabled\n");
@@ -554,6 +557,7 @@ static void tpdm_disable(struct coresight_device *csdev,
 	__tpdm_disable(drvdata);
 	coresight_set_mode(csdev, CS_MODE_DISABLED);
 	drvdata->enable = false;
+	drvdata->traceid = 0;
 	spin_unlock(&drvdata->spinlock);
 
 	dev_dbg(drvdata->dev, "TPDM tracing disabled\n");
@@ -655,9 +659,21 @@ static ssize_t integration_test_store(struct device *dev,
 }
 static DEVICE_ATTR_WO(integration_test);
 
+static ssize_t traceid_show(struct device *dev,
+			    struct device_attribute *attr, char *buf)
+{
+	unsigned long val;
+	struct tpdm_drvdata *drvdata = dev_get_drvdata(dev->parent);
+
+	val = drvdata->traceid;
+	return sprintf(buf, "%#lx\n", val);
+}
+static DEVICE_ATTR_RO(traceid);
+
 static struct attribute *tpdm_attrs[] = {
 	&dev_attr_reset_dataset.attr,
 	&dev_attr_integration_test.attr,
+	&dev_attr_traceid.attr,
 	NULL,
 };
 
diff --git a/drivers/hwtracing/coresight/coresight-tpdm.h b/drivers/hwtracing/coresight/coresight-tpdm.h
index b117543897344b689f666f6890cabb59c8ee4869..e12a64f265daa86f1b82fa3640e271e8386f99af 100644
--- a/drivers/hwtracing/coresight/coresight-tpdm.h
+++ b/drivers/hwtracing/coresight/coresight-tpdm.h
@@ -300,6 +300,7 @@ struct cmb_dataset {
  * @cmb         Specifics associated to TPDM CMB.
  * @dsb_msr_num Number of MSR supported by DSB TPDM
  * @cmb_msr_num Number of MSR supported by CMB TPDM
+ * @traceid:    Value of the current ID for this component.
  */
 
 struct tpdm_drvdata {
@@ -313,6 +314,7 @@ struct tpdm_drvdata {
 	struct cmb_dataset	*cmb;
 	u32			dsb_msr_num;
 	u32			cmb_msr_num;
+	u8			traceid;
 };
 
 /* Enumerate members of various datasets */

---
base-commit: 94305e83eccb3120c921cd3a015cd74731140bac
change-id: 20250523-showtraceid-2df91c89be8f

Best regards,
-- 
Yuanfang Zhang <quic_yuanfang@...cinc.com>