coresight: Add label sysfs node support

Mao Jinlong · Suzuki K Poulose · commit 01f96b812526 · 2025-09-23T14:14:13.000+01:00
For some coresight components like CTI and TPDM, there could be numerous of them. From the node name, we can only get the type and register address of the component. We can't identify the HW or the system the component belongs to. Add label sysfs node support for showing the intuitive name of the device. Signed-off-by: Mao Jinlong <quic_jinlmao@quicinc.com> Reviewed-by: Mike Leach <mike.leach@linaro.org> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Link: https://lore.kernel.org/r/20250816072529.3716968-3-quic_jinlmao@quicinc.com
diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-cti b/Documentation/ABI/testing/sysfs-bus-coresight-devices-cti
@@ -239,3 +239,9 @@ Date:		March 2020
 KernelVersion:	5.7
 Contact:	Mike Leach or Mathieu Poirier
 Description:	(Write) Clear all channel / trigger programming.
+
+What:           /sys/bus/coresight/devices/<cti-name>/label
+Date:           Aug 2025
+KernelVersion   6.18
+Contact:        Mao Jinlong <quic_jinlmao@quicinc.com>
+Description:    (Read) Show hardware context information of device.
diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-dummy-source b/Documentation/ABI/testing/sysfs-bus-coresight-devices-dummy-source
@@ -13,3 +13,9 @@ KernelVersion:	6.14
 Contact:	Mao Jinlong <quic_jinlmao@quicinc.com>
 Description:	(R) Show the trace ID that will appear in the trace stream
 		coming from this trace entity.
+
+What:           /sys/bus/coresight/devices/dummy_source<N>/label
+Date:           Aug 2025
+KernelVersion   6.18
+Contact:        Mao Jinlong <quic_jinlmao@quicinc.com>
+Description:    (Read) Show hardware context information of device.
diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-etb10 b/Documentation/ABI/testing/sysfs-bus-coresight-devices-etb10
@@ -19,6 +19,12 @@ Description:	(RW) Disables write access to the Trace RAM by stopping the
 		into the Trace RAM following the trigger event is equal to the
 		value stored in this register+1 (from ARM ETB-TRM).
 
+What:           /sys/bus/coresight/devices/<memory_map>.etb/label
+Date:           Aug 2025
+KernelVersion   6.18
+Contact:        Mao Jinlong <quic_jinlmao@quicinc.com>
+Description:    (Read) Show hardware context information of device.
+
 What:		/sys/bus/coresight/devices/<memory_map>.etb/mgmt/rdp
 Date:		March 2016
 KernelVersion:	4.7
diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm3x b/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm3x
@@ -251,6 +251,12 @@ KernelVersion:	4.4
 Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
 Description:	(RO) Holds the cpu number this tracer is affined to.
 
+What:           /sys/bus/coresight/devices/<memory_map>.[etm|ptm]/label
+Date:           Aug 2025
+KernelVersion   6.18
+Contact:        Mao Jinlong <quic_jinlmao@quicinc.com>
+Description:    (Read) Show hardware context information of device.
+
 What:		/sys/bus/coresight/devices/<memory_map>.[etm|ptm]/mgmt/etmccr
 Date:		September 2015
 KernelVersion:	4.4
diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x b/Documentation/ABI/testing/sysfs-bus-coresight-devices-etm4x
@@ -329,6 +329,12 @@ Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
 Description:	(RW) Access the selected single show PE comparator control
 		register.
 
+What:           /sys/bus/coresight/devices/etm<N>/label
+Date:           Aug 2025
+KernelVersion   6.18
+Contact:        Mao Jinlong <quic_jinlmao@quicinc.com>
+Description:    (Read) Show hardware context information of device.
+
 What:		/sys/bus/coresight/devices/etm<N>/mgmt/trcoslsr
 Date:		April 2015
 KernelVersion:	4.01
diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-funnel b/Documentation/ABI/testing/sysfs-bus-coresight-devices-funnel
@@ -10,3 +10,9 @@ Date:		November 2014
 KernelVersion:	3.19
 Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
 Description:	(RW) Defines input port priority order.
+
+What:           /sys/bus/coresight/devices/<memory_map>.funnel/label
+Date:           Aug 2025
+KernelVersion   6.18
+Contact:        Mao Jinlong <quic_jinlmao@quicinc.com>
+Description:    (Read) Show hardware context information of device.
diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-stm b/Documentation/ABI/testing/sysfs-bus-coresight-devices-stm
@@ -51,3 +51,9 @@ KernelVersion:	4.7
 Contact:	Mathieu Poirier <mathieu.poirier@linaro.org>
 Description:	(RW) Holds the trace ID that will appear in the trace stream
 		coming from this trace entity.
+
+What:           /sys/bus/coresight/devices/<memory_map>.stm/label
+Date:           Aug 2025
+KernelVersion   6.18
+Contact:        Mao Jinlong <quic_jinlmao@quicinc.com>
+Description:    (Read) Show hardware context information of device.
diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tmc b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tmc
@@ -107,3 +107,9 @@ Contact:	Anshuman Khandual <anshuman.khandual@arm.com>
 Description:	(RW) Current Coresight TMC-ETR buffer mode selected. But user could
 		only provide a mode which is supported for a given ETR device. This
 		file is available only for TMC ETR devices.
+
+What:           /sys/bus/coresight/devices/<memory_map>.tmc/label
+Date:           Aug 2025
+KernelVersion   6.18
+Contact:        Mao Jinlong <quic_jinlmao@quicinc.com>
+Description:    (Read) Show hardware context information of device.
diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
@@ -272,3 +272,9 @@ KernelVersion	6.15
 Contact:	Jinlong Mao (QUIC) <quic_jinlmao@quicinc.com>, Tao Zhang (QUIC) <quic_taozha@quicinc.com>
 Description:
 		(RW) Set/Get the enablement of the individual lane.
+
+What:           /sys/bus/coresight/devices/<tpdm-name>/label
+Date:           Aug 2025
+KernelVersion   6.18
+Contact:        Mao Jinlong <quic_jinlmao@quicinc.com>
+Description:    (Read) Show hardware context information of device.
diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-trbe b/Documentation/ABI/testing/sysfs-bus-coresight-devices-trbe
@@ -12,3 +12,9 @@ Contact:	Anshuman Khandual <anshuman.khandual@arm.com>
 Description:	(Read) Shows if TRBE updates in the memory are with access
 		and dirty flag updates as well. This value is fetched from
 		the TRBIDR register.
+
+What:           /sys/bus/coresight/devices/trbe<cpu>/label
+Date:           Aug 2025
+KernelVersion   6.18
+Contact:        Mao Jinlong <quic_jinlmao@quicinc.com>
+Description:    (Read) Show hardware context information of device.
diff --git a/drivers/hwtracing/coresight/coresight-sysfs.c b/drivers/hwtracing/coresight/coresight-sysfs.c
@@ -7,6 +7,7 @@
 #include <linux/device.h>
 #include <linux/idr.h>
 #include <linux/kernel.h>
+#include <linux/property.h>
 
 #include "coresight-priv.h"
 #include "coresight-trace-id.h"
@@ -371,17 +372,81 @@ static ssize_t enable_source_store(struct device *dev,
 }
 static DEVICE_ATTR_RW(enable_source);
 
+static ssize_t label_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+
+	const char *str;
+	int ret;
+
+	ret = fwnode_property_read_string(dev_fwnode(dev), "label", &str);
+	if (ret == 0)
+		return sysfs_emit(buf, "%s\n", str);
+	else
+		return ret;
+}
+static DEVICE_ATTR_RO(label);
+
+static umode_t label_is_visible(struct kobject *kobj,
+				   struct attribute *attr, int n)
+{
+	struct device *dev = kobj_to_dev(kobj);
+
+	if (attr == &dev_attr_label.attr) {
+		if (fwnode_property_present(dev_fwnode(dev), "label"))
+			return attr->mode;
+		else
+			return 0;
+	}
+
+	return attr->mode;
+}
+
 static struct attribute *coresight_sink_attrs[] = {
 	&dev_attr_enable_sink.attr,
+	&dev_attr_label.attr,
 	NULL,
 };
-ATTRIBUTE_GROUPS(coresight_sink);
+
+static struct attribute_group coresight_sink_group = {
+	.attrs = coresight_sink_attrs,
+	.is_visible = label_is_visible,
+};
+__ATTRIBUTE_GROUPS(coresight_sink);
 
 static struct attribute *coresight_source_attrs[] = {
 	&dev_attr_enable_source.attr,
+	&dev_attr_label.attr,
 	NULL,
 };
-ATTRIBUTE_GROUPS(coresight_source);
+
+static struct attribute_group coresight_source_group = {
+	.attrs = coresight_source_attrs,
+	.is_visible = label_is_visible,
+};
+__ATTRIBUTE_GROUPS(coresight_source);
+
+static struct attribute *coresight_link_attrs[] = {
+	&dev_attr_label.attr,
+	NULL,
+};
+
+static struct attribute_group coresight_link_group = {
+	.attrs = coresight_link_attrs,
+	.is_visible = label_is_visible,
+};
+__ATTRIBUTE_GROUPS(coresight_link);
+
+static struct attribute *coresight_helper_attrs[] = {
+	&dev_attr_label.attr,
+	NULL,
+};
+
+static struct attribute_group coresight_helper_group = {
+	.attrs = coresight_helper_attrs,
+	.is_visible = label_is_visible,
+};
+__ATTRIBUTE_GROUPS(coresight_helper);
 
 const struct device_type coresight_dev_type[] = {
 	[CORESIGHT_DEV_TYPE_SINK] = {
@@ -390,6 +455,7 @@ const struct device_type coresight_dev_type[] = {
 	},
 	[CORESIGHT_DEV_TYPE_LINK] = {
 		.name = "link",
+		.groups = coresight_link_groups,
 	},
 	[CORESIGHT_DEV_TYPE_LINKSINK] = {
 		.name = "linksink",
@@ -401,6 +467,7 @@ const struct device_type coresight_dev_type[] = {
 	},
 	[CORESIGHT_DEV_TYPE_HELPER] = {
 		.name = "helper",
+		.groups = coresight_helper_groups,
 	}
 };
 /* Ensure the enum matches the names and groups */
