[PATCH v5 2/2] coresight: Add label sysfs node support

[Mao Jinlong]

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 at quicinc.com>
---
 .../testing/sysfs-bus-coresight-devices-cti   |  6 ++++
 .../sysfs-bus-coresight-devices-funnel        |  6 ++++
 .../testing/sysfs-bus-coresight-devices-tpdm  |  6 ++++
 drivers/hwtracing/coresight/coresight-sysfs.c | 32 +++++++++++++++++++
 4 files changed, 50 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-cti b/Documentation/ABI/testing/sysfs-bus-coresight-devices-cti
index bf2869c413e7..631999571197 100644
--- 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:           Dec 2024
+KernelVersion   6.13
+Contact:        Mao Jinlong <quic_jinlmao at quicinc.com>
+Description:    (Read) Show hardware context information of device.
diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-funnel b/Documentation/ABI/testing/sysfs-bus-coresight-devices-funnel
index d75acda5e1b3..6497756a5ced 100644
--- 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 at linaro.org>
 Description:	(RW) Defines input port priority order.
+
+What:           /sys/bus/coresight/devices/<memory_map>.funnel/label
+Date:           Dec 2024
+KernelVersion   6.13
+Contact:        Mao Jinlong <quic_jinlmao at 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
index bf710ea6e0ef..31dbf37a8754 100644
--- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
+++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tpdm
@@ -257,3 +257,9 @@ Contact:	Jinlong Mao (QUIC) <quic_jinlmao at quicinc.com>, Tao Zhang (QUIC) <quic_t
 Description:
 		(RW) Set/Get the MSR(mux select register) for the CMB subunit
 		TPDM.
+
+What:           /sys/bus/coresight/devices/<tpdm-name>/label
+Date:           Dec 2024
+KernelVersion   6.13
+Contact:        Mao Jinlong <quic_jinlmao at 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
index a01c9e54e2ed..4af40cd7d75a 100644
--- 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"
@@ -366,18 +367,47 @@ 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 = 0;
+
+	ret = fwnode_property_read_string(dev_fwnode(dev), "label", &str);
+	if (ret == 0)
+		return scnprintf(buf, PAGE_SIZE, "%s\n", str);
+	else
+		return ret;
+}
+static DEVICE_ATTR_RO(label);
+
 static struct attribute *coresight_sink_attrs[] = {
 	&dev_attr_enable_sink.attr,
+	&dev_attr_label.attr,
 	NULL,
 };
 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 *coresight_link_attrs[] = {
+	&dev_attr_label.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(coresight_link);
+
+static struct attribute *coresight_helper_attrs[] = {
+	&dev_attr_label.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(coresight_helper);
+
 const struct device_type coresight_dev_type[] = {
 	[CORESIGHT_DEV_TYPE_SINK] = {
 		.name = "sink",
@@ -385,6 +415,7 @@ const struct device_type coresight_dev_type[] = {
 	},
 	[CORESIGHT_DEV_TYPE_LINK] = {
 		.name = "link",
+		.groups = coresight_link_groups,
 	},
 	[CORESIGHT_DEV_TYPE_LINKSINK] = {
 		.name = "linksink",
@@ -396,6 +427,7 @@ 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 */
-- 
2.17.1