coresight: Add label sysfs node support

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

1 files changed, 69 insertions, 2 deletions

diff --git a/drivers/hwtracing/coresight/coresight-sysfs.c b/drivers/hwtracing/coresight/coresight-sysfs.c
index feadaf065b53..5e52324aa9ac 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"
@@ -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 */