[PATCH v4 2/2] coresight: core: Add device name support

[Mao Jinlong <quic_jinlmao@xxxxxxxxxxx>]

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 the device-name support for
adding the intuitive name of the device.

Signed-off-by: Mao Jinlong <quic_jinlmao@xxxxxxxxxxx>
---
 drivers/hwtracing/coresight/coresight-core.c  | 37 ++++++++++---------
 .../hwtracing/coresight/coresight-platform.c  | 30 +++++++++++++++
 include/linux/coresight.h                     |  3 +-
 3 files changed, 52 insertions(+), 18 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
index 9fc6f6b863e0..1d43333bbeb0 100644
--- a/drivers/hwtracing/coresight/coresight-core.c
+++ b/drivers/hwtracing/coresight/coresight-core.c
@@ -1328,33 +1328,36 @@ EXPORT_SYMBOL_GPL(coresight_loses_context_with_cpu);
  * duplicate indices for the same device (e.g, if we defer probing of
  * a device due to dependencies), in case the index is requested again.
  */
-char *coresight_alloc_device_name(struct coresight_dev_list *dict,
+const char *coresight_alloc_device_name(struct coresight_dev_list *dict,
 				  struct device *dev)
 {
 	int idx;
-	char *name = NULL;
+	const char *name = NULL;
 	struct fwnode_handle **list;
 
 	mutex_lock(&coresight_mutex);
 
-	idx = coresight_search_device_idx(dict, dev_fwnode(dev));
-	if (idx < 0) {
-		/* Make space for the new entry */
-		idx = dict->nr_idx;
-		list = krealloc_array(dict->fwnode_list,
-				      idx + 1, sizeof(*dict->fwnode_list),
-				      GFP_KERNEL);
-		if (ZERO_OR_NULL_PTR(list)) {
-			idx = -ENOMEM;
-			goto done;
+	name = coresight_get_device_name(dev);
+	if (!name) {
+		idx = coresight_search_device_idx(dict, dev_fwnode(dev));
+		if (idx < 0) {
+			/* Make space for the new entry */
+			idx = dict->nr_idx;
+			list = krealloc_array(dict->fwnode_list,
+					      idx + 1, sizeof(*dict->fwnode_list),
+					      GFP_KERNEL);
+			if (ZERO_OR_NULL_PTR(list)) {
+				idx = -ENOMEM;
+				goto done;
+			}
+
+			list[idx] = dev_fwnode(dev);
+			dict->fwnode_list = list;
+			dict->nr_idx = idx + 1;
 		}
 
-		list[idx] = dev_fwnode(dev);
-		dict->fwnode_list = list;
-		dict->nr_idx = idx + 1;
+		name = devm_kasprintf(dev, GFP_KERNEL, "%s%d", dict->pfx, idx);
 	}
-
-	name = devm_kasprintf(dev, GFP_KERNEL, "%s%d", dict->pfx, idx);
 done:
 	mutex_unlock(&coresight_mutex);
 	return name;
diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c
index 64e171eaad82..66de52bd6c5e 100644
--- a/drivers/hwtracing/coresight/coresight-platform.c
+++ b/drivers/hwtracing/coresight/coresight-platform.c
@@ -183,6 +183,22 @@ static int of_coresight_get_cpu(struct device *dev)
 	return cpu;
 }
 
+static const char *of_coresight_get_device_name(struct device *dev)
+{
+	const char *name = NULL;
+
+	if (!dev->of_node)
+		return NULL;
+
+	/*
+	 * Get the device name from DT. The name describes the HW or
+	 * system the device is for.
+	 */
+	of_property_read_string(dev->of_node, "arm,cs-dev-name", &name);
+
+	return name;
+}
+
 /*
  * of_coresight_parse_endpoint : Parse the given output endpoint @ep
  * and fill the connection information in @pdata->out_conns
@@ -317,6 +333,11 @@ static inline int of_coresight_get_cpu(struct device *dev)
 {
 	return -ENODEV;
 }
+
+static inline const char *of_coresight_get_device_name(struct device *dev)
+{
+	return NULL;
+}
 #endif
 
 #ifdef CONFIG_ACPI
@@ -796,6 +817,15 @@ int coresight_get_cpu(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(coresight_get_cpu);
 
+const char *coresight_get_device_name(struct device *dev)
+{
+	if (is_of_node(dev->fwnode))
+		return of_coresight_get_device_name(dev);
+	else
+		return NULL;
+}
+EXPORT_SYMBOL_GPL(coresight_get_device_name);
+
 struct coresight_platform_data *
 coresight_get_platform_data(struct device *dev)
 {
diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index f09ace92176e..f021f3e93978 100644
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h
@@ -626,7 +626,7 @@ extern int coresight_claim_device_unlocked(struct coresight_device *csdev);
 
 extern void coresight_disclaim_device(struct coresight_device *csdev);
 extern void coresight_disclaim_device_unlocked(struct coresight_device *csdev);
-extern char *coresight_alloc_device_name(struct coresight_dev_list *devs,
+extern const char *coresight_alloc_device_name(struct coresight_dev_list *devs,
 					 struct device *dev);
 
 extern bool coresight_loses_context_with_cpu(struct device *dev);
@@ -643,6 +643,7 @@ void coresight_relaxed_write64(struct coresight_device *csdev,
 void coresight_write64(struct coresight_device *csdev, u64 val, u32 offset);
 
 extern int coresight_get_cpu(struct device *dev);
+extern const char *coresight_get_device_name(struct device *dev);
 
 struct coresight_platform_data *coresight_get_platform_data(struct device *dev);
 struct coresight_connection *
-- 
2.41.0