coresight: core: Use IDR for non-cpu bound sources' paths.

Except stm, there could be other sources which are not associated
with cpus. Use IDR to store and search these sources' paths.

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Mao Jinlong <quic_jinlmao@quicinc.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230117145708.16739-2-quic_jinlmao@quicinc.com

drivers/hwtracing/coresight/coresight-core.c

@@ -8,6 +8,7 @@
 #include <linux/types.h>
 #include <linux/device.h>
 #include <linux/io.h>
+#include <linux/idr.h>
 #include <linux/err.h>
 #include <linux/export.h>
 #include <linux/slab.h>
@@ -26,6 +27,13 @@
 static DEFINE_MUTEX(coresight_mutex);
 static DEFINE_PER_CPU(struct coresight_device *, csdev_sink);
 
+/*
+ * Use IDR to map the hash of the source's device name
+ * to the pointer of path for the source. The idr is for
+ * the sources which aren't associated with CPU.
+ */
+static DEFINE_IDR(path_idr);
+
 /**
  * struct coresight_node - elements of a path, from source to sink
  * @csdev:	Address of an element.
@@ -42,14 +50,6 @@ struct coresight_node {
  */
 static DEFINE_PER_CPU(struct list_head *, tracer_path);
 
-/*
- * As of this writing only a single STM can be found in CS topologies.  Since
- * there is no way to know if we'll ever see more and what kind of
- * configuration they will enact, for the time being only define a single path
- * for STM.
- */
-static struct list_head *stm_path;
-
 /*
  * When losing synchronisation a new barrier packet needs to be inserted at the
  * beginning of the data collected in a buffer.  That way the decoder knows that
@@ -1075,6 +1075,7 @@ int coresight_enable(struct coresight_device *csdev)
 	struct coresight_device *sink;
 	struct list_head *path;
 	enum coresight_dev_subtype_source subtype;
+	u32 hash;
 
 	subtype = csdev->subtype.source_subtype;
 
@@ -1129,7 +1130,14 @@ int coresight_enable(struct coresight_device *csdev)
 		per_cpu(tracer_path, cpu) = path;
 		break;
 	case CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE:
-		stm_path = path;
+		/*
+		 * Use the hash of source's device name as ID
+		 * and map the ID to the pointer of the path.
+		 */
+		hash = hashlen_hash(hashlen_string(NULL, dev_name(&csdev->dev)));
+		ret = idr_alloc_u32(&path_idr, path, &hash, hash, GFP_KERNEL);
+		if (ret)
+			goto err_source;
 		break;
 	default:
 		/* We can't be here */
@@ -1153,6 +1161,7 @@ void coresight_disable(struct coresight_device *csdev)
 {
 	int cpu, ret;
 	struct list_head *path = NULL;
+	u32 hash;
 
 	mutex_lock(&coresight_mutex);
 
@@ -1170,14 +1179,20 @@ void coresight_disable(struct coresight_device *csdev)
 		per_cpu(tracer_path, cpu) = NULL;
 		break;
 	case CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE:
-		path = stm_path;
-		stm_path = NULL;
+		hash = hashlen_hash(hashlen_string(NULL, dev_name(&csdev->dev)));
+		/* Find the path by the hash. */
+		path = idr_find(&path_idr, hash);
+		if (path == NULL) {
+			pr_err("Path is not found for %s\n", dev_name(&csdev->dev));
+			goto out;
+		}
 		break;
 	default:
 		/* We can't be here */
 		break;
 	}
 
+	idr_remove(&path_idr, hash);
 	coresight_disable_path(path);
 	coresight_release_path(path);