Coresight: Allocate trace ID after building the path

The trace_id will be stored in coresight_path instead of being declared
everywhere and allocated after building the path.

Co-developed-by: James Clark <james.clark@linaro.org>
Signed-off-by: James Clark <james.clark@linaro.org>
Signed-off-by: Jie Gan <quic_jiegan@quicinc.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250303032931.2500935-6-quic_jiegan@quicinc.com

Author: Jie Gan

drivers/hwtracing/coresight/coresight-core.c

@@ -655,6 +655,50 @@ static void coresight_drop_device(struct coresight_device *csdev)
 	}
 }
 
+/*
+ * coresight device will read their existing or alloc a trace ID, if their trace_id
+ * callback is set.
+ *
+ * Return 0 if the trace_id callback is not set.
+ * Return the result of the trace_id callback if it is set. The return value
+ * will be the trace_id if successful, and an error number if it fails.
+ */
+static int coresight_get_trace_id(struct coresight_device *csdev,
+				  enum cs_mode mode,
+				  struct coresight_device *sink)
+{
+	if (coresight_ops(csdev)->trace_id)
+		return coresight_ops(csdev)->trace_id(csdev, mode, sink);
+
+	return 0;
+}
+
+/*
+ * Call this after creating the path and before enabling it. This leaves
+ * the trace ID set on the path, or it remains 0 if it couldn't be assigned.
+ */
+void coresight_path_assign_trace_id(struct coresight_path *path,
+				    enum cs_mode mode)
+{
+	struct coresight_device *sink = coresight_get_sink(&path->path_list);
+	struct coresight_node *nd;
+	int trace_id;
+
+	list_for_each_entry(nd, &path->path_list, link) {
+		/* Assign a trace ID to the path for the first device that wants to do it */
+		trace_id = coresight_get_trace_id(nd->csdev, mode, sink);
+
+		/*
+		 * 0 in this context is that it didn't want to assign so keep searching.
+		 * Non 0 is either success or fail.
+		 */
+		if (trace_id != 0) {
+			path->trace_id = trace_id;
+			return;
+		}
+	}
+}
+
 /**
  * _coresight_build_path - recursively build a path from a @csdev to a sink.
  * @csdev:	The device to start from.

drivers/hwtracing/coresight/coresight-etm-perf.c

@@ -319,7 +319,6 @@ static void *etm_setup_aux(struct perf_event *event, void **pages,
 {
 	u32 id, cfg_hash;
 	int cpu = event->cpu;
-	int trace_id;
 	cpumask_t *mask;
 	struct coresight_device *sink = NULL;
 	struct coresight_device *user_sink = NULL, *last_sink = NULL;
@@ -409,8 +408,8 @@ static void *etm_setup_aux(struct perf_event *event, void **pages,
 		}
 
 		/* ensure we can allocate a trace ID for this CPU */
-		trace_id = coresight_trace_id_get_cpu_id_map(cpu, &sink->perf_sink_id_map);
-		if (!IS_VALID_CS_TRACE_ID(trace_id)) {
+		coresight_path_assign_trace_id(path, CS_MODE_PERF);
+		if (!IS_VALID_CS_TRACE_ID(path->trace_id)) {
 			cpumask_clear_cpu(cpu, mask);
 			coresight_release_path(path);
 			continue;

drivers/hwtracing/coresight/coresight-priv.h

@@ -152,6 +152,8 @@ int coresight_make_links(struct coresight_device *orig,
 void coresight_remove_links(struct coresight_device *orig,
 			    struct coresight_connection *conn);
 u32 coresight_get_sink_id(struct coresight_device *csdev);
+void coresight_path_assign_trace_id(struct coresight_path *path,
+				   enum cs_mode mode);
 
 #if IS_ENABLED(CONFIG_CORESIGHT_SOURCE_ETM3X)
 extern int etm_readl_cp14(u32 off, unsigned int *val);

drivers/hwtracing/coresight/coresight-sysfs.c

@@ -209,6 +209,10 @@ int coresight_enable_sysfs(struct coresight_device *csdev)
 		goto out;
 	}
 
+	coresight_path_assign_trace_id(path, CS_MODE_SYSFS);
+	if (!IS_VALID_CS_TRACE_ID(path->trace_id))
+		goto err_path;
+
 	ret = coresight_enable_path(&path->path_list, CS_MODE_SYSFS, NULL);
 	if (ret)
 		goto err_path;