topology: pre-process-class: Add helper function to look up class definition

Add a helper function to look up the class definition for
an object. ex: for an object instance, Object.Widget.pga.0{}, the
function returns the config pointing to Class.Widget.pga{} in
the input conf.

Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

topology/Makefile.am

@@ -8,7 +8,7 @@ endif
 %.1: %.rst
 	rst2man $< > $@
 
-alsatplg_SOURCES = topology.c pre-processor.c
+alsatplg_SOURCES = topology.c pre-processor.c pre-process-class.c
 
 noinst_HEADERS = topology.h pre-processor.h
 

topology/pre-process-class.c

@@ -0,0 +1,68 @@
+/*
+  Copyright(c) 2021 Intel Corporation
+  All rights reserved.
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of version 2 of the GNU General Public License as
+  published by the Free Software Foundation.
+
+  This program is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+  The full GNU General Public License is included in this distribution
+  in the file called LICENSE.GPL.
+*/
+#include <limits.h>
+#include <stdio.h>
+#include <alsa/input.h>
+#include <alsa/output.h>
+#include <alsa/conf.h>
+#include <alsa/error.h>
+#include "topology.h"
+#include "pre-processor.h"
+
+/*
+ * Helper function to look up class definition from the Object config.
+ * ex: For an object declaration, Object.Widget.pga.0{}, return the config correspdonding to
+ * Class.Widget.pga{}. Note that input config , "cfg" does not include the "Object" node.
+ */
+snd_config_t *tplg_class_lookup(struct tplg_pre_processor *tplg_pp, snd_config_t *cfg)
+{
+	snd_config_iterator_t first, end;
+	snd_config_t *class, *class_cfg = NULL;
+	const char *class_type, *class_name;
+	char *class_config_id;
+	int ret;
+
+	if (snd_config_get_id(cfg, &class_type) < 0)
+		return NULL;
+
+	first = snd_config_iterator_first(cfg);
+	end = snd_config_iterator_end(cfg);
+
+	if (first == end) {
+		SNDERR("No class name provided for object type: %s\n", class_type);
+		return NULL;
+	}
+
+	class = snd_config_iterator_entry(first);
+
+	if (snd_config_get_id(class, &class_name) < 0)
+		return NULL;
+
+	class_config_id = tplg_snprintf("Class.%s.%s", class_type, class_name);
+	if (!class_config_id)
+		return NULL;
+
+	ret = snd_config_search(tplg_pp->input_cfg, class_config_id, &class_cfg);
+	if (ret < 0)
+		SNDERR("No Class definition found for %s\n", class_config_id);
+
+	free(class_config_id);
+	return class_cfg;
+}

topology/pre-processor.h

@@ -26,6 +26,9 @@
 void tplg_pp_debug(char *fmt, ...);
 void tplg_pp_config_debug(struct tplg_pre_processor *tplg_pp, snd_config_t *cfg);
 
+/* class helpers */
+snd_config_t *tplg_class_lookup(struct tplg_pre_processor *tplg_pp, snd_config_t *cfg);
+
 /* config helpers */
 snd_config_t *tplg_find_config(snd_config_t *config, const char *name);
 int tplg_config_make_add(snd_config_t **config, const char *id, snd_config_type_t type,