ASoC: topology: Make manifest backward compatible from ABI v4

This patch adds support for old version 4 of manifest.

Topology ABI v5 added new fields to manifest while user space may still
uses v4. So kernel will check the ABI version by comparing the object
size. If user space uses v4 of manifest, kernel will create a latest
version of manifest from the old one, and use the new one internally and
free it later.
Signed-off-by: Mengdong Lin <mengdong.lin@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/soc-topology.c

@@ -53,6 +53,23 @@
 #define SOC_TPLG_PASS_START	SOC_TPLG_PASS_MANIFEST
 #define SOC_TPLG_PASS_END	SOC_TPLG_PASS_BE_DAI
 
+
+/*
+ * Old version of ABI structs, supported for backward compatibility.
+ */
+
+/* Manifest v4 */
+struct snd_soc_tplg_manifest_v4 {
+	__le32 size;		/* in bytes of this structure */
+	__le32 control_elems;	/* number of control elements */
+	__le32 widget_elems;	/* number of widget elements */
+	__le32 graph_elems;	/* number of graph elements */
+	__le32 pcm_elems;	/* number of PCM elements */
+	__le32 dai_link_elems;	/* number of DAI link elements */
+	struct snd_soc_tplg_private priv;
+} __packed;
+
+/* topology context */
 struct soc_tplg {
 	const struct firmware *fw;
 
@@ -1798,27 +1815,81 @@ static int soc_tplg_be_dai_elems_load(struct soc_tplg *tplg,
 	return 0;
 }
 
+/**
+ * manifest_new_ver - Create a new version of manifest from the old version
+ * of source.
+ * @toplogy: topology context
+ * @src: old version of manifest as a source
+ * @manifest: latest version of manifest created from the source
+ *
+ * Support from vesion 4. Users need free the returned manifest manually.
+ */
+static int manifest_new_ver(struct soc_tplg *tplg,
+			    struct snd_soc_tplg_manifest *src,
+			    struct snd_soc_tplg_manifest **manifest)
+{
+	struct snd_soc_tplg_manifest *dest;
+	struct snd_soc_tplg_manifest_v4 *src_v4;
+
+	*manifest = NULL;
+
+	if (src->size != sizeof(*src_v4)) {
+		dev_err(tplg->dev, "ASoC: invalid manifest size\n");
+		return -EINVAL;
+	}
+
+	dev_warn(tplg->dev, "ASoC: old version of manifest\n");
+
+	src_v4 = (struct snd_soc_tplg_manifest_v4 *)src;
+	dest = kzalloc(sizeof(*dest) + src_v4->priv.size, GFP_KERNEL);
+	if (!dest)
+		return -ENOMEM;
+
+	dest->size = sizeof(*dest);	/* size of latest abi version */
+	dest->control_elems = src_v4->control_elems;
+	dest->widget_elems = src_v4->widget_elems;
+	dest->graph_elems = src_v4->graph_elems;
+	dest->pcm_elems = src_v4->pcm_elems;
+	dest->dai_link_elems = src_v4->dai_link_elems;
+	dest->priv.size = src_v4->priv.size;
+	if (dest->priv.size)
+		memcpy(dest->priv.data, src_v4->priv.data,
+		       src_v4->priv.size);
+
+	*manifest = dest;
+	return 0;
+}
 
 static int soc_tplg_manifest_load(struct soc_tplg *tplg,
 				  struct snd_soc_tplg_hdr *hdr)
 {
-	struct snd_soc_tplg_manifest *manifest;
+	struct snd_soc_tplg_manifest *manifest, *_manifest;
+	bool abi_match;
+	int err;
 
 	if (tplg->pass != SOC_TPLG_PASS_MANIFEST)
 		return 0;
 
 	manifest = (struct snd_soc_tplg_manifest *)tplg->pos;
-	if (manifest->size != sizeof(*manifest)) {
-		dev_err(tplg->dev, "ASoC: invalid manifest size\n");
-		return -EINVAL;
-	}
 
-	tplg->pos += sizeof(struct snd_soc_tplg_manifest);
+	/* check ABI version by size, create a new manifest if abi not match */
+	if (manifest->size == sizeof(*manifest)) {
+		abi_match = true;
+		_manifest = manifest;
+	} else {
+		abi_match = false;
+		err = manifest_new_ver(tplg, manifest, &_manifest);
+		if (err < 0)
+			return err;
+	}
 
+	/* pass control to component driver for optional further init */
 	if (tplg->comp && tplg->ops && tplg->ops->manifest)
-		return tplg->ops->manifest(tplg->comp, manifest);
+		return tplg->ops->manifest(tplg->comp, _manifest);
+
+	if (!abi_match)	/* free the duplicated one */
+		kfree(_manifest);
 
-	dev_err(tplg->dev, "ASoC: Firmware manifest not supported\n");
 	return 0;
 }