ASoC: Add codec registration API

Another part of the backporting of Liam's ASoC v2 work. Using this is
more complicated than the other registration types since currently the
codec is instantiated during the probe of the ASoC device so we can't
currently readily wait for the codec to register.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index 4d2db7c..b098c0b 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -47,6 +47,7 @@
 static LIST_HEAD(card_list);
 static LIST_HEAD(dai_list);
 static LIST_HEAD(platform_list);
+static LIST_HEAD(codec_list);
 
 static int snd_soc_register_card(struct snd_soc_card *card);
 static int snd_soc_unregister_card(struct snd_soc_card *card);
@@ -2224,6 +2225,48 @@
 }
 EXPORT_SYMBOL_GPL(snd_soc_unregister_platform);
 
+/**
+ * snd_soc_register_codec - Register a codec with the ASoC core
+ *
+ * @param codec codec to register
+ */
+int snd_soc_register_codec(struct snd_soc_codec *codec)
+{
+	if (!codec->name)
+		return -EINVAL;
+
+	/* The device should become mandatory over time */
+	if (!codec->dev)
+		printk(KERN_WARNING "No device for codec %s\n", codec->name);
+
+	INIT_LIST_HEAD(&codec->list);
+
+	mutex_lock(&client_mutex);
+	list_add(&codec->list, &codec_list);
+	snd_soc_instantiate_cards();
+	mutex_unlock(&client_mutex);
+
+	pr_debug("Registered codec '%s'\n", codec->name);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(snd_soc_register_codec);
+
+/**
+ * snd_soc_unregister_codec - Unregister a codec from the ASoC core
+ *
+ * @param codec codec to unregister
+ */
+void snd_soc_unregister_codec(struct snd_soc_codec *codec)
+{
+	mutex_lock(&client_mutex);
+	list_del(&codec->list);
+	mutex_unlock(&client_mutex);
+
+	pr_debug("Unregistered codec '%s'\n", codec->name);
+}
+EXPORT_SYMBOL_GPL(snd_soc_unregister_codec);
+
 static int __init snd_soc_init(void)
 {
 #ifdef CONFIG_DEBUG_FS