ALSA: hda - Add a common helper to give the codec modalias string

This patch provide a new common helper function,
snd_hdac_codec_modalias(), to give the codec modalias name string.
This function will be used by multiple places in the later patches.
Reviewed-by: Vinod Koul <vinod.koul@intel.com>
Tested-by: Subhransu S Prusty <subhransu.s.prusty@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/hdaudio.h

@@ -109,6 +109,7 @@ void snd_hdac_device_exit(struct hdac_device *dev);
 int snd_hdac_device_register(struct hdac_device *codec);
 void snd_hdac_device_unregister(struct hdac_device *codec);
 int snd_hdac_device_set_chip_name(struct hdac_device *codec, const char *name);
+int snd_hdac_codec_modalias(struct hdac_device *hdac, char *buf, size_t size);
 
 int snd_hdac_refresh_widgets(struct hdac_device *codec);
 int snd_hdac_refresh_widget_sysfs(struct hdac_device *codec);

sound/hda/hdac_device.c

@@ -185,6 +185,21 @@ int snd_hdac_device_set_chip_name(struct hdac_device *codec, const char *name)
 }
 EXPORT_SYMBOL_GPL(snd_hdac_device_set_chip_name);
 
+/**
+ * snd_hdac_codec_modalias - give the module alias name
+ * @codec: HDAC device
+ * @buf: string buffer to store
+ * @size: string buffer size
+ *
+ * Returns the size of string, like snprintf(), or a negative error code.
+ */
+int snd_hdac_codec_modalias(struct hdac_device *codec, char *buf, size_t size)
+{
+	return snprintf(buf, size, "hdaudio:v%08Xr%08Xa%02X\n",
+			codec->vendor_id, codec->revision_id, codec->type);
+}
+EXPORT_SYMBOL_GPL(snd_hdac_codec_modalias);
+
 /**
  * snd_hdac_make_cmd - compose a 32bit command word to be sent to the
  *	HD-audio controller