Gangadhar,
I think you would specify either "SNDRV_PCM_FORMAT_S16_LE" for 16-bit word length or "SNDRV_PCM_FORMAT_S32_LE" for 32-bit word length in your ALSA codec driver layer.Refer to source file: \board-support\linux-3.12.10-ti2013.12.01\sound\soc\davinci\davinci-mcasp.c .
-Mark