mifois right in the above response. As of now, there are no drivers to access the I2S interface from application.
The I2S interface is used for routing audio samples while using audio profiles such as the A2DP and the selected data path is I2S. The I2S block is configured automatically by the Bluetooth firmware.
In other words, developers cannot access the I2S block from application, it can be only be used to transfer audio samples for A2DP profile and the firmware will take care of configuring the interface when used.
