AXI_I2S_BITS_PER_FRAME
i2s->ratnum.num = clk_get_rate(i2s->clk_ref) / 2 / AXI_I2S_BITS_PER_FRAME;
bclk_rate = params_rate(params) * AXI_I2S_BITS_PER_FRAME;
word_size = AXI_I2S_BITS_PER_FRAME / 2 - 1;