val = readw(U300_SYSCON_VBASE + U300_SYSCON_CCR);
val &= ~U300_SYSCON_CCR_I2S0_USE_VCXO;
writew(val, U300_SYSCON_VBASE + U300_SYSCON_CCR);
val = readw(U300_SYSCON_VBASE + U300_SYSCON_CCR);
val &= ~U300_SYSCON_CCR_I2S0_USE_VCXO;
writew(val, U300_SYSCON_VBASE + U300_SYSCON_CCR);