JZ_ADC_REG_ENABLE
val = readb(adc->base + JZ_ADC_REG_ENABLE);
writeb(val, adc->base + JZ_ADC_REG_ENABLE);
ret = readb_poll_timeout(adc->base + JZ_ADC_REG_ENABLE, val,
writeb(0x00, adc->base + JZ_ADC_REG_ENABLE);