ads7871_write_reg8
ret = ads7871_write_reg8(pdata, REG_GAIN_MUX,
ads7871_write_reg8(pdata, REG_SER_CONTROL, 0);
ads7871_write_reg8(pdata, REG_AD_CONTROL, 0);
ads7871_write_reg8(pdata, REG_OSC_CONTROL, val);