__ad7293_spi_read
ret = __ad7293_spi_read(st, reg, val);
ret = __ad7293_spi_read(st, reg, &data);
ret = __ad7293_spi_read(st, AD7293_REG_VINX_RANGE1, &data);
ret = __ad7293_spi_read(st, AD7293_REG_VINX_RANGE0, &data);
ret = __ad7293_spi_read(st, reg_rd, raw);
ret = __ad7293_spi_read(st, AD7293_REG_DEVICE_ID, &chip_id);