As per the HW manual, set the XTOSCB bit as follows: If using an external clock signal, set the XTOSCB bit as 1 to disable the crystal oscillator. If using an external crystal, the XTOSCB bit needs to be set at 0 to enable the crystal oscillator. Add isl1208_set_xtoscb() to set XTOSCB bit based on the clock-names property. Fallback is enabling the internal crystal oscillator. While at it, introduce a variable "sr" for reading the status register in probe() as it is reused for writing and also remove the unnecessary blank line. Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com> Link: https://lore.kernel.org/r/20230623140948.384762-10-biju.das.jz@bp.renesas.com Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>