choice XTAL_FREQ
    prompt "Main XTAL frequency"
    default XTAL_FREQ_40
    help
        This option selects the operating frequency of the XTAL (crystal) clock used to drive the ESP target.
        The selected value MUST reflect the frequency of the given hardware.

    config XTAL_FREQ_40
        bool "40 MHz"
endchoice

# soc_xtal_freq_t enum in soc/clk_tree_defs.h lists the XTAL frequencies can be supported
# SOC_XTAL_SUPPORT_XXX in soc_caps.h lists the XTAL frequencies already supported
config XTAL_FREQ
    int
    default 40 if XTAL_FREQ_40