Function esp_idf_sys::spi_cal_clock

pub unsafe extern "C" fn spi_cal_clock(
    fapb: c_int, 
    hz: c_int, 
    duty_cycle: c_int, 
    reg_o: *mut u32
) -> c_int

@brief Calculate the working frequency that is most close to desired frequency, and also the register value.

@param fapb The frequency of apb clock, should be APB_CLK_FREQ. @param hz Desired working frequency @param duty_cycle Duty cycle of the spi clock @param reg_o Output of value to be set in clock register, or NULL if not needed. @return Actual working frequency that most fit.