bcm2835_clkman_set_frequency
uint32_t bcm2835_clkman_set_frequency(device_t, uint32_t, uint32_t);
(void)bcm2835_clkman_set_frequency(sc->clkman, BCM_PWM_CLKSRC, 0);
u = bcm2835_clkman_set_frequency(sc->clkman, BCM_PWM_CLKSRC, sc->freq);
f = bcm2835_clkman_set_frequency(sc->clkman,