smc_mii_tick
callout_reset(&sc->smc_mii_tick_ch, hz, smc_mii_tick, sc);
static void smc_mii_tick(void *);
if (sc->smc_mii_tick != NULL)
callout_reset(&sc->smc_mii_tick_ch, hz, sc->smc_mii_tick, sc);
sc->smc_mii_tick = smc_mii_tick;
void (*smc_mii_tick)(void *);