AT91_PMC_PCR_GCKDIV_MASK
gck->gckdiv = FIELD_GET(AT91_PMC_PCR_GCKDIV_MASK, tmp);
AT91_PMC_PCR_GCKDIV_MASK | gck->layout->gckcss_mask |
FIELD_PREP(AT91_PMC_PCR_GCKDIV_MASK, gck->gckdiv) |