ST_AHCI_OOBR
old_val = readl(mmio + ST_AHCI_OOBR);
writel(old_val | ST_AHCI_OOBR_WE, mmio + ST_AHCI_OOBR);
writel(new_val | ST_AHCI_OOBR_WE, mmio + ST_AHCI_OOBR);
writel(new_val, mmio + ST_AHCI_OOBR);