SATA_IFCTL
old_ifctl = readl(port_mmio + SATA_IFCTL);
writelfl(ifctl, port_mmio + SATA_IFCTL);
writelfl(ifctl | 0x200, port_mmio + SATA_IFCTL);
writelfl(old_ifctl, port_mmio + SATA_IFCTL);
u32 reg = readl(port_mmio + SATA_IFCTL);
writelfl(reg, port_mmio + SATA_IFCTL);