SIU_SRCTL
siu_write32(base + SIU_SRCTL, 0);
siu_write32(base + SIU_SRCTL, 0x301);
siu_write32(base + SIU_SRCTL, 0);
srctl = siu_read32(base + SIU_SRCTL);
siu_write32(base + SIU_SRCTL, srctl);