VSI_MMU_FLUSH_BASE
writel(VSI_MMU_BIT_FLUSH, iommu->regs + VSI_MMU_FLUSH_BASE);
writel(0, iommu->regs + VSI_MMU_FLUSH_BASE);
writel(VSI_MMU_BIT_FLUSH, iommu->regs + VSI_MMU_FLUSH_BASE);
writel(0, iommu->regs + VSI_MMU_FLUSH_BASE);