iommu/io-pgtable: Allow io_pgtable_tlb ops optional

This patch allows io_pgtable_tlb ops could be null since the IOMMU drivers
may use the tlb ops from iommu framework.
Signed-off-by: NYong Wu <yong.wu@mediatek.com>
Reviewed-by: NRobin Murphy <robin.murphy@arm.com>
Acked-by: NWill Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210107122909.16317-6-yong.wu@mediatek.comSigned-off-by: NWill Deacon <will@kernel.org>

include/linux/io-pgtable.h

@@ -214,14 +214,16 @@ struct io_pgtable_domain_attr {
 
 static inline void io_pgtable_tlb_flush_all(struct io_pgtable *iop)
 {
-	iop->cfg.tlb->tlb_flush_all(iop->cookie);
+	if (iop->cfg.tlb && iop->cfg.tlb->tlb_flush_all)
+		iop->cfg.tlb->tlb_flush_all(iop->cookie);
 }
 
 static inline void
 io_pgtable_tlb_flush_walk(struct io_pgtable *iop, unsigned long iova,
 			  size_t size, size_t granule)
 {
-	iop->cfg.tlb->tlb_flush_walk(iova, size, granule, iop->cookie);
+	if (iop->cfg.tlb && iop->cfg.tlb->tlb_flush_walk)
+		iop->cfg.tlb->tlb_flush_walk(iova, size, granule, iop->cookie);
 }
 
 static inline void
@@ -229,7 +231,7 @@ io_pgtable_tlb_add_page(struct io_pgtable *iop,
 			struct iommu_iotlb_gather * gather, unsigned long iova,
 			size_t granule)
 {
-	if (iop->cfg.tlb->tlb_add_page)
+	if (iop->cfg.tlb && iop->cfg.tlb->tlb_add_page)
 		iop->cfg.tlb->tlb_add_page(gather, iova, granule, iop->cookie);
 }