drm/msm: convert to iommu_map_sg

Significantly simplifies things.  Also iommu_unmap() can unmap an entire
iova range.

(If backporting to downstream kernel you might need to revert this.  Or
at least double check older iommu implementation.)
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/msm_iommu.c

@@ -52,64 +52,20 @@ static int msm_iommu_map(struct msm_mmu *mmu, uint64_t iova,
 		struct sg_table *sgt, unsigned len, int prot)
 {
 	struct msm_iommu *iommu = to_msm_iommu(mmu);
-	struct iommu_domain *domain = iommu->domain;
-	struct scatterlist *sg;
-	unsigned long da = iova;
-	unsigned int i, j;
-	int ret;
+	size_t ret;
 
-	if (!domain || !sgt)
-		return -EINVAL;
+	ret = iommu_map_sg(iommu->domain, iova, sgt->sgl, sgt->nents, prot);
+	WARN_ON(ret < 0);
 
-	for_each_sg(sgt->sgl, sg, sgt->nents, i) {
-		dma_addr_t pa = sg_phys(sg) - sg->offset;
-		size_t bytes = sg->length + sg->offset;
-
-		VERB("map[%d]: %08lx %08lx(%zx)", i, da, (unsigned long)pa, bytes);
-
-		ret = iommu_map(domain, da, pa, bytes, prot);
-		if (ret)
-			goto fail;
-
-		da += bytes;
-	}
-
-	return 0;
-
-fail:
-	da = iova;
-
-	for_each_sg(sgt->sgl, sg, i, j) {
-		size_t bytes = sg->length + sg->offset;
-		iommu_unmap(domain, da, bytes);
-		da += bytes;
-	}
-	return ret;
+	return (ret == len) ? 0 : -EINVAL;
 }
 
 static int msm_iommu_unmap(struct msm_mmu *mmu, uint64_t iova,
 		struct sg_table *sgt, unsigned len)
 {
 	struct msm_iommu *iommu = to_msm_iommu(mmu);
-	struct iommu_domain *domain = iommu->domain;
-	struct scatterlist *sg;
-	unsigned long da = iova;
-	int i;
-
-	for_each_sg(sgt->sgl, sg, sgt->nents, i) {
-		size_t bytes = sg->length + sg->offset;
-		size_t unmapped;
-
-		unmapped = iommu_unmap(domain, da, bytes);
-		if (unmapped < bytes)
-			return unmapped;
-
-		VERB("unmap[%d]: %08lx(%zx)", i, da, bytes);
-
-		BUG_ON(!PAGE_ALIGNED(bytes));
 
-		da += bytes;
-	}
+	iommu_unmap(iommu->domain, iova, len);
 
 	return 0;
 }