[PATCH 7/7] drm/exynos: Add IOMMU support for mapping gem object

[Prathyush K]

A gem object is created using dma_alloc_writecombine. Currently, this
buffer is assumed to be contiguous. If a IOMMU mapping is created for
DRM, this buffer would be non-contig so the map functions are modified
to call dma_mmap_writecombine. This works for both contig and non-contig
buffers.

Signed-off-by: Prathyush K <prathyush.k at samsung.com>
---
 drivers/gpu/drm/exynos/exynos_drm_gem.c |   35 ++++++++++++++----------------
 1 files changed, 16 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
index 5c8b683..59240f7 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
@@ -162,17 +162,22 @@ static int exynos_drm_gem_map_pages(struct drm_gem_object *obj,
 {
 	struct exynos_drm_gem_obj *exynos_gem_obj = to_exynos_gem_obj(obj);
 	struct exynos_drm_gem_buf *buf = exynos_gem_obj->buffer;
-	unsigned long pfn;
 
 	if (exynos_gem_obj->flags & EXYNOS_BO_NONCONTIG) {
+		unsigned long pfn;
 		if (!buf->pages)
 			return -EINTR;
 
 		pfn = page_to_pfn(buf->pages[page_offset++]);
-	} else
-		pfn = (buf->dma_addr >> PAGE_SHIFT) + page_offset;
-
-	return vm_insert_mixed(vma, f_vaddr, pfn);
+		return vm_insert_mixed(vma, f_vaddr, pfn);
+	} else {
+		int ret;
+		ret = dma_mmap_writecombine(obj->dev->dev, vma, buf->kvaddr,
+					buf->dma_addr, buf->size);
+		if (ret)
+			DRM_ERROR("dma_mmap_writecombine failed\n");
+		return ret;
+	}
 }
 
 static int exynos_drm_gem_get_pages(struct drm_gem_object *obj)
@@ -503,7 +508,7 @@ static int exynos_drm_gem_mmap_buffer(struct file *filp,
 	struct drm_gem_object *obj = filp->private_data;
 	struct exynos_drm_gem_obj *exynos_gem_obj = to_exynos_gem_obj(obj);
 	struct exynos_drm_gem_buf *buffer;
-	unsigned long pfn, vm_size, usize, uaddr = vma->vm_start;
+	unsigned long vm_size, usize, uaddr = vma->vm_start;
 	int ret;
 
 	DRM_DEBUG_KMS("%s\n", __FILE__);
@@ -543,19 +548,11 @@ static int exynos_drm_gem_mmap_buffer(struct file *filp,
 			usize -= PAGE_SIZE;
 		} while (usize > 0);
 	} else {
-		/*
-		 * get page frame number to physical memory to be mapped
-		 * to user space.
-		 */
-		pfn = ((unsigned long)exynos_gem_obj->buffer->dma_addr) >>
-								PAGE_SHIFT;
-
-		DRM_DEBUG_KMS("pfn = 0x%lx\n", pfn);
-
-		if (remap_pfn_range(vma, vma->vm_start, pfn, vm_size,
-					vma->vm_page_prot)) {
-			DRM_ERROR("failed to remap pfn range.\n");
-			return -EAGAIN;
+		ret = dma_mmap_writecombine(obj->dev->dev, vma, buffer->kvaddr,
+					buffer->dma_addr, buffer->size);
+		if (ret) {
+			DRM_ERROR("dma_mmap_writecombine failed\n");
+			return ret;
 		}
 	}
 
-- 
1.7.0.4