[PATCH] drm/exynos: add vm_ops to specific gem mmaper

[Inki Dae]

This patch makes it takes a reference to gem object when
specific gem mmap is requested. For this, it sets
dev->driver->gem_vm_ops to vma->vm_ops.

And this patch is based on exynos-drm-next-iommu branch of
	git://git.kernel.org/pub/scm/linux/kernel/git/daeinki/drm-exynos

Signed-off-by: Inki Dae <inki.dae at samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park at samsung.com>
---
 drivers/gpu/drm/exynos/exynos_drm_gem.c |   20 +++++++++++++++++++-
 1 files changed, 19 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
index 50d73f1..b7ce8b6 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
@@ -372,10 +372,13 @@ static int exynos_drm_gem_mmap_buffer(struct file *filp,
 	struct exynos_drm_gem_obj *exynos_gem_obj = to_exynos_gem_obj(obj);
 	struct exynos_drm_gem_buf *buffer;
 	unsigned long vm_size;
+	int ret;
 
 	DRM_DEBUG_KMS("%s\n", __FILE__);
 
 	vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
+	vma->vm_private_data = obj;
+	vma->vm_ops = obj->dev->driver->gem_vm_ops;
 
 	update_vm_cache_attr(exynos_gem_obj, vma);
 
@@ -391,9 +394,22 @@ static int exynos_drm_gem_mmap_buffer(struct file *filp,
 	if (vm_size > buffer->size)
 		return -EINVAL;
 
-	return dma_mmap_attrs(obj->dev->dev, vma, buffer->kvaddr,
+	ret = dma_mmap_attrs(obj->dev->dev, vma, buffer->kvaddr,
 				buffer->dma_addr, buffer->size,
 				&buffer->dma_attrs);
+	if (ret < 0) {
+		DRM_ERROR("failed to mmap.\n");
+		return ret;
+	}
+
+	/*
+	 * take a reference to this mapping of the object. And this reference
+	 * is unreferenced by the corresponding vm_close call.
+	 */
+	drm_gem_object_reference(obj);
+	drm_vm_open_locked(obj->dev, vma);
+
+	return 0;
 }
 
 static const struct file_operations exynos_drm_gem_fops = {
@@ -426,6 +442,8 @@ int exynos_drm_gem_mmap_ioctl(struct drm_device *dev, void *data,
 	addr = vm_mmap(obj->filp, 0, args->size,
 			PROT_READ | PROT_WRITE, MAP_SHARED, 0);
 
+	/* restore it to drm_file object. */
+	obj->filp->private_data = file_priv;
 	drm_gem_object_unreference_unlocked(obj);
 
 	if (IS_ERR((void *)addr))
-- 
1.7.4.1