[Intel-gfx] [PATCH 19/43] drm/i915: Introduce i915_gem_object_create_stolen()

[Chris Wilson]

Allow for the creation of GEM objects backed by stolen memory. As these
are not backed by ordinary pages, we create a fake dma mapping and store
the address in the scatterlist rather than obj->pages.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_drv.h        |    3 +
 drivers/gpu/drm/i915/i915_gem.c        |    2 +
 drivers/gpu/drm/i915/i915_gem_gtt.c    |    2 +-
 drivers/gpu/drm/i915/i915_gem_stolen.c |  110 ++++++++++++++++++++++++++++++++
 4 files changed, 116 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 3e4e33a..dd583d7 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1382,6 +1382,9 @@ int i915_gem_evict_everything(struct drm_device *dev);
 int i915_gem_init_stolen(struct drm_device *dev);
 int i915_gem_stolen_setup_compression(struct drm_device *dev);
 void i915_gem_cleanup_stolen(struct drm_device *dev);
+struct drm_i915_gem_object *
+i915_gem_object_create_stolen(struct drm_device *dev, u32 size);
+void i915_gem_object_release_stolen(struct drm_i915_gem_object *obj);
 
 /* i915_gem_tiling.c */
 void i915_gem_detect_bit_6_swizzle(struct drm_device *dev);
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 7576937..b2b4144 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3513,6 +3513,8 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj)
 	i915_gem_object_put_pages_gtt(obj);
 	i915_gem_object_free_mmap_offset(obj);
 
+	i915_gem_object_release_stolen(obj);
+
 	drm_gem_object_release(&obj->base);
 	i915_gem_info_remove_obj(dev_priv, obj->base.size);
 
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index bd54ae4..4a0d889 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -398,7 +398,7 @@ void i915_gem_gtt_finish_object(struct drm_i915_gem_object *obj)
 
 	interruptible = do_idling(dev_priv);
 
-	if (obj->sg_list) {
+	if (obj->sg_list && !obj->stolen) {
 		intel_gtt_unmap_memory(obj->sg_list, obj->num_sg);
 		obj->sg_list = NULL;
 	}
diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
index 00b1c1d..118c54a 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -202,3 +202,113 @@ int i915_gem_init_stolen(struct drm_device *dev)
 
 	return 0;
 }
+
+struct scatterlist *
+i915_sg_create_for_stolen(struct drm_device *dev, u32 offset, u32 size)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct scatterlist *sg;
+
+	/* We hide that we have no struct page backing our stolen object
+	 * by wrapping the contiguous physical allocation with a fake
+	 * dma mapping in a single scatterlist.
+	 */
+
+	sg = kmalloc(sizeof(*sg), GFP_KERNEL);
+	if (sg == NULL)
+		return NULL;
+
+	sg_init_table(sg, 1);
+
+	sg->offset = offset;
+	sg->length = size;
+
+	sg_dma_address(sg) = dev_priv->mm.stolen_base + offset;
+	sg_dma_len(sg) = size;
+
+	return sg;
+}
+
+struct drm_i915_gem_object *
+_i915_gem_object_create_stolen(struct drm_device *dev,
+			       struct drm_mm_node *stolen)
+{
+	struct drm_i915_gem_object *obj;
+	struct scatterlist *sg;
+
+	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
+	if (obj == NULL)
+		return NULL;
+
+	if (drm_gem_private_object_init(dev, &obj->base, stolen->size))
+		goto cleanup;
+
+	sg = i915_sg_create_for_stolen(dev, stolen->start, stolen->size);
+	if (sg == NULL)
+		goto cleanup;
+
+	i915_gem_object_init(obj);
+
+	obj->stolen = stolen;
+
+	obj->base.write_domain = I915_GEM_DOMAIN_GTT;
+	obj->base.read_domains = I915_GEM_DOMAIN_GTT;
+	obj->cache_level = I915_CACHE_NONE;
+
+	obj->sg_list = sg;
+	obj->num_sg = 1;
+
+	return obj;
+
+cleanup:
+	kfree(obj);
+	return NULL;
+}
+
+struct drm_i915_gem_object *
+i915_gem_object_create_stolen(struct drm_device *dev, u32 size)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_i915_gem_object *obj;
+	struct drm_mm_node *stolen;
+
+	if (dev_priv->mm.stolen_base == 0)
+		return 0;
+
+	DRM_DEBUG_KMS("creating stolen object: size=%x\n", size);
+	if (size == 0)
+		return NULL;
+
+	stolen = drm_mm_search_free(&dev_priv->mm.stolen, size, 4096, 0);
+	if (stolen)
+		stolen = drm_mm_get_block(stolen, size, 4096);
+	if (stolen == NULL)
+		return NULL;
+
+	obj = _i915_gem_object_create_stolen(dev, stolen);
+	if (obj)
+		return obj;
+
+	drm_mm_put_block(stolen);
+	return NULL;
+}
+
+void
+i915_gem_object_release_stolen(struct drm_i915_gem_object *obj)
+{
+	if (obj->stolen) {
+		drm_mm_put_block(obj->stolen);
+		obj->stolen = NULL;
+	}
+
+	if (obj->sg_list) {
+		struct sg_table st;
+
+		st.sgl = obj->sg_list;
+		st.orig_nents = st.nents = obj->num_sg;
+
+		sg_free_table(&st);
+
+		obj->sg_list = NULL;
+	}
+}
-- 
1.7.10