1 files changed, 80 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_scatterlist.c b/drivers/gpu/drm/i915/i915_scatterlist.c
index 69e9e6c3135e..4a6712dca838 100644
--- a/drivers/gpu/drm/i915/i915_scatterlist.c
+++ b/drivers/gpu/drm/i915/i915_scatterlist.c
@@ -6,6 +6,9 @@
 
 #include "i915_scatterlist.h"
 
+#include "i915_buddy.h"
+#include "i915_ttm_buddy_manager.h"
+
 #include <drm/drm_mm.h>
 
 #include <linux/slab.h>
@@ -104,6 +107,83 @@ struct sg_table *i915_sg_from_mm_node(const struct drm_mm_node *node,
 	return st;
 }
 
+/**
+ * i915_sg_from_buddy_resource - Create an sg_table from a struct
+ * i915_buddy_block list
+ * @res: The struct i915_ttm_buddy_resource.
+ * @region_start: An offset to add to the dma addresses of the sg list.
+ *
+ * Create a struct sg_table, initializing it from struct i915_buddy_block list,
+ * taking a maximum segment length into account, splitting into segments
+ * if necessary.
+ *
+ * Return: A pointer to a kmalloced struct sg_table on success, negative
+ * error code cast to an error pointer on failure.
+ */
+struct sg_table *i915_sg_from_buddy_resource(struct ttm_resource *res,
+					     u64 region_start)
+{
+	struct i915_ttm_buddy_resource *bman_res = to_ttm_buddy_resource(res);
+	const u64 size = res->num_pages << PAGE_SHIFT;
+	const u64 max_segment = rounddown(UINT_MAX, PAGE_SIZE);
+	struct i915_buddy_mm *mm = bman_res->mm;
+	struct list_head *blocks = &bman_res->blocks;
+	struct i915_buddy_block *block;
+	struct scatterlist *sg;
+	struct sg_table *st;
+	resource_size_t prev_end;
+
+	GEM_BUG_ON(list_empty(blocks));
+
+	st = kmalloc(sizeof(*st), GFP_KERNEL);
+	if (!st)
+		return ERR_PTR(-ENOMEM);
+
+	if (sg_alloc_table(st, res->num_pages, GFP_KERNEL)) {
+		kfree(st);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	sg = st->sgl;
+	st->nents = 0;
+	prev_end = (resource_size_t)-1;
+
+	list_for_each_entry(block, blocks, link) {
+		u64 block_size, offset;
+
+		block_size = min_t(u64, size, i915_buddy_block_size(mm, block));
+		offset = i915_buddy_block_offset(block);
+
+		while (block_size) {
+			u64 len;
+
+			if (offset != prev_end || sg->length >= max_segment) {
+				if (st->nents)
+					sg = __sg_next(sg);
+
+				sg_dma_address(sg) = region_start + offset;
+				sg_dma_len(sg) = 0;
+				sg->length = 0;
+				st->nents++;
+			}
+
+			len = min(block_size, max_segment - sg->length);
+			sg->length += len;
+			sg_dma_len(sg) += len;
+
+			offset += len;
+			block_size -= len;
+
+			prev_end = offset;
+		}
+	}
+
+	sg_mark_end(sg);
+	i915_sg_trim(st);
+
+	return st;
+}
+
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 #include "selftests/scatterlist.c"
 #endif