1 files changed, 229 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_scatterlist.c b/drivers/gpu/drm/i915/i915_scatterlist.c
new file mode 100644
index 000000000..dcc081874
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_scatterlist.c
@@ -0,0 +1,229 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2016 Intel Corporation
+ */
+
+#include "i915_scatterlist.h"
+#include "i915_ttm_buddy_manager.h"
+
+#include <drm/drm_buddy.h>
+#include <drm/drm_mm.h>
+
+#include <linux/slab.h>
+
+bool i915_sg_trim(struct sg_table *orig_st)
+{
+	struct sg_table new_st;
+	struct scatterlist *sg, *new_sg;
+	unsigned int i;
+
+	if (orig_st->nents == orig_st->orig_nents)
+		return false;
+
+	if (sg_alloc_table(&new_st, orig_st->nents, GFP_KERNEL | __GFP_NOWARN))
+		return false;
+
+	new_sg = new_st.sgl;
+	for_each_sg(orig_st->sgl, sg, orig_st->nents, i) {
+		sg_set_page(new_sg, sg_page(sg), sg->length, 0);
+		sg_dma_address(new_sg) = sg_dma_address(sg);
+		sg_dma_len(new_sg) = sg_dma_len(sg);
+
+		new_sg = sg_next(new_sg);
+	}
+	GEM_BUG_ON(new_sg); /* Should walk exactly nents and hit the end */
+
+	sg_free_table(orig_st);
+
+	*orig_st = new_st;
+	return true;
+}
+
+static void i915_refct_sgt_release(struct kref *ref)
+{
+	struct i915_refct_sgt *rsgt =
+		container_of(ref, typeof(*rsgt), kref);
+
+	sg_free_table(&rsgt->table);
+	kfree(rsgt);
+}
+
+static const struct i915_refct_sgt_ops rsgt_ops = {
+	.release = i915_refct_sgt_release
+};
+
+/**
+ * i915_refct_sgt_init - Initialize a struct i915_refct_sgt with default ops
+ * @rsgt: The struct i915_refct_sgt to initialize.
+ * size: The size of the underlying memory buffer.
+ */
+void i915_refct_sgt_init(struct i915_refct_sgt *rsgt, size_t size)
+{
+	__i915_refct_sgt_init(rsgt, size, &rsgt_ops);
+}
+
+/**
+ * i915_rsgt_from_mm_node - Create a refcounted sg_table from a struct
+ * drm_mm_node
+ * @node: The drm_mm_node.
+ * @region_start: An offset to add to the dma addresses of the sg list.
+ * @page_alignment: Required page alignment for each sg entry. Power of two.
+ *
+ * Create a struct sg_table, initializing it from a struct drm_mm_node,
+ * taking a maximum segment length into account, splitting into segments
+ * if necessary.
+ *
+ * Return: A pointer to a kmalloced struct i915_refct_sgt on success, negative
+ * error code cast to an error pointer on failure.
+ */
+struct i915_refct_sgt *i915_rsgt_from_mm_node(const struct drm_mm_node *node,
+					      u64 region_start,
+					      u32 page_alignment)
+{
+	const u32 max_segment = round_down(UINT_MAX, page_alignment);
+	const u32 segment_pages = max_segment >> PAGE_SHIFT;
+	u64 block_size, offset, prev_end;
+	struct i915_refct_sgt *rsgt;
+	struct sg_table *st;
+	struct scatterlist *sg;
+
+	GEM_BUG_ON(!max_segment);
+
+	rsgt = kmalloc(sizeof(*rsgt), GFP_KERNEL);
+	if (!rsgt)
+		return ERR_PTR(-ENOMEM);
+
+	i915_refct_sgt_init(rsgt, node->size << PAGE_SHIFT);
+	st = &rsgt->table;
+	if (sg_alloc_table(st, DIV_ROUND_UP_ULL(node->size, segment_pages),
+			   GFP_KERNEL)) {
+		i915_refct_sgt_put(rsgt);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	sg = st->sgl;
+	st->nents = 0;
+	prev_end = (resource_size_t)-1;
+	block_size = node->size << PAGE_SHIFT;
+	offset = node->start << PAGE_SHIFT;
+
+	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;
+			GEM_BUG_ON(!IS_ALIGNED(sg_dma_address(sg),
+					       page_alignment));
+			sg_dma_len(sg) = 0;
+			sg->length = 0;
+			st->nents++;
+		}
+
+		len = min_t(u64, 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 rsgt;
+}
+
+/**
+ * i915_rsgt_from_buddy_resource - Create a refcounted 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.
+ * @page_alignment: Required page alignment for each sg entry. Power of two.
+ *
+ * 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 i915_refct_sgts on success, negative
+ * error code cast to an error pointer on failure.
+ */
+struct i915_refct_sgt *i915_rsgt_from_buddy_resource(struct ttm_resource *res,
+						     u64 region_start,
+						     u32 page_alignment)
+{
+	struct i915_ttm_buddy_resource *bman_res = to_ttm_buddy_resource(res);
+	const u64 size = res->num_pages << PAGE_SHIFT;
+	const u32 max_segment = round_down(UINT_MAX, page_alignment);
+	struct drm_buddy *mm = bman_res->mm;
+	struct list_head *blocks = &bman_res->blocks;
+	struct drm_buddy_block *block;
+	struct i915_refct_sgt *rsgt;
+	struct scatterlist *sg;
+	struct sg_table *st;
+	resource_size_t prev_end;
+
+	GEM_BUG_ON(list_empty(blocks));
+	GEM_BUG_ON(!max_segment);
+
+	rsgt = kmalloc(sizeof(*rsgt), GFP_KERNEL);
+	if (!rsgt)
+		return ERR_PTR(-ENOMEM);
+
+	i915_refct_sgt_init(rsgt, size);
+	st = &rsgt->table;
+	if (sg_alloc_table(st, res->num_pages, GFP_KERNEL)) {
+		i915_refct_sgt_put(rsgt);
+		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, drm_buddy_block_size(mm, block));
+		offset = drm_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;
+				GEM_BUG_ON(!IS_ALIGNED(sg_dma_address(sg),
+						       page_alignment));
+				sg_dma_len(sg) = 0;
+				sg->length = 0;
+				st->nents++;
+			}
+
+			len = min_t(u64, 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 rsgt;
+}
+
+#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
+#include "selftests/scatterlist.c"
+#endif