drm/i915/ttm Initialize the ttm device and memory managers

Temporarily remove the buddy allocator and related selftests
and hook up the TTM range manager for i915 regions.

Also modify the mock region selftests somewhat to account for a
fragmenting manager.

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210602083818.241793-2-thomas.hellstrom@linux.intel.com

1 files changed, 70 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_scatterlist.c b/drivers/gpu/drm/i915/i915_scatterlist.c
index cc6b3846a8c7..69e9e6c3135e 100644
--- a/drivers/gpu/drm/i915/i915_scatterlist.c
+++ b/drivers/gpu/drm/i915/i915_scatterlist.c
@@ -6,6 +6,10 @@
 
 #include "i915_scatterlist.h"
 
+#include <drm/drm_mm.h>
+
+#include <linux/slab.h>
+
 bool i915_sg_trim(struct sg_table *orig_st)
 {
 	struct sg_table new_st;
@@ -34,6 +38,72 @@ bool i915_sg_trim(struct sg_table *orig_st)
 	return true;
 }
 
+/**
+ * i915_sg_from_mm_node - Create an 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.
+ *
+ * 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 sg_table on success, negative
+ * error code cast to an error pointer on failure.
+ */
+struct sg_table *i915_sg_from_mm_node(const struct drm_mm_node *node,
+				      u64 region_start)
+{
+	const u64 max_segment = SZ_1G; /* Do we have a limit on this? */
+	u64 segment_pages = max_segment >> PAGE_SHIFT;
+	u64 block_size, offset, prev_end;
+	struct sg_table *st;
+	struct scatterlist *sg;
+
+	st = kmalloc(sizeof(*st), GFP_KERNEL);
+	if (!st)
+		return ERR_PTR(-ENOMEM);
+
+	if (sg_alloc_table(st, DIV_ROUND_UP(node->size, segment_pages),
+			   GFP_KERNEL)) {
+		kfree(st);
+		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;
+			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