1 files changed, 127 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_scatterlist.h b/drivers/gpu/drm/i915/i915_scatterlist.h
new file mode 100644
index 000000000000..6617963df9ed
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_scatterlist.h
@@ -0,0 +1,127 @@
+/*
+ * SPDX-License-Identifier: MIT
+ *
+ * Copyright © 2016 Intel Corporation
+ */
+
+#ifndef I915_SCATTERLIST_H
+#define I915_SCATTERLIST_H
+
+#include <linux/pfn.h>
+#include <linux/scatterlist.h>
+#include <linux/swiotlb.h>
+
+#include "i915_gem.h"
+
+/*
+ * Optimised SGL iterator for GEM objects
+ */
+static __always_inline struct sgt_iter {
+	struct scatterlist *sgp;
+	union {
+		unsigned long pfn;
+		dma_addr_t dma;
+	};
+	unsigned int curr;
+	unsigned int max;
+} __sgt_iter(struct scatterlist *sgl, bool dma) {
+	struct sgt_iter s = { .sgp = sgl };
+
+	if (s.sgp) {
+		s.max = s.curr = s.sgp->offset;
+		s.max += s.sgp->length;
+		if (dma)
+			s.dma = sg_dma_address(s.sgp);
+		else
+			s.pfn = page_to_pfn(sg_page(s.sgp));
+	}
+
+	return s;
+}
+
+static inline int __sg_page_count(const struct scatterlist *sg)
+{
+	return sg->length >> PAGE_SHIFT;
+}
+
+static inline struct scatterlist *____sg_next(struct scatterlist *sg)
+{
+	++sg;
+	if (unlikely(sg_is_chain(sg)))
+		sg = sg_chain_ptr(sg);
+	return sg;
+}
+
+/**
+ * __sg_next - return the next scatterlist entry in a list
+ * @sg:		The current sg entry
+ *
+ * Description:
+ *   If the entry is the last, return NULL; otherwise, step to the next
+ *   element in the array (@sg@+1). If that's a chain pointer, follow it;
+ *   otherwise just return the pointer to the current element.
+ **/
+static inline struct scatterlist *__sg_next(struct scatterlist *sg)
+{
+	return sg_is_last(sg) ? NULL : ____sg_next(sg);
+}
+
+/**
+ * __for_each_sgt_dma - iterate over the DMA addresses of the given sg_table
+ * @__dmap:	DMA address (output)
+ * @__iter:	'struct sgt_iter' (iterator state, internal)
+ * @__sgt:	sg_table to iterate over (input)
+ * @__step:	step size
+ */
+#define __for_each_sgt_dma(__dmap, __iter, __sgt, __step)		\
+	for ((__iter) = __sgt_iter((__sgt)->sgl, true);			\
+	     ((__dmap) = (__iter).dma + (__iter).curr);			\
+	     (((__iter).curr += (__step)) >= (__iter).max) ?		\
+	     (__iter) = __sgt_iter(__sg_next((__iter).sgp), true), 0 : 0)
+
+/**
+ * for_each_sgt_page - iterate over the pages of the given sg_table
+ * @__pp:	page pointer (output)
+ * @__iter:	'struct sgt_iter' (iterator state, internal)
+ * @__sgt:	sg_table to iterate over (input)
+ */
+#define for_each_sgt_page(__pp, __iter, __sgt)				\
+	for ((__iter) = __sgt_iter((__sgt)->sgl, false);		\
+	     ((__pp) = (__iter).pfn == 0 ? NULL :			\
+	      pfn_to_page((__iter).pfn + ((__iter).curr >> PAGE_SHIFT))); \
+	     (((__iter).curr += PAGE_SIZE) >= (__iter).max) ?		\
+	     (__iter) = __sgt_iter(__sg_next((__iter).sgp), false), 0 : 0)
+
+static inline unsigned int i915_sg_page_sizes(struct scatterlist *sg)
+{
+	unsigned int page_sizes;
+
+	page_sizes = 0;
+	while (sg) {
+		GEM_BUG_ON(sg->offset);
+		GEM_BUG_ON(!IS_ALIGNED(sg->length, PAGE_SIZE));
+		page_sizes |= sg->length;
+		sg = __sg_next(sg);
+	}
+
+	return page_sizes;
+}
+
+static inline unsigned int i915_sg_segment_size(void)
+{
+	unsigned int size = swiotlb_max_segment();
+
+	if (size == 0)
+		return SCATTERLIST_MAX_SEGMENT;
+
+	size = rounddown(size, PAGE_SIZE);
+	/* swiotlb_max_segment_size can return 1 byte when it means one page. */
+	if (size < PAGE_SIZE)
+		size = PAGE_SIZE;
+
+	return size;
+}
+
+bool i915_sg_trim(struct sg_table *orig_st);
+
+#endif