1 files changed, 231 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 000000000..b0a1db44f
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_scatterlist.h
@@ -0,0 +1,231 @@
+/*
+ * 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/dma-mapping.h>
+#include <xen/xen.h>
+
+#include "i915_gem.h"
+
+struct drm_mm_node;
+struct ttm_resource;
+
+/*
+ * 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 (dma && s.sgp && sg_dma_len(s.sgp) == 0) {
+		s.sgp = NULL;
+	} else if (s.sgp) {
+		s.max = s.curr = s.sgp->offset;
+		if (dma) {
+			s.dma = sg_dma_address(s.sgp);
+			s.max += sg_dma_len(s.sgp);
+		} else {
+			s.pfn = page_to_pfn(sg_page(s.sgp));
+			s.max += s.sgp->length;
+		}
+	}
+
+	return s;
+}
+
+static inline int __sg_page_count(const struct scatterlist *sg)
+{
+	return sg->length >> PAGE_SHIFT;
+}
+
+static inline int __sg_dma_page_count(const struct scatterlist *sg)
+{
+	return sg_dma_len(sg) >> 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_daddr - iterate over the device addresses of the given sg_table
+ * @__dp:	Device address (output)
+ * @__iter:	'struct sgt_iter' (iterator state, internal)
+ * @__sgt:	sg_table to iterate over (input)
+ * @__step:	step size
+ */
+#define __for_each_sgt_daddr(__dp, __iter, __sgt, __step)		\
+	for ((__iter) = __sgt_iter((__sgt)->sgl, true);			\
+	     ((__dp) = (__iter).dma + (__iter).curr), (__iter).sgp;	\
+	     (((__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)
+
+/**
+ * i915_sg_dma_sizes - Record the dma segment sizes of a scatterlist
+ * @sg: The scatterlist
+ *
+ * Return: An unsigned int with segment sizes logically or'ed together.
+ * A caller can use this information to determine what hardware page table
+ * entry sizes can be used to map the memory represented by the scatterlist.
+ */
+static inline unsigned int i915_sg_dma_sizes(struct scatterlist *sg)
+{
+	unsigned int page_sizes;
+
+	page_sizes = 0;
+	while (sg && sg_dma_len(sg)) {
+		GEM_BUG_ON(sg->offset);
+		GEM_BUG_ON(!IS_ALIGNED(sg_dma_len(sg), PAGE_SIZE));
+		page_sizes |= sg_dma_len(sg);
+		sg = __sg_next(sg);
+	}
+
+	return page_sizes;
+}
+
+static inline unsigned int i915_sg_segment_size(struct device *dev)
+{
+	size_t max = min_t(size_t, UINT_MAX, dma_max_mapping_size(dev));
+
+	/*
+	 * For Xen PV guests pages aren't contiguous in DMA (machine) address
+	 * space.  The DMA API takes care of that both in dma_alloc_* (by
+	 * calling into the hypervisor to make the pages contiguous) and in
+	 * dma_map_* (by bounce buffering).  But i915 abuses ignores the
+	 * coherency aspects of the DMA API and thus can't cope with bounce
+	 * buffering actually happening, so add a hack here to force small
+	 * allocations and mappings when running in PV mode on Xen.
+	 *
+	 * Note this will still break if bounce buffering is required for other
+	 * reasons, like confidential computing hypervisors or PCIe root ports
+	 * with addressing limitations.
+	 */
+	if (xen_pv_domain())
+		max = PAGE_SIZE;
+	return round_down(max, PAGE_SIZE);
+}
+
+bool i915_sg_trim(struct sg_table *orig_st);
+
+/**
+ * struct i915_refct_sgt_ops - Operations structure for struct i915_refct_sgt
+ */
+struct i915_refct_sgt_ops {
+	/**
+	 * release() - Free the memory of the struct i915_refct_sgt
+	 * @ref: struct kref that is embedded in the struct i915_refct_sgt
+	 */
+	void (*release)(struct kref *ref);
+};
+
+/**
+ * struct i915_refct_sgt - A refcounted scatter-gather table
+ * @kref: struct kref for refcounting
+ * @table: struct sg_table holding the scatter-gather table itself. Note that
+ * @table->sgl = NULL can be used to determine whether a scatter-gather table
+ * is present or not.
+ * @size: The size in bytes of the underlying memory buffer
+ * @ops: The operations structure.
+ */
+struct i915_refct_sgt {
+	struct kref kref;
+	struct sg_table table;
+	size_t size;
+	const struct i915_refct_sgt_ops *ops;
+};
+
+/**
+ * i915_refct_sgt_put - Put a refcounted sg-table
+ * @rsgt the struct i915_refct_sgt to put.
+ */
+static inline void i915_refct_sgt_put(struct i915_refct_sgt *rsgt)
+{
+	if (rsgt)
+		kref_put(&rsgt->kref, rsgt->ops->release);
+}
+
+/**
+ * i915_refct_sgt_get - Get a refcounted sg-table
+ * @rsgt the struct i915_refct_sgt to get.
+ */
+static inline struct i915_refct_sgt *
+i915_refct_sgt_get(struct i915_refct_sgt *rsgt)
+{
+	kref_get(&rsgt->kref);
+	return rsgt;
+}
+
+/**
+ * __i915_refct_sgt_init - Initialize a refcounted sg-list with a custom
+ * operations structure
+ * @rsgt The struct i915_refct_sgt to initialize.
+ * @size: Size in bytes of the underlying memory buffer.
+ * @ops: A customized operations structure in case the refcounted sg-list
+ * is embedded into another structure.
+ */
+static inline void __i915_refct_sgt_init(struct i915_refct_sgt *rsgt,
+					 size_t size,
+					 const struct i915_refct_sgt_ops *ops)
+{
+	kref_init(&rsgt->kref);
+	rsgt->table.sgl = NULL;
+	rsgt->size = size;
+	rsgt->ops = ops;
+}
+
+void i915_refct_sgt_init(struct i915_refct_sgt *rsgt, size_t size);
+
+struct i915_refct_sgt *i915_rsgt_from_mm_node(const struct drm_mm_node *node,
+					      u64 region_start,
+					      u32 page_alignment);
+
+struct i915_refct_sgt *i915_rsgt_from_buddy_resource(struct ttm_resource *res,
+						     u64 region_start,
+						     u32 page_alignment);
+
+#endif