2 * SPDX-License-Identifier: MIT
4 * Copyright © 2016 Intel Corporation
7 #ifndef I915_SCATTERLIST_H
8 #define I915_SCATTERLIST_H
10 #include <linux/pfn.h>
11 #include <linux/scatterlist.h>
12 #include <linux/swiotlb.h>
19 * Optimised SGL iterator for GEM objects
21 static __always_inline struct sgt_iter {
22 struct scatterlist *sgp;
29 } __sgt_iter(struct scatterlist *sgl, bool dma) {
30 struct sgt_iter s = { .sgp = sgl };
32 if (dma && s.sgp && sg_dma_len(s.sgp) == 0) {
35 s.max = s.curr = s.sgp->offset;
37 s.dma = sg_dma_address(s.sgp);
38 s.max += sg_dma_len(s.sgp);
40 s.pfn = page_to_pfn(sg_page(s.sgp));
41 s.max += s.sgp->length;
48 static inline int __sg_page_count(const struct scatterlist *sg)
50 return sg->length >> PAGE_SHIFT;
53 static inline int __sg_dma_page_count(const struct scatterlist *sg)
55 return sg_dma_len(sg) >> PAGE_SHIFT;
58 static inline struct scatterlist *____sg_next(struct scatterlist *sg)
61 if (unlikely(sg_is_chain(sg)))
62 sg = sg_chain_ptr(sg);
67 * __sg_next - return the next scatterlist entry in a list
68 * @sg: The current sg entry
71 * If the entry is the last, return NULL; otherwise, step to the next
72 * element in the array (@sg@+1). If that's a chain pointer, follow it;
73 * otherwise just return the pointer to the current element.
75 static inline struct scatterlist *__sg_next(struct scatterlist *sg)
77 return sg_is_last(sg) ? NULL : ____sg_next(sg);
81 * __for_each_sgt_daddr - iterate over the device addresses of the given sg_table
82 * @__dp: Device address (output)
83 * @__iter: 'struct sgt_iter' (iterator state, internal)
84 * @__sgt: sg_table to iterate over (input)
87 #define __for_each_sgt_daddr(__dp, __iter, __sgt, __step) \
88 for ((__iter) = __sgt_iter((__sgt)->sgl, true); \
89 ((__dp) = (__iter).dma + (__iter).curr), (__iter).sgp; \
90 (((__iter).curr += (__step)) >= (__iter).max) ? \
91 (__iter) = __sgt_iter(__sg_next((__iter).sgp), true), 0 : 0)
94 * for_each_sgt_page - iterate over the pages of the given sg_table
95 * @__pp: page pointer (output)
96 * @__iter: 'struct sgt_iter' (iterator state, internal)
97 * @__sgt: sg_table to iterate over (input)
99 #define for_each_sgt_page(__pp, __iter, __sgt) \
100 for ((__iter) = __sgt_iter((__sgt)->sgl, false); \
101 ((__pp) = (__iter).pfn == 0 ? NULL : \
102 pfn_to_page((__iter).pfn + ((__iter).curr >> PAGE_SHIFT))); \
103 (((__iter).curr += PAGE_SIZE) >= (__iter).max) ? \
104 (__iter) = __sgt_iter(__sg_next((__iter).sgp), false), 0 : 0)
107 * i915_sg_dma_sizes - Record the dma segment sizes of a scatterlist
108 * @sg: The scatterlist
110 * Return: An unsigned int with segment sizes logically or'ed together.
111 * A caller can use this information to determine what hardware page table
112 * entry sizes can be used to map the memory represented by the scatterlist.
114 static inline unsigned int i915_sg_dma_sizes(struct scatterlist *sg)
116 unsigned int page_sizes;
119 while (sg && sg_dma_len(sg)) {
120 GEM_BUG_ON(sg->offset);
121 GEM_BUG_ON(!IS_ALIGNED(sg_dma_len(sg), PAGE_SIZE));
122 page_sizes |= sg_dma_len(sg);
129 static inline unsigned int i915_sg_segment_size(void)
131 unsigned int size = swiotlb_max_segment();
136 size = rounddown(size, PAGE_SIZE);
137 /* swiotlb_max_segment_size can return 1 byte when it means one page. */
138 if (size < PAGE_SIZE)
144 bool i915_sg_trim(struct sg_table *orig_st);
146 struct sg_table *i915_sg_from_mm_node(const struct drm_mm_node *node,