1 /*
2 * SPDX-License-Identifier: MIT
3 *
4 * Copyright © 2016 Intel Corporation
5 */
6
7 #ifndef I915_SCATTERLIST_H
8 #define I915_SCATTERLIST_H
9
10 #include <linux/pfn.h>
11 #include <linux/scatterlist.h>
12 #include <linux/swiotlb.h>
13
14 #include "i915_gem.h"
15
16 /*
17 * Optimised SGL iterator for GEM objects
18 */
19 static __always_inline struct sgt_iter {
20 struct scatterlist *sgp;
21 union {
22 unsigned long pfn;
23 dma_addr_t dma;
24 };
25 unsigned int curr;
26 unsigned int max;
__sgt_iter(struct scatterlist * sgl,bool dma)27 } __sgt_iter(struct scatterlist *sgl, bool dma) {
28 struct sgt_iter s = { .sgp = sgl };
29
30 if (s.sgp) {
31 s.max = s.curr = s.sgp->offset;
32 s.max += s.sgp->length;
33 if (dma)
34 s.dma = sg_dma_address(s.sgp);
35 else
36 s.pfn = page_to_pfn(sg_page(s.sgp));
37 }
38
39 return s;
40 }
41
__sg_page_count(const struct scatterlist * sg)42 static inline int __sg_page_count(const struct scatterlist *sg)
43 {
44 return sg->length >> PAGE_SHIFT;
45 }
46
____sg_next(struct scatterlist * sg)47 static inline struct scatterlist *____sg_next(struct scatterlist *sg)
48 {
49 ++sg;
50 if (unlikely(sg_is_chain(sg)))
51 sg = sg_chain_ptr(sg);
52 return sg;
53 }
54
55 /**
56 * __sg_next - return the next scatterlist entry in a list
57 * @sg: The current sg entry
58 *
59 * Description:
60 * If the entry is the last, return NULL; otherwise, step to the next
61 * element in the array (@sg@+1). If that's a chain pointer, follow it;
62 * otherwise just return the pointer to the current element.
63 **/
__sg_next(struct scatterlist * sg)64 static inline struct scatterlist *__sg_next(struct scatterlist *sg)
65 {
66 return sg_is_last(sg) ? NULL : ____sg_next(sg);
67 }
68
69 /**
70 * __for_each_sgt_dma - iterate over the DMA addresses of the given sg_table
71 * @__dmap: DMA address (output)
72 * @__iter: 'struct sgt_iter' (iterator state, internal)
73 * @__sgt: sg_table to iterate over (input)
74 * @__step: step size
75 */
76 #define __for_each_sgt_dma(__dmap, __iter, __sgt, __step) \
77 for ((__iter) = __sgt_iter((__sgt)->sgl, true); \
78 ((__dmap) = (__iter).dma + (__iter).curr); \
79 (((__iter).curr += (__step)) >= (__iter).max) ? \
80 (__iter) = __sgt_iter(__sg_next((__iter).sgp), true), 0 : 0)
81
82 /**
83 * for_each_sgt_page - iterate over the pages of the given sg_table
84 * @__pp: page pointer (output)
85 * @__iter: 'struct sgt_iter' (iterator state, internal)
86 * @__sgt: sg_table to iterate over (input)
87 */
88 #define for_each_sgt_page(__pp, __iter, __sgt) \
89 for ((__iter) = __sgt_iter((__sgt)->sgl, false); \
90 ((__pp) = (__iter).pfn == 0 ? NULL : \
91 pfn_to_page((__iter).pfn + ((__iter).curr >> PAGE_SHIFT))); \
92 (((__iter).curr += PAGE_SIZE) >= (__iter).max) ? \
93 (__iter) = __sgt_iter(__sg_next((__iter).sgp), false), 0 : 0)
94
i915_sg_page_sizes(struct scatterlist * sg)95 static inline unsigned int i915_sg_page_sizes(struct scatterlist *sg)
96 {
97 unsigned int page_sizes;
98
99 page_sizes = 0;
100 while (sg) {
101 GEM_BUG_ON(sg->offset);
102 GEM_BUG_ON(!IS_ALIGNED(sg->length, PAGE_SIZE));
103 page_sizes |= sg->length;
104 sg = __sg_next(sg);
105 }
106
107 return page_sizes;
108 }
109
i915_sg_segment_size(void)110 static inline unsigned int i915_sg_segment_size(void)
111 {
112 unsigned int size = swiotlb_max_segment();
113
114 if (size == 0)
115 return SCATTERLIST_MAX_SEGMENT;
116
117 size = rounddown(size, PAGE_SIZE);
118 /* swiotlb_max_segment_size can return 1 byte when it means one page. */
119 if (size < PAGE_SIZE)
120 size = PAGE_SIZE;
121
122 return size;
123 }
124
125 bool i915_sg_trim(struct sg_table *orig_st);
126
127 #endif
128
