1 /* $NetBSD: i915_scatterlist.h,v 1.8 2021/12/19 11:37:05 riastradh Exp $ */
2
3 /*
4 * SPDX-License-Identifier: MIT
5 *
6 * Copyright © 2016 Intel Corporation
7 */
8
9 #ifndef I915_SCATTERLIST_H
10 #define I915_SCATTERLIST_H
11
12 #include <linux/pfn.h>
13 #include <linux/scatterlist.h>
14 #include <linux/swiotlb.h>
15
16 #include "i915_gem.h"
17
18 #ifdef __NetBSD__
19
20 struct sgt_iter {
21 unsigned i;
22 };
23
24 #define for_each_sgt_page(pp, iter, sgt) \
25 for ((iter).i = 0; \
26 ((iter).i < (sgt)->sgl->sg_npgs \
27 ? (((pp) = (sgt)->sgl->sg_pgs[(iter).i]), 1) \
28 : 0); \
29 (iter).i++)
30
31 static inline unsigned
i915_sg_page_sizes(struct scatterlist * sg)32 i915_sg_page_sizes(struct scatterlist *sg)
33 {
34 unsigned i, page_sizes = 0;
35
36 for (i = 0; i < sg->sg_dmamap->dm_nsegs; i++)
37 page_sizes |= sg->sg_dmamap->dm_segs[i].ds_len;
38
39 return page_sizes;
40 }
41
42 static inline unsigned
i915_sg_segment_size(void)43 i915_sg_segment_size(void)
44 {
45 return PAGE_SIZE;
46 }
47
48 #else
49
50 /*
51 * Optimised SGL iterator for GEM objects
52 */
53 static __always_inline struct sgt_iter {
54 struct scatterlist *sgp;
55 union {
56 unsigned long pfn;
57 dma_addr_t dma;
58 };
59 unsigned int curr;
60 unsigned int max;
__sgt_iter(struct scatterlist * sgl,bool dma)61 } __sgt_iter(struct scatterlist *sgl, bool dma) {
62 struct sgt_iter s = { .sgp = sgl };
63
64 if (s.sgp) {
65 s.max = s.curr = s.sgp->offset;
66 s.max += s.sgp->length;
67 if (dma)
68 s.dma = sg_dma_address(s.sgp);
69 else
70 s.pfn = page_to_pfn(sg_page(s.sgp));
71 }
72
73 return s;
74 }
75
__sg_page_count(const struct scatterlist * sg)76 static inline int __sg_page_count(const struct scatterlist *sg)
77 {
78 return sg->length >> PAGE_SHIFT;
79 }
80
____sg_next(struct scatterlist * sg)81 static inline struct scatterlist *____sg_next(struct scatterlist *sg)
82 {
83 ++sg;
84 if (unlikely(sg_is_chain(sg)))
85 sg = sg_chain_ptr(sg);
86 return sg;
87 }
88
89 /**
90 * __sg_next - return the next scatterlist entry in a list
91 * @sg: The current sg entry
92 *
93 * Description:
94 * If the entry is the last, return NULL; otherwise, step to the next
95 * element in the array (@sg@+1). If that's a chain pointer, follow it;
96 * otherwise just return the pointer to the current element.
97 **/
__sg_next(struct scatterlist * sg)98 static inline struct scatterlist *__sg_next(struct scatterlist *sg)
99 {
100 return sg_is_last(sg) ? NULL : ____sg_next(sg);
101 }
102
103 /**
104 * __for_each_sgt_daddr - iterate over the device addresses of the given sg_table
105 * @__dp: Device address (output)
106 * @__iter: 'struct sgt_iter' (iterator state, internal)
107 * @__sgt: sg_table to iterate over (input)
108 * @__step: step size
109 */
110 #define __for_each_sgt_daddr(__dp, __iter, __sgt, __step) \
111 for ((__iter) = __sgt_iter((__sgt)->sgl, true); \
112 ((__dp) = (__iter).dma + (__iter).curr), (__iter).sgp; \
113 (((__iter).curr += (__step)) >= (__iter).max) ? \
114 (__iter) = __sgt_iter(__sg_next((__iter).sgp), true), 0 : 0)
115
116 /**
117 * for_each_sgt_page - iterate over the pages of the given sg_table
118 * @__pp: page pointer (output)
119 * @__iter: 'struct sgt_iter' (iterator state, internal)
120 * @__sgt: sg_table to iterate over (input)
121 */
122 #define for_each_sgt_page(__pp, __iter, __sgt) \
123 for ((__iter) = __sgt_iter((__sgt)->sgl, false); \
124 ((__pp) = (__iter).pfn == 0 ? NULL : \
125 pfn_to_page((__iter).pfn + ((__iter).curr >> PAGE_SHIFT))); \
126 (((__iter).curr += PAGE_SIZE) >= (__iter).max) ? \
127 (__iter) = __sgt_iter(__sg_next((__iter).sgp), false), 0 : 0)
128
i915_sg_page_sizes(struct scatterlist * sg)129 static inline unsigned int i915_sg_page_sizes(struct scatterlist *sg)
130 {
131 unsigned int page_sizes;
132
133 page_sizes = 0;
134 while (sg) {
135 GEM_BUG_ON(sg->offset);
136 GEM_BUG_ON(!IS_ALIGNED(sg->length, PAGE_SIZE));
137 page_sizes |= sg->length;
138 sg = __sg_next(sg);
139 }
140
141 return page_sizes;
142 }
143
i915_sg_segment_size(void)144 static inline unsigned int i915_sg_segment_size(void)
145 {
146 unsigned int size = swiotlb_max_segment();
147
148 if (size == 0)
149 return SCATTERLIST_MAX_SEGMENT;
150
151 size = rounddown(size, PAGE_SIZE);
152 /* swiotlb_max_segment_size can return 1 byte when it means one page. */
153 if (size < PAGE_SIZE)
154 size = PAGE_SIZE;
155
156 return size;
157 }
158
159 #endif
160
161 bool i915_sg_trim(struct sg_table *orig_st);
162
163 #endif
164