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 (dma && s.sgp && sg_dma_len(s.sgp) == 0) {
31 s.sgp = NULL;
32 } else if (s.sgp) {
33 s.max = s.curr = s.sgp->offset;
34 if (dma) {
35 s.dma = sg_dma_address(s.sgp);
36 s.max += sg_dma_len(s.sgp);
37 } else {
38 s.pfn = page_to_pfn(sg_page(s.sgp));
39 s.max += s.sgp->length;
40 }
41 }
42
43 return s;
44 }
45
__sg_page_count(const struct scatterlist * sg)46 static inline int __sg_page_count(const struct scatterlist *sg)
47 {
48 return sg->length >> PAGE_SHIFT;
49 }
50
__sg_dma_page_count(const struct scatterlist * sg)51 static inline int __sg_dma_page_count(const struct scatterlist *sg)
52 {
53 return sg_dma_len(sg) >> PAGE_SHIFT;
54 }
55
____sg_next(struct scatterlist * sg)56 static inline struct scatterlist *____sg_next(struct scatterlist *sg)
57 {
58 ++sg;
59 if (unlikely(sg_is_chain(sg)))
60 sg = sg_chain_ptr(sg);
61 return sg;
62 }
63
64 /**
65 * __sg_next - return the next scatterlist entry in a list
66 * @sg: The current sg entry
67 *
68 * Description:
69 * If the entry is the last, return NULL; otherwise, step to the next
70 * element in the array (@sg@+1). If that's a chain pointer, follow it;
71 * otherwise just return the pointer to the current element.
72 **/
__sg_next(struct scatterlist * sg)73 static inline struct scatterlist *__sg_next(struct scatterlist *sg)
74 {
75 return sg_is_last(sg) ? NULL : ____sg_next(sg);
76 }
77
78 /**
79 * __for_each_sgt_daddr - iterate over the device addresses of the given sg_table
80 * @__dp: Device address (output)
81 * @__iter: 'struct sgt_iter' (iterator state, internal)
82 * @__sgt: sg_table to iterate over (input)
83 * @__step: step size
84 */
85 #define __for_each_sgt_daddr(__dp, __iter, __sgt, __step) \
86 for ((__iter) = __sgt_iter((__sgt)->sgl, true); \
87 ((__dp) = (__iter).dma + (__iter).curr), (__iter).sgp; \
88 (((__iter).curr += (__step)) >= (__iter).max) ? \
89 (__iter) = __sgt_iter(__sg_next((__iter).sgp), true), 0 : 0)
90
91 /**
92 * for_each_sgt_page - iterate over the pages of the given sg_table
93 * @__pp: page pointer (output)
94 * @__iter: 'struct sgt_iter' (iterator state, internal)
95 * @__sgt: sg_table to iterate over (input)
96 */
97 #define for_each_sgt_page(__pp, __iter, __sgt) \
98 for ((__iter) = __sgt_iter((__sgt)->sgl, false); \
99 ((__pp) = (__iter).pfn == 0 ? NULL : \
100 pfn_to_page((__iter).pfn + ((__iter).curr >> PAGE_SHIFT))); \
101 (((__iter).curr += PAGE_SIZE) >= (__iter).max) ? \
102 (__iter) = __sgt_iter(__sg_next((__iter).sgp), false), 0 : 0)
103
i915_sg_page_sizes(struct scatterlist * sg)104 static inline unsigned int i915_sg_page_sizes(struct scatterlist *sg)
105 {
106 unsigned int page_sizes;
107
108 page_sizes = 0;
109 while (sg) {
110 GEM_BUG_ON(sg->offset);
111 GEM_BUG_ON(!IS_ALIGNED(sg->length, PAGE_SIZE));
112 page_sizes |= sg->length;
113 sg = __sg_next(sg);
114 }
115
116 return page_sizes;
117 }
118
i915_sg_segment_size(void)119 static inline unsigned int i915_sg_segment_size(void)
120 {
121 unsigned int size = swiotlb_max_segment();
122
123 if (size == 0)
124 size = UINT_MAX;
125
126 size = rounddown(size, PAGE_SIZE);
127 /* swiotlb_max_segment_size can return 1 byte when it means one page. */
128 if (size < PAGE_SIZE)
129 size = PAGE_SIZE;
130
131 return size;
132 }
133
134 bool i915_sg_trim(struct sg_table *orig_st);
135
136 #endif
137