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 struct drm_mm_node;
17 struct ttm_resource;
18 
19 /*
20  * Optimised SGL iterator for GEM objects
21  */
22 static __always_inline struct sgt_iter {
23 	struct scatterlist *sgp;
24 	union {
25 		unsigned long pfn;
26 		dma_addr_t dma;
27 	};
28 	unsigned int curr;
29 	unsigned int max;
30 } __sgt_iter(struct scatterlist *sgl, bool dma) {
31 	struct sgt_iter s = { .sgp = sgl };
32 
33 	if (dma && s.sgp && sg_dma_len(s.sgp) == 0) {
34 		s.sgp = NULL;
35 	} else if (s.sgp) {
36 		s.max = s.curr = s.sgp->offset;
37 		if (dma) {
38 			s.dma = sg_dma_address(s.sgp);
39 			s.max += sg_dma_len(s.sgp);
40 		} else {
41 			s.pfn = page_to_pfn(sg_page(s.sgp));
42 			s.max += s.sgp->length;
43 		}
44 	}
45 
46 	return s;
47 }
48 
49 static inline int __sg_page_count(const struct scatterlist *sg)
50 {
51 	return sg->length >> PAGE_SHIFT;
52 }
53 
54 static inline int __sg_dma_page_count(const struct scatterlist *sg)
55 {
56 	return sg_dma_len(sg) >> PAGE_SHIFT;
57 }
58 
59 static inline struct scatterlist *____sg_next(struct scatterlist *sg)
60 {
61 	++sg;
62 	if (unlikely(sg_is_chain(sg)))
63 		sg = sg_chain_ptr(sg);
64 	return sg;
65 }
66 
67 /**
68  * __sg_next - return the next scatterlist entry in a list
69  * @sg:		The current sg entry
70  *
71  * Description:
72  *   If the entry is the last, return NULL; otherwise, step to the next
73  *   element in the array (@sg@+1). If that's a chain pointer, follow it;
74  *   otherwise just return the pointer to the current element.
75  **/
76 static inline struct scatterlist *__sg_next(struct scatterlist *sg)
77 {
78 	return sg_is_last(sg) ? NULL : ____sg_next(sg);
79 }
80 
81 /**
82  * __for_each_sgt_daddr - iterate over the device addresses of the given sg_table
83  * @__dp:	Device address (output)
84  * @__iter:	'struct sgt_iter' (iterator state, internal)
85  * @__sgt:	sg_table to iterate over (input)
86  * @__step:	step size
87  */
88 #define __for_each_sgt_daddr(__dp, __iter, __sgt, __step)		\
89 	for ((__iter) = __sgt_iter((__sgt)->sgl, true);			\
90 	     ((__dp) = (__iter).dma + (__iter).curr), (__iter).sgp;	\
91 	     (((__iter).curr += (__step)) >= (__iter).max) ?		\
92 	     (__iter) = __sgt_iter(__sg_next((__iter).sgp), true), 0 : 0)
93 
94 /**
95  * for_each_sgt_page - iterate over the pages of the given sg_table
96  * @__pp:	page pointer (output)
97  * @__iter:	'struct sgt_iter' (iterator state, internal)
98  * @__sgt:	sg_table to iterate over (input)
99  */
100 #define for_each_sgt_page(__pp, __iter, __sgt)				\
101 	for ((__iter) = __sgt_iter((__sgt)->sgl, false);		\
102 	     ((__pp) = (__iter).pfn == 0 ? NULL :			\
103 	      pfn_to_page((__iter).pfn + ((__iter).curr >> PAGE_SHIFT))); \
104 	     (((__iter).curr += PAGE_SIZE) >= (__iter).max) ?		\
105 	     (__iter) = __sgt_iter(__sg_next((__iter).sgp), false), 0 : 0)
106 
107 /**
108  * i915_sg_dma_sizes - Record the dma segment sizes of a scatterlist
109  * @sg: The scatterlist
110  *
111  * Return: An unsigned int with segment sizes logically or'ed together.
112  * A caller can use this information to determine what hardware page table
113  * entry sizes can be used to map the memory represented by the scatterlist.
114  */
115 static inline unsigned int i915_sg_dma_sizes(struct scatterlist *sg)
116 {
117 	unsigned int page_sizes;
118 
119 	page_sizes = 0;
120 	while (sg && sg_dma_len(sg)) {
121 		GEM_BUG_ON(sg->offset);
122 		GEM_BUG_ON(!IS_ALIGNED(sg_dma_len(sg), PAGE_SIZE));
123 		page_sizes |= sg_dma_len(sg);
124 		sg = __sg_next(sg);
125 	}
126 
127 	return page_sizes;
128 }
129 
130 static inline unsigned int i915_sg_segment_size(void)
131 {
132 	unsigned int size = swiotlb_max_segment();
133 
134 	if (size == 0)
135 		size = UINT_MAX;
136 
137 	size = rounddown(size, PAGE_SIZE);
138 	/* swiotlb_max_segment_size can return 1 byte when it means one page. */
139 	if (size < PAGE_SIZE)
140 		size = PAGE_SIZE;
141 
142 	return size;
143 }
144 
145 bool i915_sg_trim(struct sg_table *orig_st);
146 
147 struct sg_table *i915_sg_from_mm_node(const struct drm_mm_node *node,
148 				      u64 region_start);
149 
150 struct sg_table *i915_sg_from_buddy_resource(struct ttm_resource *res,
151 					     u64 region_start);
152 
153 #endif
154