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
20struct 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
31static inline unsigned
32i915_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
42static inline unsigned
43i915_sg_segment_size(void)
44{
45	return PAGE_SIZE;
46}
47
48#else
49
50/*
51 * Optimised SGL iterator for GEM objects
52 */
53static __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;
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
76static inline int __sg_page_count(const struct scatterlist *sg)
77{
78	return sg->length >> PAGE_SHIFT;
79}
80
81static 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 **/
98static 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
129static 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
144static 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
161bool i915_sg_trim(struct sg_table *orig_st);
162
163#endif
164