LXR linux/drivers/gpu/drm/i915/i915

   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
  16struct drm_mm_node;
  17struct ttm_resource;
  18
  19/*
  20 * Optimised SGL iterator for GEM objects
  21 */
  22static __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
  49static inline int __sg_page_count(const struct scatterlist *sg)
  50{
  51        return sg->length >> PAGE_SHIFT;
  52}
  53
  54static inline int __sg_dma_page_count(const struct scatterlist *sg)
  55{
  56        return sg_dma_len(sg) >> PAGE_SHIFT;
  57}
  58
  59static 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 **/
  76static 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 */
 115static 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
 130static 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
 145bool i915_sg_trim(struct sg_table *orig_st);
 146
 147struct sg_table *i915_sg_from_mm_node(const struct drm_mm_node *node,
 148                                      u64 region_start);
 149
 150struct sg_table *i915_sg_from_buddy_resource(struct ttm_resource *res,
 151                                             u64 region_start);
 152
 153#endif
 154