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
  16/*
  17 * Optimised SGL iterator for GEM objects
  18 */
  19static __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;
  27} __sgt_iter(struct scatterlist *sgl, bool dma) {
  28        struct sgt_iter s = { .sgp = sgl };
  29
  30        if (s.sgp) {
  31                s.max = s.curr = s.sgp->offset;
  32                s.max += s.sgp->length;
  33                if (dma)
  34                        s.dma = sg_dma_address(s.sgp);
  35                else
  36                        s.pfn = page_to_pfn(sg_page(s.sgp));
  37        }
  38
  39        return s;
  40}
  41
  42static inline int __sg_page_count(const struct scatterlist *sg)
  43{
  44        return sg->length >> PAGE_SHIFT;
  45}
  46
  47static inline struct scatterlist *____sg_next(struct scatterlist *sg)
  48{
  49        ++sg;
  50        if (unlikely(sg_is_chain(sg)))
  51                sg = sg_chain_ptr(sg);
  52        return sg;
  53}
  54
  55/**
  56 * __sg_next - return the next scatterlist entry in a list
  57 * @sg:         The current sg entry
  58 *
  59 * Description:
  60 *   If the entry is the last, return NULL; otherwise, step to the next
  61 *   element in the array (@sg@+1). If that's a chain pointer, follow it;
  62 *   otherwise just return the pointer to the current element.
  63 **/
  64static inline struct scatterlist *__sg_next(struct scatterlist *sg)
  65{
  66        return sg_is_last(sg) ? NULL : ____sg_next(sg);
  67}
  68
  69/**
  70 * __for_each_sgt_dma - iterate over the DMA addresses of the given sg_table
  71 * @__dmap:     DMA address (output)
  72 * @__iter:     'struct sgt_iter' (iterator state, internal)
  73 * @__sgt:      sg_table to iterate over (input)
  74 * @__step:     step size
  75 */
  76#define __for_each_sgt_dma(__dmap, __iter, __sgt, __step)               \
  77        for ((__iter) = __sgt_iter((__sgt)->sgl, true);                 \
  78             ((__dmap) = (__iter).dma + (__iter).curr);                 \
  79             (((__iter).curr += (__step)) >= (__iter).max) ?            \
  80             (__iter) = __sgt_iter(__sg_next((__iter).sgp), true), 0 : 0)
  81
  82/**
  83 * for_each_sgt_page - iterate over the pages of the given sg_table
  84 * @__pp:       page pointer (output)
  85 * @__iter:     'struct sgt_iter' (iterator state, internal)
  86 * @__sgt:      sg_table to iterate over (input)
  87 */
  88#define for_each_sgt_page(__pp, __iter, __sgt)                          \
  89        for ((__iter) = __sgt_iter((__sgt)->sgl, false);                \
  90             ((__pp) = (__iter).pfn == 0 ? NULL :                       \
  91              pfn_to_page((__iter).pfn + ((__iter).curr >> PAGE_SHIFT))); \
  92             (((__iter).curr += PAGE_SIZE) >= (__iter).max) ?           \
  93             (__iter) = __sgt_iter(__sg_next((__iter).sgp), false), 0 : 0)
  94
  95static inline unsigned int i915_sg_page_sizes(struct scatterlist *sg)
  96{
  97        unsigned int page_sizes;
  98
  99        page_sizes = 0;
 100        while (sg) {
 101                GEM_BUG_ON(sg->offset);
 102                GEM_BUG_ON(!IS_ALIGNED(sg->length, PAGE_SIZE));
 103                page_sizes |= sg->length;
 104                sg = __sg_next(sg);
 105        }
 106
 107        return page_sizes;
 108}
 109
 110static inline unsigned int i915_sg_segment_size(void)
 111{
 112        unsigned int size = swiotlb_max_segment();
 113
 114        if (size == 0)
 115                return SCATTERLIST_MAX_SEGMENT;
 116
 117        size = rounddown(size, PAGE_SIZE);
 118        /* swiotlb_max_segment_size can return 1 byte when it means one page. */
 119        if (size < PAGE_SIZE)
 120                size = PAGE_SIZE;
 121
 122        return size;
 123}
 124
 125bool i915_sg_trim(struct sg_table *orig_st);
 126
 127#endif
 128