drivers/gpu/drm/i915/i915_scatterlist.h

   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;
  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
  42 static inline int __sg_page_count(const struct scatterlist *sg)
  43 {
  44         return sg->length >> PAGE_SHIFT;
  45 }
  46
  47 static 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  **/
  64 static 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_daddr - iterate over the device addresses of the given sg_table
  71  * @__dp:       Device 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_daddr(__dp, __iter, __sgt, __step)               \
  77         for ((__iter) = __sgt_iter((__sgt)->sgl, true);                 \
  78              ((__dp) = (__iter).dma + (__iter).curr), (__iter).sgp;     \
  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
  95 static 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
 110 static 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
 125 bool i915_sg_trim(struct sg_table *orig_st);
 126
 127 #endif