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 (dma && s.sgp && sg_dma_len(s.sgp) == 0) {
  31                 s.sgp = NULL;
  32         } else if (s.sgp) {
  33                 s.max = s.curr = s.sgp->offset;
  34                 if (dma) {
  35                         s.dma = sg_dma_address(s.sgp);
  36                         s.max += sg_dma_len(s.sgp);
  37                 } else {
  38                         s.pfn = page_to_pfn(sg_page(s.sgp));
  39                         s.max += s.sgp->length;
  40                 }
  41         }
  42
  43         return s;
  44 }
  45
  46 static inline int __sg_page_count(const struct scatterlist *sg)
  47 {
  48         return sg->length >> PAGE_SHIFT;
  49 }
  50
  51 static inline int __sg_dma_page_count(const struct scatterlist *sg)
  52 {
  53         return sg_dma_len(sg) >> PAGE_SHIFT;
  54 }
  55
  56 static inline struct scatterlist *____sg_next(struct scatterlist *sg)
  57 {
  58         ++sg;
  59         if (unlikely(sg_is_chain(sg)))
  60                 sg = sg_chain_ptr(sg);
  61         return sg;
  62 }
  63
  64 /**
  65  * __sg_next - return the next scatterlist entry in a list
  66  * @sg:         The current sg entry
  67  *
  68  * Description:
  69  *   If the entry is the last, return NULL; otherwise, step to the next
  70  *   element in the array (@sg@+1). If that's a chain pointer, follow it;
  71  *   otherwise just return the pointer to the current element.
  72  **/
  73 static inline struct scatterlist *__sg_next(struct scatterlist *sg)
  74 {
  75         return sg_is_last(sg) ? NULL : ____sg_next(sg);
  76 }
  77
  78 /**
  79  * __for_each_sgt_daddr - iterate over the device addresses of the given sg_table
  80  * @__dp:       Device address (output)
  81  * @__iter:     'struct sgt_iter' (iterator state, internal)
  82  * @__sgt:      sg_table to iterate over (input)
  83  * @__step:     step size
  84  */
  85 #define __for_each_sgt_daddr(__dp, __iter, __sgt, __step)               \
  86         for ((__iter) = __sgt_iter((__sgt)->sgl, true);                 \
  87              ((__dp) = (__iter).dma + (__iter).curr), (__iter).sgp;     \
  88              (((__iter).curr += (__step)) >= (__iter).max) ?            \
  89              (__iter) = __sgt_iter(__sg_next((__iter).sgp), true), 0 : 0)
  90
  91 /**
  92  * for_each_sgt_page - iterate over the pages of the given sg_table
  93  * @__pp:       page pointer (output)
  94  * @__iter:     'struct sgt_iter' (iterator state, internal)
  95  * @__sgt:      sg_table to iterate over (input)
  96  */
  97 #define for_each_sgt_page(__pp, __iter, __sgt)                          \
  98         for ((__iter) = __sgt_iter((__sgt)->sgl, false);                \
  99              ((__pp) = (__iter).pfn == 0 ? NULL :                       \
 100               pfn_to_page((__iter).pfn + ((__iter).curr >> PAGE_SHIFT))); \
 101              (((__iter).curr += PAGE_SIZE) >= (__iter).max) ?           \
 102              (__iter) = __sgt_iter(__sg_next((__iter).sgp), false), 0 : 0)
 103
 104 static inline unsigned int i915_sg_page_sizes(struct scatterlist *sg)
 105 {
 106         unsigned int page_sizes;
 107
 108         page_sizes = 0;
 109         while (sg) {
 110                 GEM_BUG_ON(sg->offset);
 111                 GEM_BUG_ON(!IS_ALIGNED(sg->length, PAGE_SIZE));
 112                 page_sizes |= sg->length;
 113                 sg = __sg_next(sg);
 114         }
 115
 116         return page_sizes;
 117 }
 118
 119 static inline unsigned int i915_sg_segment_size(void)
 120 {
 121         unsigned int size = swiotlb_max_segment();
 122
 123         if (size == 0)
 124                 size = UINT_MAX;
 125
 126         size = rounddown(size, PAGE_SIZE);
 127         /* swiotlb_max_segment_size can return 1 byte when it means one page. */
 128         if (size < PAGE_SIZE)
 129                 size = PAGE_SIZE;
 130
 131         return size;
 132 }
 133
 134 bool i915_sg_trim(struct sg_table *orig_st);
 135
 136 #endif