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 128