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      1 /*	$NetBSD: i915_scatterlist.h,v 1.8 2021/12/19 11:37:05 riastradh Exp $	*/
      2 
      3 /*
      4  * SPDX-License-Identifier: MIT
      5  *
      6  * Copyright  2016 Intel Corporation
      7  */
      8 
      9 #ifndef I915_SCATTERLIST_H
     10 #define I915_SCATTERLIST_H
     11 
     12 #include <linux/pfn.h>
     13 #include <linux/scatterlist.h>
     14 #include <linux/swiotlb.h>
     15 
     16 #include "i915_gem.h"
     17 
     18 #ifdef __NetBSD__
     19 
     20 struct sgt_iter {
     21 	unsigned i;
     22 };
     23 
     24 #define	for_each_sgt_page(pp, iter, sgt)				      \
     25 	for ((iter).i = 0;						      \
     26 	     ((iter).i < (sgt)->sgl->sg_npgs				      \
     27 		 ? (((pp) = (sgt)->sgl->sg_pgs[(iter).i]), 1)		      \
     28 		 : 0);							      \
     29 	     (iter).i++)
     30 
     31 static inline unsigned
     32 i915_sg_page_sizes(struct scatterlist *sg)
     33 {
     34 	unsigned i, page_sizes = 0;
     35 
     36 	for (i = 0; i < sg->sg_dmamap->dm_nsegs; i++)
     37 		page_sizes |= sg->sg_dmamap->dm_segs[i].ds_len;
     38 
     39 	return page_sizes;
     40 }
     41 
     42 static inline unsigned
     43 i915_sg_segment_size(void)
     44 {
     45 	return PAGE_SIZE;
     46 }
     47 
     48 #else
     49 
     50 /*
     51  * Optimised SGL iterator for GEM objects
     52  */
     53 static __always_inline struct sgt_iter {
     54 	struct scatterlist *sgp;
     55 	union {
     56 		unsigned long pfn;
     57 		dma_addr_t dma;
     58 	};
     59 	unsigned int curr;
     60 	unsigned int max;
     61 } __sgt_iter(struct scatterlist *sgl, bool dma) {
     62 	struct sgt_iter s = { .sgp = sgl };
     63 
     64 	if (s.sgp) {
     65 		s.max = s.curr = s.sgp->offset;
     66 		s.max += s.sgp->length;
     67 		if (dma)
     68 			s.dma = sg_dma_address(s.sgp);
     69 		else
     70 			s.pfn = page_to_pfn(sg_page(s.sgp));
     71 	}
     72 
     73 	return s;
     74 }
     75 
     76 static inline int __sg_page_count(const struct scatterlist *sg)
     77 {
     78 	return sg->length >> PAGE_SHIFT;
     79 }
     80 
     81 static inline struct scatterlist *____sg_next(struct scatterlist *sg)
     82 {
     83 	++sg;
     84 	if (unlikely(sg_is_chain(sg)))
     85 		sg = sg_chain_ptr(sg);
     86 	return sg;
     87 }
     88 
     89 /**
     90  * __sg_next - return the next scatterlist entry in a list
     91  * @sg:		The current sg entry
     92  *
     93  * Description:
     94  *   If the entry is the last, return NULL; otherwise, step to the next
     95  *   element in the array (@sg@+1). If that's a chain pointer, follow it;
     96  *   otherwise just return the pointer to the current element.
     97  **/
     98 static inline struct scatterlist *__sg_next(struct scatterlist *sg)
     99 {
    100 	return sg_is_last(sg) ? NULL : ____sg_next(sg);
    101 }
    102 
    103 /**
    104  * __for_each_sgt_daddr - iterate over the device addresses of the given sg_table
    105  * @__dp:	Device address (output)
    106  * @__iter:	'struct sgt_iter' (iterator state, internal)
    107  * @__sgt:	sg_table to iterate over (input)
    108  * @__step:	step size
    109  */
    110 #define __for_each_sgt_daddr(__dp, __iter, __sgt, __step)		\
    111 	for ((__iter) = __sgt_iter((__sgt)->sgl, true);			\
    112 	     ((__dp) = (__iter).dma + (__iter).curr), (__iter).sgp;	\
    113 	     (((__iter).curr += (__step)) >= (__iter).max) ?		\
    114 	     (__iter) = __sgt_iter(__sg_next((__iter).sgp), true), 0 : 0)
    115 
    116 /**
    117  * for_each_sgt_page - iterate over the pages of the given sg_table
    118  * @__pp:	page pointer (output)
    119  * @__iter:	'struct sgt_iter' (iterator state, internal)
    120  * @__sgt:	sg_table to iterate over (input)
    121  */
    122 #define for_each_sgt_page(__pp, __iter, __sgt)				\
    123 	for ((__iter) = __sgt_iter((__sgt)->sgl, false);		\
    124 	     ((__pp) = (__iter).pfn == 0 ? NULL :			\
    125 	      pfn_to_page((__iter).pfn + ((__iter).curr >> PAGE_SHIFT))); \
    126 	     (((__iter).curr += PAGE_SIZE) >= (__iter).max) ?		\
    127 	     (__iter) = __sgt_iter(__sg_next((__iter).sgp), false), 0 : 0)
    128 
    129 static inline unsigned int i915_sg_page_sizes(struct scatterlist *sg)
    130 {
    131 	unsigned int page_sizes;
    132 
    133 	page_sizes = 0;
    134 	while (sg) {
    135 		GEM_BUG_ON(sg->offset);
    136 		GEM_BUG_ON(!IS_ALIGNED(sg->length, PAGE_SIZE));
    137 		page_sizes |= sg->length;
    138 		sg = __sg_next(sg);
    139 	}
    140 
    141 	return page_sizes;
    142 }
    143 
    144 static inline unsigned int i915_sg_segment_size(void)
    145 {
    146 	unsigned int size = swiotlb_max_segment();
    147 
    148 	if (size == 0)
    149 		return SCATTERLIST_MAX_SEGMENT;
    150 
    151 	size = rounddown(size, PAGE_SIZE);
    152 	/* swiotlb_max_segment_size can return 1 byte when it means one page. */
    153 	if (size < PAGE_SIZE)
    154 		size = PAGE_SIZE;
    155 
    156 	return size;
    157 }
    158 
    159 #endif
    160 
    161 bool i915_sg_trim(struct sg_table *orig_st);
    162 
    163 #endif
    164