/*
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* SPDX-License-Identifier: MIT
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*
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* Copyright © 2016 Intel Corporation
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*/
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#ifndef I915_SCATTERLIST_H
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#define I915_SCATTERLIST_H
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#include <linux/pfn.h>
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#include <linux/scatterlist.h>
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#include <linux/swiotlb.h>
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#include "i915_gem.h"
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/*
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* Optimised SGL iterator for GEM objects
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*/
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static __always_inline struct sgt_iter {
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struct scatterlist *sgp;
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union {
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unsigned long pfn;
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dma_addr_t dma;
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};
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unsigned int curr;
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unsigned int max;
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} __sgt_iter(struct scatterlist *sgl, bool dma) {
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struct sgt_iter s = { .sgp = sgl };
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if (s.sgp) {
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s.max = s.curr = s.sgp->offset;
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s.max += s.sgp->length;
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if (dma)
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s.dma = sg_dma_address(s.sgp);
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else
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s.pfn = page_to_pfn(sg_page(s.sgp));
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}
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return s;
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}
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static inline int __sg_page_count(const struct scatterlist *sg)
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{
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return sg->length >> PAGE_SHIFT;
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}
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static inline struct scatterlist *____sg_next(struct scatterlist *sg)
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{
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++sg;
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if (unlikely(sg_is_chain(sg)))
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sg = sg_chain_ptr(sg);
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return sg;
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}
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/**
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* __sg_next - return the next scatterlist entry in a list
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* @sg: The current sg entry
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*
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* Description:
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* If the entry is the last, return NULL; otherwise, step to the next
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* element in the array (@sg@+1). If that's a chain pointer, follow it;
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* otherwise just return the pointer to the current element.
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**/
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static inline struct scatterlist *__sg_next(struct scatterlist *sg)
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{
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return sg_is_last(sg) ? NULL : ____sg_next(sg);
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}
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/**
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* __for_each_sgt_daddr - iterate over the device addresses of the given sg_table
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* @__dp: Device address (output)
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* @__iter: 'struct sgt_iter' (iterator state, internal)
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* @__sgt: sg_table to iterate over (input)
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* @__step: step size
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*/
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#define __for_each_sgt_daddr(__dp, __iter, __sgt, __step) \
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for ((__iter) = __sgt_iter((__sgt)->sgl, true); \
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((__dp) = (__iter).dma + (__iter).curr), (__iter).sgp; \
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(((__iter).curr += (__step)) >= (__iter).max) ? \
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(__iter) = __sgt_iter(__sg_next((__iter).sgp), true), 0 : 0)
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/**
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* for_each_sgt_page - iterate over the pages of the given sg_table
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* @__pp: page pointer (output)
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* @__iter: 'struct sgt_iter' (iterator state, internal)
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* @__sgt: sg_table to iterate over (input)
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*/
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#define for_each_sgt_page(__pp, __iter, __sgt) \
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for ((__iter) = __sgt_iter((__sgt)->sgl, false); \
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((__pp) = (__iter).pfn == 0 ? NULL : \
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pfn_to_page((__iter).pfn + ((__iter).curr >> PAGE_SHIFT))); \
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(((__iter).curr += PAGE_SIZE) >= (__iter).max) ? \
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(__iter) = __sgt_iter(__sg_next((__iter).sgp), false), 0 : 0)
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static inline unsigned int i915_sg_page_sizes(struct scatterlist *sg)
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{
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unsigned int page_sizes;
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page_sizes = 0;
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while (sg) {
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GEM_BUG_ON(sg->offset);
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GEM_BUG_ON(!IS_ALIGNED(sg->length, PAGE_SIZE));
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page_sizes |= sg->length;
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sg = __sg_next(sg);
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}
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return page_sizes;
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}
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static inline unsigned int i915_sg_segment_size(void)
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{
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unsigned int size = swiotlb_max_segment();
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if (size == 0)
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return SCATTERLIST_MAX_SEGMENT;
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size = rounddown(size, PAGE_SIZE);
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/* swiotlb_max_segment_size can return 1 byte when it means one page. */
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if (size < PAGE_SIZE)
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size = PAGE_SIZE;
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return size;
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}
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bool i915_sg_trim(struct sg_table *orig_st);
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#endif
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