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