2 * SPDX-License-Identifier: MIT
4 * Copyright © 2016 Intel Corporation
7 #ifndef I915_SCATTERLIST_H
8 #define I915_SCATTERLIST_H
10 #include <linux/pfn.h>
11 #include <linux/scatterlist.h>
12 #include <linux/swiotlb.h>
20 * Optimised SGL iterator for GEM objects
22 static __always_inline struct sgt_iter {
23 struct scatterlist *sgp;
30 } __sgt_iter(struct scatterlist *sgl, bool dma) {
31 struct sgt_iter s = { .sgp = sgl };
33 if (dma && s.sgp && sg_dma_len(s.sgp) == 0) {
36 s.max = s.curr = s.sgp->offset;
38 s.dma = sg_dma_address(s.sgp);
39 s.max += sg_dma_len(s.sgp);
41 s.pfn = page_to_pfn(sg_page(s.sgp));
42 s.max += s.sgp->length;
49 static inline int __sg_page_count(const struct scatterlist *sg)
51 return sg->length >> PAGE_SHIFT;
54 static inline int __sg_dma_page_count(const struct scatterlist *sg)
56 return sg_dma_len(sg) >> PAGE_SHIFT;
59 static inline struct scatterlist *____sg_next(struct scatterlist *sg)
62 if (unlikely(sg_is_chain(sg)))
63 sg = sg_chain_ptr(sg);
68 * __sg_next - return the next scatterlist entry in a list
69 * @sg: The current sg entry
72 * If the entry is the last, return NULL; otherwise, step to the next
73 * element in the array (@sg@+1). If that's a chain pointer, follow it;
74 * otherwise just return the pointer to the current element.
76 static inline struct scatterlist *__sg_next(struct scatterlist *sg)
78 return sg_is_last(sg) ? NULL : ____sg_next(sg);
82 * __for_each_sgt_daddr - iterate over the device addresses of the given sg_table
83 * @__dp: Device address (output)
84 * @__iter: 'struct sgt_iter' (iterator state, internal)
85 * @__sgt: sg_table to iterate over (input)
88 #define __for_each_sgt_daddr(__dp, __iter, __sgt, __step) \
89 for ((__iter) = __sgt_iter((__sgt)->sgl, true); \
90 ((__dp) = (__iter).dma + (__iter).curr), (__iter).sgp; \
91 (((__iter).curr += (__step)) >= (__iter).max) ? \
92 (__iter) = __sgt_iter(__sg_next((__iter).sgp), true), 0 : 0)
95 * for_each_sgt_page - iterate over the pages of the given sg_table
96 * @__pp: page pointer (output)
97 * @__iter: 'struct sgt_iter' (iterator state, internal)
98 * @__sgt: sg_table to iterate over (input)
100 #define for_each_sgt_page(__pp, __iter, __sgt) \
101 for ((__iter) = __sgt_iter((__sgt)->sgl, false); \
102 ((__pp) = (__iter).pfn == 0 ? NULL : \
103 pfn_to_page((__iter).pfn + ((__iter).curr >> PAGE_SHIFT))); \
104 (((__iter).curr += PAGE_SIZE) >= (__iter).max) ? \
105 (__iter) = __sgt_iter(__sg_next((__iter).sgp), false), 0 : 0)
108 * i915_sg_dma_sizes - Record the dma segment sizes of a scatterlist
109 * @sg: The scatterlist
111 * Return: An unsigned int with segment sizes logically or'ed together.
112 * A caller can use this information to determine what hardware page table
113 * entry sizes can be used to map the memory represented by the scatterlist.
115 static inline unsigned int i915_sg_dma_sizes(struct scatterlist *sg)
117 unsigned int page_sizes;
120 while (sg && sg_dma_len(sg)) {
121 GEM_BUG_ON(sg->offset);
122 GEM_BUG_ON(!IS_ALIGNED(sg_dma_len(sg), PAGE_SIZE));
123 page_sizes |= sg_dma_len(sg);
130 static inline unsigned int i915_sg_segment_size(void)
132 unsigned int size = swiotlb_max_segment();
137 size = rounddown(size, PAGE_SIZE);
138 /* swiotlb_max_segment_size can return 1 byte when it means one page. */
139 if (size < PAGE_SIZE)
145 bool i915_sg_trim(struct sg_table *orig_st);
148 * struct i915_refct_sgt_ops - Operations structure for struct i915_refct_sgt
150 struct i915_refct_sgt_ops {
152 * release() - Free the memory of the struct i915_refct_sgt
153 * @ref: struct kref that is embedded in the struct i915_refct_sgt
155 void (*release)(struct kref *ref);
159 * struct i915_refct_sgt - A refcounted scatter-gather table
160 * @kref: struct kref for refcounting
161 * @table: struct sg_table holding the scatter-gather table itself. Note that
162 * @table->sgl = NULL can be used to determine whether a scatter-gather table
164 * @size: The size in bytes of the underlying memory buffer
165 * @ops: The operations structure.
167 struct i915_refct_sgt {
169 struct sg_table table;
171 const struct i915_refct_sgt_ops *ops;
175 * i915_refct_sgt_put - Put a refcounted sg-table
176 * @rsgt the struct i915_refct_sgt to put.
178 static inline void i915_refct_sgt_put(struct i915_refct_sgt *rsgt)
181 kref_put(&rsgt->kref, rsgt->ops->release);
185 * i915_refct_sgt_get - Get a refcounted sg-table
186 * @rsgt the struct i915_refct_sgt to get.
188 static inline struct i915_refct_sgt *
189 i915_refct_sgt_get(struct i915_refct_sgt *rsgt)
191 kref_get(&rsgt->kref);
196 * __i915_refct_sgt_init - Initialize a refcounted sg-list with a custom
197 * operations structure
198 * @rsgt The struct i915_refct_sgt to initialize.
199 * @size: Size in bytes of the underlying memory buffer.
200 * @ops: A customized operations structure in case the refcounted sg-list
201 * is embedded into another structure.
203 static inline void __i915_refct_sgt_init(struct i915_refct_sgt *rsgt,
205 const struct i915_refct_sgt_ops *ops)
207 kref_init(&rsgt->kref);
208 rsgt->table.sgl = NULL;
213 void i915_refct_sgt_init(struct i915_refct_sgt *rsgt, size_t size);
215 struct i915_refct_sgt *i915_rsgt_from_mm_node(const struct drm_mm_node *node,
219 struct i915_refct_sgt *i915_rsgt_from_buddy_resource(struct ttm_resource *res,