virtio/linux/scatterlist.h

15 #define sg_is_chain(sg)		((sg)->page_link & 0x01)
16 #define sg_is_last(sg)		((sg)->page_link & 0x02)
17 #define sg_chain_ptr(sg)	\
18 	((struct scatterlist *) ((sg)->page_link & ~0x03))
22  * @sg:		    SG entry
26  *   Assign page to sg entry. Also see sg_set_page(), the most commonly used
30 static inline void sg_assign_page(struct scatterlist *sg, struct page *page)
32 	unsigned long page_link = sg->page_link & 0x3;
40 	BUG_ON(sg_is_chain(sg));
42 	sg->page_link = page_link | (unsigned long) page;
46  * sg_set_page - Set sg entry to point at given page
47  * @sg:		 SG entry
53  *   Use this function to set an sg entry pointing at a page, never assign
54  *   the page directly. We encode sg table information in the lower bits
56  *   to an sg entry.
59 static inline void sg_set_page(struct scatterlist *sg, struct page *page,
62 	sg_assign_page(sg, page);
63 	sg->offset = offset;
64 	sg->length = len;
67 static inline struct page *sg_page(struct scatterlist *sg)
70 	BUG_ON(sg_is_chain(sg));
72 	return (struct page *)((sg)->page_link & ~0x3);
76  * Loop over each sg element, following the pointer to a new list if necessary
78 #define for_each_sg(sglist, sg, nr, __i)	\
79 	for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
109  * @sg:		 SG entryScatterlist
112  *   Marks the passed in sg entry as the termination point for the sg
116 static inline void sg_mark_end(struct scatterlist *sg)
121 	sg->page_link |= 0x02;
122 	sg->page_link &= ~0x01;
127  * @sg:		 SG entryScatterlist
133 static inline void sg_unmark_end(struct scatterlist *sg)
135 	sg->page_link &= ~0x02;
138 static inline struct scatterlist *sg_next(struct scatterlist *sg)
140 	if (sg_is_last(sg))
143 	sg++;
144 	if (unlikely(sg_is_chain(sg)))
145 		sg = sg_chain_ptr(sg);
147 	return sg;
156 static inline dma_addr_t sg_phys(struct scatterlist *sg)
158 	return page_to_phys(sg_page(sg)) + sg->offset;
161 static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
164 	sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
167 static inline void sg_init_one(struct scatterlist *sg,
170 	sg_init_table(sg, 1);
171 	sg_set_buf(sg, buf, buflen);