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1/* SPDX-License-Identifier: GPL-2.0 */2#ifndef SCATTERLIST_H3#define SCATTERLIST_H4#include <linux/kernel.h>5#include <linux/bug.h>6 7struct scatterlist {8 unsigned long page_link;9 unsigned int offset;10 unsigned int length;11 dma_addr_t dma_address;12};13 14/* Scatterlist helpers, stolen from 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))19 20/**21 * sg_assign_page - Assign a given page to an SG entry22 * @sg: SG entry23 * @page: The page24 *25 * Description:26 * Assign page to sg entry. Also see sg_set_page(), the most commonly used27 * variant.28 *29 **/30static inline void sg_assign_page(struct scatterlist *sg, struct page *page)31{32 unsigned long page_link = sg->page_link & 0x3;33 34 /*35 * In order for the low bit stealing approach to work, pages36 * must be aligned at a 32-bit boundary as a minimum.37 */38 BUG_ON((unsigned long) page & 0x03);39#ifdef CONFIG_DEBUG_SG40 BUG_ON(sg_is_chain(sg));41#endif42 sg->page_link = page_link | (unsigned long) page;43}44 45/**46 * sg_set_page - Set sg entry to point at given page47 * @sg: SG entry48 * @page: The page49 * @len: Length of data50 * @offset: Offset into page51 *52 * Description:53 * Use this function to set an sg entry pointing at a page, never assign54 * the page directly. We encode sg table information in the lower bits55 * of the page pointer. See sg_page() for looking up the page belonging56 * to an sg entry.57 *58 **/59static inline void sg_set_page(struct scatterlist *sg, struct page *page,60 unsigned int len, unsigned int offset)61{62 sg_assign_page(sg, page);63 sg->offset = offset;64 sg->length = len;65}66 67static inline struct page *sg_page(struct scatterlist *sg)68{69#ifdef CONFIG_DEBUG_SG70 BUG_ON(sg_is_chain(sg));71#endif72 return (struct page *)((sg)->page_link & ~0x3);73}74 75/*76 * Loop over each sg element, following the pointer to a new list if necessary77 */78#define for_each_sg(sglist, sg, nr, __i) \79 for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))80 81/**82 * sg_chain - Chain two sglists together83 * @prv: First scatterlist84 * @prv_nents: Number of entries in prv85 * @sgl: Second scatterlist86 *87 * Description:88 * Links @prv@ and @sgl@ together, to form a longer scatterlist.89 *90 **/91static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,92 struct scatterlist *sgl)93{94 /*95 * offset and length are unused for chain entry. Clear them.96 */97 prv[prv_nents - 1].offset = 0;98 prv[prv_nents - 1].length = 0;99 100 /*101 * Set lowest bit to indicate a link pointer, and make sure to clear102 * the termination bit if it happens to be set.103 */104 prv[prv_nents - 1].page_link = ((unsigned long) sgl | 0x01) & ~0x02;105}106 107/**108 * sg_mark_end - Mark the end of the scatterlist109 * @sg: SG entryScatterlist110 *111 * Description:112 * Marks the passed in sg entry as the termination point for the sg113 * table. A call to sg_next() on this entry will return NULL.114 *115 **/116static inline void sg_mark_end(struct scatterlist *sg)117{118 /*119 * Set termination bit, clear potential chain bit120 */121 sg->page_link |= 0x02;122 sg->page_link &= ~0x01;123}124 125/**126 * sg_unmark_end - Undo setting the end of the scatterlist127 * @sg: SG entryScatterlist128 *129 * Description:130 * Removes the termination marker from the given entry of the scatterlist.131 *132 **/133static inline void sg_unmark_end(struct scatterlist *sg)134{135 sg->page_link &= ~0x02;136}137 138static inline struct scatterlist *sg_next(struct scatterlist *sg)139{140 if (sg_is_last(sg))141 return NULL;142 143 sg++;144 if (unlikely(sg_is_chain(sg)))145 sg = sg_chain_ptr(sg);146 147 return sg;148}149 150static inline void sg_init_table(struct scatterlist *sgl, unsigned int nents)151{152 memset(sgl, 0, sizeof(*sgl) * nents);153 sg_mark_end(&sgl[nents - 1]);154}155 156static inline dma_addr_t sg_phys(struct scatterlist *sg)157{158 return page_to_phys(sg_page(sg)) + sg->offset;159}160 161static inline void sg_set_buf(struct scatterlist *sg, const void *buf,162 unsigned int buflen)163{164 sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));165}166 167static inline void sg_init_one(struct scatterlist *sg,168 const void *buf, unsigned int buflen)169{170 sg_init_table(sg, 1);171 sg_set_buf(sg, buf, buflen);172}173#endif /* SCATTERLIST_H */174