diff options
Diffstat (limited to 'include/linux/scatterlist.h')
-rw-r--r-- | include/linux/scatterlist.h | 695 |
1 files changed, 695 insertions, 0 deletions
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h new file mode 100644 index 000000000..77df3d7b1 --- /dev/null +++ b/include/linux/scatterlist.h @@ -0,0 +1,695 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_SCATTERLIST_H +#define _LINUX_SCATTERLIST_H + +#include <linux/string.h> +#include <linux/types.h> +#include <linux/bug.h> +#include <linux/mm.h> +#include <asm/io.h> + +struct scatterlist { + unsigned long page_link; + unsigned int offset; + unsigned int length; + dma_addr_t dma_address; +#ifdef CONFIG_NEED_SG_DMA_LENGTH + unsigned int dma_length; +#endif +#ifdef CONFIG_NEED_SG_DMA_FLAGS + unsigned int dma_flags; +#endif +}; + +/* + * These macros should be used after a dma_map_sg call has been done + * to get bus addresses of each of the SG entries and their lengths. + * You should only work with the number of sg entries dma_map_sg + * returns, or alternatively stop on the first sg_dma_len(sg) which + * is 0. + */ +#define sg_dma_address(sg) ((sg)->dma_address) + +#ifdef CONFIG_NEED_SG_DMA_LENGTH +#define sg_dma_len(sg) ((sg)->dma_length) +#else +#define sg_dma_len(sg) ((sg)->length) +#endif + +struct sg_table { + struct scatterlist *sgl; /* the list */ + unsigned int nents; /* number of mapped entries */ + unsigned int orig_nents; /* original size of list */ +}; + +struct sg_append_table { + struct sg_table sgt; /* The scatter list table */ + struct scatterlist *prv; /* last populated sge in the table */ + unsigned int total_nents; /* Total entries in the table */ +}; + +/* + * Notes on SG table design. + * + * We use the unsigned long page_link field in the scatterlist struct to place + * the page pointer AND encode information about the sg table as well. The two + * lower bits are reserved for this information. + * + * If bit 0 is set, then the page_link contains a pointer to the next sg + * table list. Otherwise the next entry is at sg + 1. + * + * If bit 1 is set, then this sg entry is the last element in a list. + * + * See sg_next(). + * + */ + +#define SG_CHAIN 0x01UL +#define SG_END 0x02UL + +/* + * We overload the LSB of the page pointer to indicate whether it's + * a valid sg entry, or whether it points to the start of a new scatterlist. + * Those low bits are there for everyone! (thanks mason :-) + */ +#define SG_PAGE_LINK_MASK (SG_CHAIN | SG_END) + +static inline unsigned int __sg_flags(struct scatterlist *sg) +{ + return sg->page_link & SG_PAGE_LINK_MASK; +} + +static inline struct scatterlist *sg_chain_ptr(struct scatterlist *sg) +{ + return (struct scatterlist *)(sg->page_link & ~SG_PAGE_LINK_MASK); +} + +static inline bool sg_is_chain(struct scatterlist *sg) +{ + return __sg_flags(sg) & SG_CHAIN; +} + +static inline bool sg_is_last(struct scatterlist *sg) +{ + return __sg_flags(sg) & SG_END; +} + +/** + * sg_assign_page - Assign a given page to an SG entry + * @sg: SG entry + * @page: The page + * + * Description: + * Assign page to sg entry. Also see sg_set_page(), the most commonly used + * variant. + * + **/ +static inline void sg_assign_page(struct scatterlist *sg, struct page *page) +{ + unsigned long page_link = sg->page_link & (SG_CHAIN | SG_END); + + /* + * In order for the low bit stealing approach to work, pages + * must be aligned at a 32-bit boundary as a minimum. + */ + BUG_ON((unsigned long)page & SG_PAGE_LINK_MASK); +#ifdef CONFIG_DEBUG_SG + BUG_ON(sg_is_chain(sg)); +#endif + sg->page_link = page_link | (unsigned long) page; +} + +/** + * sg_set_page - Set sg entry to point at given page + * @sg: SG entry + * @page: The page + * @len: Length of data + * @offset: Offset into page + * + * Description: + * Use this function to set an sg entry pointing at a page, never assign + * the page directly. We encode sg table information in the lower bits + * of the page pointer. See sg_page() for looking up the page belonging + * to an sg entry. + * + **/ +static inline void sg_set_page(struct scatterlist *sg, struct page *page, + unsigned int len, unsigned int offset) +{ + sg_assign_page(sg, page); + sg->offset = offset; + sg->length = len; +} + +/** + * sg_set_folio - Set sg entry to point at given folio + * @sg: SG entry + * @folio: The folio + * @len: Length of data + * @offset: Offset into folio + * + * Description: + * Use this function to set an sg entry pointing at a folio, never assign + * the folio directly. We encode sg table information in the lower bits + * of the folio pointer. See sg_page() for looking up the page belonging + * to an sg entry. + * + **/ +static inline void sg_set_folio(struct scatterlist *sg, struct folio *folio, + size_t len, size_t offset) +{ + WARN_ON_ONCE(len > UINT_MAX); + WARN_ON_ONCE(offset > UINT_MAX); + sg_assign_page(sg, &folio->page); + sg->offset = offset; + sg->length = len; +} + +static inline struct page *sg_page(struct scatterlist *sg) +{ +#ifdef CONFIG_DEBUG_SG + BUG_ON(sg_is_chain(sg)); +#endif + return (struct page *)((sg)->page_link & ~SG_PAGE_LINK_MASK); +} + +/** + * sg_set_buf - Set sg entry to point at given data + * @sg: SG entry + * @buf: Data + * @buflen: Data length + * + **/ +static inline void sg_set_buf(struct scatterlist *sg, const void *buf, + unsigned int buflen) +{ +#ifdef CONFIG_DEBUG_SG + BUG_ON(!virt_addr_valid(buf)); +#endif + sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf)); +} + +/* + * Loop over each sg element, following the pointer to a new list if necessary + */ +#define for_each_sg(sglist, sg, nr, __i) \ + for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg)) + +/* + * Loop over each sg element in the given sg_table object. + */ +#define for_each_sgtable_sg(sgt, sg, i) \ + for_each_sg((sgt)->sgl, sg, (sgt)->orig_nents, i) + +/* + * Loop over each sg element in the given *DMA mapped* sg_table object. + * Please use sg_dma_address(sg) and sg_dma_len(sg) to extract DMA addresses + * of the each element. + */ +#define for_each_sgtable_dma_sg(sgt, sg, i) \ + for_each_sg((sgt)->sgl, sg, (sgt)->nents, i) + +static inline void __sg_chain(struct scatterlist *chain_sg, + struct scatterlist *sgl) +{ + /* + * offset and length are unused for chain entry. Clear them. + */ + chain_sg->offset = 0; + chain_sg->length = 0; + + /* + * Set lowest bit to indicate a link pointer, and make sure to clear + * the termination bit if it happens to be set. + */ + chain_sg->page_link = ((unsigned long) sgl | SG_CHAIN) & ~SG_END; +} + +/** + * sg_chain - Chain two sglists together + * @prv: First scatterlist + * @prv_nents: Number of entries in prv + * @sgl: Second scatterlist + * + * Description: + * Links @prv@ and @sgl@ together, to form a longer scatterlist. + * + **/ +static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents, + struct scatterlist *sgl) +{ + __sg_chain(&prv[prv_nents - 1], sgl); +} + +/** + * sg_mark_end - Mark the end of the scatterlist + * @sg: SG entryScatterlist + * + * Description: + * Marks the passed in sg entry as the termination point for the sg + * table. A call to sg_next() on this entry will return NULL. + * + **/ +static inline void sg_mark_end(struct scatterlist *sg) +{ + /* + * Set termination bit, clear potential chain bit + */ + sg->page_link |= SG_END; + sg->page_link &= ~SG_CHAIN; +} + +/** + * sg_unmark_end - Undo setting the end of the scatterlist + * @sg: SG entryScatterlist + * + * Description: + * Removes the termination marker from the given entry of the scatterlist. + * + **/ +static inline void sg_unmark_end(struct scatterlist *sg) +{ + sg->page_link &= ~SG_END; +} + +/* + * One 64-bit architectures there is a 4-byte padding in struct scatterlist + * (assuming also CONFIG_NEED_SG_DMA_LENGTH is set). Use this padding for DMA + * flags bits to indicate when a specific dma address is a bus address or the + * buffer may have been bounced via SWIOTLB. + */ +#ifdef CONFIG_NEED_SG_DMA_FLAGS + +#define SG_DMA_BUS_ADDRESS (1 << 0) +#define SG_DMA_SWIOTLB (1 << 1) + +/** + * sg_dma_is_bus_address - Return whether a given segment was marked + * as a bus address + * @sg: SG entry + * + * Description: + * Returns true if sg_dma_mark_bus_address() has been called on + * this segment. + **/ +static inline bool sg_dma_is_bus_address(struct scatterlist *sg) +{ + return sg->dma_flags & SG_DMA_BUS_ADDRESS; +} + +/** + * sg_dma_mark_bus_address - Mark the scatterlist entry as a bus address + * @sg: SG entry + * + * Description: + * Marks the passed in sg entry to indicate that the dma_address is + * a bus address and doesn't need to be unmapped. This should only be + * used by dma_map_sg() implementations to mark bus addresses + * so they can be properly cleaned up in dma_unmap_sg(). + **/ +static inline void sg_dma_mark_bus_address(struct scatterlist *sg) +{ + sg->dma_flags |= SG_DMA_BUS_ADDRESS; +} + +/** + * sg_unmark_bus_address - Unmark the scatterlist entry as a bus address + * @sg: SG entry + * + * Description: + * Clears the bus address mark. + **/ +static inline void sg_dma_unmark_bus_address(struct scatterlist *sg) +{ + sg->dma_flags &= ~SG_DMA_BUS_ADDRESS; +} + +/** + * sg_dma_is_swiotlb - Return whether the scatterlist was marked for SWIOTLB + * bouncing + * @sg: SG entry + * + * Description: + * Returns true if the scatterlist was marked for SWIOTLB bouncing. Not all + * elements may have been bounced, so the caller would have to check + * individual SG entries with is_swiotlb_buffer(). + */ +static inline bool sg_dma_is_swiotlb(struct scatterlist *sg) +{ + return sg->dma_flags & SG_DMA_SWIOTLB; +} + +/** + * sg_dma_mark_swiotlb - Mark the scatterlist for SWIOTLB bouncing + * @sg: SG entry + * + * Description: + * Marks a a scatterlist for SWIOTLB bounce. Not all SG entries may be + * bounced. + */ +static inline void sg_dma_mark_swiotlb(struct scatterlist *sg) +{ + sg->dma_flags |= SG_DMA_SWIOTLB; +} + +#else + +static inline bool sg_dma_is_bus_address(struct scatterlist *sg) +{ + return false; +} +static inline void sg_dma_mark_bus_address(struct scatterlist *sg) +{ +} +static inline void sg_dma_unmark_bus_address(struct scatterlist *sg) +{ +} +static inline bool sg_dma_is_swiotlb(struct scatterlist *sg) +{ + return false; +} +static inline void sg_dma_mark_swiotlb(struct scatterlist *sg) +{ +} + +#endif /* CONFIG_NEED_SG_DMA_FLAGS */ + +/** + * sg_phys - Return physical address of an sg entry + * @sg: SG entry + * + * Description: + * This calls page_to_phys() on the page in this sg entry, and adds the + * sg offset. The caller must know that it is legal to call page_to_phys() + * on the sg page. + * + **/ +static inline dma_addr_t sg_phys(struct scatterlist *sg) +{ + return page_to_phys(sg_page(sg)) + sg->offset; +} + +/** + * sg_virt - Return virtual address of an sg entry + * @sg: SG entry + * + * Description: + * This calls page_address() on the page in this sg entry, and adds the + * sg offset. The caller must know that the sg page has a valid virtual + * mapping. + * + **/ +static inline void *sg_virt(struct scatterlist *sg) +{ + return page_address(sg_page(sg)) + sg->offset; +} + +/** + * sg_init_marker - Initialize markers in sg table + * @sgl: The SG table + * @nents: Number of entries in table + * + **/ +static inline void sg_init_marker(struct scatterlist *sgl, + unsigned int nents) +{ + sg_mark_end(&sgl[nents - 1]); +} + +int sg_nents(struct scatterlist *sg); +int sg_nents_for_len(struct scatterlist *sg, u64 len); +struct scatterlist *sg_next(struct scatterlist *); +struct scatterlist *sg_last(struct scatterlist *s, unsigned int); +void sg_init_table(struct scatterlist *, unsigned int); +void sg_init_one(struct scatterlist *, const void *, unsigned int); +int sg_split(struct scatterlist *in, const int in_mapped_nents, + const off_t skip, const int nb_splits, + const size_t *split_sizes, + struct scatterlist **out, int *out_mapped_nents, + gfp_t gfp_mask); + +typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t); +typedef void (sg_free_fn)(struct scatterlist *, unsigned int); + +void __sg_free_table(struct sg_table *, unsigned int, unsigned int, + sg_free_fn *, unsigned int); +void sg_free_table(struct sg_table *); +void sg_free_append_table(struct sg_append_table *sgt); +int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int, + struct scatterlist *, unsigned int, gfp_t, sg_alloc_fn *); +int sg_alloc_table(struct sg_table *, unsigned int, gfp_t); +int sg_alloc_append_table_from_pages(struct sg_append_table *sgt, + struct page **pages, unsigned int n_pages, + unsigned int offset, unsigned long size, + unsigned int max_segment, + unsigned int left_pages, gfp_t gfp_mask); +int sg_alloc_table_from_pages_segment(struct sg_table *sgt, struct page **pages, + unsigned int n_pages, unsigned int offset, + unsigned long size, + unsigned int max_segment, gfp_t gfp_mask); + +/** + * sg_alloc_table_from_pages - Allocate and initialize an sg table from + * an array of pages + * @sgt: The sg table header to use + * @pages: Pointer to an array of page pointers + * @n_pages: Number of pages in the pages array + * @offset: Offset from start of the first page to the start of a buffer + * @size: Number of valid bytes in the buffer (after offset) + * @gfp_mask: GFP allocation mask + * + * Description: + * Allocate and initialize an sg table from a list of pages. Contiguous + * ranges of the pages are squashed into a single scatterlist node. A user + * may provide an offset at a start and a size of valid data in a buffer + * specified by the page array. The returned sg table is released by + * sg_free_table. + * + * Returns: + * 0 on success, negative error on failure + */ +static inline int sg_alloc_table_from_pages(struct sg_table *sgt, + struct page **pages, + unsigned int n_pages, + unsigned int offset, + unsigned long size, gfp_t gfp_mask) +{ + return sg_alloc_table_from_pages_segment(sgt, pages, n_pages, offset, + size, UINT_MAX, gfp_mask); +} + +#ifdef CONFIG_SGL_ALLOC +struct scatterlist *sgl_alloc_order(unsigned long long length, + unsigned int order, bool chainable, + gfp_t gfp, unsigned int *nent_p); +struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp, + unsigned int *nent_p); +void sgl_free_n_order(struct scatterlist *sgl, int nents, int order); +void sgl_free_order(struct scatterlist *sgl, int order); +void sgl_free(struct scatterlist *sgl); +#endif /* CONFIG_SGL_ALLOC */ + +size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf, + size_t buflen, off_t skip, bool to_buffer); + +size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents, + const void *buf, size_t buflen); +size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents, + void *buf, size_t buflen); + +size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents, + const void *buf, size_t buflen, off_t skip); +size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents, + void *buf, size_t buflen, off_t skip); +size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents, + size_t buflen, off_t skip); + +/* + * Maximum number of entries that will be allocated in one piece, if + * a list larger than this is required then chaining will be utilized. + */ +#define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist)) + +/* + * The maximum number of SG segments that we will put inside a + * scatterlist (unless chaining is used). Should ideally fit inside a + * single page, to avoid a higher order allocation. We could define this + * to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The + * minimum value is 32 + */ +#define SG_CHUNK_SIZE 128 + +/* + * Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit + * is totally arbitrary, a setting of 2048 will get you at least 8mb ios. + */ +#ifdef CONFIG_ARCH_NO_SG_CHAIN +#define SG_MAX_SEGMENTS SG_CHUNK_SIZE +#else +#define SG_MAX_SEGMENTS 2048 +#endif + +#ifdef CONFIG_SG_POOL +void sg_free_table_chained(struct sg_table *table, + unsigned nents_first_chunk); +int sg_alloc_table_chained(struct sg_table *table, int nents, + struct scatterlist *first_chunk, + unsigned nents_first_chunk); +#endif + +/* + * sg page iterator + * + * Iterates over sg entries page-by-page. On each successful iteration, you + * can call sg_page_iter_page(@piter) to get the current page. + * @piter->sg will point to the sg holding this page and @piter->sg_pgoffset to + * the page's page offset within the sg. The iteration will stop either when a + * maximum number of sg entries was reached or a terminating sg + * (sg_last(sg) == true) was reached. + */ +struct sg_page_iter { + struct scatterlist *sg; /* sg holding the page */ + unsigned int sg_pgoffset; /* page offset within the sg */ + + /* these are internal states, keep away */ + unsigned int __nents; /* remaining sg entries */ + int __pg_advance; /* nr pages to advance at the + * next step */ +}; + +/* + * sg page iterator for DMA addresses + * + * This is the same as sg_page_iter however you can call + * sg_page_iter_dma_address(@dma_iter) to get the page's DMA + * address. sg_page_iter_page() cannot be called on this iterator. + */ +struct sg_dma_page_iter { + struct sg_page_iter base; +}; + +bool __sg_page_iter_next(struct sg_page_iter *piter); +bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter); +void __sg_page_iter_start(struct sg_page_iter *piter, + struct scatterlist *sglist, unsigned int nents, + unsigned long pgoffset); +/** + * sg_page_iter_page - get the current page held by the page iterator + * @piter: page iterator holding the page + */ +static inline struct page *sg_page_iter_page(struct sg_page_iter *piter) +{ + return nth_page(sg_page(piter->sg), piter->sg_pgoffset); +} + +/** + * sg_page_iter_dma_address - get the dma address of the current page held by + * the page iterator. + * @dma_iter: page iterator holding the page + */ +static inline dma_addr_t +sg_page_iter_dma_address(struct sg_dma_page_iter *dma_iter) +{ + return sg_dma_address(dma_iter->base.sg) + + (dma_iter->base.sg_pgoffset << PAGE_SHIFT); +} + +/** + * for_each_sg_page - iterate over the pages of the given sg list + * @sglist: sglist to iterate over + * @piter: page iterator to hold current page, sg, sg_pgoffset + * @nents: maximum number of sg entries to iterate over + * @pgoffset: starting page offset (in pages) + * + * Callers may use sg_page_iter_page() to get each page pointer. + * In each loop it operates on PAGE_SIZE unit. + */ +#define for_each_sg_page(sglist, piter, nents, pgoffset) \ + for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \ + __sg_page_iter_next(piter);) + +/** + * for_each_sg_dma_page - iterate over the pages of the given sg list + * @sglist: sglist to iterate over + * @dma_iter: DMA page iterator to hold current page + * @dma_nents: maximum number of sg entries to iterate over, this is the value + * returned from dma_map_sg + * @pgoffset: starting page offset (in pages) + * + * Callers may use sg_page_iter_dma_address() to get each page's DMA address. + * In each loop it operates on PAGE_SIZE unit. + */ +#define for_each_sg_dma_page(sglist, dma_iter, dma_nents, pgoffset) \ + for (__sg_page_iter_start(&(dma_iter)->base, sglist, dma_nents, \ + pgoffset); \ + __sg_page_iter_dma_next(dma_iter);) + +/** + * for_each_sgtable_page - iterate over all pages in the sg_table object + * @sgt: sg_table object to iterate over + * @piter: page iterator to hold current page + * @pgoffset: starting page offset (in pages) + * + * Iterates over the all memory pages in the buffer described by + * a scatterlist stored in the given sg_table object. + * See also for_each_sg_page(). In each loop it operates on PAGE_SIZE unit. + */ +#define for_each_sgtable_page(sgt, piter, pgoffset) \ + for_each_sg_page((sgt)->sgl, piter, (sgt)->orig_nents, pgoffset) + +/** + * for_each_sgtable_dma_page - iterate over the DMA mapped sg_table object + * @sgt: sg_table object to iterate over + * @dma_iter: DMA page iterator to hold current page + * @pgoffset: starting page offset (in pages) + * + * Iterates over the all DMA mapped pages in the buffer described by + * a scatterlist stored in the given sg_table object. + * See also for_each_sg_dma_page(). In each loop it operates on PAGE_SIZE + * unit. + */ +#define for_each_sgtable_dma_page(sgt, dma_iter, pgoffset) \ + for_each_sg_dma_page((sgt)->sgl, dma_iter, (sgt)->nents, pgoffset) + + +/* + * Mapping sg iterator + * + * Iterates over sg entries mapping page-by-page. On each successful + * iteration, @miter->page points to the mapped page and + * @miter->length bytes of data can be accessed at @miter->addr. As + * long as an iteration is enclosed between start and stop, the user + * is free to choose control structure and when to stop. + * + * @miter->consumed is set to @miter->length on each iteration. It + * can be adjusted if the user can't consume all the bytes in one go. + * Also, a stopped iteration can be resumed by calling next on it. + * This is useful when iteration needs to release all resources and + * continue later (e.g. at the next interrupt). + */ + +#define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */ +#define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */ +#define SG_MITER_FROM_SG (1 << 2) /* nop */ + +struct sg_mapping_iter { + /* the following three fields can be accessed directly */ + struct page *page; /* currently mapped page */ + void *addr; /* pointer to the mapped area */ + size_t length; /* length of the mapped area */ + size_t consumed; /* number of consumed bytes */ + struct sg_page_iter piter; /* page iterator */ + + /* these are internal states, keep away */ + unsigned int __offset; /* offset within page */ + unsigned int __remaining; /* remaining bytes on page */ + unsigned int __flags; +}; + +void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl, + unsigned int nents, unsigned int flags); +bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset); +bool sg_miter_next(struct sg_mapping_iter *miter); +void sg_miter_stop(struct sg_mapping_iter *miter); + +#endif /* _LINUX_SCATTERLIST_H */ |