[mirror_ubuntu-bionic-kernel.git] / include / linux / scatterlist.h

/* 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 {
#ifdef CONFIG_DEBUG_SG
	unsigned long	sg_magic;
#endif
	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
};

/*
 * Since the above length field is an unsigned int, below we define the maximum
 * length in bytes that can be stored in one scatterlist entry.
 */
#define SCATTERLIST_MAX_SEGMENT (UINT_MAX & PAGE_MASK)

/*
 * 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 */
};

/*
 * 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_MAGIC	0x87654321

/*
 * 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_is_chain(sg)		((sg)->page_link & 0x01)
#define sg_is_last(sg)		((sg)->page_link & 0x02)
#define sg_chain_ptr(sg)	\
	((struct scatterlist *) ((sg)->page_link & ~0x03))

/**
 * 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 & 0x3;

	/*
	 * 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 & 0x03);
#ifdef CONFIG_DEBUG_SG
	BUG_ON(sg->sg_magic != SG_MAGIC);
	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;
}

static inline struct page *sg_page(struct scatterlist *sg)
{
#ifdef CONFIG_DEBUG_SG
	BUG_ON(sg->sg_magic != SG_MAGIC);
	BUG_ON(sg_is_chain(sg));
#endif
	return (struct page *)((sg)->page_link & ~0x3);
}

/**
 * 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))

/**
 * 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)
{
	/*
	 * offset and length are unused for chain entry.  Clear them.
	 */
	prv[prv_nents - 1].offset = 0;
	prv[prv_nents - 1].length = 0;

	/*
	 * Set lowest bit to indicate a link pointer, and make sure to clear
	 * the termination bit if it happens to be set.
	 */
	prv[prv_nents - 1].page_link = ((unsigned long) sgl | 0x01) & ~0x02;
}

/**
 * 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)
{
#ifdef CONFIG_DEBUG_SG
	BUG_ON(sg->sg_magic != SG_MAGIC);
#endif
	/*
	 * Set termination bit, clear potential chain bit
	 */
	sg->page_link |= 0x02;
	sg->page_link &= ~0x01;
}

/**
 * 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)
{
#ifdef CONFIG_DEBUG_SG
	BUG_ON(sg->sg_magic != SG_MAGIC);
#endif
	sg->page_link &= ~0x02;
}

/**
 * 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;
}

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, bool, sg_free_fn *);
void sg_free_table(struct sg_table *);
int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int,
		     struct scatterlist *, gfp_t, sg_alloc_fn *);
int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
int __sg_alloc_table_from_pages(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);
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);

#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_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_HAS_SG_CHAIN
#define SG_MAX_SEGMENTS	2048
#else
#define SG_MAX_SEGMENTS	SG_CHUNK_SIZE
#endif

#ifdef CONFIG_SG_POOL
void sg_free_table_chained(struct sg_table *table, bool first_chunk);
int sg_alloc_table_chained(struct sg_table *table, int nents,
			   struct scatterlist *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) and sg_page_iter_dma_address(@piter)
 * to get the current page and its dma address. @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 */
};

bool __sg_page_iter_next(struct sg_page_iter *piter);
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.
 * @piter:	page iterator holding the page
 */
static inline dma_addr_t sg_page_iter_dma_address(struct sg_page_iter *piter)
{
	return sg_dma_address(piter->sg) + (piter->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
 */
#define for_each_sg_page(sglist, piter, nents, pgoffset)		   \
	for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \
	     __sg_page_iter_next(piter);)

/*
 * 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 interation 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 */
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
1da177e4 LT	2	#ifndef _LINUX_SCATTERLIST_H
	3	#define _LINUX_SCATTERLIST_H
	4
187f1882	5	#include <linux/string.h>
84be456f	6	#include <linux/types.h>
187f1882 PG	7	#include <linux/bug.h>
187f1882 PG	8	#include <linux/mm.h>
18dabf47 JA	9	#include <asm/io.h>
18dabf47 JA	10
84be456f CH	11	struct scatterlist {
	12	#ifdef CONFIG_DEBUG_SG
	13	unsigned long sg_magic;
	14	#endif
	15	unsigned long page_link;
	16	unsigned int offset;
	17	unsigned int length;
	18	dma_addr_t dma_address;
	19	#ifdef CONFIG_NEED_SG_DMA_LENGTH
	20	unsigned int dma_length;
	21	#endif
	22	};
	23
c125906b TU	24	/*
	25	* Since the above length field is an unsigned int, below we define the maximum
	26	* length in bytes that can be stored in one scatterlist entry.
	27	*/
	28	#define SCATTERLIST_MAX_SEGMENT (UINT_MAX & PAGE_MASK)
	29
84be456f CH	30	/*
	31	* These macros should be used after a dma_map_sg call has been done
	32	* to get bus addresses of each of the SG entries and their lengths.
	33	* You should only work with the number of sg entries dma_map_sg
	34	* returns, or alternatively stop on the first sg_dma_len(sg) which
	35	* is 0.
	36	*/
	37	#define sg_dma_address(sg) ((sg)->dma_address)
	38
	39	#ifdef CONFIG_NEED_SG_DMA_LENGTH
	40	#define sg_dma_len(sg) ((sg)->dma_length)
	41	#else
	42	#define sg_dma_len(sg) ((sg)->length)
	43	#endif
	44
0db9299f JA	45	struct sg_table {
	46	struct scatterlist sgl; / the list */
	47	unsigned int nents; /* number of mapped entries */
	48	unsigned int orig_nents; /* original size of list */
	49	};
	50
18dabf47 JA	51	/*
	52	* Notes on SG table design.
	53	*
84be456f CH	54	* We use the unsigned long page_link field in the scatterlist struct to place
	55	* the page pointer AND encode information about the sg table as well. The two
	56	* lower bits are reserved for this information.
18dabf47 JA	57	*
	58	* If bit 0 is set, then the page_link contains a pointer to the next sg
	59	* table list. Otherwise the next entry is at sg + 1.
	60	*
	61	* If bit 1 is set, then this sg entry is the last element in a list.
	62	*
	63	* See sg_next().
	64	*
	65	*/
1da177e4	66
d6ec0842 JA	67	#define SG_MAGIC 0x87654321
d6ec0842 JA	68
645a8d94 TH	69	/*
	70	* We overload the LSB of the page pointer to indicate whether it's
	71	* a valid sg entry, or whether it points to the start of a new scatterlist.
	72	* Those low bits are there for everyone! (thanks mason :-)
	73	*/
	74	#define sg_is_chain(sg) ((sg)->page_link & 0x01)
	75	#define sg_is_last(sg) ((sg)->page_link & 0x02)
	76	#define sg_chain_ptr(sg) \
	77	((struct scatterlist *) ((sg)->page_link & ~0x03))
	78
82f66fbe	79	/**
642f1490 JA	80	* sg_assign_page - Assign a given page to an SG entry
	81	* @sg: SG entry
	82	* @page: The page
82f66fbe JA	83	*
82f66fbe JA	84	* Description:
642f1490 JA	85	* Assign page to sg entry. Also see sg_set_page(), the most commonly used
642f1490 JA	86	* variant.
82f66fbe JA	87	*
82f66fbe JA	88	**/
642f1490	89	static inline void sg_assign_page(struct scatterlist sg, struct page page)
82f66fbe	90	{
18dabf47 JA	91	unsigned long page_link = sg->page_link & 0x3;
18dabf47 JA	92
de26103d JA	93	/*
	94	* In order for the low bit stealing approach to work, pages
	95	* must be aligned at a 32-bit boundary as a minimum.
	96	*/
	97	BUG_ON((unsigned long) page & 0x03);
d6ec0842 JA	98	#ifdef CONFIG_DEBUG_SG
d6ec0842 JA	99	BUG_ON(sg->sg_magic != SG_MAGIC);
645a8d94	100	BUG_ON(sg_is_chain(sg));
d6ec0842	101	#endif
18dabf47	102	sg->page_link = page_link \| (unsigned long) page;
82f66fbe JA	103	}
82f66fbe JA	104
642f1490 JA	105	/**
	106	* sg_set_page - Set sg entry to point at given page
	107	* @sg: SG entry
	108	* @page: The page
	109	* @len: Length of data
	110	* @offset: Offset into page
	111	*
	112	* Description:
	113	* Use this function to set an sg entry pointing at a page, never assign
	114	* the page directly. We encode sg table information in the lower bits
	115	* of the page pointer. See sg_page() for looking up the page belonging
	116	* to an sg entry.
	117	*
	118	**/
	119	static inline void sg_set_page(struct scatterlist sg, struct page page,
	120	unsigned int len, unsigned int offset)
	121	{
	122	sg_assign_page(sg, page);
	123	sg->offset = offset;
	124	sg->length = len;
	125	}
	126
645a8d94 TH	127	static inline struct page sg_page(struct scatterlist sg)
	128	{
	129	#ifdef CONFIG_DEBUG_SG
	130	BUG_ON(sg->sg_magic != SG_MAGIC);
	131	BUG_ON(sg_is_chain(sg));
	132	#endif
	133	return (struct page *)((sg)->page_link & ~0x3);
	134	}
82f66fbe	135
18dabf47 JA	136	/**
	137	* sg_set_buf - Set sg entry to point at given data
	138	* @sg: SG entry
	139	* @buf: Data
	140	* @buflen: Data length
	141	*
	142	**/
03fd9cee	143	static inline void sg_set_buf(struct scatterlist sg, const void buf,
d32311fe HX	144	unsigned int buflen)
d32311fe HX	145	{
ac4e97ab RR	146	#ifdef CONFIG_DEBUG_SG
	147	BUG_ON(!virt_addr_valid(buf));
	148	#endif
642f1490	149	sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
1da177e4 LT	150	}
1da177e4 LT	151
96b418c9 JA	152	/*
	153	* Loop over each sg element, following the pointer to a new list if necessary
	154	*/
	155	#define for_each_sg(sglist, sg, nr, __i) \
	156	for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
	157
70eb8040 JA	158	/**
	159	* sg_chain - Chain two sglists together
	160	* @prv: First scatterlist
	161	* @prv_nents: Number of entries in prv
	162	* @sgl: Second scatterlist
	163	*
18dabf47 JA	164	* Description:
18dabf47 JA	165	* Links @prv@ and @sgl@ together, to form a longer scatterlist.
70eb8040	166	*
18dabf47	167	**/
70eb8040 JA	168	static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
	169	struct scatterlist *sgl)
	170	{
645a8d94 TH	171	/*
	172	* offset and length are unused for chain entry. Clear them.
	173	*/
b801a1e7 RR	174	prv[prv_nents - 1].offset = 0;
b801a1e7 RR	175	prv[prv_nents - 1].length = 0;
645a8d94	176
73fd546a JA	177	/*
	178	* Set lowest bit to indicate a link pointer, and make sure to clear
	179	* the termination bit if it happens to be set.
	180	*/
	181	prv[prv_nents - 1].page_link = ((unsigned long) sgl \| 0x01) & ~0x02;
70eb8040 JA	182	}
70eb8040 JA	183
82f66fbe JA	184	/**
82f66fbe JA	185	* sg_mark_end - Mark the end of the scatterlist
c46f2334	186	* @sg: SG entryScatterlist
82f66fbe JA	187	*
82f66fbe JA	188	* Description:
c46f2334 JA	189	* Marks the passed in sg entry as the termination point for the sg
c46f2334 JA	190	* table. A call to sg_next() on this entry will return NULL.
82f66fbe JA	191	*
82f66fbe JA	192	**/
c46f2334	193	static inline void sg_mark_end(struct scatterlist *sg)
82f66fbe	194	{
c46f2334 JA	195	#ifdef CONFIG_DEBUG_SG
	196	BUG_ON(sg->sg_magic != SG_MAGIC);
	197	#endif
	198	/*
	199	* Set termination bit, clear potential chain bit
	200	*/
18dabf47	201	sg->page_link \|= 0x02;
c46f2334	202	sg->page_link &= ~0x01;
82f66fbe JA	203	}
82f66fbe JA	204
c8164d89 PB	205	/**
	206	* sg_unmark_end - Undo setting the end of the scatterlist
	207	* @sg: SG entryScatterlist
	208	*
	209	* Description:
	210	* Removes the termination marker from the given entry of the scatterlist.
	211	*
	212	**/
	213	static inline void sg_unmark_end(struct scatterlist *sg)
	214	{
	215	#ifdef CONFIG_DEBUG_SG
	216	BUG_ON(sg->sg_magic != SG_MAGIC);
	217	#endif
	218	sg->page_link &= ~0x02;
	219	}
	220
82f66fbe JA	221	/**
	222	* sg_phys - Return physical address of an sg entry
	223	* @sg: SG entry
	224	*
	225	* Description:
	226	* This calls page_to_phys() on the page in this sg entry, and adds the
	227	* sg offset. The caller must know that it is legal to call page_to_phys()
	228	* on the sg page.
	229	*
	230	**/
85cdffcd	231	static inline dma_addr_t sg_phys(struct scatterlist *sg)
82f66fbe JA	232	{
	233	return page_to_phys(sg_page(sg)) + sg->offset;
	234	}
	235
	236	/**
	237	* sg_virt - Return virtual address of an sg entry
18dabf47	238	* @sg: SG entry
82f66fbe JA	239	*
	240	* Description:
	241	* This calls page_address() on the page in this sg entry, and adds the
	242	* sg offset. The caller must know that the sg page has a valid virtual
	243	* mapping.
	244	*
	245	**/
	246	static inline void sg_virt(struct scatterlist sg)
	247	{
	248	return page_address(sg_page(sg)) + sg->offset;
	249	}
	250
2e484610	251	int sg_nents(struct scatterlist *sg);
cfaed10d	252	int sg_nents_for_len(struct scatterlist *sg, u64 len);
0db9299f JA	253	struct scatterlist sg_next(struct scatterlist );
	254	struct scatterlist sg_last(struct scatterlist s, unsigned int);
	255	void sg_init_table(struct scatterlist *, unsigned int);
	256	void sg_init_one(struct scatterlist , const void , unsigned int);
f8bcbe62 RJ	257	int sg_split(struct scatterlist *in, const int in_mapped_nents,
	258	const off_t skip, const int nb_splits,
	259	const size_t *split_sizes,
	260	struct scatterlist *out, int out_mapped_nents,
	261	gfp_t gfp_mask);
0db9299f JA	262
	263	typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t);
	264	typedef void (sg_free_fn)(struct scatterlist *, unsigned int);
	265
c53c6d6a	266	void __sg_free_table(struct sg_table , unsigned int, bool, sg_free_fn );
0db9299f	267	void sg_free_table(struct sg_table *);
c53c6d6a CH	268	int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int,
c53c6d6a CH	269	struct scatterlist , gfp_t, sg_alloc_fn );
0db9299f	270	int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
89d8589c TU	271	int __sg_alloc_table_from_pages(struct sg_table sgt, struct page *pages,
	272	unsigned int n_pages, unsigned int offset,
	273	unsigned long size, unsigned int max_segment,
	274	gfp_t gfp_mask);
	275	int sg_alloc_table_from_pages(struct sg_table sgt, struct page *pages,
	276	unsigned int n_pages, unsigned int offset,
	277	unsigned long size, gfp_t gfp_mask);
0db9299f	278
2b08897b BVA	279	#ifdef CONFIG_SGL_ALLOC
	280	struct scatterlist *sgl_alloc_order(unsigned long long length,
	281	unsigned int order, bool chainable,
	282	gfp_t gfp, unsigned int *nent_p);
	283	struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
	284	unsigned int *nent_p);
	285	void sgl_free_order(struct scatterlist *sgl, int order);
	286	void sgl_free(struct scatterlist *sgl);
	287	#endif /* CONFIG_SGL_ALLOC */
	288
386ecb12 DG	289	size_t sg_copy_buffer(struct scatterlist sgl, unsigned int nents, void buf,
	290	size_t buflen, off_t skip, bool to_buffer);
	291
b1adaf65	292	size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
2a1bf8f9	293	const void *buf, size_t buflen);
b1adaf65 FT	294	size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
	295	void *buf, size_t buflen);
	296
df642cea	297	size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
2a1bf8f9	298	const void *buf, size_t buflen, off_t skip);
df642cea AM	299	size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
df642cea AM	300	void *buf, size_t buflen, off_t skip);
0945e569 JT	301	size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents,
0945e569 JT	302	size_t buflen, off_t skip);
df642cea	303
0db9299f JA	304	/*
	305	* Maximum number of entries that will be allocated in one piece, if
	306	* a list larger than this is required then chaining will be utilized.
	307	*/
	308	#define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))
	309
9b1d6c89 ML	310	/*
	311	* The maximum number of SG segments that we will put inside a
	312	* scatterlist (unless chaining is used). Should ideally fit inside a
	313	* single page, to avoid a higher order allocation. We could define this
	314	* to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The
	315	* minimum value is 32
	316	*/
	317	#define SG_CHUNK_SIZE 128
	318
	319	/*
	320	* Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit
	321	* is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
	322	*/
	323	#ifdef CONFIG_ARCH_HAS_SG_CHAIN
	324	#define SG_MAX_SEGMENTS 2048
	325	#else
	326	#define SG_MAX_SEGMENTS SG_CHUNK_SIZE
	327	#endif
	328
	329	#ifdef CONFIG_SG_POOL
	330	void sg_free_table_chained(struct sg_table *table, bool first_chunk);
	331	int sg_alloc_table_chained(struct sg_table *table, int nents,
	332	struct scatterlist *first_chunk);
	333	#endif
	334
a321e91b ID	335	/*
	336	* sg page iterator
	337	*
	338	* Iterates over sg entries page-by-page. On each successful iteration,
2db76d7c ID	339	* you can call sg_page_iter_page(@piter) and sg_page_iter_dma_address(@piter)
	340	* to get the current page and its dma address. @piter->sg will point to the
	341	* sg holding this page and @piter->sg_pgoffset to the page's page offset
	342	* within the sg. The iteration will stop either when a maximum number of sg
	343	* entries was reached or a terminating sg (sg_last(sg) == true) was reached.
a321e91b ID	344	*/
a321e91b ID	345	struct sg_page_iter {
a321e91b ID	346	struct scatterlist sg; / sg holding the page */
	347	unsigned int sg_pgoffset; /* page offset within the sg */
	348
	349	/* these are internal states, keep away */
	350	unsigned int __nents; /* remaining sg entries */
	351	int __pg_advance; /* nr pages to advance at the
	352	* next step */
	353	};
	354
	355	bool __sg_page_iter_next(struct sg_page_iter *piter);
	356	void __sg_page_iter_start(struct sg_page_iter *piter,
	357	struct scatterlist *sglist, unsigned int nents,
	358	unsigned long pgoffset);
2db76d7c ID	359	/**
	360	* sg_page_iter_page - get the current page held by the page iterator
	361	* @piter: page iterator holding the page
	362	*/
	363	static inline struct page sg_page_iter_page(struct sg_page_iter piter)
	364	{
	365	return nth_page(sg_page(piter->sg), piter->sg_pgoffset);
	366	}
	367
	368	/**
	369	* sg_page_iter_dma_address - get the dma address of the current page held by
	370	* the page iterator.
	371	* @piter: page iterator holding the page
	372	*/
	373	static inline dma_addr_t sg_page_iter_dma_address(struct sg_page_iter *piter)
	374	{
	375	return sg_dma_address(piter->sg) + (piter->sg_pgoffset << PAGE_SHIFT);
	376	}
a321e91b ID	377
	378	/**
	379	* for_each_sg_page - iterate over the pages of the given sg list
	380	* @sglist: sglist to iterate over
	381	* @piter: page iterator to hold current page, sg, sg_pgoffset
	382	* @nents: maximum number of sg entries to iterate over
	383	* @pgoffset: starting page offset
	384	*/
	385	#define for_each_sg_page(sglist, piter, nents, pgoffset) \
	386	for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \
	387	__sg_page_iter_next(piter);)
137d3edb TH	388
	389	/*
	390	* Mapping sg iterator
	391	*
	392	* Iterates over sg entries mapping page-by-page. On each successful
	393	* iteration, @miter->page points to the mapped page and
	394	* @miter->length bytes of data can be accessed at @miter->addr. As
	395	* long as an interation is enclosed between start and stop, the user
	396	* is free to choose control structure and when to stop.
	397	*
	398	* @miter->consumed is set to @miter->length on each iteration. It
	399	* can be adjusted if the user can't consume all the bytes in one go.
	400	* Also, a stopped iteration can be resumed by calling next on it.
	401	* This is useful when iteration needs to release all resources and
	402	* continue later (e.g. at the next interrupt).
	403	*/
	404
	405	#define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */
6de7e356 SAS	406	#define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */
6de7e356 SAS	407	#define SG_MITER_FROM_SG (1 << 2) /* nop */
137d3edb TH	408
	409	struct sg_mapping_iter {
	410	/* the following three fields can be accessed directly */
	411	struct page page; / currently mapped page */
	412	void addr; / pointer to the mapped area */
	413	size_t length; /* length of the mapped area */
	414	size_t consumed; /* number of consumed bytes */
4225fc85	415	struct sg_page_iter piter; /* page iterator */
137d3edb TH	416
137d3edb TH	417	/* these are internal states, keep away */
4225fc85 ID	418	unsigned int __offset; /* offset within page */
4225fc85 ID	419	unsigned int __remaining; /* remaining bytes on page */
137d3edb TH	420	unsigned int __flags;
	421	};
	422
	423	void sg_miter_start(struct sg_mapping_iter miter, struct scatterlist sgl,
	424	unsigned int nents, unsigned int flags);
0d6077f8	425	bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset);
137d3edb TH	426	bool sg_miter_next(struct sg_mapping_iter *miter);
	427	void sg_miter_stop(struct sg_mapping_iter *miter);
	428
1da177e4	429	#endif /* _LINUX_SCATTERLIST_H */