include/linux/scatterlist.h - arm/linux-arm64-legacy - Git at Google

 #ifndef _LINUX_SCATTERLIST_H
 #define _LINUX_SCATTERLIST_H

 #include <asm/types.h>
 #include <asm/scatterlist.h>
 #include <linux/mm.h>
 #include <linux/string.h>
 #include <asm/io.h>

 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.
  *
  * Architectures must provide an unsigned long page_link field in the
  * scatterlist struct. We use that 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)
 {
 	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)
 {
 #ifndef ARCH_HAS_SG_CHAIN
 	BUG();
 #endif

 	/*
 	 * 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_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;
 }

 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);

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

 size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
 			   void *buf, size_t buflen);
 size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
 			 void *buf, size_t buflen);

 /*
  * 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))


 /*
  * 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 */

 	/* these are internal states, keep away */
 	struct scatterlist	*__sg;		/* current entry */
 	unsigned int		__nents;	/* nr of remaining entries */
 	unsigned int		__offset;	/* offset within sg */
 	unsigned int		__flags;
 };

 void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
 		    unsigned int nents, unsigned int flags);
 bool sg_miter_next(struct sg_mapping_iter *miter);
 void sg_miter_stop(struct sg_mapping_iter *miter);

 #endif /* _LINUX_SCATTERLIST_H */
	#ifndef _LINUX_SCATTERLIST_H
	#define _LINUX_SCATTERLIST_H

	#include <asm/types.h>
	#include <asm/scatterlist.h>
	#include <linux/mm.h>
	#include <linux/string.h>
	#include <asm/io.h>

	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.
	*
	* Architectures must provide an unsigned long page_link field in the
	* scatterlist struct. We use that 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)
	{
	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)
	{
	#ifndef ARCH_HAS_SG_CHAIN
	BUG();
	#endif

	/*
	* 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_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;
	}

	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);

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

	size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
	void *buf, size_t buflen);
	size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
	void *buf, size_t buflen);

	/*
	* 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))


	/*
	* 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 */

	/* these are internal states, keep away */
	struct scatterlist __sg; / current entry */
	unsigned int __nents; /* nr of remaining entries */
	unsigned int __offset; /* offset within sg */
	unsigned int __flags;
	};

	void sg_miter_start(struct sg_mapping_iter miter, struct scatterlist sgl,
	unsigned int nents, unsigned int flags);
	bool sg_miter_next(struct sg_mapping_iter *miter);
	void sg_miter_stop(struct sg_mapping_iter *miter);

	#endif /* _LINUX_SCATTERLIST_H */