/* 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
  };
  
  /*

   * 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_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_is_chain(sg)		((sg)->page_link & SG_CHAIN)
  #define sg_is_last(sg)		((sg)->page_link & SG_END)

  #define sg_chain_ptr(sg)	\

  	((struct scatterlist *) ((sg)->page_link & ~(SG_CHAIN | 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_CHAIN | SG_END));

  #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;
  }

  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_CHAIN | SG_END));

  }

  /**
   * 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;

  }
  
  /**

   * 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 *);

  void sg_free_table(struct sg_table *);

  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);

  struct scatterlist *__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,
  		struct scatterlist *prv, unsigned int left_pages,
  		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_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 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 */