WebSVN – Kolibri OS – Diff – /drivers/include/linux/scatterlist.h

 #ifndef _LINUX_SCATTERLIST_H
 #define _LINUX_SCATTERLIST_H
 #include
 #include
 #include
 #include
 #include
 //#include
 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_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);
 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);
 int sg_alloc_table_from_pages(struct sg_table *sgt,
 	struct page **pages, unsigned int n_pages,
 	unsigned long offset, unsigned long size,
 	gfp_t gfp_mask);
 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     (4*PAGE_SIZE / sizeof(struct scatterlist))
+/*
+ * 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 */
-	struct scatterlist	*__sg;		/* current entry */
+	/* these are internal states, keep away */
-	unsigned int		__nents;	/* nr of remaining entries */
+	unsigned int		__offset;	/* offset within page */
-	unsigned int		__offset;	/* offset within sg */
+	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_next(struct sg_mapping_iter *miter);
 void sg_miter_stop(struct sg_mapping_iter *miter);
 #endif /* _LINUX_SCATTERLIST_H */

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(root)/drivers/include/linux/scatterlist.h – Rev 3297 → 3747