Initial import

1 files changed, 352 insertions, 0 deletions

diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
new file mode 100644
index 000000000..ed8f9e70d
--- /dev/null
+++ b/include/linux/scatterlist.h
@@ -0,0 +1,352 @@
+#ifndef _LINUX_SCATTERLIST_H
+#define _LINUX_SCATTERLIST_H
+
+#include <linux/string.h>
+#include <linux/bug.h>
+#include <linux/mm.h>
+
+#include <asm/types.h>
+#include <asm/scatterlist.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)
+{
+#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)
+{
+#ifndef CONFIG_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, 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 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);
+
+size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
+			    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);
+
+/*
+ * 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))
+
+/*
+ * 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 */