+/**
+ * sg_last - return the last scatterlist entry in a list
+ * @sgl: First entry in the scatterlist
+ * @nents: Number of entries in the scatterlist
+ *
+ * Description:
+ * Should only be used casually, it (currently) scan the entire list
+ * to get the last entry.
+ *
+ * Note that the @sgl@ pointer passed in need not be the first one,
+ * the important bit is that @nents@ denotes the number of entries that
+ * exist from @sgl@.
+ *
+ **/
+static inline struct scatterlist *sg_last(struct scatterlist *sgl,
+ unsigned int nents)
+{
+#ifndef ARCH_HAS_SG_CHAIN
+ struct scatterlist *ret = &sgl[nents - 1];
+#else
+ struct scatterlist *sg, *ret = NULL;
+ int i;
+
+ for_each_sg(sgl, sg, nents, i)
+ ret = sg;
+
+#endif
+#ifdef CONFIG_DEBUG_SG
+ BUG_ON(sgl[0].sg_magic != SG_MAGIC);
+ BUG_ON(!sg_is_last(ret));
+#endif
+ return ret;
+}
+
+/**
+ * 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
+ prv[prv_nents - 1].page_link = (unsigned long) sgl | 0x01;
+}
+
+/**
+ * sg_mark_end - Mark the end of the scatterlist
+ * @sgl: Scatterlist
+ * @nents: Number of entries in sgl
+ *
+ * Description:
+ * Marks the last entry as the termination point for sg_next()
+ *
+ **/
+static inline void sg_mark_end(struct scatterlist *sgl, unsigned int nents)
+{
+ sgl[nents - 1].page_link = 0x02;
+}
+
+static inline void __sg_mark_end(struct scatterlist *sg)
+{
+ sg->page_link |= 0x02;
+}
+
+/**
+ * sg_init_one - Initialize a single entry sg list
+ * @sg: SG entry
+ * @buf: Virtual address for IO
+ * @buflen: IO length
+ *
+ * Notes:
+ * This should not be used on a single entry that is part of a larger
+ * table. Use sg_init_table() for that.
+ *
+ **/
+static inline void sg_init_one(struct scatterlist *sg, const void *buf,
+ unsigned int buflen)
+{
+ memset(sg, 0, sizeof(*sg));
+#ifdef CONFIG_DEBUG_SG
+ sg->sg_magic = SG_MAGIC;
+#endif
+ sg_mark_end(sg, 1);
+ sg_set_buf(sg, buf, buflen);
+}
+
+/**
+ * sg_init_table - Initialize SG table
+ * @sgl: The SG table
+ * @nents: Number of entries in table
+ *
+ * Notes:
+ * If this is part of a chained sg table, sg_mark_end() should be
+ * used only on the last table part.
+ *
+ **/
+static inline void sg_init_table(struct scatterlist *sgl, unsigned int nents)
+{
+ memset(sgl, 0, sizeof(*sgl) * nents);
+ sg_mark_end(sgl, nents);
+#ifdef CONFIG_DEBUG_SG
+ {
+ int i;
+ for (i = 0; i < nents; i++)
+ sgl[i].sg_magic = SG_MAGIC;
+ }
+#endif
+}
+
+/**
+ * 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;
+}
+