We can then transition drivers without changing the generated code.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---
include/linux/scatterlist.h | 112 +++++++++++++++++++++++++++++++++++++++---
1 files changed, 104 insertions(+), 8 deletions(-)
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 2dc7464..1645795 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -2,24 +2,37 @@
#define _LINUX_SCATTERLIST_H
#include <asm/scatterlist.h>
+#include <asm/io.h>
#include <linux/mm.h>
#include <linux/string.h>
+/**
+ * sg_set_page - Set sg entry to point at given page
+ * @sg: SG entry
+ * @page: The 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)
+{
+ sg->page = page;
+}
+
+#define sg_page(sg) ((sg)->page)
+
static inline void sg_set_buf(struct scatterlist *sg, const void *buf,
unsigned int buflen)
{
- sg->page = virt_to_page(buf);
+ sg_set_page(sg, virt_to_page(buf));
sg->offset = offset_in_page(buf);
sg->length = buflen;
}
-static inline void sg_init_one(struct scatterlist *sg, const void *buf,
- unsigned int buflen)
-{
- memset(sg, 0, sizeof(*sg));
- sg_set_buf(sg, buf, buflen);
-}
-
/*
* 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.
@@ -104,4 +117,87 @@ static inline void sg_chain(struct scatterlist *prv, unsigned int prv_nents,
prv[prv_nents - 1].page = (struct page *) ((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)
+{
+}
+
+static inline void __sg_mark_end(struct scatterlist *sg)
+{
+}
+
+
+/**
+ * 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));
+ 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);
+}
+
+/**
+ * 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 unsigned long 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;
+}
+
#endif /* _LINUX_SCATTERLIST_H */
--
1.5.3.GIT
-
