#ifndef _LINUX_SCATTERLIST_H
#define _LINUX_SCATTERLIST_H
+#include <asm/types.h>
#include <asm/scatterlist.h>
-#include <asm/io.h>
#include <linux/mm.h>
#include <linux/string.h>
+#include <asm/io.h>
+
+/*
+ * 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
+
+/**
+ * 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);
+#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
* to an sg entry.
*
**/
-static inline void sg_set_page(struct scatterlist *sg, struct page *page)
+static inline void sg_set_page(struct scatterlist *sg, struct page *page,
+ unsigned int len, unsigned int offset)
{
- sg->page = page;
+ sg_assign_page(sg, page);
+ sg->offset = offset;
+ sg->length = len;
}
-#define sg_page(sg) ((sg)->page)
+#define sg_page(sg) ((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));
- sg->offset = offset_in_page(buf);
- sg->length = buflen;
+ sg_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
}
/*
* 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) ((unsigned long) (sg)->page & 0x01)
+#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 *) ((unsigned long) (sg)->page & ~0x01))
+ ((struct scatterlist *) ((sg)->page_link & ~0x03))
/**
* sg_next - return the next scatterlist entry in a list
* @sg: The current sg entry
*
- * Usually the next entry will be @sg@ + 1, but if this sg element is part
- * of a chained scatterlist, it could jump to the start of a new
- * scatterlist array.
- *
- * Note that the caller must ensure that there are further entries after
- * the current entry, this function will NOT return NULL for an end-of-list.
+ * Description:
+ * Usually the next entry will be @sg@ + 1, but if this sg element is part
+ * of a chained scatterlist, it could jump to the start of a new
+ * scatterlist array.
*
- */
+ **/
static inline struct scatterlist *sg_next(struct scatterlist *sg)
{
- sg++;
+#ifdef CONFIG_DEBUG_SG
+ BUG_ON(sg->sg_magic != SG_MAGIC);
+#endif
+ if (sg_is_last(sg))
+ return NULL;
+ sg++;
if (unlikely(sg_is_chain(sg)))
sg = sg_chain_ptr(sg);
* @sgl: First entry in the scatterlist
* @nents: Number of entries in the scatterlist
*
- * Should only be used casually, it (currently) scan the entire list
- * to get the last entry.
+ * 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@.
+ * 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)
{
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;
}
* @prv_nents: Number of entries in prv
* @sgl: Second scatterlist
*
- * Links @prv@ and @sgl@ together, to form a longer 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 = (struct page *) ((unsigned long) sgl | 0x01);
+ prv[prv_nents - 1].page_link = (unsigned long) sgl | 0x01;
}
/**
**/
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
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);
}
{
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
}
/**
* on the sg page.
*
**/
-static inline unsigned long sg_phys(struct scatterlist *sg)
+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
+ * @sg: SG entry
*
* Description:
* This calls page_address() on the page in this sg entry, and adds the
git.openpandora.org / pandora-kernel.git / blobdiff