#include <linux/string.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.
*
#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
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->length = len;
}
-#define sg_page(sg) ((struct page *) ((sg)->page_link & ~0x3))
+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_set_page(sg, virt_to_page(buf), buflen, offset_in_page(buf));
}
-/*
- * 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_next - return the next scatterlist entry in a list
- * @sg: The current sg entry
- *
- * 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)
-{
-#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);
-
- return sg;
-}
-
/*
* 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_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;
- unsigned 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
#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.
/**
* sg_mark_end - Mark the end of the scatterlist
- * @sgl: Scatterlist
- * @nents: Number of entries in sgl
+ * @sg: SG entryScatterlist
*
* 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.
+ * 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_init_table(struct scatterlist *sgl, unsigned int nents)
+static inline void sg_mark_end(struct scatterlist *sg)
{
- memset(sgl, 0, sizeof(*sgl) * nents);
- sg_mark_end(sgl, nents);
#ifdef CONFIG_DEBUG_SG
- {
- unsigned int i;
- for (i = 0; i < nents; i++)
- sgl[i].sg_magic = SG_MAGIC;
- }
+ BUG_ON(sg->sg_magic != SG_MAGIC);
#endif
+ /*
+ * Set termination bit, clear potential chain bit
+ */
+ sg->page_link |= 0x02;
+ sg->page_link &= ~0x01;
}
/**
return page_address(sg_page(sg)) + sg->offset;
}
+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);
+
+/*
+ * 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))
+
#endif /* _LINUX_SCATTERLIST_H */
git.openpandora.org / pandora-kernel.git / blobdiff