228 строки
6.2 KiB
C
228 строки
6.2 KiB
C
#ifndef _LINUX_SCATTERLIST_H
|
|
#define _LINUX_SCATTERLIST_H
|
|
|
|
#include <asm/types.h>
|
|
#include <asm/scatterlist.h>
|
|
#include <linux/mm.h>
|
|
#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.
|
|
*
|
|
* 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)
|
|
{
|
|
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 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_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;
|
|
}
|
|
|
|
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);
|
|
|
|
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);
|
|
|
|
/*
|
|
* 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 */
|