#include <linux/string.h>
#include <linux/bug.h>
#include <linux/mm.h>
#include <asm/types.h>
#include <asm/scatterlist.h>
#include <asm/io.h>

Data Structures
struct	sg_table

struct	sg_mapping_iter

Macros
#define	SG_MAGIC 0x87654321

#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))

#define	for_each_sg(sglist, sg, nr, __i) for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))

#define	SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))

#define	SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */

#define	SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */

#define	SG_MITER_FROM_SG (1 << 2) /* nop */

Typedefs
typedef struct scatterlist *(	sg_alloc_fn )(unsigned int, gfp_t)

typedef void(	sg_free_fn )(struct scatterlist *, unsigned int)

Functions
int	sg_nents (struct scatterlist *sg)

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)

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)

int	sg_alloc_table_from_pages (struct sg_table sgt, struct page *pages, unsigned int n_pages, unsigned long offset, unsigned long size, gfp_t gfp_mask)

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)

void	sg_miter_start (struct sg_mapping_iter miter, struct scatterlist sgl, unsigned int nents, unsigned int flags)

bool	sg_miter_next (struct sg_mapping_iter *miter)

void	sg_miter_stop (struct sg_mapping_iter *miter)

Macro Definition Documentation

#define for_each_sg	(	sglist,
		sg,
		nr,
		__i
	)	for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))

Definition at line 120 of file scatterlist.h.

#define sg_chain_ptr ( sg ) ((struct scatterlist *) ((sg)->page_link & ~0x03))

Definition at line 44 of file scatterlist.h.

#define sg_is_chain ( sg ) ((sg)->page_link & 0x01)

Definition at line 42 of file scatterlist.h.

#define sg_is_last ( sg ) ((sg)->page_link & 0x02)

Definition at line 43 of file scatterlist.h.

#define SG_MAGIC 0x87654321

Definition at line 35 of file scatterlist.h.

#define SG_MAX_SINGLE_ALLOC (PAGE_SIZE / sizeof(struct scatterlist))

Definition at line 232 of file scatterlist.h.

#define SG_MITER_ATOMIC (1 << 0) /* use kmap_atomic */

Definition at line 251 of file scatterlist.h.

#define SG_MITER_FROM_SG (1 << 2) /* nop */

Definition at line 253 of file scatterlist.h.

#define SG_MITER_TO_SG (1 << 1) /* flush back to phys on unmap */

Definition at line 252 of file scatterlist.h.

Typedef Documentation

typedef struct scatterlist*( sg_alloc_fn)(unsigned int, gfp_t)

read

Definition at line 210 of file scatterlist.h.

typedef void( sg_free_fn)(struct scatterlist *, unsigned int)

Definition at line 211 of file scatterlist.h.

Function Documentation

int __sg_alloc_table	(	struct sg_table *	table,
		unsigned int	nents,
		unsigned int	max_ents,
		gfp_t	gfp_mask,
		sg_alloc_fn *	alloc_fn
	)

__sg_alloc_table - Allocate and initialize an sg table with given allocator : The sg table header to use : Number of entries in sg list : The maximum number of entries the allocator returns per call : GFP allocation mask : Allocator to use

Description: This function returns a long. The allocator is defined to return scatterlist chunks of maximum size . Thus if is bigger than , the scatterlists will be chained in units of .

Notes: If this function returns non-0 (eg failure), the caller must call __sg_free_table() to cleanup any leftover allocations.

Definition at line 243 of file scatterlist.c.

void __sg_free_table	(	struct sg_table *	table,
		unsigned int	max_ents,
		sg_free_fn *	free_fn
	)

__sg_free_table - Free a previously mapped sg table : The sg table header to use : The maximum number of entries per single scatterlist : Free function

Description: Free an sg table previously allocated and setup with __sg_alloc_table(). The value must be identical to that previously used with __sg_alloc_table().

Definition at line 176 of file scatterlist.c.

int sg_alloc_table	(	struct sg_table *	table,
		unsigned int	nents,
		gfp_t	gfp_mask
	)

sg_alloc_table - Allocate and initialize an sg table : The sg table header to use : Number of entries in sg list : GFP allocation mask

Description: Allocate and initialize an sg table. If @ is larger than SG_MAX_SINGLE_ALLOC a chained sg table will be setup.

Definition at line 319 of file scatterlist.c.

int sg_alloc_table_from_pages	(	struct sg_table *	sgt,
		struct page **	pages,
		unsigned int	n_pages,
		unsigned long	offset,
		unsigned long	size,
		gfp_t	gfp_mask
	)

sg_alloc_table_from_pages - Allocate and initialize an sg table from an array of pages : The sg table header to use : Pointer to an array of page pointers : Number of pages in the pages array : Offset from start of the first page to the start of a buffer : Number of valid bytes in the buffer (after offset) : GFP allocation mask

Description: Allocate and initialize an sg table from a list of pages. Contiguous ranges of the pages are squashed into a single scatterlist node. A user may provide an offset at a start and a size of valid data in a buffer specified by the page array. The returned sg table is released by sg_free_table.

Returns: 0 on success, negative error on failure

Definition at line 352 of file scatterlist.c.

size_t sg_copy_from_buffer	(	struct scatterlist *	sgl,
		unsigned int	nents,
		void *	buf,
		size_t	buflen
	)

sg_copy_from_buffer - Copy from a linear buffer to an SG list : The SG list : Number of SG entries : Where to copy from : The number of bytes to copy

Returns the number of copied bytes.

Definition at line 572 of file scatterlist.c.

size_t sg_copy_to_buffer	(	struct scatterlist *	sgl,
		unsigned int	nents,
		void *	buf,
		size_t	buflen
	)

sg_copy_to_buffer - Copy from an SG list to a linear buffer : The SG list : Number of SG entries : Where to copy to : The number of bytes to copy

Returns the number of copied bytes.

Definition at line 589 of file scatterlist.c.

void sg_free_table ( struct sg_table * table )

sg_free_table - Free a previously allocated sg table : The mapped sg table header

Definition at line 218 of file scatterlist.c.

void sg_init_one	(	struct scatterlist *	sg,
		const void *	buf,
		unsigned int	buflen
	)

sg_init_one - Initialize a single entry sg list : SG entry : Virtual address for IO : IO length

Definition at line 125 of file scatterlist.c.

void sg_init_table	(	struct scatterlist *	sgl,
		unsigned int	nents
	)

sg_init_table - Initialize SG table : The SG table : 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.

Definition at line 104 of file scatterlist.c.

struct scatterlist* sg_last	(	struct scatterlist *	sgl,
		unsigned int	nents
	)

read

sg_last - return the last scatterlist entry in a list : First entry in the scatterlist : Number of entries in the scatterlist

Description: Should only be used casually, it (currently) scans the entire list to get the last entry.

Note that the @ pointer passed in need not be the first one, the important bit is that @ denotes the number of entries that exist from

Definition at line 74 of file scatterlist.c.

bool sg_miter_next ( struct sg_mapping_iter * miter )

sg_miter_next - proceed mapping iterator to the next mapping : sg mapping iter to proceed

Description: Proceeds to the next mapping. should have been started using sg_miter_start(). On successful return, ->page, ->addr and ->length point to the current mapping.

Context: Preemption disabled if SG_MITER_ATOMIC. Preemption must stay disabled till is stopped. May sleep if !SG_MITER_ATOMIC.

Returns: true if contains the next mapping. false if end of sg list is reached.

Definition at line 438 of file scatterlist.c.

void sg_miter_start	(	struct sg_mapping_iter *	miter,
		struct scatterlist *	sgl,
		unsigned int	nents,
		unsigned int	flags
	)

sg_miter_start - start mapping iteration over a sg list : sg mapping iter to be started : sg list to iterate over : number of sg entries

Description: Starts mapping iterator .

Context: Don't care.

Definition at line 408 of file scatterlist.c.

void sg_miter_stop ( struct sg_mapping_iter * miter )

sg_miter_stop - stop mapping iteration : sg mapping iter to be stopped

Description: Stops mapping iterator . should have been started started using sg_miter_start(). A stopped iteration can be resumed by calling sg_miter_next() on it. This is useful when resources (kmap) need to be released during iteration.

Context: Preemption disabled if the SG_MITER_ATOMIC is set. Don't care otherwise.

Definition at line 489 of file scatterlist.c.

int sg_nents ( struct scatterlist * sg )

sg_nents - return total count of entries in scatterlist : The scatterlist

Description: Allows to know how many entries are in sg, taking into acount chaining as well

Definition at line 50 of file scatterlist.c.

struct scatterlist* sg_next ( struct scatterlist * sg )

read

sg_next - return the next scatterlist entry in a list : The current sg entry

Description: Usually the next entry will be @ + 1, but if this sg element is part of a chained scatterlist, it could jump to the start of a new scatterlist array.

Definition at line 25 of file scatterlist.c.

Data Structures

Macros

Typedefs

Functions

Macro Definition Documentation

Typedef Documentation

Function Documentation