636 lines
20 KiB
C
636 lines
20 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef _LINUX_SCATTERLIST_H
|
|
#define _LINUX_SCATTERLIST_H
|
|
|
|
#include <linux/string.h>
|
|
#include <linux/types.h>
|
|
#include <linux/bug.h>
|
|
#include <linux/mm.h>
|
|
#include <asm/io.h>
|
|
|
|
struct scatterlist {
|
|
unsigned long page_link;
|
|
unsigned int offset;
|
|
unsigned int length;
|
|
dma_addr_t dma_address;
|
|
#ifdef CONFIG_NEED_SG_DMA_LENGTH
|
|
unsigned int dma_length;
|
|
#endif
|
|
#ifdef CONFIG_PCI_P2PDMA
|
|
unsigned int dma_flags;
|
|
#endif
|
|
};
|
|
|
|
/*
|
|
* These macros should be used after a dma_map_sg call has been done
|
|
* to get bus addresses of each of the SG entries and their lengths.
|
|
* You should only work with the number of sg entries dma_map_sg
|
|
* returns, or alternatively stop on the first sg_dma_len(sg) which
|
|
* is 0.
|
|
*/
|
|
#define sg_dma_address(sg) ((sg)->dma_address)
|
|
|
|
#ifdef CONFIG_NEED_SG_DMA_LENGTH
|
|
#define sg_dma_len(sg) ((sg)->dma_length)
|
|
#else
|
|
#define sg_dma_len(sg) ((sg)->length)
|
|
#endif
|
|
|
|
struct sg_table {
|
|
struct scatterlist *sgl; /* the list */
|
|
unsigned int nents; /* number of mapped entries */
|
|
unsigned int orig_nents; /* original size of list */
|
|
};
|
|
|
|
struct sg_append_table {
|
|
struct sg_table sgt; /* The scatter list table */
|
|
struct scatterlist *prv; /* last populated sge in the table */
|
|
unsigned int total_nents; /* Total entries in the table */
|
|
};
|
|
|
|
/*
|
|
* Notes on SG table design.
|
|
*
|
|
* We use the unsigned long page_link field in the scatterlist struct 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_CHAIN 0x01UL
|
|
#define SG_END 0x02UL
|
|
|
|
/*
|
|
* 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_PAGE_LINK_MASK (SG_CHAIN | SG_END)
|
|
|
|
static inline unsigned int __sg_flags(struct scatterlist *sg)
|
|
{
|
|
return sg->page_link & SG_PAGE_LINK_MASK;
|
|
}
|
|
|
|
static inline struct scatterlist *sg_chain_ptr(struct scatterlist *sg)
|
|
{
|
|
return (struct scatterlist *)(sg->page_link & ~SG_PAGE_LINK_MASK);
|
|
}
|
|
|
|
static inline bool sg_is_chain(struct scatterlist *sg)
|
|
{
|
|
return __sg_flags(sg) & SG_CHAIN;
|
|
}
|
|
|
|
static inline bool sg_is_last(struct scatterlist *sg)
|
|
{
|
|
return __sg_flags(sg) & SG_END;
|
|
}
|
|
|
|
/**
|
|
* 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 & (SG_CHAIN | SG_END);
|
|
|
|
/*
|
|
* 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 & SG_PAGE_LINK_MASK);
|
|
#ifdef CONFIG_DEBUG_SG
|
|
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_is_chain(sg));
|
|
#endif
|
|
return (struct page *)((sg)->page_link & ~SG_PAGE_LINK_MASK);
|
|
}
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
#ifdef CONFIG_DEBUG_SG
|
|
BUG_ON(!virt_addr_valid(buf));
|
|
#endif
|
|
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))
|
|
|
|
/*
|
|
* Loop over each sg element in the given sg_table object.
|
|
*/
|
|
#define for_each_sgtable_sg(sgt, sg, i) \
|
|
for_each_sg((sgt)->sgl, sg, (sgt)->orig_nents, i)
|
|
|
|
/*
|
|
* Loop over each sg element in the given *DMA mapped* sg_table object.
|
|
* Please use sg_dma_address(sg) and sg_dma_len(sg) to extract DMA addresses
|
|
* of the each element.
|
|
*/
|
|
#define for_each_sgtable_dma_sg(sgt, sg, i) \
|
|
for_each_sg((sgt)->sgl, sg, (sgt)->nents, i)
|
|
|
|
static inline void __sg_chain(struct scatterlist *chain_sg,
|
|
struct scatterlist *sgl)
|
|
{
|
|
/*
|
|
* offset and length are unused for chain entry. Clear them.
|
|
*/
|
|
chain_sg->offset = 0;
|
|
chain_sg->length = 0;
|
|
|
|
/*
|
|
* Set lowest bit to indicate a link pointer, and make sure to clear
|
|
* the termination bit if it happens to be set.
|
|
*/
|
|
chain_sg->page_link = ((unsigned long) sgl | SG_CHAIN) & ~SG_END;
|
|
}
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
__sg_chain(&prv[prv_nents - 1], sgl);
|
|
}
|
|
|
|
/**
|
|
* 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)
|
|
{
|
|
/*
|
|
* Set termination bit, clear potential chain bit
|
|
*/
|
|
sg->page_link |= SG_END;
|
|
sg->page_link &= ~SG_CHAIN;
|
|
}
|
|
|
|
/**
|
|
* sg_unmark_end - Undo setting the end of the scatterlist
|
|
* @sg: SG entryScatterlist
|
|
*
|
|
* Description:
|
|
* Removes the termination marker from the given entry of the scatterlist.
|
|
*
|
|
**/
|
|
static inline void sg_unmark_end(struct scatterlist *sg)
|
|
{
|
|
sg->page_link &= ~SG_END;
|
|
}
|
|
|
|
/*
|
|
* CONFGI_PCI_P2PDMA depends on CONFIG_64BIT which means there is 4 bytes
|
|
* in struct scatterlist (assuming also CONFIG_NEED_SG_DMA_LENGTH is set).
|
|
* Use this padding for DMA flags bits to indicate when a specific
|
|
* dma address is a bus address.
|
|
*/
|
|
#ifdef CONFIG_PCI_P2PDMA
|
|
|
|
#define SG_DMA_BUS_ADDRESS (1 << 0)
|
|
|
|
/**
|
|
* sg_dma_is_bus address - Return whether a given segment was marked
|
|
* as a bus address
|
|
* @sg: SG entry
|
|
*
|
|
* Description:
|
|
* Returns true if sg_dma_mark_bus_address() has been called on
|
|
* this segment.
|
|
**/
|
|
static inline bool sg_is_dma_bus_address(struct scatterlist *sg)
|
|
{
|
|
return sg->dma_flags & SG_DMA_BUS_ADDRESS;
|
|
}
|
|
|
|
/**
|
|
* sg_dma_mark_bus address - Mark the scatterlist entry as a bus address
|
|
* @sg: SG entry
|
|
*
|
|
* Description:
|
|
* Marks the passed in sg entry to indicate that the dma_address is
|
|
* a bus address and doesn't need to be unmapped. This should only be
|
|
* used by dma_map_sg() implementations to mark bus addresses
|
|
* so they can be properly cleaned up in dma_unmap_sg().
|
|
**/
|
|
static inline void sg_dma_mark_bus_address(struct scatterlist *sg)
|
|
{
|
|
sg->dma_flags |= SG_DMA_BUS_ADDRESS;
|
|
}
|
|
|
|
/**
|
|
* sg_unmark_bus_address - Unmark the scatterlist entry as a bus address
|
|
* @sg: SG entry
|
|
*
|
|
* Description:
|
|
* Clears the bus address mark.
|
|
**/
|
|
static inline void sg_dma_unmark_bus_address(struct scatterlist *sg)
|
|
{
|
|
sg->dma_flags &= ~SG_DMA_BUS_ADDRESS;
|
|
}
|
|
|
|
#else
|
|
|
|
static inline bool sg_is_dma_bus_address(struct scatterlist *sg)
|
|
{
|
|
return false;
|
|
}
|
|
static inline void sg_dma_mark_bus_address(struct scatterlist *sg)
|
|
{
|
|
}
|
|
static inline void sg_dma_unmark_bus_address(struct scatterlist *sg)
|
|
{
|
|
}
|
|
|
|
#endif
|
|
|
|
/**
|
|
* 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;
|
|
}
|
|
|
|
/**
|
|
* sg_init_marker - Initialize markers in sg table
|
|
* @sgl: The SG table
|
|
* @nents: Number of entries in table
|
|
*
|
|
**/
|
|
static inline void sg_init_marker(struct scatterlist *sgl,
|
|
unsigned int nents)
|
|
{
|
|
sg_mark_end(&sgl[nents - 1]);
|
|
}
|
|
|
|
int sg_nents(struct scatterlist *sg);
|
|
int sg_nents_for_len(struct scatterlist *sg, u64 len);
|
|
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);
|
|
int sg_split(struct scatterlist *in, const int in_mapped_nents,
|
|
const off_t skip, const int nb_splits,
|
|
const size_t *split_sizes,
|
|
struct scatterlist **out, int *out_mapped_nents,
|
|
gfp_t gfp_mask);
|
|
|
|
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, unsigned int,
|
|
sg_free_fn *, unsigned int);
|
|
void sg_free_table(struct sg_table *);
|
|
void sg_free_append_table(struct sg_append_table *sgt);
|
|
int __sg_alloc_table(struct sg_table *, unsigned int, unsigned int,
|
|
struct scatterlist *, unsigned int, gfp_t, sg_alloc_fn *);
|
|
int sg_alloc_table(struct sg_table *, unsigned int, gfp_t);
|
|
int sg_alloc_append_table_from_pages(struct sg_append_table *sgt,
|
|
struct page **pages, unsigned int n_pages,
|
|
unsigned int offset, unsigned long size,
|
|
unsigned int max_segment,
|
|
unsigned int left_pages, gfp_t gfp_mask);
|
|
int sg_alloc_table_from_pages_segment(struct sg_table *sgt, struct page **pages,
|
|
unsigned int n_pages, unsigned int offset,
|
|
unsigned long size,
|
|
unsigned int max_segment, gfp_t gfp_mask);
|
|
|
|
/**
|
|
* sg_alloc_table_from_pages - Allocate and initialize an sg table from
|
|
* an array of pages
|
|
* @sgt: The sg table header to use
|
|
* @pages: Pointer to an array of page pointers
|
|
* @n_pages: Number of pages in the pages array
|
|
* @offset: Offset from start of the first page to the start of a buffer
|
|
* @size: Number of valid bytes in the buffer (after offset)
|
|
* @gfp_mask: 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
|
|
*/
|
|
static inline int sg_alloc_table_from_pages(struct sg_table *sgt,
|
|
struct page **pages,
|
|
unsigned int n_pages,
|
|
unsigned int offset,
|
|
unsigned long size, gfp_t gfp_mask)
|
|
{
|
|
return sg_alloc_table_from_pages_segment(sgt, pages, n_pages, offset,
|
|
size, UINT_MAX, gfp_mask);
|
|
}
|
|
|
|
#ifdef CONFIG_SGL_ALLOC
|
|
struct scatterlist *sgl_alloc_order(unsigned long long length,
|
|
unsigned int order, bool chainable,
|
|
gfp_t gfp, unsigned int *nent_p);
|
|
struct scatterlist *sgl_alloc(unsigned long long length, gfp_t gfp,
|
|
unsigned int *nent_p);
|
|
void sgl_free_n_order(struct scatterlist *sgl, int nents, int order);
|
|
void sgl_free_order(struct scatterlist *sgl, int order);
|
|
void sgl_free(struct scatterlist *sgl);
|
|
#endif /* CONFIG_SGL_ALLOC */
|
|
|
|
size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
|
|
size_t buflen, off_t skip, bool to_buffer);
|
|
|
|
size_t sg_copy_from_buffer(struct scatterlist *sgl, unsigned int nents,
|
|
const void *buf, size_t buflen);
|
|
size_t sg_copy_to_buffer(struct scatterlist *sgl, unsigned int nents,
|
|
void *buf, size_t buflen);
|
|
|
|
size_t sg_pcopy_from_buffer(struct scatterlist *sgl, unsigned int nents,
|
|
const void *buf, size_t buflen, off_t skip);
|
|
size_t sg_pcopy_to_buffer(struct scatterlist *sgl, unsigned int nents,
|
|
void *buf, size_t buflen, off_t skip);
|
|
size_t sg_zero_buffer(struct scatterlist *sgl, unsigned int nents,
|
|
size_t buflen, off_t skip);
|
|
|
|
/*
|
|
* 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))
|
|
|
|
/*
|
|
* The maximum number of SG segments that we will put inside a
|
|
* scatterlist (unless chaining is used). Should ideally fit inside a
|
|
* single page, to avoid a higher order allocation. We could define this
|
|
* to SG_MAX_SINGLE_ALLOC to pack correctly at the highest order. The
|
|
* minimum value is 32
|
|
*/
|
|
#define SG_CHUNK_SIZE 128
|
|
|
|
/*
|
|
* Like SG_CHUNK_SIZE, but for archs that have sg chaining. This limit
|
|
* is totally arbitrary, a setting of 2048 will get you at least 8mb ios.
|
|
*/
|
|
#ifdef CONFIG_ARCH_NO_SG_CHAIN
|
|
#define SG_MAX_SEGMENTS SG_CHUNK_SIZE
|
|
#else
|
|
#define SG_MAX_SEGMENTS 2048
|
|
#endif
|
|
|
|
#ifdef CONFIG_SG_POOL
|
|
void sg_free_table_chained(struct sg_table *table,
|
|
unsigned nents_first_chunk);
|
|
int sg_alloc_table_chained(struct sg_table *table, int nents,
|
|
struct scatterlist *first_chunk,
|
|
unsigned nents_first_chunk);
|
|
#endif
|
|
|
|
/*
|
|
* sg page iterator
|
|
*
|
|
* Iterates over sg entries page-by-page. On each successful iteration, you
|
|
* can call sg_page_iter_page(@piter) to get the current page.
|
|
* @piter->sg will point to the sg holding this page and @piter->sg_pgoffset to
|
|
* the page's page offset within the sg. The iteration will stop either when a
|
|
* maximum number of sg entries was reached or a terminating sg
|
|
* (sg_last(sg) == true) was reached.
|
|
*/
|
|
struct sg_page_iter {
|
|
struct scatterlist *sg; /* sg holding the page */
|
|
unsigned int sg_pgoffset; /* page offset within the sg */
|
|
|
|
/* these are internal states, keep away */
|
|
unsigned int __nents; /* remaining sg entries */
|
|
int __pg_advance; /* nr pages to advance at the
|
|
* next step */
|
|
};
|
|
|
|
/*
|
|
* sg page iterator for DMA addresses
|
|
*
|
|
* This is the same as sg_page_iter however you can call
|
|
* sg_page_iter_dma_address(@dma_iter) to get the page's DMA
|
|
* address. sg_page_iter_page() cannot be called on this iterator.
|
|
*/
|
|
struct sg_dma_page_iter {
|
|
struct sg_page_iter base;
|
|
};
|
|
|
|
bool __sg_page_iter_next(struct sg_page_iter *piter);
|
|
bool __sg_page_iter_dma_next(struct sg_dma_page_iter *dma_iter);
|
|
void __sg_page_iter_start(struct sg_page_iter *piter,
|
|
struct scatterlist *sglist, unsigned int nents,
|
|
unsigned long pgoffset);
|
|
/**
|
|
* sg_page_iter_page - get the current page held by the page iterator
|
|
* @piter: page iterator holding the page
|
|
*/
|
|
static inline struct page *sg_page_iter_page(struct sg_page_iter *piter)
|
|
{
|
|
return nth_page(sg_page(piter->sg), piter->sg_pgoffset);
|
|
}
|
|
|
|
/**
|
|
* sg_page_iter_dma_address - get the dma address of the current page held by
|
|
* the page iterator.
|
|
* @dma_iter: page iterator holding the page
|
|
*/
|
|
static inline dma_addr_t
|
|
sg_page_iter_dma_address(struct sg_dma_page_iter *dma_iter)
|
|
{
|
|
return sg_dma_address(dma_iter->base.sg) +
|
|
(dma_iter->base.sg_pgoffset << PAGE_SHIFT);
|
|
}
|
|
|
|
/**
|
|
* for_each_sg_page - iterate over the pages of the given sg list
|
|
* @sglist: sglist to iterate over
|
|
* @piter: page iterator to hold current page, sg, sg_pgoffset
|
|
* @nents: maximum number of sg entries to iterate over
|
|
* @pgoffset: starting page offset (in pages)
|
|
*
|
|
* Callers may use sg_page_iter_page() to get each page pointer.
|
|
* In each loop it operates on PAGE_SIZE unit.
|
|
*/
|
|
#define for_each_sg_page(sglist, piter, nents, pgoffset) \
|
|
for (__sg_page_iter_start((piter), (sglist), (nents), (pgoffset)); \
|
|
__sg_page_iter_next(piter);)
|
|
|
|
/**
|
|
* for_each_sg_dma_page - iterate over the pages of the given sg list
|
|
* @sglist: sglist to iterate over
|
|
* @dma_iter: DMA page iterator to hold current page
|
|
* @dma_nents: maximum number of sg entries to iterate over, this is the value
|
|
* returned from dma_map_sg
|
|
* @pgoffset: starting page offset (in pages)
|
|
*
|
|
* Callers may use sg_page_iter_dma_address() to get each page's DMA address.
|
|
* In each loop it operates on PAGE_SIZE unit.
|
|
*/
|
|
#define for_each_sg_dma_page(sglist, dma_iter, dma_nents, pgoffset) \
|
|
for (__sg_page_iter_start(&(dma_iter)->base, sglist, dma_nents, \
|
|
pgoffset); \
|
|
__sg_page_iter_dma_next(dma_iter);)
|
|
|
|
/**
|
|
* for_each_sgtable_page - iterate over all pages in the sg_table object
|
|
* @sgt: sg_table object to iterate over
|
|
* @piter: page iterator to hold current page
|
|
* @pgoffset: starting page offset (in pages)
|
|
*
|
|
* Iterates over the all memory pages in the buffer described by
|
|
* a scatterlist stored in the given sg_table object.
|
|
* See also for_each_sg_page(). In each loop it operates on PAGE_SIZE unit.
|
|
*/
|
|
#define for_each_sgtable_page(sgt, piter, pgoffset) \
|
|
for_each_sg_page((sgt)->sgl, piter, (sgt)->orig_nents, pgoffset)
|
|
|
|
/**
|
|
* for_each_sgtable_dma_page - iterate over the DMA mapped sg_table object
|
|
* @sgt: sg_table object to iterate over
|
|
* @dma_iter: DMA page iterator to hold current page
|
|
* @pgoffset: starting page offset (in pages)
|
|
*
|
|
* Iterates over the all DMA mapped pages in the buffer described by
|
|
* a scatterlist stored in the given sg_table object.
|
|
* See also for_each_sg_dma_page(). In each loop it operates on PAGE_SIZE
|
|
* unit.
|
|
*/
|
|
#define for_each_sgtable_dma_page(sgt, dma_iter, pgoffset) \
|
|
for_each_sg_dma_page((sgt)->sgl, dma_iter, (sgt)->nents, pgoffset)
|
|
|
|
|
|
/*
|
|
* Mapping sg iterator
|
|
*
|
|
* Iterates over sg entries mapping page-by-page. On each successful
|
|
* iteration, @miter->page points to the mapped page and
|
|
* @miter->length bytes of data can be accessed at @miter->addr. As
|
|
* long as an iteration is enclosed between start and stop, the user
|
|
* is free to choose control structure and when to stop.
|
|
*
|
|
* @miter->consumed is set to @miter->length on each iteration. It
|
|
* can be adjusted if the user can't consume all the bytes in one go.
|
|
* Also, a stopped iteration can be resumed by calling next on it.
|
|
* This is useful when iteration needs to release all resources and
|
|
* continue later (e.g. at the next interrupt).
|
|
*/
|
|
|
|
#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 */
|
|
|
|
struct sg_mapping_iter {
|
|
/* the following three fields can be accessed directly */
|
|
struct page *page; /* currently mapped page */
|
|
void *addr; /* pointer to the mapped area */
|
|
size_t length; /* length of the mapped area */
|
|
size_t consumed; /* number of consumed bytes */
|
|
struct sg_page_iter piter; /* page iterator */
|
|
|
|
/* these are internal states, keep away */
|
|
unsigned int __offset; /* offset within page */
|
|
unsigned int __remaining; /* remaining bytes on page */
|
|
unsigned int __flags;
|
|
};
|
|
|
|
void sg_miter_start(struct sg_mapping_iter *miter, struct scatterlist *sgl,
|
|
unsigned int nents, unsigned int flags);
|
|
bool sg_miter_skip(struct sg_mapping_iter *miter, off_t offset);
|
|
bool sg_miter_next(struct sg_mapping_iter *miter);
|
|
void sg_miter_stop(struct sg_mapping_iter *miter);
|
|
|
|
#endif /* _LINUX_SCATTERLIST_H */
|