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#ifndef _LINUX_SCATTERLIST_H |
#define _LINUX_SCATTERLIST_H |
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#include <linux/string.h> |
#include <linux/bug.h> |
#include <linux/mm.h> |
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#include <asm/types.h> |
#include <asm/scatterlist.h> |
//#include <asm/io.h> |
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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(). |
* |
*/ |
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#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; |
//} |
|
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); |
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typedef struct scatterlist *(sg_alloc_fn)(unsigned int, gfp_t); |
typedef void (sg_free_fn)(struct scatterlist *, unsigned int); |
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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); |
|
/* |
* 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)) |
|
|
/* |
* 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 interation 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). |
*/ |
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#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 */ |
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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 */ |
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/* these are internal states, keep away */ |
struct scatterlist *__sg; /* current entry */ |
unsigned int __nents; /* nr of remaining entries */ |
unsigned int __offset; /* offset within sg */ |
unsigned int __flags; |
}; |
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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); |
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#endif /* _LINUX_SCATTERLIST_H */ |