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crypto: scatterwalk - Add support for calculating number of SG elements 

Crypto layer only passes nbytes to encrypt but in omap-aes driver we need to
know number of SG elements to pass to dmaengine slave API.  We add function for
the same to scatterwalk library.

Signed-off-by: Joel Fernandes <joelf@ti.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Joel Fernandes 2013-08-17 21:42:22 -05:00 committed by Herbert Xu
parent b4eba0ca34
commit 257aff5154
2 changed files with 24 additions and 0 deletions
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22
crypto/scatterwalk.c
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@ -124,3 +124,25 @@ void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
scatterwalk_done(&walk, out, 0);
}
EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy);
int scatterwalk_bytes_sglen(struct scatterlist *sg, int num_bytes)
{
int offset = 0, n = 0;
/* num_bytes is too small */
if (num_bytes < sg->length)
return -1;
do {
offset += sg->length;
n++;
sg = scatterwalk_sg_next(sg);
/* num_bytes is too large */
if (unlikely(!sg && (num_bytes < offset)))
return -1;
} while (sg && (num_bytes > offset));
return n;
}
EXPORT_SYMBOL_GPL(scatterwalk_bytes_sglen);

2
include/crypto/scatterwalk.h
View File

@ -113,4 +113,6 @@ void scatterwalk_done(struct scatter_walk *walk, int out, int more);
void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg,
unsigned int start, unsigned int nbytes, int out);
int scatterwalk_bytes_sglen(struct scatterlist *sg, int num_bytes);
#endif /* _CRYPTO_SCATTERWALK_H */