From 257aff515409f9455edff3a946344e71baf9e116 Mon Sep 17 00:00:00 2001 From: Joel Fernandes Date: Sat, 17 Aug 2013 21:42:22 -0500 Subject: 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 Signed-off-by: Herbert Xu --- crypto/scatterwalk.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'crypto') diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c index 7281b8a93ad3..79ca2278c2a3 100644 --- a/crypto/scatterwalk.c +++ b/crypto/scatterwalk.c @@ -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); -- cgit v1.2.3-59-g8ed1b