crypto: xts: add interface for parallelized cipher implementations

Add xts_crypt() function that can be used by cipher implementations that can
benefit from parallelized cipher operations.

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/include/crypto/xts.h b/include/crypto/xts.h
new file mode 100644
index 0000000..72c09eb
--- /dev/null
+++ b/include/crypto/xts.h
@@ -0,0 +1,27 @@
+#ifndef _CRYPTO_XTS_H
+#define _CRYPTO_XTS_H
+
+#include <crypto/b128ops.h>
+
+struct scatterlist;
+struct blkcipher_desc;
+
+#define XTS_BLOCK_SIZE 16
+
+struct xts_crypt_req {
+	be128 *tbuf;
+	unsigned int tbuflen;
+
+	void *tweak_ctx;
+	void (*tweak_fn)(void *ctx, u8* dst, const u8* src);
+	void *crypt_ctx;
+	void (*crypt_fn)(void *ctx, u8 *blks, unsigned int nbytes);
+};
+
+#define XTS_TWEAK_CAST(x) ((void (*)(void *, u8*, const u8*))(x))
+
+int xts_crypt(struct blkcipher_desc *desc, struct scatterlist *dst,
+	      struct scatterlist *src, unsigned int nbytes,
+	      struct xts_crypt_req *req);
+
+#endif  /* _CRYPTO_XTS_H */