crypto: lrw - add interface for parallelized cipher implementions

Export gf128mul table initialization routines and add lrw_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>

include/crypto/lrw.h

@@ -0,0 +1,43 @@
+#ifndef _CRYPTO_LRW_H
+#define _CRYPTO_LRW_H
+
+#include <crypto/b128ops.h>
+
+struct scatterlist;
+struct gf128mul_64k;
+struct blkcipher_desc;
+
+#define LRW_BLOCK_SIZE 16
+
+struct lrw_table_ctx {
+	/* optimizes multiplying a random (non incrementing, as at the
+	 * start of a new sector) value with key2, we could also have
+	 * used 4k optimization tables or no optimization at all. In the
+	 * latter case we would have to store key2 here */
+	struct gf128mul_64k *table;
+	/* stores:
+	 *  key2*{ 0,0,...0,0,0,0,1 }, key2*{ 0,0,...0,0,0,1,1 },
+	 *  key2*{ 0,0,...0,0,1,1,1 }, key2*{ 0,0,...0,1,1,1,1 }
+	 *  key2*{ 0,0,...1,1,1,1,1 }, etc
+	 * needed for optimized multiplication of incrementing values
+	 * with key2 */
+	be128 mulinc[128];
+};
+
+int lrw_init_table(struct lrw_table_ctx *ctx, const u8 *tweak);
+void lrw_free_table(struct lrw_table_ctx *ctx);
+
+struct lrw_crypt_req {
+	be128 *tbuf;
+	unsigned int tbuflen;
+
+	struct lrw_table_ctx *table_ctx;
+	void *crypt_ctx;
+	void (*crypt_fn)(void *ctx, u8 *blks, unsigned int nbytes);
+};
+
+int lrw_crypt(struct blkcipher_desc *desc, struct scatterlist *dst,
+	      struct scatterlist *src, unsigned int nbytes,
+	      struct lrw_crypt_req *req);
+
+#endif  /* _CRYPTO_LRW_H */