crypto: ahash - Add init_tfm/exit_tfm

This patch adds the type-safe init_tfm/exit_tfm functions to the
ahash interface.  This is meant to replace the unsafe cra_init and
cra_exit interface.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

include/crypto/hash.h

@@ -123,6 +123,17 @@ struct ahash_request {
  *	    data so the transformation can continue from this point onward. No
  *	    data processing happens at this point. Driver must not use
  *	    req->result.
+ * @init_tfm: Initialize the cryptographic transformation object.
+ *	      This function is called only once at the instantiation
+ *	      time, right after the transformation context was
+ *	      allocated. In case the cryptographic hardware has
+ *	      some special requirements which need to be handled
+ *	      by software, this function shall check for the precise
+ *	      requirement of the transformation and put any software
+ *	      fallbacks in place.
+ * @exit_tfm: Deinitialize the cryptographic transformation object.
+ *	      This is a counterpart to @init_tfm, used to remove
+ *	      various changes set in @init_tfm.
  * @halg: see struct hash_alg_common
  */
 struct ahash_alg {
@@ -135,6 +146,8 @@ struct ahash_alg {
 	int (*import)(struct ahash_request *req, const void *in);
 	int (*setkey)(struct crypto_ahash *tfm, const u8 *key,
 		      unsigned int keylen);
+	int (*init_tfm)(struct crypto_ahash *tfm);
+	void (*exit_tfm)(struct crypto_ahash *tfm);
 
 	struct hash_alg_common halg;
 };