crypto: cryptd - Add support to access underlying blkcipher

cryptd_alloc_ablkcipher() will allocate a cryptd-ed ablkcipher for
specified algorithm name. The new allocated one is guaranteed to be
cryptd-ed ablkcipher, so the blkcipher underlying can be gotten via
cryptd_ablkcipher_child().

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/include/crypto/cryptd.h b/include/crypto/cryptd.h
new file mode 100644
index 0000000..55fa7bb
--- /dev/null
+++ b/include/crypto/cryptd.h
@@ -0,0 +1,27 @@
+/*
+ * Software async crypto daemon
+ */
+
+#ifndef _CRYPTO_CRYPT_H
+#define _CRYPTO_CRYPT_H
+
+#include <linux/crypto.h>
+#include <linux/kernel.h>
+
+struct cryptd_ablkcipher {
+	struct crypto_ablkcipher base;
+};
+
+static inline struct cryptd_ablkcipher *__cryptd_ablkcipher_cast(
+	struct crypto_ablkcipher *tfm)
+{
+	return (struct cryptd_ablkcipher *)tfm;
+}
+
+/* alg_name should be algorithm to be cryptd-ed */
+struct cryptd_ablkcipher *cryptd_alloc_ablkcipher(const char *alg_name,
+						  u32 type, u32 mask);
+struct crypto_blkcipher *cryptd_ablkcipher_child(struct cryptd_ablkcipher *tfm);
+void cryptd_free_ablkcipher(struct cryptd_ablkcipher *tfm);
+
+#endif