crypto: s390 - add System z hardware support for GHASH

This patch adds System z hardware acceleration support for the GHASH
algorithm for GCM (Galois/Counter Mode).
The hardware support is available beginning with System z196.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/drivers/crypto/Kconfig b/drivers/crypto/Kconfig
index 78df36a..d459cc78 100644
--- a/drivers/crypto/Kconfig
+++ b/drivers/crypto/Kconfig
@@ -151,6 +151,16 @@
 	  ANSI X9.17 standard. The PRNG is usable via the char device
 	  /dev/prandom.
 
+config CRYPTO_GHASH_S390
+	tristate "GHASH digest algorithm"
+	depends on S390
+	select CRYPTO_HASH
+	help
+	  This is the s390 hardware accelerated implementation of the
+	  GHASH message digest algorithm for GCM (Galois/Counter Mode).
+
+	  It is available as of z196.
+
 config CRYPTO_DEV_MV_CESA
 	tristate "Marvell's Cryptographic Engine"
 	depends on PLAT_ORION