[S390] zcrypt: add support for large random numbers

This patch allows user space applications to access large amounts of
truly random data. The random data source is the build-in hardware
random number generator on the CEX2C cards.

Signed-off-by: Ralph Wuerthner <rwuerthn@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
diff --git a/drivers/s390/crypto/zcrypt_api.h b/drivers/s390/crypto/zcrypt_api.h
index de4877e..0e94852 100644
--- a/drivers/s390/crypto/zcrypt_api.h
+++ b/drivers/s390/crypto/zcrypt_api.h
@@ -100,6 +100,13 @@
 #define ZCRYPT_CEX2C		5
 #define ZCRYPT_CEX2A		6
 
+/**
+ * Large random numbers are pulled in 4096 byte chunks from the crypto cards
+ * and stored in a page. Be carefull when increasing this buffer due to size
+ * limitations for AP requests.
+ */
+#define ZCRYPT_RNG_BUFFER_SIZE	4096
+
 struct zcrypt_device;
 
 struct zcrypt_ops {
@@ -107,6 +114,7 @@
 	long (*rsa_modexpo_crt)(struct zcrypt_device *,
 				struct ica_rsa_modexpo_crt *);
 	long (*send_cprb)(struct zcrypt_device *, struct ica_xcRB *);
+	long (*rng)(struct zcrypt_device *, char *);
 };
 
 struct zcrypt_device {