crypto: caam - set RDB bit in security configuration register

This change is required for post SEC-5.0 devices which have RNG4.
Setting RDB in security configuration register allows CAAM to use the
"Random Data Buffer" to be filled by a single request. The Random Data
Buffer is large enough for ten packets to get their IVs from a single
request. If the Random Data Buffer is not enabled, then each IV causes a
separate request, and RNG4 hardware cannot keep up resulting in lower
IPSEC throughput if random IVs are used.
Signed-off-by: NVakul Garg <vakul@freescale.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/caam/ctrl.c

@@ -304,6 +304,9 @@ static int caam_probe(struct platform_device *pdev)
 			caam_remove(pdev);
 			return ret;
 		}
+
+		/* Enable RDB bit so that RNG works faster */
+		setbits32(&topregs->ctrl.scfgr, SCFGR_RDBENABLE);
 	}
 
 	/* NOTE: RTIC detection ought to go here, around Si time */

drivers/crypto/caam/regs.h

@@ -252,7 +252,8 @@ struct caam_ctrl {
 	/* Read/Writable					        */
 	u32 rsvd1;
 	u32 mcr;		/* MCFG      Master Config Register  */
-	u32 rsvd2[2];
+	u32 rsvd2;
+	u32 scfgr;		/* SCFGR, Security Config Register */
 
 	/* Bus Access Configuration Section			010-11f */
 	/* Read/Writable                                                */
@@ -299,6 +300,7 @@ struct caam_ctrl {
 #define MCFGR_WDFAIL		0x20000000 /* DECO watchdog force-fail */
 #define MCFGR_DMA_RESET		0x10000000
 #define MCFGR_LONG_PTR		0x00010000 /* Use >32-bit desc addressing */
+#define SCFGR_RDBENABLE		0x00000400
 
 /* AXI read cache control */
 #define MCFGR_ARCACHE_SHIFT	12