From f5dad36954c74f831b962996a611e58221605b1b Mon Sep 17 00:00:00 2001
From: Alex Porosanu <alexandru.porosanu@freescale.com>
Date: Mon, 11 Aug 2014 11:40:16 +0300
Subject: crypto: caam - change starting entropy delay value

The entropy delay (the length in system clocks of each
entropy sample) for the RNG4 block of CAAM is dependent
on the frequency of the SoC. By elaborate methods, it
has been determined that a good starting value for all
platforms integrating the CAAM IP is 3200. Using a
higher value has additional benefit of  speeding up
the process of instantiating the RNG, since the entropy
delay will be increased and instantiation of the RNG
state handles will be reattempted by the driver. If the
starting value is low, for certain platforms, this can
lead to a quite lengthy process.
This patch changes the starting value of the length of
the entropy sample to 3200 system clocks.
In addition to this change, the attempted entropy delay
values are now printed on the console upon initialization
of the RNG block.
While here, a safeguard for yielding the processor was
added for ensuring that in very adverse cases,
the CPU isn't hogged by the instantiation loop.

Signed-off-by: Alex Porosanu <alexandru.porosanu@freescale.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
(cherry picked from commit eeaa1724a2e9c8958a8621b3c10d5ca0667e78fa)

Conflicts:
	drivers/crypto/caam/ctrl.c

Change-Id: Ibc271d629cef3cab291ac8e5c8e7b68b0dc7c1e3
Reviewed-on: http://git.am.freescale.net:8181/23840
Tested-by: Review Code-CDREVIEW <CDREVIEW@freescale.com>
Reviewed-by: Horia Ioan Geanta Neag <horia.geanta@freescale.com>
Reviewed-by: Matthew Weigel <Matthew.Weigel@freescale.com>

diff --git a/drivers/crypto/caam/ctrl.c b/drivers/crypto/caam/ctrl.c
index c2f1fd7..e662376 100644
--- a/drivers/crypto/caam/ctrl.c
+++ b/drivers/crypto/caam/ctrl.c
@@ -421,6 +421,9 @@ static int caam_rng_init(struct device *dev)
 			 * the TRNG parameters.
 			 */
 			if (!(ctrlpriv->rng4_sh_init || inst_handles)) {
+					dev_info(dev,
+						 "Entropy delay = %u\n",
+						 ent_delay);
 				kick_trng(dev, ent_delay);
 				ent_delay += 400;
 			}
@@ -433,6 +436,12 @@ static int caam_rng_init(struct device *dev)
 			 */
 			ret = instantiate_rng(dev, inst_handles,
 					      gen_sk);
+			if (ret == -EAGAIN)
+				/*
+				 * if here, the loop will rerun,
+				 * so don't hog the CPU
+				 */
+				cpu_relax();
 		} while ((ret == -EAGAIN) && (ent_delay < RTSDCTL_ENT_DLY_MAX));
 		if (ret) {
 			dev_err(dev, "failed to instantiate RNG");
diff --git a/drivers/crypto/caam/regs.h b/drivers/crypto/caam/regs.h
index dde2e1a..6b62a6c 100644
--- a/drivers/crypto/caam/regs.h
+++ b/drivers/crypto/caam/regs.h
@@ -286,7 +286,7 @@ struct rng4tst {
 	};
 #define RTSDCTL_ENT_DLY_SHIFT 16
 #define RTSDCTL_ENT_DLY_MASK (0xffff << RTSDCTL_ENT_DLY_SHIFT)
-#define RTSDCTL_ENT_DLY_MIN 1200
+#define RTSDCTL_ENT_DLY_MIN 3200
 #define RTSDCTL_ENT_DLY_MAX 12800
 	u32 rtsdctl;		/* seed control register */
 	union {
-- 
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