drivers/crypto/fsl: 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.

Signed-off-by: Alex Porosanu <alexandru.porosanu@freescale.com>
Acked-by: Ruchika Gupta<ruchika.gupta@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>

diff --git a/include/fsl_sec.h b/include/fsl_sec.h
index 6ad5262b278acc820642110ec4975ee955ccf101..addb39b95f264d79d28bba72f81ea3fbda76c078 100644 (file)
--- a/include/fsl_sec.h
+++ b/include/fsl_sec.h
@@ -35,7 +35,7 @@ struct rng4tst {
        u32 rtmctl;             /* misc. control register */
        u32 rtscmisc;           /* statistical check misc. register */
        u32 rtpkrrng;           /* poker range register */
-#define RTSDCTL_ENT_DLY_MIN    1200
+#define RTSDCTL_ENT_DLY_MIN    3200
 #define RTSDCTL_ENT_DLY_MAX    12800
        union {
                u32 rtpkrmax;   /* PRGM=1: poker max. limit register */