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Date: Mon, 12 Jun 2023 10:30:42 +0200
From: meenakshi.aggarwal@....com
To: horia.geanta@....com, V.sethi@....com, pankaj.gupta@....com,
gaurav.jain@....com, herbert@...dor.apana.org.au,
davem@...emloft.net, linux-crypto@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Meenakshi Aggarwal <meenakshi.aggarwal@....com>
Subject: [PATCH] crypto: caam - optimize RNG sample size
From: Meenakshi Aggarwal <meenakshi.aggarwal@....com>
TRNG "sample size" (the total number of entropy samples that will be taken
during entropy generation) default / POR value is very conservatively
set to 2500.
Let's set it to 512, the same as the caam driver in U-boot
(drivers/crypto/fsl_caam.c) does.
This solves the issue of RNG performance dropping after a suspend/resume
cycle on parts where caam loses power, since the initial U-boot setttings
are lost and kernel does not restore them when resuming.
Note: when changing the sample size, the self-test parameters need to be
updated accordingly.
Signed-off-by: Horia Geantă <horia.geanta@....com>
Signed-off-by: Meenakshi Aggarwal <meenakshi.aggarwal@....com>
---
drivers/crypto/caam/ctrl.c | 52 +++++++++++++++++++++++---------------
drivers/crypto/caam/regs.h | 14 ++++++++--
2 files changed, 44 insertions(+), 22 deletions(-)
diff --git a/drivers/crypto/caam/ctrl.c b/drivers/crypto/caam/ctrl.c
index 62dd069942e4..b06bb64c6c23 100644
--- a/drivers/crypto/caam/ctrl.c
+++ b/drivers/crypto/caam/ctrl.c
@@ -352,7 +352,7 @@ static void kick_trng(struct device *dev, int ent_delay)
struct caam_drv_private *ctrlpriv = dev_get_drvdata(dev);
struct caam_ctrl __iomem *ctrl;
struct rng4tst __iomem *r4tst;
- u32 val;
+ u32 val, rtsdctl;
ctrl = (struct caam_ctrl __iomem *)ctrlpriv->ctrl;
r4tst = &ctrl->r4tst[0];
@@ -368,26 +368,38 @@ static void kick_trng(struct device *dev, int ent_delay)
* Performance-wise, it does not make sense to
* set the delay to a value that is lower
* than the last one that worked (i.e. the state handles
- * were instantiated properly. Thus, instead of wasting
- * time trying to set the values controlling the sample
- * frequency, the function simply returns.
+ * were instantiated properly).
*/
- val = (rd_reg32(&r4tst->rtsdctl) & RTSDCTL_ENT_DLY_MASK)
- >> RTSDCTL_ENT_DLY_SHIFT;
- if (ent_delay <= val)
- goto start_rng;
-
- val = rd_reg32(&r4tst->rtsdctl);
- val = (val & ~RTSDCTL_ENT_DLY_MASK) |
- (ent_delay << RTSDCTL_ENT_DLY_SHIFT);
- wr_reg32(&r4tst->rtsdctl, val);
- /* min. freq. count, equal to 1/4 of the entropy sample length */
- wr_reg32(&r4tst->rtfrqmin, ent_delay >> 2);
- /* max. freq. count, equal to 16 times the entropy sample length */
- wr_reg32(&r4tst->rtfrqmax, ent_delay << 4);
- /* read the control register */
- val = rd_reg32(&r4tst->rtmctl);
-start_rng:
+ rtsdctl = rd_reg32(&r4tst->rtsdctl);
+ val = (rtsdctl & RTSDCTL_ENT_DLY_MASK) >> RTSDCTL_ENT_DLY_SHIFT;
+ if (ent_delay > val) {
+ val = ent_delay;
+ /* min. freq. count, equal to 1/4 of the entropy sample length */
+ wr_reg32(&r4tst->rtfrqmin, val >> 2);
+ /* max. freq. count, equal to 16 times the entropy sample length */
+ wr_reg32(&r4tst->rtfrqmax, val << 4);
+ }
+
+ wr_reg32(&r4tst->rtsdctl, (val << RTSDCTL_ENT_DLY_SHIFT) |
+ RTSDCTL_SAMP_SIZE_VAL);
+
+ /*
+ * To avoid reprogramming the self-test parameters over and over again,
+ * use RTSDCTL[SAMP_SIZE] as an indicator.
+ */
+ if ((rtsdctl & RTSDCTL_SAMP_SIZE_MASK) != RTSDCTL_SAMP_SIZE_VAL) {
+ wr_reg32(&r4tst->rtscmisc, (2 << 16) | 32);
+ wr_reg32(&r4tst->rtpkrrng, 570);
+ wr_reg32(&r4tst->rtpkrmax, 1600);
+ wr_reg32(&r4tst->rtscml, (122 << 16) | 317);
+ wr_reg32(&r4tst->rtscrl[0], (80 << 16) | 107);
+ wr_reg32(&r4tst->rtscrl[1], (57 << 16) | 62);
+ wr_reg32(&r4tst->rtscrl[2], (39 << 16) | 39);
+ wr_reg32(&r4tst->rtscrl[3], (27 << 16) | 26);
+ wr_reg32(&r4tst->rtscrl[4], (19 << 16) | 18);
+ wr_reg32(&r4tst->rtscrl[5], (18 << 16) | 17);
+ }
+
/*
* select raw sampling in both entropy shifter
* and statistical checker; ; put RNG4 into run mode
diff --git a/drivers/crypto/caam/regs.h b/drivers/crypto/caam/regs.h
index 66928f8a0c4b..189e74c21f0c 100644
--- a/drivers/crypto/caam/regs.h
+++ b/drivers/crypto/caam/regs.h
@@ -3,7 +3,7 @@
* CAAM hardware register-level view
*
* Copyright 2008-2011 Freescale Semiconductor, Inc.
- * Copyright 2018 NXP
+ * Copyright 2018, 2023 NXP
*/
#ifndef REGS_H
@@ -523,6 +523,8 @@ struct rng4tst {
#define RTSDCTL_ENT_DLY_MASK (0xffff << RTSDCTL_ENT_DLY_SHIFT)
#define RTSDCTL_ENT_DLY_MIN 3200
#define RTSDCTL_ENT_DLY_MAX 12800
+#define RTSDCTL_SAMP_SIZE_MASK 0xffff
+#define RTSDCTL_SAMP_SIZE_VAL 512
u32 rtsdctl; /* seed control register */
union {
u32 rtsblim; /* PRGM=1: sparse bit limit register */
@@ -534,7 +536,15 @@ struct rng4tst {
u32 rtfrqmax; /* PRGM=1: freq. count max. limit register */
u32 rtfrqcnt; /* PRGM=0: freq. count register */
};
- u32 rsvd1[40];
+ union {
+ u32 rtscmc; /* statistical check run monobit count */
+ u32 rtscml; /* statistical check run monobit limit */
+ };
+ union {
+ u32 rtscrc[6]; /* statistical check run length count */
+ u32 rtscrl[6]; /* statistical check run length limit */
+ };
+ u32 rsvd1[33];
#define RDSTA_SKVT 0x80000000
#define RDSTA_SKVN 0x40000000
#define RDSTA_PR0 BIT(4)
--
2.25.1
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