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From b7791eea502e0d98ae204750aff2abafc431fb11 Mon Sep 17 00:00:00 2001
From: popcornmix <popcornmix@gmail.com>
Date: Tue, 6 Dec 2016 17:05:39 +0000
Subject: [PATCH] bcm2835-rng: Avoid initialising if already enabled
Avoids the 0x40000 cycles of warmup again if firmware has already used it
---
drivers/char/hw_random/bcm2835-rng.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- a/drivers/char/hw_random/bcm2835-rng.c
+++ b/drivers/char/hw_random/bcm2835-rng.c
@@ -62,9 +62,10 @@ static int bcm2835_rng_probe(struct plat
bcm2835_rng_ops.priv = (unsigned long)rng_base;
/* set warm-up count & enable */
- __raw_writel(RNG_WARMUP_COUNT, rng_base + RNG_STATUS);
- __raw_writel(RNG_RBGEN, rng_base + RNG_CTRL);
-
+ if (!(__raw_readl(rng_base + RNG_CTRL) & RNG_RBGEN)) {
+ __raw_writel(RNG_WARMUP_COUNT, rng_base + RNG_STATUS);
+ __raw_writel(RNG_RBGEN, rng_base + RNG_CTRL);
+ }
/* register driver */
err = hwrng_register(&bcm2835_rng_ops);
if (err) {
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