From: popcornmix <popcornmix@gmail.com>
Date: Tue, 6 Dec 2016 17:05:39 +0000 (+0000)
Subject: bcm2835-rng: Avoid initialising if already enabled
X-Git-Tag: archive/raspbian/4.9.82-1+deb9u3+rpi1_jessie~5^2~459
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=f8e64ce6cd1ff4a82280c6d85629e9d0e90403da;p=linux-4.9.git

bcm2835-rng: Avoid initialising if already enabled

Avoids the 0x40000 cycles of warmup again if firmware has already used it
---

diff --git a/drivers/char/hw_random/bcm2835-rng.c b/drivers/char/hw_random/bcm2835-rng.c
index 574211a49549..e66c0fca8c60 100644
--- a/drivers/char/hw_random/bcm2835-rng.c
+++ b/drivers/char/hw_random/bcm2835-rng.c
@@ -102,9 +102,10 @@ static int bcm2835_rng_probe(struct platform_device *pdev)
 		rng_setup(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) {