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 4c08efe..2fc6dd5 100644 (file)
--- a/drivers/char/hw_random/bcm2835-rng.c
+++ b/drivers/char/hw_random/bcm2835-rng.c
@@ -105,8 +105,10 @@ static int bcm2835_rng_init(struct hwrng *rng)
        }
 
        /* set warm-up count & enable */
-       rng_writel(priv, RNG_WARMUP_COUNT, RNG_STATUS);
-       rng_writel(priv, RNG_RBGEN, RNG_CTRL);
+       if (!(rng_readl(priv, RNG_CTRL) & RNG_RBGEN)) {
+               rng_writel(priv, RNG_WARMUP_COUNT, RNG_STATUS);
+               rng_writel(priv, RNG_RBGEN, RNG_CTRL);
+       }
 
        return ret;
 }