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 574211a495491d9d6021dcaefe4274a63ed02055..e66c0fca8c6090e32f72796c0877a1cf1d499fb6 100644 (file)
--- 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) {