From: Matt Porter Date: Thu, 10 Apr 2014 19:22:10 +0000 (-0400) Subject: hwrng: bcm2835 - fix oops when rng h/w is accessed during registration X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=eb4a5346e777784f1b5ae9fd0c29b96344bdc3ae;p=linux-beck.git hwrng: bcm2835 - fix oops when rng h/w is accessed during registration Commit "d9e7972 hwrng: add randomness to system from rng sources" exposed a bug in the bcm2835-rng driver resulting in boot failure on Raspberry Pi due to the following oops: [ 28.261523] BUG: soft lockup - CPU#0 stuck for 23s! [swapper:1] [ 28.271058] [ 28.275958] CPU: 0 PID: 1 Comm: swapper Not tainted 3.14.0+ #11 [ 28.285374] task: db480000 ti: db484000 task.ti: db484000 [ 28.294279] PC is at bcm2835_rng_read+0x28/0x48 [ 28.302276] LR is at hwrng_register+0x1a8/0x238 . . . The RNG h/w is not completely initialized and enabled before hwrng_register() is called and so the bcm2835_rng_read() fails. Fix this by making the warmup/enable writes before registering the RNG source with the hwrng core. Signed-off-by: Matt Porter Signed-off-by: Herbert Xu --- diff --git a/drivers/char/hw_random/bcm2835-rng.c b/drivers/char/hw_random/bcm2835-rng.c index 8c3b255e629a..e900961cdd2e 100644 --- a/drivers/char/hw_random/bcm2835-rng.c +++ b/drivers/char/hw_random/bcm2835-rng.c @@ -61,18 +61,18 @@ static int bcm2835_rng_probe(struct platform_device *pdev) } 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); + /* register driver */ err = hwrng_register(&bcm2835_rng_ops); if (err) { dev_err(dev, "hwrng registration failed\n"); iounmap(rng_base); - } else { + } else dev_info(dev, "hwrng registered\n"); - /* set warm-up count & enable */ - __raw_writel(RNG_WARMUP_COUNT, rng_base + RNG_STATUS); - __raw_writel(RNG_RBGEN, rng_base + RNG_CTRL); - } return err; }