diff options
Diffstat (limited to 'drivers/char/hw_random/stm32-rng.c')
| -rw-r--r-- | drivers/char/hw_random/stm32-rng.c | 25 |
1 files changed, 10 insertions, 15 deletions
diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/stm32-rng.c index 709a8d061be3..0d2328da3b76 100644 --- a/drivers/char/hw_random/stm32-rng.c +++ b/drivers/char/hw_random/stm32-rng.c @@ -16,6 +16,7 @@ #include <linux/delay.h> #include <linux/hw_random.h> #include <linux/io.h> +#include <linux/iopoll.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/of_address.h> @@ -35,15 +36,6 @@ #define RNG_DR 0x08 -/* - * It takes 40 cycles @ 48MHz to generate each random number (e.g. <1us). - * At the time of writing STM32 parts max out at ~200MHz meaning a timeout - * of 500 leaves us a very comfortable margin for error. The loop to which - * the timeout applies takes at least 4 instructions per iteration so the - * timeout is enough to take us up to multi-GHz parts! - */ -#define RNG_TIMEOUT 500 - struct stm32_rng_private { struct hwrng rng; void __iomem *base; @@ -63,13 +55,16 @@ static int stm32_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) while (max > sizeof(u32)) { sr = readl_relaxed(priv->base + RNG_SR); + /* Manage timeout which is based on timer and take */ + /* care of initial delay time when enabling rng */ if (!sr && wait) { - unsigned int timeout = RNG_TIMEOUT; - - do { - cpu_relax(); - sr = readl_relaxed(priv->base + RNG_SR); - } while (!sr && --timeout); + retval = readl_relaxed_poll_timeout_atomic(priv->base + + RNG_SR, + sr, sr, + 10, 50000); + if (retval) + dev_err((struct device *)priv->rng.priv, + "%s: timeout %x!\n", __func__, sr); } /* If error detected or data not ready... */ |