diff options
Diffstat (limited to 'drivers/char/hw_random/stm32-rng.c')
| -rw-r--r-- | drivers/char/hw_random/stm32-rng.c | 44 |
1 files changed, 28 insertions, 16 deletions
diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/stm32-rng.c index 63d84e6f1891..0d2328da3b76 100644 --- a/drivers/char/hw_random/stm32-rng.c +++ b/drivers/char/hw_random/stm32-rng.c @@ -16,15 +16,18 @@ #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> #include <linux/of_platform.h> #include <linux/pm_runtime.h> +#include <linux/reset.h> #include <linux/slab.h> #define RNG_CR 0x00 #define RNG_CR_RNGEN BIT(2) +#define RNG_CR_CED BIT(5) #define RNG_SR 0x04 #define RNG_SR_SEIS BIT(6) @@ -33,19 +36,12 @@ #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; struct clk *clk; + struct reset_control *rst; + bool ced; }; static int stm32_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) @@ -59,13 +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... */ @@ -99,7 +98,11 @@ static int stm32_rng_init(struct hwrng *rng) if (err) return err; - writel_relaxed(RNG_CR_RNGEN, priv->base + RNG_CR); + if (priv->ced) + writel_relaxed(RNG_CR_RNGEN, priv->base + RNG_CR); + else + writel_relaxed(RNG_CR_RNGEN | RNG_CR_CED, + priv->base + RNG_CR); /* clear error indicators */ writel_relaxed(0, priv->base + RNG_SR); @@ -140,6 +143,15 @@ static int stm32_rng_probe(struct platform_device *ofdev) if (IS_ERR(priv->clk)) return PTR_ERR(priv->clk); + priv->rst = devm_reset_control_get(&ofdev->dev, NULL); + if (!IS_ERR(priv->rst)) { + reset_control_assert(priv->rst); + udelay(2); + reset_control_deassert(priv->rst); + } + + priv->ced = of_property_read_bool(np, "clock-error-detect"); + dev_set_drvdata(dev, priv); priv->rng.name = dev_driver_string(dev), |