hwrng: stm32 - allow disable clock error detection

Add a new property that allow to disable the clock error
detection which is required when the clock source selected
is out of specification (which is not mandatory).

Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/stm32-rng.c
index 83c6959..709a8d0 100644 (file)
--- a/drivers/char/hw_random/stm32-rng.c
+++ b/drivers/char/hw_random/stm32-rng.c
@@ -26,6 +26,7 @@
 
 #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)
@@ -48,6 +49,7 @@ struct stm32_rng_private {
        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)
@@ -101,7 +103,11 @@ 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);
@@ -149,6 +155,8 @@ static int stm32_rng_probe(struct platform_device *ofdev)
                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),