linux-kernel - [PATCH 3/5] hwrng: stm32 - allow disable clock error detection

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Message-ID: <20180129170521.1862-4-lionel.debieve@st.com>
Date:   Mon, 29 Jan 2018 18:05:19 +0100
From:   Lionel Debieve <lionel.debieve@...com>
To:     Matt Mackall <mpm@...enic.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        <linux-crypto@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
CC:     Benjamin Gaignard <benjamin.gaignard@...com>,
        Ludovic Barre <ludovic.barre@...com>
Subject: [PATCH 3/5] 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@...com>
---
 drivers/char/hw_random/stm32-rng.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/stm32-rng.c
index 83c695938a2d..709a8d061be3 100644
--- 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),
-- 
2.15.1