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From:   Lionel Debieve <lionel.debieve@st.com>
To:     Matt Mackall <mpm@selenic.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Alexandre Torgue <alexandre.torgue@st.com>,
        <linux-crypto@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>
CC:     Benjamin Gaignard <benjamin.gaignard@st.com>,
        Ludovic Barre <ludovic.barre@st.com>
Subject: [PATCH 1/5] hwrng: stm32 - add reset during probe
Date:   Mon, 29 Jan 2018 18:05:17 +0100
Message-ID: <20180129170521.1862-2-lionel.debieve@st.com>
In-Reply-To: <20180129170521.1862-1-lionel.debieve@st.com>
References: <20180129170521.1862-1-lionel.debieve@st.com>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Avoid issue when probing the RNG without
reset if bad status has been detected previously

Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
---
 drivers/char/hw_random/stm32-rng.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/stm32-rng.c
index 63d84e6f1891..83c695938a2d 100644
--- a/drivers/char/hw_random/stm32-rng.c
+++ b/drivers/char/hw_random/stm32-rng.c
@@ -21,6 +21,7 @@
 #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
@@ -46,6 +47,7 @@ struct stm32_rng_private {
 	struct hwrng rng;
 	void __iomem *base;
 	struct clk *clk;
+	struct reset_control *rst;
 };
 
 static int stm32_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
@@ -140,6 +142,13 @@ 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);
+	}
+
 	dev_set_drvdata(dev, priv);
 
 	priv->rng.name = dev_driver_string(dev),
-- 
2.15.1