linux-kernel - [PATCH v2 07/12] hwrng: bcm2835-rng: Manage an optional clock

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Date:   Tue,  7 Nov 2017 16:44:44 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Matt Mackall <mpm@...enic.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Ray Jui <rjui@...adcom.com>,
        Scott Branden <sbranden@...adcom.com>,
        bcm-kernel-feedback-list@...adcom.com (maintainer:BROADCOM
        BCM281XX/BCM11XXX/BCM216XX ARM ARCHITE...),
        Eric Anholt <eric@...olt.net>,
        Stefan Wahren <stefan.wahren@...e.com>,
        PrasannaKumar Muralidharan <prasannatsmkumar@...il.com>,
        Russell King <rmk+kernel@...linux.org.uk>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Harald Freudenberger <freude@...ux.vnet.ibm.com>,
        Sean Wang <sean.wang@...iatek.com>,
        Martin Kaiser <martin@...ser.cx>,
        Steffen Trumtrar <s.trumtrar@...gutronix.de>,
        linux-crypto@...r.kernel.org (open list:HARDWARE RANDOM NUMBER
        GENERATOR CORE),
        devicetree@...r.kernel.org (open list:OPEN FIRMWARE AND FLATTENED
        DEVICE TREE BINDINGS),
        linux-rpi-kernel@...ts.infradead.org (moderated list:BROADCOM BCM2835
        ARM ARCHITECTURE),
        linux-arm-kernel@...ts.infradead.org (moderated list:BROADCOM BCM2835
        ARM ARCHITECTURE)
Subject: [PATCH v2 07/12] hwrng: bcm2835-rng: Manage an optional clock

One of the last steps before bcm63xx-rng can be eliminated is to manage
a clock during hwrng::init and hwrng::cleanup, so fetch it in the probe
function, and manage it during these two steps when valid.

Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
---
 drivers/char/hw_random/bcm2835-rng.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/char/hw_random/bcm2835-rng.c b/drivers/char/hw_random/bcm2835-rng.c
index ed20e0b6b7ae..99b56fd5482c 100644
--- a/drivers/char/hw_random/bcm2835-rng.c
+++ b/drivers/char/hw_random/bcm2835-rng.c
@@ -15,6 +15,7 @@
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/printk.h>
+#include <linux/clk.h>
 
 #define RNG_CTRL	0x0
 #define RNG_STATUS	0x4
@@ -33,6 +34,7 @@ struct bcm2835_rng_priv {
 	struct hwrng rng;
 	void __iomem *base;
 	bool mask_interrupts;
+	struct clk *clk;
 };
 
 static inline struct bcm2835_rng_priv *to_rng_priv(struct hwrng *rng)
@@ -66,8 +68,15 @@ static int bcm2835_rng_read(struct hwrng *rng, void *buf, size_t max,
 static int bcm2835_rng_init(struct hwrng *rng)
 {
 	struct bcm2835_rng_priv *priv = to_rng_priv(rng);
+	int ret = 0;
 	u32 val;
 
+	if (!IS_ERR(priv->clk)) {
+		ret = clk_prepare_enable(priv->clk);
+		if (ret)
+			return ret;
+	}
+
 	if (priv->mask_interrupts) {
 		/* mask the interrupt */
 		val = readl(priv->base + RNG_INT_MASK);
@@ -79,7 +88,7 @@ static int bcm2835_rng_init(struct hwrng *rng)
 	__raw_writel(RNG_WARMUP_COUNT, priv->base + RNG_STATUS);
 	__raw_writel(RNG_RBGEN, priv->base + RNG_CTRL);
 
-	return 0;
+	return ret;
 }
 
 static void bcm2835_rng_cleanup(struct hwrng *rng)
@@ -88,6 +97,9 @@ static void bcm2835_rng_cleanup(struct hwrng *rng)
 
 	/* disable rng hardware */
 	__raw_writel(0, priv->base + RNG_CTRL);
+
+	if (!IS_ERR(priv->clk))
+		clk_disable_unprepare(priv->clk);
 }
 
 struct bcm2835_rng_of_data {
@@ -130,6 +142,9 @@ static int bcm2835_rng_probe(struct platform_device *pdev)
 		return PTR_ERR(priv->base);
 	}
 
+	/* Clock is optional on most platforms */
+	priv->clk = devm_clk_get(dev, NULL);
+
 	priv->rng.name = "bcm2835-rng";
 	priv->rng.init = bcm2835_rng_init;
 	priv->rng.read = bcm2835_rng_read;
-- 
2.9.3