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

[Florian Fainelli]

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.faine...@gmail.com>
---
 drivers/char/hw_random/bcm2835-rng.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/char/hw_random/bcm2835-rng.c 
b/drivers/char/hw_random/bcm2835-rng.c
index ed20e0b6b7ae..35928efb52e7 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)
@@ -67,6 +69,11 @@ static int bcm2835_rng_init(struct hwrng *rng)
 {
        struct bcm2835_rng_priv *priv = to_rng_priv(rng);
        u32 val;
+       int ret;
+
+       ret = clk_prepare_enable(priv->clk);
+       if (ret)
+               return ret;
 
        if (priv->mask_interrupts) {
                /* mask the interrupt */
@@ -88,6 +95,8 @@ static void bcm2835_rng_cleanup(struct hwrng *rng)
 
        /* disable rng hardware */
        __raw_writel(0, priv->base + RNG_CTRL);
+
+       clk_disable_unprepare(priv->clk);
 }
 
 struct bcm2835_rng_of_data {
@@ -130,6 +139,11 @@ 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);
+       if (IS_ERR(priv->clk))
+               priv->clk = NULL;
+
        priv->rng.name = "bcm2835-rng";
        priv->rng.init = bcm2835_rng_init;
        priv->rng.read = bcm2835_rng_read;
-- 
2.9.3