[PATCH v3 4/4] hwrng: meson: add clock handling to driver

[Heiner Kallweit]

Add handling of RNG0 clock to the driver.

Signed-off-by: Heiner Kallweit <hkallwe...@gmail.com>
---
v2:
- consider that clock is optional
- use managed call to clk_disable_unprepare to ensure that
  cleaning up is done in the right order if driver is removed
v3:
- no changes
---
 drivers/char/hw_random/meson-rng.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/char/hw_random/meson-rng.c 
b/drivers/char/hw_random/meson-rng.c
index 119d6984..2e23be80 100644
--- a/drivers/char/hw_random/meson-rng.c
+++ b/drivers/char/hw_random/meson-rng.c
@@ -62,6 +62,7 @@
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/of.h>
+#include <linux/clk.h>
 
 #define RNG_DATA 0x00
 
@@ -69,6 +70,7 @@ struct meson_rng_data {
        void __iomem *base;
        struct platform_device *pdev;
        struct hwrng rng;
+       struct clk *core_clk;
 };
 
 static int meson_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
@@ -81,11 +83,17 @@ static int meson_rng_read(struct hwrng *rng, void *buf, 
size_t max, bool wait)
        return sizeof(u32);
 }
 
+static void meson_rng_clk_disable(void *data)
+{
+       clk_disable_unprepare(data);
+}
+
 static int meson_rng_probe(struct platform_device *pdev)
 {
        struct device *dev = &pdev->dev;
        struct meson_rng_data *data;
        struct resource *res;
+       int ret;
 
        data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
        if (!data)
@@ -98,6 +106,20 @@ static int meson_rng_probe(struct platform_device *pdev)
        if (IS_ERR(data->base))
                return PTR_ERR(data->base);
 
+       data->core_clk = devm_clk_get(dev, "core");
+       if (IS_ERR(data->core_clk))
+               data->core_clk = NULL;
+
+       if (data->core_clk) {
+               ret = clk_prepare_enable(data->core_clk);
+               if (ret)
+                       return ret;
+               ret = devm_add_action_or_reset(dev, meson_rng_clk_disable,
+                                              data->core_clk);
+               if (ret)
+                       return ret;
+       }
+
        data->rng.name = pdev->name;
        data->rng.read = meson_rng_read;
 
-- 
2.11.1