On 20 February 2017 at 02:05, Heiner Kallweit <hkallweit1@xxxxxxxxx> wrote:
> Add handling of RNG0 clock to the driver.
>
> Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
> ---
> drivers/char/hw_random/meson-rng.c | 27 ++++++++++++++++++++++++++-
> 1 file changed, 26 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/char/hw_random/meson-rng.c b/drivers/char/hw_random/meson-rng.c
> index 119d6984..1f586e48 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)
> @@ -86,6 +88,7 @@ static int meson_rng_probe(struct platform_device *pdev)
> struct device *dev = &pdev->dev;
> struct meson_rng_data *data;
> struct resource *res;
> + int ret;
Variable ret is not used. It can be removed.
> data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> if (!data)
> @@ -98,12 +101,33 @@ 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))
> + return PTR_ERR(data->core_clk);
> +
> + ret = clk_prepare_enable(data->core_clk);
> + if (ret)
> + return ret;
> +
> data->rng.name = pdev->name;
> data->rng.read = meson_rng_read;
>
> platform_set_drvdata(pdev, data);
>
> - return devm_hwrng_register(dev, &data->rng);
> + ret = devm_hwrng_register(dev, &data->rng);
> + if (ret)
> + clk_disable_unprepare(data->core_clk);
> +
> + return ret;
> +}
> +
> +static int meson_rng_remove(struct platform_device *pdev)
> +{
> + struct meson_rng_data *data = platform_get_drvdata(pdev);
> +
> + clk_disable_unprepare(data->core_clk);
> +
> + return 0;
> }
In .remove clock gets disabled before the hwrng_unregister is called.
The device node '/dev/hwrng' could be accessed while meson_rng_remove
is called which could lead to problems. Instead of devm_hwrng_register
use hwrng_register in .probe and call hwrng_unregister in .remove.
> static const struct of_device_id meson_rng_of_match[] = {
> @@ -114,6 +138,7 @@ MODULE_DEVICE_TABLE(of, meson_rng_of_match);
>
> static struct platform_driver meson_rng_driver = {
> .probe = meson_rng_probe,
> + .remove = meson_rng_remove,
> .driver = {
> .name = "meson-rng",
> .of_match_table = meson_rng_of_match,
> --
> 2.11.1
>
>
