Hi Florian,
> Florian Fainelli <f.fainelli@xxxxxxxxx> hat am 2. November 2017 um 02:04 geschrieben:
>
>
> 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@xxxxxxxxx>
> ---
> 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;
at least in case of EPROBE_DEFERED this isn't the expected behavior. Maybe we should better trigger on non-existing clock?
> +
> priv->rng.name = "bcm2835-rng";
> priv->rng.init = bcm2835_rng_init;
> priv->rng.read = bcm2835_rng_read;
> --
> 2.9.3
>
