Hi Stefan, On 11/04/2017 06:50 AM, Stefan Wahren wrote: > 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? Good point, so more like: if (IS_ERR(priv->clk) && PTR_ERR(priv->clk) == -ENODEV)? -- Florian