Hi Stefan,

On 11/04/2017 06:50 AM, Stefan Wahren wrote:

Hi Florian,

quoted

Florian Fainelli [off-list ref] 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 <redacted>
---
 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
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html