From: Stefan Wahren <stefan.wahren@i2se.com>
To: Florian Fainelli <f.fainelli@gmail.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>,
Ray Jui <rjui@broadcom.com>, Eric Anholt <eric@anholt.net>,
Rob Herring <robh+dt@kernel.org>,
Steffen Trumtrar <s.trumtrar@pengutronix.de>,
Harald Freudenberger <freude@linux.vnet.ibm.com>,
Russell King <rmk+kernel@armlinux.org.uk>,
"moderated list:BROADCOM BCM2835 ARM ARCHITECTURE"
<linux-arm-kernel@lists.infradead.org>,
PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>,
Scott Branden <sbranden@broadcom.com>,
"open list:HARDWARE RANDOM NUMBER GENERATOR CORE"
<linux-crypto@vger.kernel.org>, Martin Kaiser <martin@kaiser.cx>,
Herbert Xu <herbert@gondor.apana.org.au>,
linux-kernel@vger.kernel.org, Matt Mackall <mpm@selenic.com>,
"maintainer:BROADCOM BCM281XX/BCM11XXX/BCM216XX ARM ARCHITE..."
<bcm-kernel-feedback-list@broadcom.com>,
Mark Rutland <mark.rutland@arm.com>,
"moderated list:BROADCOM BCM2835 ARM ARCHITECTURE"
<linux-rpi-kernel@lists.infradead.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>, Sean Wang <sean.wang@mediatek.com>
Subject: Re: [PATCH 07/12] hwrng: bcm2835-rng: Manage an optional clock
Date: Sat, 4 Nov 2017 19:22:34 +0100 (CET) [thread overview]
Message-ID: <547786283.132202.1509819754396@email.1und1.de> (raw)
In-Reply-To: <e12063f9-86e4-e9ce-2a7f-f85fe2ce352f@gmail.com>
> Florian Fainelli <f.fainelli@gmail.com> hat am 4. November 2017 um 18:59 geschrieben:
>
>
> Hi Stefan,
>
> On 11/04/2017 06:50 AM, Stefan Wahren wrote:
> > Hi Florian,
> >
> >> Florian Fainelli <f.fainelli@gmail.com> 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@gmail.com>
> >> ---
> >> 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)?
Unfortunately we need to return the error in all other cases. Please take a look at devm_usb_get_phy in dwc2 [1]. AFAIK we don't need to take care of ENXIO in our case.
http://elixir.free-electrons.com/linux/latest/source/drivers/usb/dwc2/platform.c#L247
>
> --
> Florian
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2017-11-04 18:23 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-02 1:03 [PATCH 00/12] bcm63xx-rng conversion to bcm2835-rng Florian Fainelli
2017-11-02 1:03 ` [PATCH 01/12] hwrng: bcm2835-rng: Obtain base register via resource Florian Fainelli
2017-11-02 1:03 ` [PATCH 02/12] hwrng: bcm2835-rng: Define a driver private context Florian Fainelli
2017-11-02 1:03 ` [PATCH 03/12] hwrng: bcm2835-rng: Move enabling to hwrng::init Florian Fainelli
2017-11-02 1:04 ` [PATCH 04/12] hwrng: bcm2835-rng: Implementation cleanup callback Florian Fainelli
2017-11-02 1:04 ` [PATCH 05/12] hwrng: bcm2835-rng: Use device managed helpers Florian Fainelli
2017-11-02 1:04 ` [PATCH 06/12] hwrng: bcm2835-rng: Rework interrupt masking Florian Fainelli
2017-11-02 1:04 ` [PATCH 07/12] hwrng: bcm2835-rng: Manage an optional clock Florian Fainelli
2017-11-04 13:50 ` Stefan Wahren
2017-11-04 17:59 ` Florian Fainelli
2017-11-04 18:22 ` Stefan Wahren [this message]
2017-11-04 19:37 ` Andrew Lunn
2017-11-04 20:08 ` Russell King - ARM Linux
2017-11-04 20:17 ` Andrew Lunn
2017-11-02 1:04 ` [PATCH 08/12] hwrng: bcm2835-rng: Abstract I/O accessors Florian Fainelli
2017-11-03 20:19 ` Eric Anholt
2017-11-03 22:04 ` Florian Fainelli
2017-11-02 1:04 ` [PATCH 09/12] hwrng: bcm2835-rng: Add Broadcom MIPS " Florian Fainelli
2017-11-02 1:04 ` [PATCH 10/12] dt-bindings: rng: Incorporate brcm,bcm6368.txt binding Florian Fainelli
2017-11-06 21:38 ` Rob Herring
2017-11-02 1:04 ` [PATCH 11/12] hwrng: bcm2835-rng: Enable BCM2835 RNG to work on BCM63xx platforms Florian Fainelli
2017-11-04 18:27 ` Stefan Wahren
2017-11-06 20:16 ` Florian Fainelli
2017-11-07 6:45 ` Stefan Wahren
2017-11-07 23:27 ` Stefan Wahren
2017-11-02 1:04 ` [PATCH 12/12] hwrng: bcm63xx-rng: Remove since bcm2835-rng takes over Florian Fainelli
2017-11-03 20:18 ` Eric Anholt
2017-11-03 21:58 ` Florian Fainelli
2017-11-02 19:00 ` [PATCH 00/12] bcm63xx-rng conversion to bcm2835-rng Stefan Wahren
2017-11-02 19:01 ` Stefan Wahren
2017-11-02 19:06 ` Florian Fainelli
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