linux-kernel - Re: [PATCH v5 5/9] rtc: at91sam9: make use of syscon/regmap to access GPBR registers

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Message-ID: <20140912073306.5ac2c295@bbrezillon>
Date:	Fri, 12 Sep 2014 07:33:06 +0200
From:	Boris BREZILLON <boris.brezillon@...e-electrons.com>
To:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Cc:	Nicolas Ferre <nicolas.ferre@...el.com>,
	Jean-Christophe Plagniol-Villard <plagnioj@...osoft.com>,
	Andrew Victor <linux@...im.org.za>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	rtc-linux@...glegroups.com, Johan Hovold <jhovold@...il.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 5/9] rtc: at91sam9: make use of syscon/regmap to
 access GPBR registers

On Thu, 11 Sep 2014 19:42:09 +0200
Alexandre Belloni <alexandre.belloni@...e-electrons.com> wrote:

> On 11/09/2014 at 15:53:08 +0200, Boris Brezillon wrote :
> > The GPBR registers are not part of the RTT block and thus should not be
> > defined in the reg property of the rtt node.
> > 
> > Use syscon to provide a proper DT representation and reference the GPBR
> > syscon device in a new "atmel,time-reg" property which store both the
> > syscon device phandle and the register offset within the GPBR block.
> > 
> > When using non DT boards, we won't be able to retrieve the syscon regmap,
> > hence we need to create our own regmap using the memory region defined
> > in the 2nd memory resource assigned to the RTT platform device.
> > 
> > Signed-off-by: Boris BREZILLON <boris.brezillon@...e-electrons.com>
> > ---
> >  drivers/rtc/Kconfig        |  1 +
> >  drivers/rtc/rtc-at91sam9.c | 59 +++++++++++++++++++++++++++++++++++++++-------
> >  2 files changed, 51 insertions(+), 9 deletions(-)
> > 
> > diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> > index a168e96..7d76da8 100644
> > --- a/drivers/rtc/Kconfig
> > +++ b/drivers/rtc/Kconfig
> > @@ -1081,6 +1081,7 @@ config RTC_DRV_AT91RM9200
> >  config RTC_DRV_AT91SAM9
> >  	tristate "AT91SAM9x/AT91CAP9 RTT as RTC"
> >  	depends on ARCH_AT91 && !(ARCH_AT91RM9200 || ARCH_AT91X40)
> > +	select MFD_SYSCON
> >  	help
> >  	  RTC driver for the Atmel AT91SAM9x and AT91CAP9 internal RTT
> >  	  (Real Time Timer). These timers are powered by the backup power
> > diff --git a/drivers/rtc/rtc-at91sam9.c b/drivers/rtc/rtc-at91sam9.c
> > index d72c34d..944e317 100644
> > --- a/drivers/rtc/rtc-at91sam9.c
> > +++ b/drivers/rtc/rtc-at91sam9.c
> > @@ -21,6 +21,8 @@
> >  #include <linux/slab.h>
> >  #include <linux/platform_data/atmel.h>
> >  #include <linux/io.h>
> > +#include <linux/mfd/syscon.h>
> > +#include <linux/regmap.h>
> >  
> >  /*
> >   * This driver uses two configurable hardware resources that live in the
> > @@ -72,7 +74,8 @@ struct sam9_rtc {
> >  	void __iomem		*rtt;
> >  	struct rtc_device	*rtcdev;
> >  	u32			imr;
> > -	void __iomem		*gpbr;
> > +	struct regmap		*gpbr;
> > +	unsigned int		gpbr_offset;
> >  	int 			irq;
> >  };
> >  
> > @@ -81,10 +84,19 @@ struct sam9_rtc {
> >  #define rtt_writel(rtc, field, val) \
> >  	writel((val), (rtc)->rtt + AT91_RTT_ ## field)
> >  
> > -#define gpbr_readl(rtc) \
> > -	readl((rtc)->gpbr)
> > -#define gpbr_writel(rtc, val) \
> > -	writel((val), (rtc)->gpbr)
> > +static inline unsigned int gpbr_readl(struct sam9_rtc *rtc)
> > +{
> > +	unsigned int val;
> > +
> > +	regmap_read(rtc->gpbr, rtc->gpbr_offset, &val);
> > +
> > +	return val;
> > +}
> > +
> > +static inline void gpbr_writel(struct sam9_rtc *rtc, unsigned int val)
> > +{
> > +	regmap_write(rtc->gpbr, rtc->gpbr_offset, val);
> > +}
> >  
> >  /*
> >   * Read current time and date in RTC
> > @@ -301,6 +313,12 @@ static const struct rtc_class_ops at91_rtc_ops = {
> >  	.alarm_irq_enable = at91_rtc_alarm_irq_enable,
> >  };
> >  
> > +static struct regmap_config gpbr_regmap_config = {
> > +	.reg_bits = 32,
> > +	.val_bits = 32,
> > +	.reg_stride = 4,
> > +};
> > +
> >  /*
> >   * Initialize and install RTC driver
> >   */
> > @@ -334,10 +352,33 @@ static int at91_rtc_probe(struct platform_device *pdev)
> >  	if (IS_ERR(rtc->rtt))
> >  		return PTR_ERR(rtc->rtt);
> >  
> > -	r = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> > -	rtc->gpbr = devm_ioremap_resource(&pdev->dev, r);
> > -	if (IS_ERR(rtc->gpbr))
> > -		return PTR_ERR(rtc->rtt);
> > +	if (!pdev->dev.of_node) {
> > +		void __iomem *gpbr;
> > +
> > +		r = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> > +		gpbr = devm_ioremap_resource(&pdev->dev, r);
> > +		if (IS_ERR(gpbr))
> > +			return PTR_ERR(gpbr);
> > +
> 
> Maybe you could add a comment here as this is soon to be dead code.

Sure. I'll add a TODO comment.

Thanks.

Boris

-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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