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Date: Mon, 22 Sep 2014 17:06:30 +0200
From: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To: Boris BREZILLON <boris.brezillon@...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, Samuel Ortiz <sameo@...ux.intel.com>,
Lee Jones <lee.jones@...aro.org>,
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 22/09/2014 at 11:10:54 +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>
Acked-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
> ---
> drivers/rtc/Kconfig | 1 +
> drivers/rtc/rtc-at91sam9.c | 64 +++++++++++++++++++++++++++++++++++++++-------
> 2 files changed, 56 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..902cd01 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 +352,38 @@ 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) {
> + /*
> + * TODO: Remove this code chunk when when removing non DT
> + * board support. Remember to remove the gpbr_regmap_config
> + * variable too.
> + */
> + 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);
> +
> + rtc->gpbr = regmap_init_mmio(NULL, gpbr,
> + &gpbr_regmap_config);
> + } else {
> + struct of_phandle_args args;
> +
> + ret = of_parse_phandle_with_fixed_args(pdev->dev.of_node,
> + "atmel,rtt-rtc-time-reg", 1, 0,
> + &args);
> + if (ret)
> + return ret;
> +
> + rtc->gpbr = syscon_node_to_regmap(args.np);
> + rtc->gpbr_offset = args.args[0];
> + }
> +
> + if (IS_ERR(rtc->gpbr)) {
> + dev_err(&pdev->dev, "failed to retrieve gpbr regmap, aborting.\n");
> + return -ENOMEM;
> + }
>
> mr = rtt_readl(rtc, MR);
>
> --
> 1.9.1
>
--
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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