[PATCH] sun4i/sun7i: RTC driver

[maxime.ripard@free-electrons.com (Maxime Ripard)]

Hi Carlo,

On Tue, Oct 08, 2013 at 07:59:50PM +0200, Carlo Caione wrote:
> This patch introduces the driver for the RTC in the Allwinner A10 and
> A20 SoCs.
> 
> Signed-off-by: Carlo Caione <carlo.caione@gmail.com>
> ---
>  arch/arm/boot/dts/sun4i-a10.dtsi |   6 +
>  arch/arm/boot/dts/sun7i-a20.dtsi |   6 +

Please split the DT patches and the rtc patches.

>  drivers/rtc/Kconfig              |   8 +
>  drivers/rtc/Makefile             |   1 +
>  drivers/rtc/rtc-sunxi.c          | 468 +++++++++++++++++++++++++++++++++++++++
>  5 files changed, 489 insertions(+)
>  create mode 100644 drivers/rtc/rtc-sunxi.c
> 
> diff --git a/arch/arm/boot/dts/sun4i-a10.dtsi b/arch/arm/boot/dts/sun4i-a10.dtsi
> index c32770a..e93a0c9 100644
> --- a/arch/arm/boot/dts/sun4i-a10.dtsi
> +++ b/arch/arm/boot/dts/sun4i-a10.dtsi
> @@ -266,6 +266,12 @@
>  			reg = <0x01c20c90 0x10>;
>  		};
>  
> +		rtc: rtc at 01c20d00 {
> +			compatible = "allwinner,sun4i-a10-rtc";
> +			reg = <0x01c20d00 0x20>;
> +			interrupts = <24>;
> +		};
> +
>  		uart0: serial at 01c28000 {
>  			compatible = "snps,dw-apb-uart";
>  			reg = <0x01c28000 0x400>;
> diff --git a/arch/arm/boot/dts/sun7i-a20.dtsi b/arch/arm/boot/dts/sun7i-a20.dtsi
> index 80559cb..12160d8 100644
> --- a/arch/arm/boot/dts/sun7i-a20.dtsi
> +++ b/arch/arm/boot/dts/sun7i-a20.dtsi
> @@ -244,6 +244,12 @@
>  			reg = <0x01c20c90 0x10>;
>  		};
>  
> +		rtc: rtc at 01c20d00 {
> +			compatible = "allwinner,sun7i-a20-rtc";
> +			reg = <0x01c20d00 0x20>;
> +			interrupts = <0 24 1>;
> +		};
> +
>  		uart0: serial at 01c28000 {
>  			compatible = "snps,dw-apb-uart";
>  			reg = <0x01c28000 0x400>;
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 9654aa3..d7c158c 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -1076,6 +1076,14 @@ config RTC_DRV_SUN4V
>  	  If you say Y here you will get support for the Hypervisor
>  	  based RTC on SUN4V systems.
>  
> +config RTC_DRV_SUNXI
> +	tristate "SUNXI RTC"

Maybe we can have something more meaningful here, like "Allwinner sunXi
RTC" or something like that.

> +	depends on ARCH_SUNXI
> +	default y

Please remove this. I don't want to force this down to everyone that
will enable the sunxi arch.

> +	help
> +	  If you say Y here you will get support for the RTC found on
> +	  Allwinner A10/A20.
> +
>  config RTC_DRV_STARFIRE
>  	bool "Starfire RTC"
>  	depends on SPARC64
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 2dff3d2..8b52b5a 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -115,6 +115,7 @@ obj-$(CONFIG_RTC_DRV_STARFIRE)	+= rtc-starfire.o
>  obj-$(CONFIG_RTC_DRV_STK17TA8)	+= rtc-stk17ta8.o
>  obj-$(CONFIG_RTC_DRV_STMP)	+= rtc-stmp3xxx.o
>  obj-$(CONFIG_RTC_DRV_SUN4V)	+= rtc-sun4v.o
> +obj-$(CONFIG_RTC_DRV_SUNXI)	+= rtc-sunxi.o
>  obj-$(CONFIG_RTC_DRV_TEGRA)	+= rtc-tegra.o
>  obj-$(CONFIG_RTC_DRV_TEST)	+= rtc-test.o
>  obj-$(CONFIG_RTC_DRV_TILE)	+= rtc-tile.o
> diff --git a/drivers/rtc/rtc-sunxi.c b/drivers/rtc/rtc-sunxi.c
> new file mode 100644
> index 0000000..2c23f64
> --- /dev/null
> +++ b/drivers/rtc/rtc-sunxi.c
> @@ -0,0 +1,468 @@
> +/*
> + * An RTC driver for Allwinner A10/A20
> + *
> + * Copyright (c) 2013, Carlo Caione <carlo.caione@gmail.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along
> + * with this program; if not, write to the Free Software Foundation, Inc.,
> + * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/fs.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/rtc.h>
> +#include <linux/types.h>
> +
> +#define SUNXI_LOSC_CTRL				0x0000
> +#define SUNXI_LOSC_CTRL_RTC_HMS_ACC		BIT(8)
> +#define SUNXI_LOSC_CTRL_RTC_YMD_ACC		BIT(7)
> +
> +#define SUNXI_RTC_YMD				0x0004
> +
> +#define SUNXI_RTC_HMS				0x0008
> +
> +#define SUNXI_ALRM_DHMS				0x000c
> +
> +#define SUNXI_ALRM_EN				0x0014
> +#define SUNXI_ALRM_EN_CNT_EN			BIT(8)
> +
> +#define SUNXI_ALRM_IRQ_EN			0x0018
> +#define SUNXI_ALRM_IRQ_EN_CNT_IRQ_EN		BIT(0)
> +
> +#define SUNXI_ALRM_IRQ_STA			0x001c
> +#define SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND		BIT(0)
> +
> +#define SUNXI_LOSC_CTRL_RTC_ACC (SUNXI_LOSC_CTRL_RTC_HMS_ACC | SUNXI_LOSC_CTRL_RTC_YMD_ACC)
> +
> +#define SUNXI_MASK_DGD_TSH_ASH			0x0000001f
> +#define SUNXI_MASK_TGH_AGH			0x001f0000
> +#define SUNXI_MASK_TGS_AGS_TSM_ASM		0x0000003f
> +#define SUNXI_MASK_TGM				0x00003f00
> +#define SUNXI_MASK_DSM				0x0000000f
> +#define SUNXI_MASK_LY				0x00000001
> +#define SUNXI_MASK_ASD				0x00000ffe
> +#define SUNXI_MASK_GMD				0x00000f00
> +
> +/* Get date values */
> +#define SUNXI_DATE_GET_DAY_VALUE(x)		((x) & SUNXI_MASK_DGD_TSH_ASH)
> +#define SUNXI_DATE_GET_MON_VALUE(x)		(((x) & SUNXI_MASK_GMD) >> 8)
> +#define SUNXI_DATE_GET_YEAR_VALUE(x, mask)	(((x) & mask) >> 16)
> +
> +/* Get time values */
> +#define SUNXI_TIME_GET_SEC_VALUE(x)		((x) & SUNXI_MASK_TGS_AGS_TSM_ASM)
> +#define SUNXI_TIME_GET_MIN_VALUE(x)		(((x) & SUNXI_MASK_TGM) >> 8)
> +#define SUNXI_TIME_GET_HOUR_VALUE(x)		(((x) & SUNXI_MASK_TGH_AGH) >> 16)
> +
> +/* Get alarm values */
> +#define SUNXI_ALARM_GET_SEC_VALUE(x)		((x) & SUNXI_MASK_TGS_AGS_TSM_ASM)
> +#define SUNXI_ALARM_GET_MIN_VALUE(x)		(((x) & SUNXI_MASK_TGM) >> 8)
> +#define SUNXI_ALARM_GET_HOUR_VALUE(x)		(((x) & SUNXI_MASK_TGH_AGH) >> 16)
> +
> +/* Set date values */
> +#define SUNXI_DATE_SET_DAY_VALUE(x)		SUNXI_DATE_GET_DAY_VALUE(x)
> +#define SUNXI_DATE_SET_MON_VALUE(x)		(((x) & SUNXI_MASK_DSM) << 8)
> +#define SUNXI_DATE_SET_YEAR_VALUE(x, mask)	(((x) & mask) << 16)
> +#define SUNXI_LEAP_SET_VALUE(x, shift)		(((x) & SUNXI_MASK_LY) << shift)
> +
> +/* Set time values */
> +#define SUNXI_TIME_SET_SEC_VALUE(x)		SUNXI_TIME_GET_SEC_VALUE(x)
> +#define SUNXI_TIME_SET_MIN_VALUE(x)		(((x) & SUNXI_MASK_TGS_AGS_TSM_ASM) << 8)
> +#define SUNXI_TIME_SET_HOUR_VALUE(x)		(((x) & SUNXI_MASK_DGD_TSH_ASH) << 16)
> +
> +/* set alarm values */
> +#define SUNXI_ALARM_SET_SEC_VALUE(x)		SUNXI_ALARM_GET_SEC_VALUE(x)
> +#define SUNXI_ALARM_SET_MIN_VALUE(x)		(((x) & SUNXI_MASK_TGS_AGS_TSM_ASM) << 8)
> +#define SUNXI_ALARM_SET_HOUR_VALUE(x)		(((x) & SUNXI_MASK_DGD_TSH_ASH) << 16)
> +#define SUNXI_ALARM_SET_DAY_VALUE(x)		(((x) & SUNXI_MASK_ASD) << 21)
> +
> +/* time unit conversions */
> +#define SEC_IN_MIN				60
> +#define SEC_IN_HOUR				(60 * SEC_IN_MIN)
> +#define SEC_IN_DAY				(24 * SEC_IN_HOUR)

Overall, I'm not really fond of this. 

The indentation you use is a mess, you use some times alarm, other alrm,
most of the registers names are cryptic, etc.

> +struct sunxi_rtc_data_year {
> +	unsigned int min;
> +	unsigned int max;
> +	unsigned int off;
> +	unsigned int mask;
> +	unsigned char leap_shift;
> +};

Please document that structure. It's quite hard to figure easily what
mask, off and leapshift are all about.

> +static struct sunxi_rtc_data_year data_year_param[] = {
> +	[0] = {
> +		.min	= 1970,
> +		.max	= 2100,
> +		.off	= 0,
> +		.mask	= 0x00ff0000,
> +		.leap_shift	= 24,
> +	},
> +	[1] = {
> +		.min	= 2010,
> +		.max	= 2073,
> +		.off	= 110,
> +		.mask	= 0x003f0000,
> +		.leap_shift	= 22,
> +	},
> +};
> +
> +struct sunxi_rtc_dev {
> +	struct rtc_device *rtc;
> +	struct device *dev;
> +	struct sunxi_rtc_data_year *data_year;

(Why is it called year btw?)

> +	void __iomem *base;
> +	int irq;
> +};
> +
> +static irqreturn_t sunxi_rtc_alarmirq(int irq, void *id)
> +{
> +	struct sunxi_rtc_dev *chip = (struct sunxi_rtc_dev *) id;
> +	unsigned int val;
> +
> +	val = readl(chip->base + SUNXI_ALRM_IRQ_STA);
> +
> +	if (val & SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND) {
> +
> +		val |= SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND;
> +		writel(val, chip->base + SUNXI_ALRM_IRQ_STA);
> +
> +		rtc_update_irq(chip->rtc, 1, RTC_AF | RTC_IRQF);
> +
> +		return IRQ_HANDLED;
> +	}
> +
> +	return IRQ_NONE;
> +}
> +
> +static void sunxi_rtc_setaie(int to, struct sunxi_rtc_dev *chip)
> +{
> +	unsigned int alarm_val = 0x0;
> +	unsigned int alarm_irq_val = 0x0;
> +
> +	if (to) {
> +		alarm_val = readl(chip->base + SUNXI_ALRM_EN);
> +		alarm_val |= SUNXI_ALRM_EN_CNT_EN;
> +
> +		alarm_irq_val = readl(chip->base + SUNXI_ALRM_IRQ_EN);
> +		alarm_irq_val |= SUNXI_ALRM_IRQ_EN_CNT_IRQ_EN;
> +	} else
> +		writel(SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND,
> +				chip->base + SUNXI_ALRM_IRQ_STA);
> +
> +	writel(alarm_val, chip->base + SUNXI_ALRM_EN);
> +	writel(alarm_irq_val, chip->base + SUNXI_ALRM_IRQ_EN);
> +}
> +
> +static int sunxi_rtc_getalarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> +	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
> +	struct rtc_time *alrm_tm = &alrm->time;
> +	unsigned int alarm;
> +	unsigned int alarm_en;
> +	unsigned int date;
> +
> +	alarm = readl(chip->base + SUNXI_ALRM_DHMS);
> +	date = readl(chip->base + SUNXI_RTC_YMD);
> +
> +	alrm_tm->tm_sec = SUNXI_ALARM_GET_SEC_VALUE(alarm);
> +	alrm_tm->tm_min = SUNXI_ALARM_GET_MIN_VALUE(alarm);
> +	alrm_tm->tm_hour = SUNXI_ALARM_GET_HOUR_VALUE(alarm);
> +
> +	alrm_tm->tm_mday = SUNXI_DATE_GET_DAY_VALUE(date);
> +	alrm_tm->tm_mon = SUNXI_DATE_GET_MON_VALUE(date);
> +	alrm_tm->tm_year = SUNXI_DATE_GET_YEAR_VALUE(date,
> +			chip->data_year->mask);
> +
> +	alrm_tm->tm_year += chip->data_year->off;
> +	alrm_tm->tm_mon -= 1;
> +
> +	alarm_en = readl(chip->base + SUNXI_ALRM_IRQ_EN);
> +	if (alarm_en & SUNXI_ALRM_EN_CNT_EN)
> +		alrm->enabled = 1;
> +
> +	return 0;
> +}
> +
> +static int sunxi_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm)
> +{
> +	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
> +	unsigned int date, time;
> +	int t;
> +
> +	/* read again if the system was mid-updated */
> +
> +	for (t = 0; t < 2; t++) {
> +		date = readl(chip->base + SUNXI_RTC_YMD);
> +		time = readl(chip->base + SUNXI_RTC_HMS);
> +
> +		rtc_tm->tm_sec  = SUNXI_TIME_GET_SEC_VALUE(time);
> +		rtc_tm->tm_min  = SUNXI_TIME_GET_MIN_VALUE(time);
> +		rtc_tm->tm_hour = SUNXI_TIME_GET_HOUR_VALUE(time);
> +
> +		rtc_tm->tm_mday = SUNXI_DATE_GET_DAY_VALUE(date);
> +		rtc_tm->tm_mon  = SUNXI_DATE_GET_MON_VALUE(date);
> +		rtc_tm->tm_year = SUNXI_DATE_GET_YEAR_VALUE(date,
> +				chip->data_year->mask);
> +
> +		if (rtc_tm->tm_sec == 0)
> +			msleep(500);
> +		else
> +			break;
> +	}
> +
> +	rtc_tm->tm_year += chip->data_year->off;
> +	rtc_tm->tm_mon  -= 1;
> +
> +	return rtc_valid_tm(rtc_tm);
> +}
> +
> +static int sunxi_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> +	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
> +	struct rtc_time *alrm_tm = &alrm->time;
> +	struct rtc_time tm_now;
> +	unsigned int alarm = 0;
> +	unsigned long time_now = 0;
> +	unsigned long time_set = 0;
> +	unsigned long time_gap = 0;
> +	unsigned long time_gap_day = 0;
> +	unsigned long time_gap_hour = 0;
> +	unsigned long time_gap_min = 0;
> +	int ret = 0;
> +
> +	ret = sunxi_rtc_gettime(dev, &tm_now);
> +	if (ret < 0) {
> +		dev_err(dev, "Error in getting time\n");
> +		return -EINVAL;
> +	}
> +
> +	rtc_tm_to_time(alrm_tm, &time_set);
> +	rtc_tm_to_time(&tm_now, &time_now);
> +	if (time_set <= time_now) {
> +		dev_err(dev, "Date to set in the past\n");
> +		return -EINVAL;
> +	}
> +
> +	time_gap = time_set - time_now;
> +	time_gap_day = time_gap / SEC_IN_DAY;
> +	time_gap -= time_gap_day * SEC_IN_DAY;
> +	time_gap_hour = time_gap / SEC_IN_HOUR;
> +	time_gap -= time_gap_hour * SEC_IN_HOUR;
> +	time_gap_min = time_gap / SEC_IN_MIN;
> +	time_gap -= time_gap_min * SEC_IN_MIN;
> +
> +	if (time_gap_day > 255) {
> +		dev_err(dev, "Day must be in the range 0 - 255\n");
> +		return -EINVAL;
> +	}
> +
> +	sunxi_rtc_setaie(0, chip);
> +	writel(0x0, chip->base + SUNXI_ALRM_DHMS);
> +	usleep_range(100, 300);
> +
> +	alarm = SUNXI_ALARM_SET_SEC_VALUE(time_gap) |
> +		SUNXI_ALARM_SET_MIN_VALUE(time_gap_min) |
> +		SUNXI_ALARM_SET_HOUR_VALUE(time_gap_hour) |
> +		SUNXI_ALARM_SET_DAY_VALUE(time_gap_day);
> +	writel(alarm, chip->base + SUNXI_ALRM_DHMS);
> +
> +	writel(0x0, chip->base + SUNXI_ALRM_IRQ_EN);
> +	writel(SUNXI_ALRM_IRQ_EN_CNT_IRQ_EN, chip->base + SUNXI_ALRM_IRQ_EN);
> +
> +	sunxi_rtc_setaie(alrm->enabled, chip);
> +
> +	return 0;
> +}
> +
> +static int sunxi_rtc_settime(struct device *dev, struct rtc_time *rtc_tm)
> +{
> +	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
> +	unsigned int date = 0;
> +	unsigned int time = 0;
> +	int year;
> +	int t;
> +
> +	year = rtc_tm->tm_year + 1900;
> +	if (year < chip->data_year->min || year > chip->data_year->max) {
> +		dev_err(dev, "rtc only supports year in range %d - %d\n", chip->data_year->min,
> +				chip->data_year->max);

This line looks way too long.

> +		return -EINVAL;
> +	}
> +
> +	t = 3;
> +	while ((readl(chip->base + SUNXI_LOSC_CTRL) & SUNXI_LOSC_CTRL_RTC_ACC) && --t)
> +		msleep(500);

What is this loop all about? 500ms seems to be a lot here.
This line is also looks way too long.

> +
> +	rtc_tm->tm_year -= chip->data_year->off;
> +	rtc_tm->tm_mon += 1;
> +
> +	date = SUNXI_DATE_SET_DAY_VALUE(rtc_tm->tm_mday) |
> +		SUNXI_DATE_SET_MON_VALUE(rtc_tm->tm_mon)  |
> +		SUNXI_DATE_SET_YEAR_VALUE(rtc_tm->tm_year,
> +				chip->data_year->mask);
> +
> +	if (is_leap_year(year))
> +		date |= SUNXI_LEAP_SET_VALUE(1, chip->data_year->leap_shift);
> +
> +	time = SUNXI_TIME_SET_SEC_VALUE(rtc_tm->tm_sec)  |
> +		SUNXI_TIME_SET_MIN_VALUE(rtc_tm->tm_min)  |
> +		SUNXI_TIME_SET_HOUR_VALUE(rtc_tm->tm_hour);
> +
> +	writel(0x0, chip->base + SUNXI_RTC_HMS);
> +	writel(0x0, chip->base + SUNXI_RTC_YMD);
> +
> +	writel(time, chip->base + SUNXI_RTC_HMS);
> +	t = 3;
> +	while ((readl(chip->base + SUNXI_LOSC_CTRL) & SUNXI_LOSC_CTRL_RTC_HMS_ACC) && --t)
> +		msleep(250);

What is this loop all about? 250ms seems to be a lot here.
This line is also way too long.

What about:

for (i = 0; i < 3; i++) {
	if (readl(..) & SUNXI_LOSC...)
		break;
	msleep(250);
}

> +	if (t == 0) {
> +		dev_err(dev, "Failed to set rtc time.\n");
> +		return -1;
> +	}
> +
> +	writel(date, chip->base + SUNXI_RTC_YMD);
> +	t = 3;
> +	while ((readl(chip->base + SUNXI_LOSC_CTRL) & SUNXI_LOSC_CTRL_RTC_YMD_ACC) && --t)
> +		msleep(250);

Ditto. What is this loop all about?

> +	if (t == 0) {
> +		dev_err(dev, "Failed to set rtc date.\n");
> +		return -1;
> +	}
> +
> +	usleep_range(70, 100);
> +
> +	return 0;
> +}
> +
> +static int sunxi_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)

This line looks way too long.

> +{
> +	struct sunxi_rtc_dev *chip = dev_get_drvdata(dev);
> +
> +	if (!enabled)
> +		sunxi_rtc_setaie(enabled, chip);
> +
> +	return 0;
> +}
> +
> +static const struct rtc_class_ops sunxi_rtc_ops = {
> +	.read_time		= sunxi_rtc_gettime,
> +	.set_time		= sunxi_rtc_settime,
> +	.read_alarm		= sunxi_rtc_getalarm,
> +	.set_alarm		= sunxi_rtc_setalarm,
> +	.alarm_irq_enable	= sunxi_rtc_alarm_irq_enable
> +};
> +
> +static const struct of_device_id sunxi_rtc_dt_ids[] = {
> +	{ .compatible = "allwinner,sun4i-a10-rtc", .data = (void *) &data_year_param[0] },
> +	{ .compatible = "allwinner,sun7i-a20-rtc", .data = (void *) &data_year_param[1] },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, sunxi_rtc_dt_ids);
> +
> +
> +static int sunxi_rtc_probe(struct platform_device *pdev)
> +{
> +	struct sunxi_rtc_dev *chip;
> +	struct resource *res;
> +	const struct of_device_id *of_id;
> +	int ret;
> +
> +	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
> +	if (!chip)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, chip);
> +	chip->dev = &pdev->dev;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	chip->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(chip->base))
> +		return PTR_ERR(chip->base);
> +
> +	chip->irq = platform_get_irq(pdev, 0);
> +	if (chip->irq < 0) {
> +		dev_err(&pdev->dev, "No IRQ resource\n");
> +		return chip->irq;
> +	}
> +	ret = devm_request_irq(&pdev->dev, chip->irq, sunxi_rtc_alarmirq,
> +			0, dev_name(&pdev->dev), chip);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Could not request IRQ\n");
> +		return ret;
> +	}
> +
> +	of_id = of_match_device(sunxi_rtc_dt_ids, &pdev->dev);
> +	if (!of_id) {
> +		dev_err(&pdev->dev, "Unable to setup RTC data\n");
> +		return -ENODEV;
> +	}
> +	chip->data_year = (struct sunxi_rtc_data_year *) of_id->data;
> +
> +	/* clear the alarm count value */
> +	writel(0x0, chip->base + SUNXI_ALRM_DHMS);
> +
> +	/* disable alarm, not generate irq pending */
> +	writel(0x0, chip->base + SUNXI_ALRM_EN);
> +
> +	/* disable alarm week/cnt irq, unset to cpu */
> +	writel(0x0, chip->base + SUNXI_ALRM_IRQ_EN);
> +
> +	/* clear alarm week/cnt irq pending */
> +	writel(SUNXI_ALRM_IRQ_STA_CNT_IRQ_PEND, chip->base + SUNXI_ALRM_IRQ_STA);

This line looks too long.

> +
> +	chip->rtc = rtc_device_register("rtc-sunxi", &pdev->dev,
> +			&sunxi_rtc_ops, THIS_MODULE);
> +	if (IS_ERR(chip->rtc)) {
> +		dev_err(&pdev->dev, "unable to register device\n");
> +		return PTR_ERR(chip->rtc);
> +	}
> +
> +	dev_info(&pdev->dev, "RTC enabled\n");
> +
> +	return 0;
> +}
> +
> +static int sunxi_rtc_remove(struct platform_device *pdev)
> +{
> +	struct sunxi_rtc_dev *chip = platform_get_drvdata(pdev);
> +
> +	rtc_device_unregister(chip->rtc);
> +	platform_set_drvdata(pdev, NULL);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver sunxi_rtc_driver = {
> +	.probe		= sunxi_rtc_probe,
> +	.remove		= sunxi_rtc_remove,
> +	.driver		= {
> +		.name		= "sunxi-rtc",
> +		.owner		= THIS_MODULE,
> +		.of_match_table = sunxi_rtc_dt_ids,
> +	},
> +};
> +
> +module_platform_driver(sunxi_rtc_driver);
> +
> +MODULE_DESCRIPTION("sunxi RTC driver");
> +MODULE_AUTHOR("Carlo Caione <carlo.caione@gmail.com");
> +MODULE_LICENSE("GPL");

Thanks for working on this!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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