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Commit 9765d2d9 authored by Chen-Yu Tsai's avatar Chen-Yu Tsai Committed by Maxime Ripard
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rtc: sun6i: Add sun6i RTC driver 



This patch introduces the driver for the RTC in the Allwinner A31 and
A23 SoCs.

Unlike the RTC found in A10/A20 SoCs, which was part of the timer, the
RTC in A31/A23 are a separate hardware block, which also contain a few
controls for the RTC block hardware (a regulator and RTC block GPIO pin
latches), while also having separate interrupts for the alarms.

The hardware is different enough to make a different driver for it.

Signed-off-by: default avatarChen-Yu Tsai <wens@csie.org>
Reviewed-by: default avatarVarka Bhadram <varkabhadram@gmail.com>
Signed-off-by: default avatarMaxime Ripard <maxime.ripard@free-electrons.com>
parent 7d1311b9

Documentation/devicetree/bindings/rtc/sun6i-rtc.txt

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+17 −0
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* sun6i Real Time Clock



RTC controller for the Allwinner A31



Required properties:

- compatible	: Should be "allwinner,sun6i-a31-rtc"

- reg		: physical base address of the controller and length of

		  memory mapped region.

- interrupts	: IRQ lines for the RTC alarm 0 and alarm 1, in that order.



Example:



rtc: rtc@01f00000 {

	compatible = "allwinner,sun6i-a31-rtc";

	reg = <0x01f00000 0x54>;

	interrupts = <0 40 4>, <0 41 4>;

};

drivers/rtc/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -1175,6 +1175,13 @@ config RTC_DRV_SUN4V 
	  If you say Y here you will get support for the Hypervisor

	  based RTC on SUN4V systems.



config RTC_DRV_SUN6I

	tristate "Allwinner A31 RTC"

	depends on MACH_SUN6I || MACH_SUN8I

	help

	  If you say Y here you will get support for the RTC found on

	  Allwinner A31.



config RTC_DRV_SUNXI

	tristate "Allwinner sun4i/sun7i RTC"

	depends on ARCH_SUNXI

drivers/rtc/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -128,6 +128,7 @@ 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_SUN6I)	+= rtc-sun6i.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

drivers/rtc/rtc-sun6i.c

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/*

 * An RTC driver for Allwinner A31/A23

 *

 * Copyright (c) 2014, Chen-Yu Tsai <wens@csie.org>

 *

 * based on rtc-sunxi.c

 *

 * 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.

 */



#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>



/* Control register */

#define SUN6I_LOSC_CTRL				0x0000

#define SUN6I_LOSC_CTRL_ALM_DHMS_ACC		BIT(9)

#define SUN6I_LOSC_CTRL_RTC_HMS_ACC		BIT(8)

#define SUN6I_LOSC_CTRL_RTC_YMD_ACC		BIT(7)

#define SUN6I_LOSC_CTRL_ACC_MASK		GENMASK(9, 7)



/* RTC */

#define SUN6I_RTC_YMD				0x0010

#define SUN6I_RTC_HMS				0x0014



/* Alarm 0 (counter) */

#define SUN6I_ALRM_COUNTER			0x0020

#define SUN6I_ALRM_CUR_VAL			0x0024

#define SUN6I_ALRM_EN				0x0028

#define SUN6I_ALRM_EN_CNT_EN			BIT(0)

#define SUN6I_ALRM_IRQ_EN			0x002c

#define SUN6I_ALRM_IRQ_EN_CNT_IRQ_EN		BIT(0)

#define SUN6I_ALRM_IRQ_STA			0x0030

#define SUN6I_ALRM_IRQ_STA_CNT_IRQ_PEND		BIT(0)



/* Alarm 1 (wall clock) */

#define SUN6I_ALRM1_EN				0x0044

#define SUN6I_ALRM1_IRQ_EN			0x0048

#define SUN6I_ALRM1_IRQ_STA			0x004c

#define SUN6I_ALRM1_IRQ_STA_WEEK_IRQ_PEND	BIT(0)



/* Alarm config */

#define SUN6I_ALARM_CONFIG			0x0050

#define SUN6I_ALARM_CONFIG_WAKEUP		BIT(0)



/*

 * Get date values

 */

#define SUN6I_DATE_GET_DAY_VALUE(x)		((x)  & 0x0000001f)

#define SUN6I_DATE_GET_MON_VALUE(x)		(((x) & 0x00000f00) >> 8)

#define SUN6I_DATE_GET_YEAR_VALUE(x)		(((x) & 0x003f0000) >> 16)

#define SUN6I_LEAP_GET_VALUE(x)			(((x) & 0x00400000) >> 22)



/*

 * Get time values

 */

#define SUN6I_TIME_GET_SEC_VALUE(x)		((x)  & 0x0000003f)

#define SUN6I_TIME_GET_MIN_VALUE(x)		(((x) & 0x00003f00) >> 8)

#define SUN6I_TIME_GET_HOUR_VALUE(x)		(((x) & 0x001f0000) >> 16)



/*

 * Set date values

 */

#define SUN6I_DATE_SET_DAY_VALUE(x)		((x)       & 0x0000001f)

#define SUN6I_DATE_SET_MON_VALUE(x)		((x) <<  8 & 0x00000f00)

#define SUN6I_DATE_SET_YEAR_VALUE(x)		((x) << 16 & 0x003f0000)

#define SUN6I_LEAP_SET_VALUE(x)			((x) << 22 & 0x00400000)



/*

 * Set time values

 */

#define SUN6I_TIME_SET_SEC_VALUE(x)		((x)       & 0x0000003f)

#define SUN6I_TIME_SET_MIN_VALUE(x)		((x) <<  8 & 0x00003f00)

#define SUN6I_TIME_SET_HOUR_VALUE(x)		((x) << 16 & 0x001f0000)



/*

 * The year parameter passed to the driver is usually an offset relative to

 * the year 1900. This macro is used to convert this offset to another one

 * relative to the minimum year allowed by the hardware.

 *

 * The year range is 1970 - 2033. This range is selected to match Allwinner's

 * driver, even though it is somewhat limited.

 */

#define SUN6I_YEAR_MIN				1970

#define SUN6I_YEAR_MAX				2033

#define SUN6I_YEAR_OFF				(SUN6I_YEAR_MIN - 1900)



struct sun6i_rtc_dev {

	struct rtc_device *rtc;

	struct device *dev;

	void __iomem *base;

	int irq;

	unsigned long alarm;

};



static irqreturn_t sun6i_rtc_alarmirq(int irq, void *id)

{

	struct sun6i_rtc_dev *chip = (struct sun6i_rtc_dev *) id;

	u32 val;



	val = readl(chip->base + SUN6I_ALRM_IRQ_STA);



	if (val & SUN6I_ALRM_IRQ_STA_CNT_IRQ_PEND) {

		val |= SUN6I_ALRM_IRQ_STA_CNT_IRQ_PEND;

		writel(val, chip->base + SUN6I_ALRM_IRQ_STA);



		rtc_update_irq(chip->rtc, 1, RTC_AF | RTC_IRQF);



		return IRQ_HANDLED;

	}



	return IRQ_NONE;

}



static void sun6i_rtc_setaie(int to, struct sun6i_rtc_dev *chip)

{

	u32 alrm_val = 0;

	u32 alrm_irq_val = 0;

	u32 alrm_wake_val = 0;



	if (to) {

		alrm_val = SUN6I_ALRM_EN_CNT_EN;

		alrm_irq_val = SUN6I_ALRM_IRQ_EN_CNT_IRQ_EN;

		alrm_wake_val = SUN6I_ALARM_CONFIG_WAKEUP;

	} else {

		writel(SUN6I_ALRM_IRQ_STA_CNT_IRQ_PEND,

		       chip->base + SUN6I_ALRM_IRQ_STA);

	}



	writel(alrm_val, chip->base + SUN6I_ALRM_EN);

	writel(alrm_irq_val, chip->base + SUN6I_ALRM_IRQ_EN);

	writel(alrm_wake_val, chip->base + SUN6I_ALARM_CONFIG);

}



static int sun6i_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm)

{

	struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);

	u32 date, time;



	/*

	 * read again in case it changes

	 */

	do {

		date = readl(chip->base + SUN6I_RTC_YMD);

		time = readl(chip->base + SUN6I_RTC_HMS);

	} while ((date != readl(chip->base + SUN6I_RTC_YMD)) ||

		 (time != readl(chip->base + SUN6I_RTC_HMS)));



	rtc_tm->tm_sec  = SUN6I_TIME_GET_SEC_VALUE(time);

	rtc_tm->tm_min  = SUN6I_TIME_GET_MIN_VALUE(time);

	rtc_tm->tm_hour = SUN6I_TIME_GET_HOUR_VALUE(time);



	rtc_tm->tm_mday = SUN6I_DATE_GET_DAY_VALUE(date);

	rtc_tm->tm_mon  = SUN6I_DATE_GET_MON_VALUE(date);

	rtc_tm->tm_year = SUN6I_DATE_GET_YEAR_VALUE(date);



	rtc_tm->tm_mon  -= 1;



	/*

	 * switch from (data_year->min)-relative offset to

	 * a (1900)-relative one

	 */

	rtc_tm->tm_year += SUN6I_YEAR_OFF;



	return rtc_valid_tm(rtc_tm);

}



static int sun6i_rtc_getalarm(struct device *dev, struct rtc_wkalrm *wkalrm)

{

	struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);

	u32 alrm_st;

	u32 alrm_en;



	alrm_en = readl(chip->base + SUN6I_ALRM_IRQ_EN);

	alrm_st = readl(chip->base + SUN6I_ALRM_IRQ_STA);

	wkalrm->enabled = !!(alrm_en & SUN6I_ALRM_EN_CNT_EN);

	wkalrm->pending = !!(alrm_st & SUN6I_ALRM_EN_CNT_EN);

	rtc_time_to_tm(chip->alarm, &wkalrm->time);



	return 0;

}



static int sun6i_rtc_setalarm(struct device *dev, struct rtc_wkalrm *wkalrm)

{

	struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);

	struct rtc_time *alrm_tm = &wkalrm->time;

	struct rtc_time tm_now;

	unsigned long time_now = 0;

	unsigned long time_set = 0;

	unsigned long time_gap = 0;

	int ret = 0;



	ret = sun6i_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;



	if (time_gap > U32_MAX) {

		dev_err(dev, "Date too far in the future\n");

		return -EINVAL;

	}



	sun6i_rtc_setaie(0, chip);

	writel(0, chip->base + SUN6I_ALRM_COUNTER);

	usleep_range(100, 300);



	writel(time_gap, chip->base + SUN6I_ALRM_COUNTER);

	chip->alarm = time_set;



	sun6i_rtc_setaie(wkalrm->enabled, chip);



	return 0;

}



static int sun6i_rtc_wait(struct sun6i_rtc_dev *chip, int offset,

			  unsigned int mask, unsigned int ms_timeout)

{

	const unsigned long timeout = jiffies + msecs_to_jiffies(ms_timeout);

	u32 reg;



	do {

		reg = readl(chip->base + offset);

		reg &= mask;



		if (!reg)

			return 0;



	} while (time_before(jiffies, timeout));



	return -ETIMEDOUT;

}



static int sun6i_rtc_settime(struct device *dev, struct rtc_time *rtc_tm)

{

	struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);

	u32 date = 0;

	u32 time = 0;

	int year;



	year = rtc_tm->tm_year + 1900;

	if (year < SUN6I_YEAR_MIN || year > SUN6I_YEAR_MAX) {

		dev_err(dev, "rtc only supports year in range %d - %d\n",

			SUN6I_YEAR_MIN, SUN6I_YEAR_MAX);

		return -EINVAL;

	}



	rtc_tm->tm_year -= SUN6I_YEAR_OFF;

	rtc_tm->tm_mon += 1;



	date = SUN6I_DATE_SET_DAY_VALUE(rtc_tm->tm_mday) |

		SUN6I_DATE_SET_MON_VALUE(rtc_tm->tm_mon)  |

		SUN6I_DATE_SET_YEAR_VALUE(rtc_tm->tm_year);



	if (is_leap_year(year))

		date |= SUN6I_LEAP_SET_VALUE(1);



	time = SUN6I_TIME_SET_SEC_VALUE(rtc_tm->tm_sec)  |

		SUN6I_TIME_SET_MIN_VALUE(rtc_tm->tm_min)  |

		SUN6I_TIME_SET_HOUR_VALUE(rtc_tm->tm_hour);



	/* Check whether registers are writable */

	if (sun6i_rtc_wait(chip, SUN6I_LOSC_CTRL,

			   SUN6I_LOSC_CTRL_ACC_MASK, 50)) {

		dev_err(dev, "rtc is still busy.\n");

		return -EBUSY;

	}



	writel(time, chip->base + SUN6I_RTC_HMS);



	/*

	 * After writing the RTC HH-MM-SS register, the

	 * SUN6I_LOSC_CTRL_RTC_HMS_ACC bit is set and it will not

	 * be cleared until the real writing operation is finished

	 */



	if (sun6i_rtc_wait(chip, SUN6I_LOSC_CTRL,

			   SUN6I_LOSC_CTRL_RTC_HMS_ACC, 50)) {

		dev_err(dev, "Failed to set rtc time.\n");

		return -ETIMEDOUT;

	}



	writel(date, chip->base + SUN6I_RTC_YMD);



	/*

	 * After writing the RTC YY-MM-DD register, the

	 * SUN6I_LOSC_CTRL_RTC_YMD_ACC bit is set and it will not

	 * be cleared until the real writing operation is finished

	 */



	if (sun6i_rtc_wait(chip, SUN6I_LOSC_CTRL,

			   SUN6I_LOSC_CTRL_RTC_YMD_ACC, 50)) {

		dev_err(dev, "Failed to set rtc time.\n");

		return -ETIMEDOUT;

	}



	return 0;

}



static int sun6i_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)

{

	struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);



	if (!enabled)

		sun6i_rtc_setaie(enabled, chip);



	return 0;

}



static const struct rtc_class_ops sun6i_rtc_ops = {

	.read_time		= sun6i_rtc_gettime,

	.set_time		= sun6i_rtc_settime,

	.read_alarm		= sun6i_rtc_getalarm,

	.set_alarm		= sun6i_rtc_setalarm,

	.alarm_irq_enable	= sun6i_rtc_alarm_irq_enable

};



static int sun6i_rtc_probe(struct platform_device *pdev)

{

	struct sun6i_rtc_dev *chip;

	struct resource *res;

	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, sun6i_rtc_alarmirq,

			       0, dev_name(&pdev->dev), chip);

	if (ret) {

		dev_err(&pdev->dev, "Could not request IRQ\n");

		return ret;

	}



	/* clear the alarm counter value */

	writel(0, chip->base + SUN6I_ALRM_COUNTER);



	/* disable counter alarm */

	writel(0, chip->base + SUN6I_ALRM_EN);



	/* disable counter alarm interrupt */

	writel(0, chip->base + SUN6I_ALRM_IRQ_EN);



	/* disable week alarm */

	writel(0, chip->base + SUN6I_ALRM1_EN);



	/* disable week alarm interrupt */

	writel(0, chip->base + SUN6I_ALRM1_IRQ_EN);



	/* clear counter alarm pending interrupts */

	writel(SUN6I_ALRM_IRQ_STA_CNT_IRQ_PEND,

	       chip->base + SUN6I_ALRM_IRQ_STA);



	/* clear week alarm pending interrupts */

	writel(SUN6I_ALRM1_IRQ_STA_WEEK_IRQ_PEND,

	       chip->base + SUN6I_ALRM1_IRQ_STA);



	/* disable alarm wakeup */

	writel(0, chip->base + SUN6I_ALARM_CONFIG);



	chip->rtc = rtc_device_register("rtc-sun6i", &pdev->dev,

					&sun6i_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 sun6i_rtc_remove(struct platform_device *pdev)

{

	struct sun6i_rtc_dev *chip = platform_get_drvdata(pdev);



	rtc_device_unregister(chip->rtc);



	return 0;

}



static const struct of_device_id sun6i_rtc_dt_ids[] = {

	{ .compatible = "allwinner,sun6i-a31-rtc" },

	{ /* sentinel */ },

};

MODULE_DEVICE_TABLE(of, sun6i_rtc_dt_ids);



static struct platform_driver sun6i_rtc_driver = {

	.probe		= sun6i_rtc_probe,

	.remove		= sun6i_rtc_remove,

	.driver		= {

		.name		= "sun6i-rtc",

		.of_match_table = sun6i_rtc_dt_ids,

	},

};



module_platform_driver(sun6i_rtc_driver);



MODULE_DESCRIPTION("sun6i RTC driver");

MODULE_AUTHOR("Chen-Yu Tsai <wens@csie.org>");

MODULE_LICENSE("GPL");