Message-ID: <1508379527.21840.94.camel@mtkswgap22>
Date:   Thu, 19 Oct 2017 10:18:47 +0800
From:   Sean Wang <sean.wang@...iatek.com>
To:     Yingjoe Chen <yingjoe.chen@...iatek.com>
CC:     <a.zummo@...ertech.it>, <alexandre.belloni@...e-electrons.com>,
        <robh+dt@...nel.org>, <mark.rutland@....com>,
        <linux-rtc@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/4] rtc: mediatek: add driver for RTC on MT7622 SoC

On Wed, 2017-10-18 at 17:52 +0800, Yingjoe Chen wrote:
> On Tue, 2017-10-17 at 17:40 +0800, sean.wang@...iatek.com wrote:
> > From: Sean Wang <sean.wang@...iatek.com>
> > 
> > This patch introduces the driver for the RTC on MT7622 SoC.
> > 
> > Signed-off-by: Sean Wang <sean.wang@...iatek.com>
> > ---
> >  drivers/rtc/Kconfig      |  10 ++
> >  drivers/rtc/Makefile     |   1 +
> >  drivers/rtc/rtc-mt7622.c | 418 +++++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 429 insertions(+)
> >  create mode 100644 drivers/rtc/rtc-mt7622.c
> > 
> > diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> > index e0e58f3..4226295 100644
> > --- a/drivers/rtc/Kconfig
> > +++ b/drivers/rtc/Kconfig
> > @@ -1705,6 +1705,16 @@ config RTC_DRV_MOXART
> >  	   This driver can also be built as a module. If so, the module
> >  	   will be called rtc-moxart
> >  
> > +config RTC_DRV_MEDIATEK
> > +	tristate "MediaTek SoC based RTC"
> > +	depends on ARCH_MEDIATEK || COMPILE_TEST
> > +	help
> > +	  This enables support for the real time clock built in the MediaTek
> > +	  SoCs.
> > +
> > +	  This drive can also be built as a module. If so, the module
> > +	  will be called rtc-mediatek.
> > +
> >  config RTC_DRV_MT6397
> >  	tristate "Mediatek Real Time Clock driver"
> >  	depends on MFD_MT6397 || (COMPILE_TEST && IRQ_DOMAIN)
> > diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> > index 7230014..593a02c 100644
> > --- a/drivers/rtc/Makefile
> > +++ b/drivers/rtc/Makefile
> > @@ -101,6 +101,7 @@ obj-$(CONFIG_RTC_DRV_MOXART)	+= rtc-moxart.o
> >  obj-$(CONFIG_RTC_DRV_MPC5121)	+= rtc-mpc5121.o
> >  obj-$(CONFIG_RTC_DRV_VRTC)	+= rtc-mrst.o
> >  obj-$(CONFIG_RTC_DRV_MSM6242)	+= rtc-msm6242.o
> > +obj-$(CONFIG_RTC_DRV_MEDIATEK)	+= rtc-mt7622.o
> >  obj-$(CONFIG_RTC_DRV_MT6397)	+= rtc-mt6397.o
> >  obj-$(CONFIG_RTC_DRV_MV)	+= rtc-mv.o
> >  obj-$(CONFIG_RTC_DRV_MXC)	+= rtc-mxc.o
> > diff --git a/drivers/rtc/rtc-mt7622.c b/drivers/rtc/rtc-mt7622.c
> > new file mode 100644
> > index 0000000..1f00494
> > --- /dev/null
> > +++ b/drivers/rtc/rtc-mt7622.c
> > @@ -0,0 +1,418 @@
> > +/*
> > + * Driver for MediaTek SoC based RTC
> > + *
> > + * Copyright (C) 2017 Sean Wang <sean.wang@...iatek.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/clk.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/module.h>
> > +#include <linux/of_address.h>
> > +#include <linux/of_device.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/rtc.h>
> > +
> > +#define MTK_RTC_DEV KBUILD_MODNAME
> > +
> > +#define MTK_RTC_PWRCHK1		0x4
> > +#define	RTC_PWRCHK1_MAGIC	0xc6
> > +
> > +#define MTK_RTC_PWRCHK2		0x8
> > +#define	RTC_PWRCHK2_MAGIC	0x9a
> > +
> > +#define MTK_RTC_KEY		0xc
> > +#define	RTC_KEY_MAGIC		0x59
> > +
> > +#define MTK_RTC_PROT1		0x10
> > +#define	RTC_PROT1_MAGIC		0xa3
> > +
> > +#define MTK_RTC_PROT2		0x14
> > +#define	RTC_PROT2_MAGIC		0x57
> > +
> > +#define MTK_RTC_PROT3		0x18
> > +#define	RTC_PROT3_MAGIC		0x67
> > +
> > +#define MTK_RTC_PROT4		0x1c
> > +#define	RTC_PROT4_MAGIC		0xd2
> > +
> > +#define MTK_RTC_CTL		0x20
> > +#define	RTC_RC_STOP		BIT(0)
> > +
> > +#define MTK_RTC_DEBNCE		0x2c
> > +#define	RTC_DEBNCE_MASK		GENMASK(2, 0)
> > +
> > +#define MTK_RTC_INT		0x30
> > +#define RTC_INT_AL_STA		BIT(4)
> > +
> > +/* Ranges from 0x40 to 0x78 provide RTC time setup for year, month,
> > + * day of month, day of week, hour, minute and second.
> > + */
> > +#define MTK_RTC_TREG(_t, _f)	(0x40 + (0x4 * (_f)) + ((_t) * 0x20))
> > +
> > +#define MTK_RTC_AL_CTL		0x7c
> > +#define	RTC_AL_EN		BIT(0)
> > +#define	RTC_AL_ALL		GENMASK(7, 0)
> > +
> > +#define MTK_RTC_TM_YR_L		100
> > +
> > +/* The maximum years the RTC can support is 99, For MT7622 */
> > +#define MTK_RTC_HW_YR_LIMIT	100
> > +
> > +/* Types of the function the RTC provides are time counter and alarm. */
> > +enum {
> > +	MTK_TC,
> > +	MTK_AL,
> > +	MTK_TYPE_MAX,
> > +};
> > +
> > +/* Indexes are used for the pointer to relevant registers in MTK_RTC_TREG */
> > +enum {
> > +	MTK_YEA,
> > +	MTK_MON,
> > +	MTK_DOM,
> > +	MTK_DOW,
> > +	MTK_HOU,
> > +	MTK_MIN,
> > +	MTK_SEC
> > +};
> > +
> > +struct mtk_rtc {
> > +	struct rtc_device *rtc;
> > +	void __iomem *base;
> > +	int irq;
> > +	struct clk *clk;
> > +	u32 yr_base[MTK_TYPE_MAX];
> > +};
> > +
> > +static void mtk_w32(struct mtk_rtc *rtc, u32 reg, u32 val)
> > +{
> > +	writel_relaxed(val, rtc->base + reg);
> > +}
> > +
> > +static u32 mtk_r32(struct mtk_rtc *rtc, u32 reg)
> > +{
> > +	return readl_relaxed(rtc->base + reg);
> > +}
> > +
> > +static void mtk_rmw(struct mtk_rtc *rtc, u32 reg, u32 mask, u32 set)
> > +{
> > +	u32 val;
> > +
> > +	val = mtk_r32(rtc, reg);
> > +	val &= ~mask;
> > +	val |= set;
> > +	mtk_w32(rtc, reg, val);
> > +}
> > +
> > +static void mtk_set(struct mtk_rtc *rtc, u32 reg, u32 val)
> > +{
> > +	mtk_rmw(rtc, reg, 0, val);
> > +}
> > +
> > +static void mtk_clr(struct mtk_rtc *rtc, u32 reg, u32 val)
> > +{
> > +	mtk_rmw(rtc, reg, val, 0);
> > +}
> > +
> > +static void mtk_rtc_hw_init(struct mtk_rtc *hw)
> > +{
> > +	/* The setup of the init sequence is for allowing RTC got to work */
> > +	mtk_w32(hw, MTK_RTC_PWRCHK1, RTC_PWRCHK1_MAGIC);
> > +	mtk_w32(hw, MTK_RTC_PWRCHK2, RTC_PWRCHK2_MAGIC);
> > +	mtk_w32(hw, MTK_RTC_KEY, RTC_KEY_MAGIC);
> > +	mtk_w32(hw, MTK_RTC_PROT1, RTC_PROT1_MAGIC);
> > +	mtk_w32(hw, MTK_RTC_PROT2, RTC_PROT2_MAGIC);
> > +	mtk_w32(hw, MTK_RTC_PROT3, RTC_PROT3_MAGIC);
> > +	mtk_w32(hw, MTK_RTC_PROT4, RTC_PROT4_MAGIC);
> > +	mtk_rmw(hw, MTK_RTC_DEBNCE, RTC_DEBNCE_MASK, 0);
> > +	mtk_clr(hw, MTK_RTC_CTL, RTC_RC_STOP);
> > +}
> > +
> > +static void mtk_rtc_get_alarm_or_time(struct mtk_rtc *hw, struct rtc_time *tm,
> > +				      int time_alarm)
> > +{
> > +	u32 year, mon, mday, wday, hour, min, sec;
> > +
> > +	/*
> > +	 * Read again until the field of the second is not changed which
> > +	 * ensures all fields in the consistent state.
> 
> Sean,
> 
> You need to read sec first for this to work.
> It is possible sec changed from 59 to 00 after you read min.
> 
> Joe.C
> 

Nice catch. It will be fixed. Thanks for your careful review.

	Sean


> > +	 */
> > +	do {
> > +		year = mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_YEA));
> > +		mon = mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_MON));
> > +		wday = mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_DOW));
> > +		mday = mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_DOM));
> > +		hour = mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_HOU));
> > +		min = mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_MIN));
> > +		sec = mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_SEC));
> > +	} while (sec != mtk_r32(hw, MTK_RTC_TREG(time_alarm, MTK_SEC)));
> > +
> > +	tm->tm_sec  = sec;
> > +	tm->tm_min  = min;
> > +	tm->tm_hour = hour;
> > +	tm->tm_wday = wday;
> > +	tm->tm_mday = mday;
> > +	tm->tm_mon  = mon - 1;
> > +
> > +	/* Rebase to the absolute year which userspace requires */
> > +	tm->tm_year = year + MTK_RTC_TM_YR_L + hw->yr_base[time_alarm];
> > +}
> > +
> > +static void mtk_rtc_set_alarm_or_time(struct mtk_rtc *hw, struct rtc_time *tm,
> > +				      int time_alarm)
> > +{
> > +	u32 year;
> > +
> > +	/* Rebase to the relative year which RTC hardware requires */
> > +	year = tm->tm_year - MTK_RTC_TM_YR_L - hw->yr_base[time_alarm];
> > +
> > +	mtk_w32(hw, MTK_RTC_TREG(time_alarm, MTK_YEA), year);
> > +	mtk_w32(hw, MTK_RTC_TREG(time_alarm, MTK_MON), tm->tm_mon + 1);
> > +	mtk_w32(hw, MTK_RTC_TREG(time_alarm, MTK_DOW), tm->tm_wday);
> > +	mtk_w32(hw, MTK_RTC_TREG(time_alarm, MTK_DOM), tm->tm_mday);
> > +	mtk_w32(hw, MTK_RTC_TREG(time_alarm, MTK_HOU), tm->tm_hour);
> > +	mtk_w32(hw, MTK_RTC_TREG(time_alarm, MTK_MIN), tm->tm_min);
> > +	mtk_w32(hw, MTK_RTC_TREG(time_alarm, MTK_SEC), tm->tm_sec);
> > +}
> > +
> > +static irqreturn_t mtk_rtc_alarmirq(int irq, void *id)
> > +{
> > +	struct mtk_rtc *hw = (struct mtk_rtc *)id;
> > +	u32 irq_sta;
> > +
> > +	irq_sta = mtk_r32(hw, MTK_RTC_INT);
> > +	if (irq_sta & RTC_INT_AL_STA) {
> > +		/* Stop alarm also implicitly disables the alarm interrupt */
> > +		mtk_w32(hw, MTK_RTC_AL_CTL, 0);
> > +		rtc_update_irq(hw->rtc, 1, RTC_IRQF | RTC_AF);
> > +
> > +		/* Ack alarm interrupt status */
> > +		mtk_w32(hw, MTK_RTC_INT, RTC_INT_AL_STA);
> > +		return IRQ_HANDLED;
> > +	}
> > +
> > +	return IRQ_NONE;
> > +}
> > +
> > +static int mtk_rtc_gettime(struct device *dev, struct rtc_time *tm)
> > +{
> > +	struct mtk_rtc *hw = dev_get_drvdata(dev);
> > +
> > +	mtk_rtc_get_alarm_or_time(hw, tm, MTK_TC);
> > +
> > +	return rtc_valid_tm(tm);
> > +}
> > +
> > +static int mtk_rtc_settime(struct device *dev, struct rtc_time *tm)
> > +{
> > +	struct mtk_rtc *hw = dev_get_drvdata(dev);
> > +
> > +	/* Epoch == 1900, and the driver assumes that tm->tm_year has to be
> > +	 * at least MTK_RTC_TM_YR_L.
> > +	 */
> > +	if (tm->tm_year <  MTK_RTC_TM_YR_L)
> > +		return -EINVAL;
> > +
> > +	/* Keep yr_base used to calculate the calculate year when userspace
> > +	 * queries and extend the maximum year the RTC can count.
> > +	 */
> > +	hw->yr_base[MTK_TC] = tm->tm_year - MTK_RTC_TM_YR_L -
> > +			      (tm->tm_year % MTK_RTC_HW_YR_LIMIT);
> > +
> > +	/* Stop time counter before setting a new one*/
> > +	mtk_set(hw, MTK_RTC_CTL, RTC_RC_STOP);
> > +
> > +	mtk_rtc_set_alarm_or_time(hw, tm, MTK_TC);
> > +
> > +	/* Restart the time counter */
> > +	mtk_clr(hw, MTK_RTC_CTL, RTC_RC_STOP);
> > +
> > +	return 0;
> > +}
> > +
> > +static int mtk_rtc_getalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
> > +{
> > +	struct mtk_rtc *hw = dev_get_drvdata(dev);
> > +	struct rtc_time *alrm_tm = &wkalrm->time;
> > +
> > +	mtk_rtc_get_alarm_or_time(hw, alrm_tm, MTK_AL);
> > +
> > +	wkalrm->enabled = !!(mtk_r32(hw, MTK_RTC_AL_CTL) & RTC_AL_EN);
> > +	wkalrm->pending = !!(mtk_r32(hw, MTK_RTC_INT) & RTC_INT_AL_STA);
> > +
> > +	return 0;
> > +}
> > +
> > +static int mtk_rtc_setalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
> > +{
> > +	struct mtk_rtc *hw = dev_get_drvdata(dev);
> > +	struct rtc_time *alrm_tm = &wkalrm->time;
> > +
> > +	/* Epoch == 1900, and the driver assumes that alrm_tm->tm_year has to
> > +	 * be at least MTK_RTC_TM_YR_L.
> > +	 */
> > +	if (alrm_tm->tm_year < MTK_RTC_TM_YR_L)
> > +		return -EINVAL;
> > +
> > +	/* Keep yr_base used to calculate the calculate year when userspace
> > +	 * queries and extend the maximum time the alarm can support.
> > +	 */
> > +	hw->yr_base[MTK_AL] = alrm_tm->tm_year - MTK_RTC_TM_YR_L -
> > +			      (alrm_tm->tm_year % MTK_RTC_HW_YR_LIMIT);
> > +
> > +	/*
> > +	 * Stop the alarm also implicitly including disables interrupt before
> > +	 * setting a new one.
> > +	 */
> > +	mtk_clr(hw, MTK_RTC_AL_CTL, RTC_AL_EN);
> > +
> > +	/*
> > +	 * Avoid contention between mtk_rtc_setalarm and IRQ handler so that
> > +	 * disabling the interrupt and awaiting for pending IRQ handler to
> > +	 * complete.
> > +	 */
> > +	synchronize_irq(hw->irq);
> > +
> > +	mtk_rtc_set_alarm_or_time(hw, alrm_tm, MTK_AL);
> > +
> > +	/* Restart the alarm with the new setup */
> > +	mtk_w32(hw, MTK_RTC_AL_CTL, RTC_AL_ALL);
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct rtc_class_ops mtk_rtc_ops = {
> > +	.read_time		= mtk_rtc_gettime,
> > +	.set_time		= mtk_rtc_settime,
> > +	.read_alarm		= mtk_rtc_getalarm,
> > +	.set_alarm		= mtk_rtc_setalarm,
> > +};
> > +
> > +static const struct of_device_id mtk_rtc_match[] = {
> > +	{ .compatible = "mediatek,mt7622-rtc" },
> > +	{ .compatible = "mediatek,soc-rtc" },
> > +	{},
> > +};
> > +
> > +static int mtk_rtc_probe(struct platform_device *pdev)
> > +{
> > +	struct mtk_rtc *hw;
> > +	struct resource *res;
> > +	int ret;
> > +
> > +	hw = devm_kzalloc(&pdev->dev, sizeof(*hw), GFP_KERNEL);
> > +	if (!hw)
> > +		return -ENOMEM;
> > +
> > +	platform_set_drvdata(pdev, hw);
> > +
> > +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +	hw->base = devm_ioremap_resource(&pdev->dev, res);
> > +	if (IS_ERR(hw->base))
> > +		return PTR_ERR(hw->base);
> > +
> > +	hw->clk = devm_clk_get(&pdev->dev, "rtc");
> > +	if (IS_ERR(hw->clk)) {
> > +		dev_err(&pdev->dev, "No clock\n");
> > +		return PTR_ERR(hw->clk);
> > +	}
> > +
> > +	ret = clk_prepare_enable(hw->clk);
> > +	if (ret)
> > +		return ret;
> > +
> > +	hw->irq = platform_get_irq(pdev, 0);
> > +	if (hw->irq < 0) {
> > +		dev_err(&pdev->dev, "No IRQ resource\n");
> > +		ret = hw->irq;
> > +		goto err;
> > +	}
> > +
> > +	ret = devm_request_irq(&pdev->dev, hw->irq, mtk_rtc_alarmirq,
> > +			       0, dev_name(&pdev->dev), hw);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "Can't request IRQ\n");
> > +		goto err;
> > +	}
> > +
> > +	mtk_rtc_hw_init(hw);
> > +
> > +	device_init_wakeup(&pdev->dev, true);
> > +
> > +	hw->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
> > +					   &mtk_rtc_ops, THIS_MODULE);
> > +	if (IS_ERR(hw->rtc)) {
> > +		ret = PTR_ERR(hw->rtc);
> > +		dev_err(&pdev->dev, "Unable to register device\n");
> > +		goto err;
> > +	}
> > +
> > +	return 0;
> > +err:
> > +	clk_disable_unprepare(hw->clk);
> > +
> > +	return ret;
> > +}
> > +
> > +static int mtk_rtc_remove(struct platform_device *pdev)
> > +{
> > +	struct mtk_rtc *hw = platform_get_drvdata(pdev);
> > +
> > +	clk_disable_unprepare(hw->clk);
> > +
> > +	return 0;
> > +}
> > +
> > +#ifdef CONFIG_PM_SLEEP
> > +static int mtk_rtc_suspend(struct device *dev)
> > +{
> > +	struct mtk_rtc *hw = dev_get_drvdata(dev);
> > +
> > +	if (device_may_wakeup(dev))
> > +		enable_irq_wake(hw->irq);
> > +
> > +	return 0;
> > +}
> > +
> > +static int mtk_rtc_resume(struct device *dev)
> > +{
> > +	struct mtk_rtc *hw = dev_get_drvdata(dev);
> > +
> > +	if (device_may_wakeup(dev))
> > +		disable_irq_wake(hw->irq);
> > +
> > +	return 0;
> > +}
> > +
> > +static SIMPLE_DEV_PM_OPS(mtk_rtc_pm_ops, mtk_rtc_suspend, mtk_rtc_resume);
> > +
> > +#define MTK_RTC_PM_OPS (&mtk_rtc_pm_ops)
> > +#else	/* CONFIG_PM */
> > +#define MTK_RTC_PM_OPS NULL
> > +#endif	/* CONFIG_PM */
> > +
> > +static struct platform_driver mtk_rtc_driver = {
> > +	.probe	= mtk_rtc_probe,
> > +	.remove	= mtk_rtc_remove,
> > +	.driver = {
> > +		.name = MTK_RTC_DEV,
> > +		.of_match_table = mtk_rtc_match,
> > +		.pm = MTK_RTC_PM_OPS,
> > +	},
> > +};
> > +
> > +module_platform_driver(mtk_rtc_driver);
> > +
> > +MODULE_DESCRIPTION("MediaTek SoC based RTC Driver");
> > +MODULE_AUTHOR("Sean Wang <sean.wang@...iatek.com>");
> > +MODULE_LICENSE("GPL");
> 
> 

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