Message-ID: <1508320354.13340.19.camel@mtksdaap41>
Date:   Wed, 18 Oct 2017 17:52:34 +0800
From:   Yingjoe Chen <yingjoe.chen@...iatek.com>
To:     <sean.wang@...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 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

> +	 */
> +	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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