Date:	Fri, 8 Jul 2016 18:21:52 +0200
From:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:	Chen-Yu Tsai <wens@...e.org>
Cc:	Lee Jones <lee.jones@...aro.org>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	linux-kernel@...r.kernel.org, rtc-linux@...glegroups.com,
	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v5 3/7] rtc: ac100: Add RTC driver for X-Powers AC100

On 08/07/2016 at 22:33:38 +0800, Chen-Yu Tsai wrote :
> X-Powers AC100 is a codec / RTC combo chip. This driver supports
> the RTC sub-device.
> 
> The RTC block also has clock outputs and non-volatile storage.
> Non-volatile storage wthin the RTC hardware is not supported.
> Clock output support is added in the next patch.
> 
> Signed-off-by: Chen-Yu Tsai <wens@...e.org>
Acked-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>

> ---
> Changes since v4:
> 
>   - None.
> 
> Changes since v3:
> 
>   - Moved month/year conversion offsets inline with reg[] assignments
>   - Used platform_get_irq instead of of_get_irq
>   - Dropped separate mutex and use rtc->ops_lock in interrupt handler
>   - Dropped of_irq.h from includes
>   - Added of_device_id and .of_match_table
> 
> Changes since v2:
> 
>   - Fixed off-by-1 errors in register mask macros
>   - Fixed copy-paste error in set_alarm function
>   - Drop uie_unsupported, since the alarm works now
>   - Fixed up copyright notice
>   - Changed license to GPL v2, matching mfd driver
> 
> ---
>  drivers/rtc/Kconfig     |  10 ++
>  drivers/rtc/Makefile    |   1 +
>  drivers/rtc/rtc-ac100.c | 325 ++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 336 insertions(+)
>  create mode 100644 drivers/rtc/rtc-ac100.c
> 
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 18639e0cb6e2..b9d7cbb6bd76 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -183,6 +183,16 @@ config RTC_DRV_ABX80X
>  	  This driver can also be built as a module. If so, the module
>  	  will be called rtc-abx80x.
>  
> +config RTC_DRV_AC100
> +	tristate "X-Powers AC100"
> +	depends on MFD_AC100
> +	help
> +	  If you say yes here you get support for the real-time clock found
> +	  in X-Powers AC100 family peripheral ICs.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called rtc-ac100.
> +
>  config RTC_DRV_AS3722
>  	tristate "ams AS3722 RTC driver"
>  	depends on MFD_AS3722
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index ea2833723fa9..b07c28779573 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -26,6 +26,7 @@ obj-$(CONFIG_RTC_DRV_AB3100)	+= rtc-ab3100.o
>  obj-$(CONFIG_RTC_DRV_AB8500)	+= rtc-ab8500.o
>  obj-$(CONFIG_RTC_DRV_ABB5ZES3)	+= rtc-ab-b5ze-s3.o
>  obj-$(CONFIG_RTC_DRV_ABX80X)	+= rtc-abx80x.o
> +obj-$(CONFIG_RTC_DRV_AC100)	+= rtc-ac100.o
>  obj-$(CONFIG_RTC_DRV_ARMADA38X)	+= rtc-armada38x.o
>  obj-$(CONFIG_RTC_DRV_AS3722)	+= rtc-as3722.o
>  obj-$(CONFIG_RTC_DRV_ASM9260)	+= rtc-asm9260.o
> diff --git a/drivers/rtc/rtc-ac100.c b/drivers/rtc/rtc-ac100.c
> new file mode 100644
> index 000000000000..5a9ca89d04c7
> --- /dev/null
> +++ b/drivers/rtc/rtc-ac100.c
> @@ -0,0 +1,325 @@
> +/*
> + * RTC Driver for X-Powers AC100
> + *
> + * Copyright (c) 2016 Chen-Yu Tsai
> + *
> + * Chen-Yu Tsai <wens@...e.org>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * 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/bcd.h>
> +#include <linux/device.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/ac100.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/rtc.h>
> +#include <linux/types.h>
> +
> +/* Control register */
> +#define AC100_RTC_CTRL_24HOUR	BIT(0)
> +
> +/* RTC */
> +#define AC100_RTC_SEC_MASK	GENMASK(6, 0)
> +#define AC100_RTC_MIN_MASK	GENMASK(6, 0)
> +#define AC100_RTC_HOU_MASK	GENMASK(5, 0)
> +#define AC100_RTC_WEE_MASK	GENMASK(2, 0)
> +#define AC100_RTC_DAY_MASK	GENMASK(5, 0)
> +#define AC100_RTC_MON_MASK	GENMASK(4, 0)
> +#define AC100_RTC_YEA_MASK	GENMASK(7, 0)
> +#define AC100_RTC_YEA_LEAP	BIT(15)
> +#define AC100_RTC_UPD_TRIGGER	BIT(15)
> +
> +/* Alarm (wall clock) */
> +#define AC100_ALM_INT_ENABLE	BIT(0)
> +
> +#define AC100_ALM_SEC_MASK	GENMASK(6, 0)
> +#define AC100_ALM_MIN_MASK	GENMASK(6, 0)
> +#define AC100_ALM_HOU_MASK	GENMASK(5, 0)
> +#define AC100_ALM_WEE_MASK	GENMASK(2, 0)
> +#define AC100_ALM_DAY_MASK	GENMASK(5, 0)
> +#define AC100_ALM_MON_MASK	GENMASK(4, 0)
> +#define AC100_ALM_YEA_MASK	GENMASK(7, 0)
> +#define AC100_ALM_ENABLE_FLAG	BIT(15)
> +#define AC100_ALM_UPD_TRIGGER	BIT(15)
> +
> +/*
> + * 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 - 2069. This range is selected to match Allwinner's
> + * driver.
> + */
> +#define AC100_YEAR_MIN				1970
> +#define AC100_YEAR_MAX				2069
> +#define AC100_YEAR_OFF				(AC100_YEAR_MIN - 1900)
> +
> +struct ac100_rtc_dev {
> +	struct rtc_device *rtc;
> +	struct device *dev;
> +	struct regmap *regmap;
> +	int irq;
> +	unsigned long alarm;
> +};
> +
> +static int ac100_rtc_get_time(struct device *dev, struct rtc_time *rtc_tm)
> +{
> +	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
> +	struct regmap *regmap = chip->regmap;
> +	u16 reg[7];
> +	int ret;
> +
> +	ret = regmap_bulk_read(regmap, AC100_RTC_SEC, reg, 7);
> +	if (ret)
> +		return ret;
> +
> +	rtc_tm->tm_sec  = bcd2bin(reg[0] & AC100_RTC_SEC_MASK);
> +	rtc_tm->tm_min  = bcd2bin(reg[1] & AC100_RTC_MIN_MASK);
> +	rtc_tm->tm_hour = bcd2bin(reg[2] & AC100_RTC_HOU_MASK);
> +	rtc_tm->tm_wday = bcd2bin(reg[3] & AC100_RTC_WEE_MASK);
> +	rtc_tm->tm_mday = bcd2bin(reg[4] & AC100_RTC_DAY_MASK);
> +	rtc_tm->tm_mon  = bcd2bin(reg[5] & AC100_RTC_MON_MASK) - 1;
> +	rtc_tm->tm_year = bcd2bin(reg[6] & AC100_RTC_YEA_MASK) +
> +			  AC100_YEAR_OFF;
> +
> +	return rtc_valid_tm(rtc_tm);
> +}
> +
> +static int ac100_rtc_set_time(struct device *dev, struct rtc_time *rtc_tm)
> +{
> +	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
> +	struct regmap *regmap = chip->regmap;
> +	int year;
> +	u16 reg[8];
> +
> +	/* our RTC has a limited year range... */
> +	year = rtc_tm->tm_year - AC100_YEAR_OFF;
> +	if (year < 0 || year > (AC100_YEAR_MAX - 1900)) {
> +		dev_err(dev, "rtc only supports year in range %d - %d\n",
> +			AC100_YEAR_MIN, AC100_YEAR_MAX);
> +		return -EINVAL;
> +	}
> +
> +	/* convert to BCD */
> +	reg[0] = bin2bcd(rtc_tm->tm_sec)     & AC100_RTC_SEC_MASK;
> +	reg[1] = bin2bcd(rtc_tm->tm_min)     & AC100_RTC_MIN_MASK;
> +	reg[2] = bin2bcd(rtc_tm->tm_hour)    & AC100_RTC_HOU_MASK;
> +	reg[3] = bin2bcd(rtc_tm->tm_wday)    & AC100_RTC_WEE_MASK;
> +	reg[4] = bin2bcd(rtc_tm->tm_mday)    & AC100_RTC_DAY_MASK;
> +	reg[5] = bin2bcd(rtc_tm->tm_mon + 1) & AC100_RTC_MON_MASK;
> +	reg[6] = bin2bcd(year)		     & AC100_RTC_YEA_MASK;
> +	/* trigger write */
> +	reg[7] = AC100_RTC_UPD_TRIGGER;
> +
> +	/* Is it a leap year? */
> +	if (is_leap_year(year + AC100_YEAR_OFF + 1900))
> +		reg[6] |= AC100_RTC_YEA_LEAP;
> +
> +	return regmap_bulk_write(regmap, AC100_RTC_SEC, reg, 8);
> +}
> +
> +static int ac100_rtc_alarm_irq_enable(struct device *dev, unsigned int en)
> +{
> +	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
> +	struct regmap *regmap = chip->regmap;
> +	unsigned int val;
> +
> +	val = en ? AC100_ALM_INT_ENABLE : 0;
> +
> +	return regmap_write(regmap, AC100_ALM_INT_ENA, val);
> +}
> +
> +static int ac100_rtc_get_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> +	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
> +	struct regmap *regmap = chip->regmap;
> +	struct rtc_time *alrm_tm = &alrm->time;
> +	u16 reg[7];
> +	unsigned int val;
> +	int ret;
> +
> +	ret = regmap_read(regmap, AC100_ALM_INT_ENA, &val);
> +	if (ret)
> +		return ret;
> +
> +	alrm->enabled = !!(val & AC100_ALM_INT_ENABLE);
> +
> +	ret = regmap_bulk_read(regmap, AC100_ALM_SEC, reg, 7);
> +	if (ret)
> +		return ret;
> +
> +	alrm_tm->tm_sec  = bcd2bin(reg[0] & AC100_ALM_SEC_MASK);
> +	alrm_tm->tm_min  = bcd2bin(reg[1] & AC100_ALM_MIN_MASK);
> +	alrm_tm->tm_hour = bcd2bin(reg[2] & AC100_ALM_HOU_MASK);
> +	alrm_tm->tm_wday = bcd2bin(reg[3] & AC100_ALM_WEE_MASK);
> +	alrm_tm->tm_mday = bcd2bin(reg[4] & AC100_ALM_DAY_MASK);
> +	alrm_tm->tm_mon  = bcd2bin(reg[5] & AC100_ALM_MON_MASK) - 1;
> +	alrm_tm->tm_year = bcd2bin(reg[6] & AC100_ALM_YEA_MASK) +
> +			   AC100_YEAR_OFF;
> +
> +	return 0;
> +}
> +
> +static int ac100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
> +{
> +	struct ac100_rtc_dev *chip = dev_get_drvdata(dev);
> +	struct regmap *regmap = chip->regmap;
> +	struct rtc_time *alrm_tm = &alrm->time;
> +	u16 reg[8];
> +	int year;
> +	int ret;
> +
> +	/* our alarm has a limited year range... */
> +	year = alrm_tm->tm_year - AC100_YEAR_OFF;
> +	if (year < 0 || year > (AC100_YEAR_MAX - 1900)) {
> +		dev_err(dev, "alarm only supports year in range %d - %d\n",
> +			AC100_YEAR_MIN, AC100_YEAR_MAX);
> +		return -EINVAL;
> +	}
> +
> +	/* convert to BCD */
> +	reg[0] = (bin2bcd(alrm_tm->tm_sec)  & AC100_ALM_SEC_MASK) |
> +			AC100_ALM_ENABLE_FLAG;
> +	reg[1] = (bin2bcd(alrm_tm->tm_min)  & AC100_ALM_MIN_MASK) |
> +			AC100_ALM_ENABLE_FLAG;
> +	reg[2] = (bin2bcd(alrm_tm->tm_hour) & AC100_ALM_HOU_MASK) |
> +			AC100_ALM_ENABLE_FLAG;
> +	/* Do not enable weekday alarm */
> +	reg[3] = bin2bcd(alrm_tm->tm_wday) & AC100_ALM_WEE_MASK;
> +	reg[4] = (bin2bcd(alrm_tm->tm_mday) & AC100_ALM_DAY_MASK) |
> +			AC100_ALM_ENABLE_FLAG;
> +	reg[5] = (bin2bcd(alrm_tm->tm_mon + 1)  & AC100_ALM_MON_MASK) |
> +			AC100_ALM_ENABLE_FLAG;
> +	reg[6] = (bin2bcd(year) & AC100_ALM_YEA_MASK) |
> +			AC100_ALM_ENABLE_FLAG;
> +	/* trigger write */
> +	reg[7] = AC100_ALM_UPD_TRIGGER;
> +
> +	ret = regmap_bulk_write(regmap, AC100_ALM_SEC, reg, 8);
> +	if (ret)
> +		return ret;
> +
> +	return ac100_rtc_alarm_irq_enable(dev, alrm->enabled);
> +}
> +
> +static irqreturn_t ac100_rtc_irq(int irq, void *data)
> +{
> +	struct ac100_rtc_dev *chip = data;
> +	struct regmap *regmap = chip->regmap;
> +	unsigned int val = 0;
> +	int ret;
> +
> +	mutex_lock(&chip->rtc->ops_lock);
> +
> +	/* read status */
> +	ret = regmap_read(regmap, AC100_ALM_INT_STA, &val);
> +	if (ret)
> +		goto out;
> +
> +	if (val & AC100_ALM_INT_ENABLE) {
> +		/* signal rtc framework */
> +		rtc_update_irq(chip->rtc, 1, RTC_AF | RTC_IRQF);
> +
> +		/* clear status */
> +		ret = regmap_write(regmap, AC100_ALM_INT_STA, val);
> +		if (ret)
> +			goto out;
> +
> +		/* disable interrupt */
> +		ret = ac100_rtc_alarm_irq_enable(chip->dev, 0);
> +		if (ret)
> +			goto out;
> +	}
> +
> +out:
> +	mutex_unlock(&chip->rtc->ops_lock);
> +	return IRQ_HANDLED;
> +}
> +
> +static const struct rtc_class_ops ac100_rtc_ops = {
> +	.read_time	  = ac100_rtc_get_time,
> +	.set_time	  = ac100_rtc_set_time,
> +	.read_alarm	  = ac100_rtc_get_alarm,
> +	.set_alarm	  = ac100_rtc_set_alarm,
> +	.alarm_irq_enable = ac100_rtc_alarm_irq_enable,
> +};
> +
> +static int ac100_rtc_probe(struct platform_device *pdev)
> +{
> +	struct ac100_dev *ac100 = dev_get_drvdata(pdev->dev.parent);
> +	struct ac100_rtc_dev *chip;
> +	int ret;
> +
> +	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
> +	platform_set_drvdata(pdev, chip);
> +	chip->dev = &pdev->dev;
> +	chip->regmap = ac100->regmap;
> +
> +	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_threaded_irq(&pdev->dev, chip->irq, NULL,
> +					ac100_rtc_irq,
> +					IRQF_SHARED | IRQF_ONESHOT,
> +					dev_name(&pdev->dev), chip);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Could not request IRQ\n");
> +		return ret;
> +	}
> +
> +	/* always use 24 hour mode */
> +	regmap_write_bits(chip->regmap, AC100_RTC_CTRL, AC100_RTC_CTRL_24HOUR,
> +			  AC100_RTC_CTRL_24HOUR);
> +
> +	/* disable counter alarm interrupt */
> +	regmap_write(chip->regmap, AC100_ALM_INT_ENA, 0);
> +
> +	/* clear counter alarm pending interrupts */
> +	regmap_write(chip->regmap, AC100_ALM_INT_STA, AC100_ALM_INT_ENABLE);
> +
> +	chip->rtc = devm_rtc_device_register(&pdev->dev, "rtc-ac100",
> +					     &ac100_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 const struct of_device_id ac100_rtc_match[] = {
> +	{ .compatible = "x-powers,ac100-rtc" },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, ac100_rtc_match);
> +
> +static struct platform_driver ac100_rtc_driver = {
> +	.probe		= ac100_rtc_probe,
> +	.driver		= {
> +		.name		= "ac100-rtc",
> +		.of_match_table	= of_match_ptr(ac100_rtc_match),
> +	},
> +};
> +module_platform_driver(ac100_rtc_driver);
> +
> +MODULE_DESCRIPTION("X-Powers AC100 RTC driver");
> +MODULE_AUTHOR("Chen-Yu Tsai <wens@...e.org>");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.8.1
> 

-- 
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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