text: /*
  * Copyright (c) 2014-2015 MediaTek Inc.
  * Author: Tianping.Fang <tianping.fang@mediatek.com>
  *
  * 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/delay.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/regmap.h>
  #include <linux/rtc.h>
  #include <linux/irqdomain.h>
  #include <linux/platform_device.h>
  #include <linux/of_address.h>
  #include <linux/of_irq.h>
  #include <linux/io.h>
  #include <linux/mfd/mt6397/core.h>
  
  #define RTC_BBPU		0x0000
  #define RTC_BBPU_CBUSY		BIT(6)
  
  #define RTC_WRTGR		0x003c
  
  #define RTC_IRQ_STA		0x0002
  #define RTC_IRQ_STA_AL		BIT(0)
  #define RTC_IRQ_STA_LP		BIT(3)
  
  #define RTC_IRQ_EN		0x0004
  #define RTC_IRQ_EN_AL		BIT(0)
  #define RTC_IRQ_EN_ONESHOT	BIT(2)
  #define RTC_IRQ_EN_LP		BIT(3)
  #define RTC_IRQ_EN_ONESHOT_AL	(RTC_IRQ_EN_ONESHOT | RTC_IRQ_EN_AL)
  
  #define RTC_AL_MASK		0x0008
  #define RTC_AL_MASK_DOW		BIT(4)
  
  #define RTC_TC_SEC		0x000a
  /* Min, Hour, Dom... register offset to RTC_TC_SEC */
  #define RTC_OFFSET_SEC		0
  #define RTC_OFFSET_MIN		1
  #define RTC_OFFSET_HOUR		2
  #define RTC_OFFSET_DOM		3
  #define RTC_OFFSET_DOW		4
  #define RTC_OFFSET_MTH		5
  #define RTC_OFFSET_YEAR		6
  #define RTC_OFFSET_COUNT	7
  
  #define RTC_AL_SEC		0x0018
  
  #define RTC_PDN2		0x002e
  #define RTC_PDN2_PWRON_ALARM	BIT(4)
  
  #define RTC_MIN_YEAR		1968
  #define RTC_BASE_YEAR		1900
  #define RTC_NUM_YEARS		128
  #define RTC_MIN_YEAR_OFFSET	(RTC_MIN_YEAR - RTC_BASE_YEAR)
  
  struct mt6397_rtc {
  	struct device		*dev;
  	struct rtc_device	*rtc_dev;
  	struct mutex		lock;
  	struct regmap		*regmap;
  	int			irq;
  	u32			addr_base;
  };
  
  static int mtk_rtc_write_trigger(struct mt6397_rtc *rtc)
  {
  	unsigned long timeout = jiffies + HZ;
  	int ret;
  	u32 data;
  
  	ret = regmap_write(rtc->regmap, rtc->addr_base + RTC_WRTGR, 1);
  	if (ret < 0)
  		return ret;
  
  	while (1) {
  		ret = regmap_read(rtc->regmap, rtc->addr_base + RTC_BBPU,
  				  &data);
  		if (ret < 0)
  			break;
  		if (!(data & RTC_BBPU_CBUSY))
  			break;
  		if (time_after(jiffies, timeout)) {
  			ret = -ETIMEDOUT;
  			break;
  		}
  		cpu_relax();
  	}
  
  	return ret;
  }
  
  static irqreturn_t mtk_rtc_irq_handler_thread(int irq, void *data)
  {
  	struct mt6397_rtc *rtc = data;
  	u32 irqsta, irqen;
  	int ret;
  
  	ret = regmap_read(rtc->regmap, rtc->addr_base + RTC_IRQ_STA, &irqsta);
  	if ((ret >= 0) && (irqsta & RTC_IRQ_STA_AL)) {
  		rtc_update_irq(rtc->rtc_dev, 1, RTC_IRQF | RTC_AF);
  		irqen = irqsta & ~RTC_IRQ_EN_AL;
  		mutex_lock(&rtc->lock);
  		if (regmap_write(rtc->regmap, rtc->addr_base + RTC_IRQ_EN,
  				 irqen) < 0)
  			mtk_rtc_write_trigger(rtc);
  		mutex_unlock(&rtc->lock);
  
  		return IRQ_HANDLED;
  	}
  
  	return IRQ_NONE;
  }
  
  static int __mtk_rtc_read_time(struct mt6397_rtc *rtc,
  			       struct rtc_time *tm, int *sec)
  {
  	int ret;
  	u16 data[RTC_OFFSET_COUNT];
  
  	mutex_lock(&rtc->lock);
  	ret = regmap_bulk_read(rtc->regmap, rtc->addr_base + RTC_TC_SEC,
  			       data, RTC_OFFSET_COUNT);
  	if (ret < 0)
  		goto exit;
  
  	tm->tm_sec = data[RTC_OFFSET_SEC];
  	tm->tm_min = data[RTC_OFFSET_MIN];
  	tm->tm_hour = data[RTC_OFFSET_HOUR];
  	tm->tm_mday = data[RTC_OFFSET_DOM];
  	tm->tm_mon = data[RTC_OFFSET_MTH];
  	tm->tm_year = data[RTC_OFFSET_YEAR];
  
  	ret = regmap_read(rtc->regmap, rtc->addr_base + RTC_TC_SEC, sec);
  exit:
  	mutex_unlock(&rtc->lock);
  	return ret;
  }
  
  static int mtk_rtc_read_time(struct device *dev, struct rtc_time *tm)
  {
  	time64_t time;
  	struct mt6397_rtc *rtc = dev_get_drvdata(dev);
  	int days, sec, ret;
  
  	do {
  		ret = __mtk_rtc_read_time(rtc, tm, &sec);
  		if (ret < 0)
  			goto exit;
  	} while (sec < tm->tm_sec);
  
  	/* HW register use 7 bits to store year data, minus
  	 * RTC_MIN_YEAR_OFFSET before write year data to register, and plus
  	 * RTC_MIN_YEAR_OFFSET back after read year from register
  	 */
  	tm->tm_year += RTC_MIN_YEAR_OFFSET;
  
  	/* HW register start mon from one, but tm_mon start from zero. */
  	tm->tm_mon--;
  	time = rtc_tm_to_time64(tm);
  
  	/* rtc_tm_to_time64 covert Gregorian date to seconds since
  	 * 01-01-1970 00:00:00, and this date is Thursday.
  	 */
  	days = div_s64(time, 86400);
  	tm->tm_wday = (days + 4) % 7;
  
  exit:
  	return ret;
  }
  
  static int mtk_rtc_set_time(struct device *dev, struct rtc_time *tm)
  {
  	struct mt6397_rtc *rtc = dev_get_drvdata(dev);
  	int ret;
  	u16 data[RTC_OFFSET_COUNT];
  
  	tm->tm_year -= RTC_MIN_YEAR_OFFSET;
  	tm->tm_mon++;
  
  	data[RTC_OFFSET_SEC] = tm->tm_sec;
  	data[RTC_OFFSET_MIN] = tm->tm_min;
  	data[RTC_OFFSET_HOUR] = tm->tm_hour;
  	data[RTC_OFFSET_DOM] = tm->tm_mday;
  	data[RTC_OFFSET_MTH] = tm->tm_mon;
  	data[RTC_OFFSET_YEAR] = tm->tm_year;
  
  	mutex_lock(&rtc->lock);
  	ret = regmap_bulk_write(rtc->regmap, rtc->addr_base + RTC_TC_SEC,
  				data, RTC_OFFSET_COUNT);
  	if (ret < 0)
  		goto exit;
  
  	/* Time register write to hardware after call trigger function */
  	ret = mtk_rtc_write_trigger(rtc);
  
  exit:
  	mutex_unlock(&rtc->lock);
  	return ret;
  }
  
  static int mtk_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
  {
  	struct rtc_time *tm = &alm->time;
  	struct mt6397_rtc *rtc = dev_get_drvdata(dev);
  	u32 irqen, pdn2;
  	int ret;
  	u16 data[RTC_OFFSET_COUNT];
  
  	mutex_lock(&rtc->lock);
  	ret = regmap_read(rtc->regmap, rtc->addr_base + RTC_IRQ_EN, &irqen);
  	if (ret < 0)
  		goto err_exit;
  	ret = regmap_read(rtc->regmap, rtc->addr_base + RTC_PDN2, &pdn2);
  	if (ret < 0)
  		goto err_exit;
  
  	ret = regmap_bulk_read(rtc->regmap, rtc->addr_base + RTC_AL_SEC,
  			       data, RTC_OFFSET_COUNT);
  	if (ret < 0)
  		goto err_exit;
  
  	alm->enabled = !!(irqen & RTC_IRQ_EN_AL);
  	alm->pending = !!(pdn2 & RTC_PDN2_PWRON_ALARM);
  	mutex_unlock(&rtc->lock);
  
  	tm->tm_sec = data[RTC_OFFSET_SEC];
  	tm->tm_min = data[RTC_OFFSET_MIN];
  	tm->tm_hour = data[RTC_OFFSET_HOUR];
  	tm->tm_mday = data[RTC_OFFSET_DOM];
  	tm->tm_mon = data[RTC_OFFSET_MTH];
  	tm->tm_year = data[RTC_OFFSET_YEAR];
  
  	tm->tm_year += RTC_MIN_YEAR_OFFSET;
  	tm->tm_mon--;
  
  	return 0;
  err_exit:
  	mutex_unlock(&rtc->lock);
  	return ret;
  }
  
  static int mtk_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
  {
  	struct rtc_time *tm = &alm->time;
  	struct mt6397_rtc *rtc = dev_get_drvdata(dev);
  	int ret;
  	u16 data[RTC_OFFSET_COUNT];
  
  	tm->tm_year -= RTC_MIN_YEAR_OFFSET;
  	tm->tm_mon++;
  
  	data[RTC_OFFSET_SEC] = tm->tm_sec;
  	data[RTC_OFFSET_MIN] = tm->tm_min;
  	data[RTC_OFFSET_HOUR] = tm->tm_hour;
  	data[RTC_OFFSET_DOM] = tm->tm_mday;
  	data[RTC_OFFSET_MTH] = tm->tm_mon;
  	data[RTC_OFFSET_YEAR] = tm->tm_year;
  
  	mutex_lock(&rtc->lock);
  	if (alm->enabled) {
  		ret = regmap_bulk_write(rtc->regmap,
  					rtc->addr_base + RTC_AL_SEC,
  					data, RTC_OFFSET_COUNT);
  		if (ret < 0)
  			goto exit;
  		ret = regmap_write(rtc->regmap, rtc->addr_base + RTC_AL_MASK,
  				   RTC_AL_MASK_DOW);
  		if (ret < 0)
  			goto exit;
  		ret = regmap_update_bits(rtc->regmap,
  					 rtc->addr_base + RTC_IRQ_EN,
  					 RTC_IRQ_EN_ONESHOT_AL,
  					 RTC_IRQ_EN_ONESHOT_AL);
  		if (ret < 0)
  			goto exit;
  	} else {
  		ret = regmap_update_bits(rtc->regmap,
  					 rtc->addr_base + RTC_IRQ_EN,
  					 RTC_IRQ_EN_ONESHOT_AL, 0);
  		if (ret < 0)
  			goto exit;
  	}
  
  	/* All alarm time register write to hardware after calling
  	 * mtk_rtc_write_trigger. This can avoid race condition if alarm
  	 * occur happen during writing alarm time register.
  	 */
  	ret = mtk_rtc_write_trigger(rtc);
  exit:
  	mutex_unlock(&rtc->lock);
  	return ret;
  }
  
  static struct rtc_class_ops mtk_rtc_ops = {
  	.read_time  = mtk_rtc_read_time,
  	.set_time   = mtk_rtc_set_time,
  	.read_alarm = mtk_rtc_read_alarm,
  	.set_alarm  = mtk_rtc_set_alarm,
  };
  
  static int mtk_rtc_probe(struct platform_device *pdev)
  {
  	struct resource *res;
  	struct mt6397_chip *mt6397_chip = dev_get_drvdata(pdev->dev.parent);
  	struct mt6397_rtc *rtc;
  	int ret;
  
  	rtc = devm_kzalloc(&pdev->dev, sizeof(struct mt6397_rtc), GFP_KERNEL);
  	if (!rtc)
  		return -ENOMEM;
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	rtc->addr_base = res->start;
  
  	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
  	rtc->irq = irq_create_mapping(mt6397_chip->irq_domain, res->start);
  	if (rtc->irq <= 0)
  		return -EINVAL;
  
  	rtc->regmap = mt6397_chip->regmap;
  	rtc->dev = &pdev->dev;
  	mutex_init(&rtc->lock);
  
  	platform_set_drvdata(pdev, rtc);
  
  	ret = request_threaded_irq(rtc->irq, NULL,
  				   mtk_rtc_irq_handler_thread,
  				   IRQF_ONESHOT | IRQF_TRIGGER_HIGH,
  				   "mt6397-rtc", rtc);
  	if (ret) {
  		dev_err(&pdev->dev, "Failed to request alarm IRQ: %d: %d\n",
  			rtc->irq, ret);
  		goto out_dispose_irq;
  	}
  
  	device_init_wakeup(&pdev->dev, 1);
  
  	rtc->rtc_dev = rtc_device_register("mt6397-rtc", &pdev->dev,
  					   &mtk_rtc_ops, THIS_MODULE);
  	if (IS_ERR(rtc->rtc_dev)) {
  		dev_err(&pdev->dev, "register rtc device failed\n");
  		ret = PTR_ERR(rtc->rtc_dev);
  		goto out_free_irq;
  	}
  
  	return 0;
  
  out_free_irq:
  	free_irq(rtc->irq, rtc->rtc_dev);
  out_dispose_irq:
  	irq_dispose_mapping(rtc->irq);
  	return ret;
  }
  
  static int mtk_rtc_remove(struct platform_device *pdev)
  {
  	struct mt6397_rtc *rtc = platform_get_drvdata(pdev);
  
  	rtc_device_unregister(rtc->rtc_dev);
  	free_irq(rtc->irq, rtc->rtc_dev);
  	irq_dispose_mapping(rtc->irq);
  
  	return 0;
  }
  
  #ifdef CONFIG_PM_SLEEP
  static int mt6397_rtc_suspend(struct device *dev)
  {
  	struct mt6397_rtc *rtc = dev_get_drvdata(dev);
  
  	if (device_may_wakeup(dev))
  		enable_irq_wake(rtc->irq);
  
  	return 0;
  }
  
  static int mt6397_rtc_resume(struct device *dev)
  {
  	struct mt6397_rtc *rtc = dev_get_drvdata(dev);
  
  	if (device_may_wakeup(dev))
  		disable_irq_wake(rtc->irq);
  
  	return 0;
  }
  #endif
  
  static SIMPLE_DEV_PM_OPS(mt6397_pm_ops, mt6397_rtc_suspend,
  			mt6397_rtc_resume);
  
  static const struct of_device_id mt6397_rtc_of_match[] = {
  	{ .compatible = "mediatek,mt6397-rtc", },
  	{ }
  };
  MODULE_DEVICE_TABLE(of, mt6397_rtc_of_match);
  
  static struct platform_driver mtk_rtc_driver = {
  	.driver = {
  		.name = "mt6397-rtc",
  		.of_match_table = mt6397_rtc_of_match,
  		.pm = &mt6397_pm_ops,
  	},
  	.probe	= mtk_rtc_probe,
  	.remove = mtk_rtc_remove,
  };
  
  module_platform_driver(mtk_rtc_driver);
  
  MODULE_LICENSE("GPL v2");
  MODULE_AUTHOR("Tianping Fang <tianping.fang@mediatek.com>");
  MODULE_DESCRIPTION("RTC Driver for MediaTek MT6397 PMIC");
  