/*
   * Copyright (c) 2008-2009 Nuvoton technology corporation.
   *
   * Wan ZongShun <mcuos.com@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;version 2 of the License.
   *
   */
  
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/platform_device.h>

  #include <linux/slab.h>

  #include <linux/rtc.h>
  #include <linux/delay.h>
  #include <linux/io.h>
  #include <linux/bcd.h>
  
  /* RTC Control Registers */
  #define REG_RTC_INIR		0x00
  #define REG_RTC_AER		0x04
  #define REG_RTC_FCR		0x08
  #define REG_RTC_TLR		0x0C
  #define REG_RTC_CLR		0x10
  #define REG_RTC_TSSR		0x14
  #define REG_RTC_DWR		0x18
  #define REG_RTC_TAR		0x1C
  #define REG_RTC_CAR		0x20
  #define REG_RTC_LIR		0x24
  #define REG_RTC_RIER		0x28
  #define REG_RTC_RIIR		0x2C
  #define REG_RTC_TTR		0x30
  
  #define RTCSET			0x01
  #define AERRWENB		0x10000
  #define INIRRESET		0xa5eb1357
  #define AERPOWERON		0xA965
  #define AERPOWEROFF		0x0000
  #define LEAPYEAR		0x0001
  #define TICKENB			0x80
  #define TICKINTENB		0x0002
  #define ALARMINTENB		0x0001
  #define MODE24			0x0001
  
  struct nuc900_rtc {
  	int			irq_num;
  	void __iomem		*rtc_reg;
  	struct rtc_device	*rtcdev;
  };
  
  struct nuc900_bcd_time {
  	int bcd_sec;
  	int bcd_min;
  	int bcd_hour;
  	int bcd_mday;
  	int bcd_mon;
  	int bcd_year;
  };
  
  static irqreturn_t nuc900_rtc_interrupt(int irq, void *_rtc)
  {
  	struct nuc900_rtc *rtc = _rtc;
  	unsigned long events = 0, rtc_irq;
  
  	rtc_irq = __raw_readl(rtc->rtc_reg + REG_RTC_RIIR);
  
  	if (rtc_irq & ALARMINTENB) {
  		rtc_irq &= ~ALARMINTENB;
  		__raw_writel(rtc_irq, rtc->rtc_reg + REG_RTC_RIIR);
  		events |= RTC_AF | RTC_IRQF;
  	}
  
  	if (rtc_irq & TICKINTENB) {
  		rtc_irq &= ~TICKINTENB;
  		__raw_writel(rtc_irq, rtc->rtc_reg + REG_RTC_RIIR);
  		events |= RTC_UF | RTC_IRQF;
  	}
  
  	rtc_update_irq(rtc->rtcdev, 1, events);
  
  	return IRQ_HANDLED;
  }
  
  static int *check_rtc_access_enable(struct nuc900_rtc *nuc900_rtc)
  {

  	unsigned int timeout = 0x1000;

  	__raw_writel(INIRRESET, nuc900_rtc->rtc_reg + REG_RTC_INIR);
  
  	mdelay(10);
  
  	__raw_writel(AERPOWERON, nuc900_rtc->rtc_reg + REG_RTC_AER);

  	while (!(__raw_readl(nuc900_rtc->rtc_reg + REG_RTC_AER) & AERRWENB)
  								&& timeout--)
  		mdelay(1);

  	if (!timeout)
  		return ERR_PTR(-EPERM);

  	return 0;

  }

  static int nuc900_rtc_bcd2bin(unsigned int timereg,

  				unsigned int calreg, struct rtc_time *tm)
  {
  	tm->tm_mday	= bcd2bin(calreg >> 0);
  	tm->tm_mon	= bcd2bin(calreg >> 8);
  	tm->tm_year	= bcd2bin(calreg >> 16) + 100;
  
  	tm->tm_sec	= bcd2bin(timereg >> 0);
  	tm->tm_min	= bcd2bin(timereg >> 8);
  	tm->tm_hour	= bcd2bin(timereg >> 16);

  	return rtc_valid_tm(tm);

  }

  static void nuc900_rtc_bin2bcd(struct device *dev, struct rtc_time *settm,

  						struct nuc900_bcd_time *gettm)
  {
  	gettm->bcd_mday = bin2bcd(settm->tm_mday) << 0;
  	gettm->bcd_mon  = bin2bcd(settm->tm_mon) << 8;

  
  	if (settm->tm_year < 100) {
  		dev_warn(dev, "The year will be between 1970-1999, right?
  ");
  		gettm->bcd_year = bin2bcd(settm->tm_year) << 16;
  	} else {
  		gettm->bcd_year = bin2bcd(settm->tm_year - 100) << 16;
  	}

  
  	gettm->bcd_sec  = bin2bcd(settm->tm_sec) << 0;
  	gettm->bcd_min  = bin2bcd(settm->tm_min) << 8;
  	gettm->bcd_hour = bin2bcd(settm->tm_hour) << 16;
  }

  static int nuc900_alarm_irq_enable(struct device *dev, unsigned int enabled)
  {
  	struct nuc900_rtc *rtc = dev_get_drvdata(dev);
  
  	if (enabled)
  		__raw_writel(__raw_readl(rtc->rtc_reg + REG_RTC_RIER)|
  				(ALARMINTENB), rtc->rtc_reg + REG_RTC_RIER);
  	else
  		__raw_writel(__raw_readl(rtc->rtc_reg + REG_RTC_RIER)&
  				(~ALARMINTENB), rtc->rtc_reg + REG_RTC_RIER);
  
  	return 0;
  }
  
  static int nuc900_rtc_read_time(struct device *dev, struct rtc_time *tm)
  {
  	struct nuc900_rtc *rtc = dev_get_drvdata(dev);
  	unsigned int timeval, clrval;
  
  	timeval = __raw_readl(rtc->rtc_reg + REG_RTC_TLR);
  	clrval	= __raw_readl(rtc->rtc_reg + REG_RTC_CLR);

  	return nuc900_rtc_bcd2bin(timeval, clrval, tm);

  }
  
  static int nuc900_rtc_set_time(struct device *dev, struct rtc_time *tm)
  {
  	struct nuc900_rtc *rtc = dev_get_drvdata(dev);
  	struct nuc900_bcd_time gettm;
  	unsigned long val;
  	int *err;

  	nuc900_rtc_bin2bcd(dev, tm, &gettm);

  
  	err = check_rtc_access_enable(rtc);
  	if (IS_ERR(err))
  		return PTR_ERR(err);
  
  	val = gettm.bcd_mday | gettm.bcd_mon | gettm.bcd_year;
  	__raw_writel(val, rtc->rtc_reg + REG_RTC_CLR);
  
  	val = gettm.bcd_sec | gettm.bcd_min | gettm.bcd_hour;
  	__raw_writel(val, rtc->rtc_reg + REG_RTC_TLR);
  
  	return 0;
  }
  
  static int nuc900_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	struct nuc900_rtc *rtc = dev_get_drvdata(dev);
  	unsigned int timeval, carval;
  
  	timeval = __raw_readl(rtc->rtc_reg + REG_RTC_TAR);
  	carval	= __raw_readl(rtc->rtc_reg + REG_RTC_CAR);

  	return nuc900_rtc_bcd2bin(timeval, carval, &alrm->time);

  }
  
  static int nuc900_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	struct nuc900_rtc *rtc = dev_get_drvdata(dev);
  	struct nuc900_bcd_time tm;
  	unsigned long val;
  	int *err;

  	nuc900_rtc_bin2bcd(dev, &alrm->time, &tm);

  
  	err = check_rtc_access_enable(rtc);
  	if (IS_ERR(err))
  		return PTR_ERR(err);
  
  	val = tm.bcd_mday | tm.bcd_mon | tm.bcd_year;
  	__raw_writel(val, rtc->rtc_reg + REG_RTC_CAR);
  
  	val = tm.bcd_sec | tm.bcd_min | tm.bcd_hour;
  	__raw_writel(val, rtc->rtc_reg + REG_RTC_TAR);
  
  	return 0;
  }
  
  static struct rtc_class_ops nuc900_rtc_ops = {
  	.read_time = nuc900_rtc_read_time,
  	.set_time = nuc900_rtc_set_time,
  	.read_alarm = nuc900_rtc_read_alarm,
  	.set_alarm = nuc900_rtc_set_alarm,
  	.alarm_irq_enable = nuc900_alarm_irq_enable,

  };
  
  static int __devinit nuc900_rtc_probe(struct platform_device *pdev)
  {
  	struct resource *res;
  	struct nuc900_rtc *nuc900_rtc;
  	int err = 0;
  
  	nuc900_rtc = kzalloc(sizeof(struct nuc900_rtc), GFP_KERNEL);
  	if (!nuc900_rtc) {
  		dev_err(&pdev->dev, "kzalloc nuc900_rtc failed
  ");
  		return -ENOMEM;
  	}
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!res) {
  		dev_err(&pdev->dev, "platform_get_resource failed
  ");
  		err = -ENXIO;
  		goto fail1;
  	}
  
  	if (!request_mem_region(res->start, resource_size(res),
  				pdev->name)) {
  		dev_err(&pdev->dev, "request_mem_region failed
  ");
  		err = -EBUSY;
  		goto fail1;
  	}
  
  	nuc900_rtc->rtc_reg = ioremap(res->start, resource_size(res));
  	if (!nuc900_rtc->rtc_reg) {
  		dev_err(&pdev->dev, "ioremap rtc_reg failed
  ");
  		err = -ENOMEM;
  		goto fail2;
  	}

  	platform_set_drvdata(pdev, nuc900_rtc);

  
  	nuc900_rtc->rtcdev = rtc_device_register(pdev->name, &pdev->dev,
  						&nuc900_rtc_ops, THIS_MODULE);
  	if (IS_ERR(nuc900_rtc->rtcdev)) {

  		dev_err(&pdev->dev, "rtc device register failed
  ");

  		err = PTR_ERR(nuc900_rtc->rtcdev);

  		goto fail3;

  	}

  	__raw_writel(__raw_readl(nuc900_rtc->rtc_reg + REG_RTC_TSSR) | MODE24,
  					nuc900_rtc->rtc_reg + REG_RTC_TSSR);

  	nuc900_rtc->irq_num = platform_get_irq(pdev, 0);
  	if (request_irq(nuc900_rtc->irq_num, nuc900_rtc_interrupt,
  				IRQF_DISABLED, "nuc900rtc", nuc900_rtc)) {
  		dev_err(&pdev->dev, "NUC900 RTC request irq failed
  ");
  		err = -EBUSY;
  		goto fail4;
  	}

  	return 0;

  fail4:	rtc_device_unregister(nuc900_rtc->rtcdev);

  fail3:	iounmap(nuc900_rtc->rtc_reg);
  fail2:	release_mem_region(res->start, resource_size(res));
  fail1:	kfree(nuc900_rtc);
  	return err;
  }
  
  static int __devexit nuc900_rtc_remove(struct platform_device *pdev)
  {
  	struct nuc900_rtc *nuc900_rtc = platform_get_drvdata(pdev);
  	struct resource *res;

  	free_irq(nuc900_rtc->irq_num, nuc900_rtc);

  	rtc_device_unregister(nuc900_rtc->rtcdev);

  	iounmap(nuc900_rtc->rtc_reg);
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	release_mem_region(res->start, resource_size(res));
  
  	kfree(nuc900_rtc);
  
  	platform_set_drvdata(pdev, NULL);
  
  	return 0;
  }
  
  static struct platform_driver nuc900_rtc_driver = {
  	.remove		= __devexit_p(nuc900_rtc_remove),
  	.driver		= {
  		.name	= "nuc900-rtc",
  		.owner	= THIS_MODULE,
  	},
  };
  
  static int __init nuc900_rtc_init(void)
  {
  	return platform_driver_probe(&nuc900_rtc_driver, nuc900_rtc_probe);
  }
  
  static void __exit nuc900_rtc_exit(void)
  {
  	platform_driver_unregister(&nuc900_rtc_driver);
  }
  
  module_init(nuc900_rtc_init);
  module_exit(nuc900_rtc_exit);
  
  MODULE_AUTHOR("Wan ZongShun <mcuos.com@gmail.com>");
  MODULE_DESCRIPTION("nuc910/nuc920 RTC driver");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("platform:nuc900-rtc");