/*
   * drivers/rtc/rtc-vt8500.c
   *
   *  Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>
   *
   * Based on rtc-pxa.c
   *
   * This software is licensed under the terms of the GNU General Public
   * License version 2, as published by the Free Software Foundation, and
   * may be copied, distributed, and modified under those terms.
   *
   * 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/module.h>
  #include <linux/rtc.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>
  #include <linux/io.h>
  #include <linux/bcd.h>
  #include <linux/platform_device.h>
  #include <linux/slab.h>
  
  /*
   * Register definitions
   */
  #define VT8500_RTC_TS		0x00	/* Time set */
  #define VT8500_RTC_DS		0x04	/* Date set */
  #define VT8500_RTC_AS		0x08	/* Alarm set */
  #define VT8500_RTC_CR		0x0c	/* Control */
  #define VT8500_RTC_TR		0x10	/* Time read */
  #define VT8500_RTC_DR		0x14	/* Date read */
  #define VT8500_RTC_WS		0x18	/* Write status */
  #define VT8500_RTC_CL		0x20	/* Calibration */
  #define VT8500_RTC_IS		0x24	/* Interrupt status */
  #define VT8500_RTC_ST		0x28	/* Status */
  
  #define INVALID_TIME_BIT	(1 << 31)
  
  #define DATE_CENTURY_S		19
  #define DATE_YEAR_S		11
  #define DATE_YEAR_MASK		(0xff << DATE_YEAR_S)
  #define DATE_MONTH_S		6
  #define DATE_MONTH_MASK		(0x1f << DATE_MONTH_S)
  #define DATE_DAY_MASK		0x3f
  
  #define TIME_DOW_S		20
  #define TIME_DOW_MASK		(0x07 << TIME_DOW_S)
  #define TIME_HOUR_S		14
  #define TIME_HOUR_MASK		(0x3f << TIME_HOUR_S)
  #define TIME_MIN_S		7
  #define TIME_MIN_MASK		(0x7f << TIME_MIN_S)
  #define TIME_SEC_MASK		0x7f
  
  #define ALARM_DAY_S		20
  #define ALARM_DAY_MASK		(0x3f << ALARM_DAY_S)
  
  #define ALARM_DAY_BIT		(1 << 29)
  #define ALARM_HOUR_BIT		(1 << 28)
  #define ALARM_MIN_BIT		(1 << 27)
  #define ALARM_SEC_BIT		(1 << 26)
  
  #define ALARM_ENABLE_MASK	(ALARM_DAY_BIT \
  				| ALARM_HOUR_BIT \
  				| ALARM_MIN_BIT \
  				| ALARM_SEC_BIT)
  
  #define VT8500_RTC_CR_ENABLE	(1 << 0)	/* Enable RTC */
  #define VT8500_RTC_CR_24H	(1 << 1)	/* 24h time format */
  #define VT8500_RTC_CR_SM_ENABLE	(1 << 2)	/* Enable periodic irqs */
  #define VT8500_RTC_CR_SM_SEC	(1 << 3)	/* 0: 1Hz/60, 1: 1Hz */
  #define VT8500_RTC_CR_CALIB	(1 << 4)	/* Enable calibration */

  #define VT8500_RTC_IS_ALARM	(1 << 0)	/* Alarm interrupt status */

  struct vt8500_rtc {
  	void __iomem		*regbase;
  	struct resource		*res;
  	int			irq_alarm;

  	struct rtc_device	*rtc;
  	spinlock_t		lock;		/* Protects this structure */
  };
  
  static irqreturn_t vt8500_rtc_irq(int irq, void *dev_id)
  {
  	struct vt8500_rtc *vt8500_rtc = dev_id;
  	u32 isr;
  	unsigned long events = 0;
  
  	spin_lock(&vt8500_rtc->lock);
  
  	/* clear interrupt sources */
  	isr = readl(vt8500_rtc->regbase + VT8500_RTC_IS);
  	writel(isr, vt8500_rtc->regbase + VT8500_RTC_IS);
  
  	spin_unlock(&vt8500_rtc->lock);

  	if (isr & VT8500_RTC_IS_ALARM)

  		events |= RTC_AF | RTC_IRQF;

  	rtc_update_irq(vt8500_rtc->rtc, 1, events);
  
  	return IRQ_HANDLED;
  }
  
  static int vt8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
  {
  	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
  	u32 date, time;
  
  	date = readl(vt8500_rtc->regbase + VT8500_RTC_DR);
  	time = readl(vt8500_rtc->regbase + VT8500_RTC_TR);
  
  	tm->tm_sec = bcd2bin(time & TIME_SEC_MASK);
  	tm->tm_min = bcd2bin((time & TIME_MIN_MASK) >> TIME_MIN_S);
  	tm->tm_hour = bcd2bin((time & TIME_HOUR_MASK) >> TIME_HOUR_S);
  	tm->tm_mday = bcd2bin(date & DATE_DAY_MASK);
  	tm->tm_mon = bcd2bin((date & DATE_MONTH_MASK) >> DATE_MONTH_S);
  	tm->tm_year = bcd2bin((date & DATE_YEAR_MASK) >> DATE_YEAR_S)
  			+ ((date >> DATE_CENTURY_S) & 1 ? 200 : 100);
  	tm->tm_wday = (time & TIME_DOW_MASK) >> TIME_DOW_S;
  
  	return 0;
  }
  
  static int vt8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
  {
  	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
  
  	if (tm->tm_year < 100) {
  		dev_warn(dev, "Only years 2000-2199 are supported by the "
  			      "hardware!
  ");
  		return -EINVAL;
  	}
  
  	writel((bin2bcd(tm->tm_year - 100) << DATE_YEAR_S)
  		| (bin2bcd(tm->tm_mon) << DATE_MONTH_S)
  		| (bin2bcd(tm->tm_mday)),
  		vt8500_rtc->regbase + VT8500_RTC_DS);
  	writel((bin2bcd(tm->tm_wday) << TIME_DOW_S)
  		| (bin2bcd(tm->tm_hour) << TIME_HOUR_S)
  		| (bin2bcd(tm->tm_min) << TIME_MIN_S)
  		| (bin2bcd(tm->tm_sec)),
  		vt8500_rtc->regbase + VT8500_RTC_TS);
  
  	return 0;
  }
  
  static int vt8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
  	u32 isr, alarm;
  
  	alarm = readl(vt8500_rtc->regbase + VT8500_RTC_AS);
  	isr = readl(vt8500_rtc->regbase + VT8500_RTC_IS);
  
  	alrm->time.tm_mday = bcd2bin((alarm & ALARM_DAY_MASK) >> ALARM_DAY_S);
  	alrm->time.tm_hour = bcd2bin((alarm & TIME_HOUR_MASK) >> TIME_HOUR_S);
  	alrm->time.tm_min = bcd2bin((alarm & TIME_MIN_MASK) >> TIME_MIN_S);
  	alrm->time.tm_sec = bcd2bin((alarm & TIME_SEC_MASK));
  
  	alrm->enabled = (alarm & ALARM_ENABLE_MASK) ? 1 : 0;

  	alrm->pending = (isr & VT8500_RTC_IS_ALARM) ? 1 : 0;

  	return rtc_valid_tm(&alrm->time);
  }
  
  static int vt8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
  
  	writel((alrm->enabled ? ALARM_ENABLE_MASK : 0)
  		| (bin2bcd(alrm->time.tm_mday) << ALARM_DAY_S)
  		| (bin2bcd(alrm->time.tm_hour) << TIME_HOUR_S)
  		| (bin2bcd(alrm->time.tm_min) << TIME_MIN_S)
  		| (bin2bcd(alrm->time.tm_sec)),
  		vt8500_rtc->regbase + VT8500_RTC_AS);
  
  	return 0;
  }
  
  static int vt8500_alarm_irq_enable(struct device *dev, unsigned int enabled)
  {
  	struct vt8500_rtc *vt8500_rtc = dev_get_drvdata(dev);
  	unsigned long tmp = readl(vt8500_rtc->regbase + VT8500_RTC_AS);
  
  	if (enabled)
  		tmp |= ALARM_ENABLE_MASK;
  	else
  		tmp &= ~ALARM_ENABLE_MASK;
  
  	writel(tmp, vt8500_rtc->regbase + VT8500_RTC_AS);
  	return 0;
  }

  static const struct rtc_class_ops vt8500_rtc_ops = {
  	.read_time = vt8500_rtc_read_time,
  	.set_time = vt8500_rtc_set_time,
  	.read_alarm = vt8500_rtc_read_alarm,
  	.set_alarm = vt8500_rtc_set_alarm,
  	.alarm_irq_enable = vt8500_alarm_irq_enable,

  };
  
  static int __devinit vt8500_rtc_probe(struct platform_device *pdev)
  {
  	struct vt8500_rtc *vt8500_rtc;
  	int ret;
  
  	vt8500_rtc = kzalloc(sizeof(struct vt8500_rtc), GFP_KERNEL);
  	if (!vt8500_rtc)
  		return -ENOMEM;
  
  	spin_lock_init(&vt8500_rtc->lock);
  	platform_set_drvdata(pdev, vt8500_rtc);
  
  	vt8500_rtc->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!vt8500_rtc->res) {
  		dev_err(&pdev->dev, "No I/O memory resource defined
  ");
  		ret = -ENXIO;
  		goto err_free;
  	}
  
  	vt8500_rtc->irq_alarm = platform_get_irq(pdev, 0);
  	if (vt8500_rtc->irq_alarm < 0) {
  		dev_err(&pdev->dev, "No alarm IRQ resource defined
  ");
  		ret = -ENXIO;
  		goto err_free;
  	}

  	vt8500_rtc->res = request_mem_region(vt8500_rtc->res->start,
  					     resource_size(vt8500_rtc->res),
  					     "vt8500-rtc");
  	if (vt8500_rtc->res == NULL) {
  		dev_err(&pdev->dev, "failed to request I/O memory
  ");
  		ret = -EBUSY;
  		goto err_free;
  	}
  
  	vt8500_rtc->regbase = ioremap(vt8500_rtc->res->start,
  				      resource_size(vt8500_rtc->res));
  	if (!vt8500_rtc->regbase) {
  		dev_err(&pdev->dev, "Unable to map RTC I/O memory
  ");
  		ret = -EBUSY;
  		goto err_release;
  	}

  	/* Enable RTC and set it to 24-hour mode */
  	writel(VT8500_RTC_CR_ENABLE | VT8500_RTC_CR_24H,

  	       vt8500_rtc->regbase + VT8500_RTC_CR);
  
  	vt8500_rtc->rtc = rtc_device_register("vt8500-rtc", &pdev->dev,
  					      &vt8500_rtc_ops, THIS_MODULE);
  	if (IS_ERR(vt8500_rtc->rtc)) {
  		ret = PTR_ERR(vt8500_rtc->rtc);
  		dev_err(&pdev->dev,
  			"Failed to register RTC device -> %d
  ", ret);
  		goto err_unmap;
  	}

  	ret = request_irq(vt8500_rtc->irq_alarm, vt8500_rtc_irq, 0,
  			  "rtc alarm", vt8500_rtc);
  	if (ret < 0) {
  		dev_err(&pdev->dev, "can't get irq %i, err %d
  ",
  			vt8500_rtc->irq_alarm, ret);

  		goto err_unreg;

  	}
  
  	return 0;

  err_unreg:
  	rtc_device_unregister(vt8500_rtc->rtc);
  err_unmap:
  	iounmap(vt8500_rtc->regbase);
  err_release:
  	release_mem_region(vt8500_rtc->res->start,
  			   resource_size(vt8500_rtc->res));
  err_free:
  	kfree(vt8500_rtc);
  	return ret;
  }
  
  static int __devexit vt8500_rtc_remove(struct platform_device *pdev)
  {
  	struct vt8500_rtc *vt8500_rtc = platform_get_drvdata(pdev);
  
  	free_irq(vt8500_rtc->irq_alarm, vt8500_rtc);

  
  	rtc_device_unregister(vt8500_rtc->rtc);
  
  	/* Disable alarm matching */
  	writel(0, vt8500_rtc->regbase + VT8500_RTC_IS);
  	iounmap(vt8500_rtc->regbase);
  	release_mem_region(vt8500_rtc->res->start,
  			   resource_size(vt8500_rtc->res));
  
  	kfree(vt8500_rtc);
  	platform_set_drvdata(pdev, NULL);
  
  	return 0;
  }
  
  static struct platform_driver vt8500_rtc_driver = {
  	.probe		= vt8500_rtc_probe,
  	.remove		= __devexit_p(vt8500_rtc_remove),
  	.driver		= {
  		.name	= "vt8500-rtc",
  		.owner	= THIS_MODULE,
  	},
  };

  module_platform_driver(vt8500_rtc_driver);

  
  MODULE_AUTHOR("Alexey Charkov <alchark@gmail.com>");
  MODULE_DESCRIPTION("VIA VT8500 SoC Realtime Clock Driver (RTC)");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("platform:vt8500-rtc");