/*
   * rtc-rc5t583.c -- RICOH RC5T583 Real Time Clock
   *
   * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
   * Author: Venu Byravarasu <vbyravarasu@nvidia.com>
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms and conditions of the GNU General Public License,
   * version 2, as published by the Free Software Foundation.
   *
   * This program is distributed in the hope 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.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>. */
  
  #include <linux/kernel.h>
  #include <linux/errno.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/rtc.h>
  #include <linux/bcd.h>
  #include <linux/platform_device.h>
  #include <linux/interrupt.h>
  #include <linux/mfd/rc5t583.h>
  
  struct rc5t583_rtc {
  	struct rtc_device	*rtc;
  	/* To store the list of enabled interrupts, during system suspend */
  	u32 irqen;
  };
  
  /* Total number of RTC registers needed to set time*/
  #define NUM_TIME_REGS	(RC5T583_RTC_YEAR - RC5T583_RTC_SEC + 1)
  
  /* Total number of RTC registers needed to set Y-Alarm*/
  #define NUM_YAL_REGS	(RC5T583_RTC_AY_YEAR - RC5T583_RTC_AY_MIN + 1)
  
  /* Set Y-Alarm interrupt */
  #define SET_YAL BIT(5)
  
  /* Get Y-Alarm interrupt status*/
  #define GET_YAL_STATUS BIT(3)
  
  static int rc5t583_rtc_alarm_irq_enable(struct device *dev, unsigned enabled)
  {
  	struct rc5t583 *rc5t583 = dev_get_drvdata(dev->parent);
  	u8 val;
  
  	/* Set Y-Alarm, based on 'enabled' */
  	val = enabled ? SET_YAL : 0;
  
  	return regmap_update_bits(rc5t583->regmap, RC5T583_RTC_CTL1, SET_YAL,
  		val);
  }
  
  /*
   * Gets current rc5t583 RTC time and date parameters.
   *
   * The RTC's time/alarm representation is not what gmtime(3) requires
   * Linux to use:
   *
   *  - Months are 1..12 vs Linux 0-11
   *  - Years are 0..99 vs Linux 1900..N (we assume 21st century)
   */
  static int rc5t583_rtc_read_time(struct device *dev, struct rtc_time *tm)
  {
  	struct rc5t583 *rc5t583 = dev_get_drvdata(dev->parent);
  	u8 rtc_data[NUM_TIME_REGS];
  	int ret;
  
  	ret = regmap_bulk_read(rc5t583->regmap, RC5T583_RTC_SEC, rtc_data,
  		NUM_TIME_REGS);
  	if (ret < 0) {
  		dev_err(dev, "RTC read time failed with err:%d
  ", ret);
  		return ret;
  	}
  
  	tm->tm_sec = bcd2bin(rtc_data[0]);
  	tm->tm_min = bcd2bin(rtc_data[1]);
  	tm->tm_hour = bcd2bin(rtc_data[2]);
  	tm->tm_wday = bcd2bin(rtc_data[3]);
  	tm->tm_mday = bcd2bin(rtc_data[4]);
  	tm->tm_mon = bcd2bin(rtc_data[5]) - 1;
  	tm->tm_year = bcd2bin(rtc_data[6]) + 100;
  
  	return ret;
  }
  
  static int rc5t583_rtc_set_time(struct device *dev, struct rtc_time *tm)
  {
  	struct rc5t583 *rc5t583 = dev_get_drvdata(dev->parent);
  	unsigned char rtc_data[NUM_TIME_REGS];
  	int ret;
  
  	rtc_data[0] = bin2bcd(tm->tm_sec);
  	rtc_data[1] = bin2bcd(tm->tm_min);
  	rtc_data[2] = bin2bcd(tm->tm_hour);
  	rtc_data[3] = bin2bcd(tm->tm_wday);
  	rtc_data[4] = bin2bcd(tm->tm_mday);
  	rtc_data[5] = bin2bcd(tm->tm_mon + 1);
  	rtc_data[6] = bin2bcd(tm->tm_year - 100);
  
  	ret = regmap_bulk_write(rc5t583->regmap, RC5T583_RTC_SEC, rtc_data,
  		NUM_TIME_REGS);
  	if (ret < 0) {
  		dev_err(dev, "RTC set time failed with error %d
  ", ret);
  		return ret;
  	}
  
  	return ret;
  }
  
  static int rc5t583_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
  {
  	struct rc5t583 *rc5t583 = dev_get_drvdata(dev->parent);
  	unsigned char alarm_data[NUM_YAL_REGS];
  	u32 interrupt_enable;
  	int ret;
  
  	ret = regmap_bulk_read(rc5t583->regmap, RC5T583_RTC_AY_MIN, alarm_data,
  		NUM_YAL_REGS);
  	if (ret < 0) {
  		dev_err(dev, "rtc_read_alarm error %d
  ", ret);
  		return ret;
  	}
  
  	alm->time.tm_min = bcd2bin(alarm_data[0]);
  	alm->time.tm_hour = bcd2bin(alarm_data[1]);
  	alm->time.tm_mday = bcd2bin(alarm_data[2]);
  	alm->time.tm_mon = bcd2bin(alarm_data[3]) - 1;
  	alm->time.tm_year = bcd2bin(alarm_data[4]) + 100;
  
  	ret = regmap_read(rc5t583->regmap, RC5T583_RTC_CTL1, &interrupt_enable);
  	if (ret < 0)
  		return ret;
  
  	/* check if YALE is set */
  	if (interrupt_enable & SET_YAL)
  		alm->enabled = 1;
  
  	return ret;
  }
  
  static int rc5t583_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
  {
  	struct rc5t583 *rc5t583 = dev_get_drvdata(dev->parent);
  	unsigned char alarm_data[NUM_YAL_REGS];
  	int ret;
  
  	ret = rc5t583_rtc_alarm_irq_enable(dev, 0);
  	if (ret)
  		return ret;
  
  	alarm_data[0] = bin2bcd(alm->time.tm_min);
  	alarm_data[1] = bin2bcd(alm->time.tm_hour);
  	alarm_data[2] = bin2bcd(alm->time.tm_mday);
  	alarm_data[3] = bin2bcd(alm->time.tm_mon + 1);
  	alarm_data[4] = bin2bcd(alm->time.tm_year - 100);
  
  	ret = regmap_bulk_write(rc5t583->regmap, RC5T583_RTC_AY_MIN, alarm_data,
  		NUM_YAL_REGS);
  	if (ret) {
  		dev_err(dev, "rtc_set_alarm error %d
  ", ret);
  		return ret;
  	}
  
  	if (alm->enabled)
  		ret = rc5t583_rtc_alarm_irq_enable(dev, 1);
  
  	return ret;
  }
  
  static irqreturn_t rc5t583_rtc_interrupt(int irq, void *rtc)
  {
  	struct device *dev = rtc;
  	struct rc5t583 *rc5t583 = dev_get_drvdata(dev->parent);
  	struct rc5t583_rtc *rc5t583_rtc = dev_get_drvdata(dev);
  	unsigned long events = 0;
  	int ret;
  	u32 rtc_reg;
  
  	ret = regmap_read(rc5t583->regmap, RC5T583_RTC_CTL2, &rtc_reg);
  	if (ret < 0)
  		return IRQ_NONE;
  
  	if (rtc_reg & GET_YAL_STATUS) {
  		events = RTC_IRQF | RTC_AF;
  		/* clear pending Y-alarm interrupt bit */
  		rtc_reg &= ~GET_YAL_STATUS;
  	}
  
  	ret = regmap_write(rc5t583->regmap, RC5T583_RTC_CTL2, rtc_reg);
  	if (ret)
  		return IRQ_NONE;
  
  	/* Notify RTC core on event */
  	rtc_update_irq(rc5t583_rtc->rtc, 1, events);
  
  	return IRQ_HANDLED;
  }
  
  static const struct rtc_class_ops rc5t583_rtc_ops = {
  	.read_time	= rc5t583_rtc_read_time,
  	.set_time	= rc5t583_rtc_set_time,
  	.read_alarm	= rc5t583_rtc_read_alarm,
  	.set_alarm	= rc5t583_rtc_set_alarm,
  	.alarm_irq_enable = rc5t583_rtc_alarm_irq_enable,
  };
  
  static int rc5t583_rtc_probe(struct platform_device *pdev)
  {
  	struct rc5t583 *rc5t583 = dev_get_drvdata(pdev->dev.parent);
  	struct rc5t583_rtc *ricoh_rtc;
  	struct rc5t583_platform_data *pmic_plat_data;
  	int ret;
  	int irq;
  
  	ricoh_rtc = devm_kzalloc(&pdev->dev, sizeof(struct rc5t583_rtc),
  			GFP_KERNEL);
  	if (!ricoh_rtc)
  		return -ENOMEM;
  
  	platform_set_drvdata(pdev, ricoh_rtc);
  
  	/* Clear pending interrupts */
  	ret = regmap_write(rc5t583->regmap, RC5T583_RTC_CTL2, 0);
  	if (ret < 0)
  		return ret;
  
  	/* clear RTC Adjust register */
  	ret = regmap_write(rc5t583->regmap, RC5T583_RTC_ADJ, 0);
  	if (ret < 0) {
  		dev_err(&pdev->dev, "unable to program rtc_adjust reg
  ");
  		return -EBUSY;
  	}
  
  	pmic_plat_data = dev_get_platdata(rc5t583->dev);
  	irq = pmic_plat_data->irq_base;
  	if (irq <= 0) {
  		dev_warn(&pdev->dev, "Wake up is not possible as irq = %d
  ",
  			irq);
  		return ret;
  	}
  
  	irq += RC5T583_IRQ_YALE;
  	ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
  		rc5t583_rtc_interrupt, IRQF_TRIGGER_LOW,
  		"rtc-rc5t583", &pdev->dev);
  	if (ret < 0) {
  		dev_err(&pdev->dev, "IRQ is not free.
  ");
  		return ret;
  	}
  	device_init_wakeup(&pdev->dev, 1);
  
  	ricoh_rtc->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
  		&rc5t583_rtc_ops, THIS_MODULE);
  	if (IS_ERR(ricoh_rtc->rtc)) {
  		ret = PTR_ERR(ricoh_rtc->rtc);
  		dev_err(&pdev->dev, "RTC device register: err %d
  ", ret);
  		return ret;
  	}
  
  	return 0;
  }
  
  /*
   * Disable rc5t583 RTC interrupts.
   * Sets status flag to free.
   */
  static int rc5t583_rtc_remove(struct platform_device *pdev)
  {
  	struct rc5t583_rtc *rc5t583_rtc = platform_get_drvdata(pdev);
  
  	rc5t583_rtc_alarm_irq_enable(&rc5t583_rtc->rtc->dev, 0);
  	return 0;
  }
  
  #ifdef CONFIG_PM_SLEEP
  static int rc5t583_rtc_suspend(struct device *dev)
  {
  	struct rc5t583 *rc5t583 = dev_get_drvdata(dev->parent);
  	struct rc5t583_rtc *rc5t583_rtc = dev_get_drvdata(dev);
  	int ret;
  
  	/* Store current list of enabled interrupts*/
  	ret = regmap_read(rc5t583->regmap, RC5T583_RTC_CTL1,
  		&rc5t583_rtc->irqen);
  	return ret;
  }
  
  static int rc5t583_rtc_resume(struct device *dev)
  {
  	struct rc5t583 *rc5t583 = dev_get_drvdata(dev->parent);
  	struct rc5t583_rtc *rc5t583_rtc = dev_get_drvdata(dev);
  
  	/* Restore list of enabled interrupts before suspend */
  	return regmap_write(rc5t583->regmap, RC5T583_RTC_CTL1,
  		rc5t583_rtc->irqen);
  }
  #endif
  
  static SIMPLE_DEV_PM_OPS(rc5t583_rtc_pm_ops, rc5t583_rtc_suspend,
  			rc5t583_rtc_resume);
  
  static struct platform_driver rc5t583_rtc_driver = {
  	.probe		= rc5t583_rtc_probe,
  	.remove		= rc5t583_rtc_remove,
  	.driver		= {
  		.owner	= THIS_MODULE,
  		.name	= "rtc-rc5t583",
  		.pm	= &rc5t583_rtc_pm_ops,
  	},
  };
  
  module_platform_driver(rc5t583_rtc_driver);
  MODULE_ALIAS("platform:rtc-rc5t583");
  MODULE_AUTHOR("Venu Byravarasu <vbyravarasu@nvidia.com>");
  MODULE_LICENSE("GPL v2");