/*
   * rtc-palmas.c -- Palmas Real Time Clock driver.
  
   * RTC driver for TI Palma series devices like TPS65913,
   * TPS65914 power management IC.
   *
   * Copyright (c) 2012, NVIDIA Corporation.
   *
   * Author: Laxman Dewangan <ldewangan@nvidia.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.
   *
   * This program is distributed "as is" WITHOUT ANY WARRANTY of any kind,
   * whether express or implied; 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, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   * 02111-1307, USA
   */
  
  #include <linux/bcd.h>
  #include <linux/errno.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>
  #include <linux/kernel.h>
  #include <linux/mfd/palmas.h>
  #include <linux/module.h>
  #include <linux/of.h>
  #include <linux/rtc.h>
  #include <linux/types.h>
  #include <linux/platform_device.h>
  #include <linux/pm.h>
  
  struct palmas_rtc {
  	struct rtc_device	*rtc;
  	struct device		*dev;
  	unsigned int		irq;
  };
  
  /* Total number of RTC registers needed to set time*/
  #define PALMAS_NUM_TIME_REGS	(PALMAS_YEARS_REG - PALMAS_SECONDS_REG + 1)
  
  static int palmas_rtc_read_time(struct device *dev, struct rtc_time *tm)
  {
  	unsigned char rtc_data[PALMAS_NUM_TIME_REGS];
  	struct palmas *palmas = dev_get_drvdata(dev->parent);
  	int ret;
  
  	/* Copy RTC counting registers to static registers or latches */
  	ret = palmas_update_bits(palmas, PALMAS_RTC_BASE, PALMAS_RTC_CTRL_REG,
  		PALMAS_RTC_CTRL_REG_GET_TIME, PALMAS_RTC_CTRL_REG_GET_TIME);
  	if (ret < 0) {
  		dev_err(dev, "RTC CTRL reg update failed, err: %d
  ", ret);
  		return ret;
  	}
  
  	ret = palmas_bulk_read(palmas, PALMAS_RTC_BASE, PALMAS_SECONDS_REG,
  			rtc_data, PALMAS_NUM_TIME_REGS);
  	if (ret < 0) {
  		dev_err(dev, "RTC_SECONDS reg read failed, 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_mday = bcd2bin(rtc_data[3]);
  	tm->tm_mon = bcd2bin(rtc_data[4]) - 1;
  	tm->tm_year = bcd2bin(rtc_data[5]) + 100;
  
  	return ret;
  }
  
  static int palmas_rtc_set_time(struct device *dev, struct rtc_time *tm)
  {
  	unsigned char rtc_data[PALMAS_NUM_TIME_REGS];
  	struct palmas *palmas = dev_get_drvdata(dev->parent);
  	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_mday);
  	rtc_data[4] = bin2bcd(tm->tm_mon + 1);
  	rtc_data[5] = bin2bcd(tm->tm_year - 100);
  
  	/* Stop RTC while updating the RTC time registers */
  	ret = palmas_update_bits(palmas, PALMAS_RTC_BASE, PALMAS_RTC_CTRL_REG,
  		PALMAS_RTC_CTRL_REG_STOP_RTC, 0);
  	if (ret < 0) {
  		dev_err(dev, "RTC stop failed, err = %d
  ", ret);
  		return ret;
  	}
  
  	ret = palmas_bulk_write(palmas, PALMAS_RTC_BASE, PALMAS_SECONDS_REG,
  		rtc_data, PALMAS_NUM_TIME_REGS);
  	if (ret < 0) {
  		dev_err(dev, "RTC_SECONDS reg write failed, err = %d
  ", ret);
  		return ret;
  	}
  
  	/* Start back RTC */
  	ret = palmas_update_bits(palmas, PALMAS_RTC_BASE, PALMAS_RTC_CTRL_REG,
  		PALMAS_RTC_CTRL_REG_STOP_RTC, PALMAS_RTC_CTRL_REG_STOP_RTC);
  	if (ret < 0)
  		dev_err(dev, "RTC start failed, err = %d
  ", ret);
  	return ret;
  }
  
  static int palmas_rtc_alarm_irq_enable(struct device *dev, unsigned enabled)
  {
  	struct palmas *palmas = dev_get_drvdata(dev->parent);
  	u8 val;
  
  	val = enabled ? PALMAS_RTC_INTERRUPTS_REG_IT_ALARM : 0;
  	return palmas_write(palmas, PALMAS_RTC_BASE,
  		PALMAS_RTC_INTERRUPTS_REG, val);
  }
  
  static int palmas_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
  {
  	unsigned char alarm_data[PALMAS_NUM_TIME_REGS];
  	u32 int_val;
  	struct palmas *palmas = dev_get_drvdata(dev->parent);
  	int ret;
  
  	ret = palmas_bulk_read(palmas, PALMAS_RTC_BASE,
  			PALMAS_ALARM_SECONDS_REG,
  			alarm_data, PALMAS_NUM_TIME_REGS);
  	if (ret < 0) {
  		dev_err(dev, "RTC_ALARM_SECONDS read failed, err = %d
  ", ret);
  		return ret;
  	}
  
  	alm->time.tm_sec = bcd2bin(alarm_data[0]);
  	alm->time.tm_min = bcd2bin(alarm_data[1]);
  	alm->time.tm_hour = bcd2bin(alarm_data[2]);
  	alm->time.tm_mday = bcd2bin(alarm_data[3]);
  	alm->time.tm_mon = bcd2bin(alarm_data[4]) - 1;
  	alm->time.tm_year = bcd2bin(alarm_data[5]) + 100;
  
  	ret = palmas_read(palmas, PALMAS_RTC_BASE, PALMAS_RTC_INTERRUPTS_REG,
  			&int_val);
  	if (ret < 0) {
  		dev_err(dev, "RTC_INTERRUPTS reg read failed, err = %d
  ", ret);
  		return ret;
  	}
  
  	if (int_val & PALMAS_RTC_INTERRUPTS_REG_IT_ALARM)
  		alm->enabled = 1;
  	return ret;
  }
  
  static int palmas_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
  {
  	unsigned char alarm_data[PALMAS_NUM_TIME_REGS];
  	struct palmas *palmas = dev_get_drvdata(dev->parent);
  	int ret;
  
  	ret = palmas_rtc_alarm_irq_enable(dev, 0);
  	if (ret < 0) {
  		dev_err(dev, "Disable RTC alarm failed
  ");
  		return ret;
  	}
  
  	alarm_data[0] = bin2bcd(alm->time.tm_sec);
  	alarm_data[1] = bin2bcd(alm->time.tm_min);
  	alarm_data[2] = bin2bcd(alm->time.tm_hour);
  	alarm_data[3] = bin2bcd(alm->time.tm_mday);
  	alarm_data[4] = bin2bcd(alm->time.tm_mon + 1);
  	alarm_data[5] = bin2bcd(alm->time.tm_year - 100);
  
  	ret = palmas_bulk_write(palmas, PALMAS_RTC_BASE,
  		PALMAS_ALARM_SECONDS_REG, alarm_data, PALMAS_NUM_TIME_REGS);
  	if (ret < 0) {
  		dev_err(dev, "ALARM_SECONDS_REG write failed, err = %d
  ", ret);
  		return ret;
  	}
  
  	if (alm->enabled)
  		ret = palmas_rtc_alarm_irq_enable(dev, 1);
  	return ret;
  }
  
  static int palmas_clear_interrupts(struct device *dev)
  {
  	struct palmas *palmas = dev_get_drvdata(dev->parent);
  	unsigned int rtc_reg;
  	int ret;
  
  	ret = palmas_read(palmas, PALMAS_RTC_BASE, PALMAS_RTC_STATUS_REG,
  				&rtc_reg);
  	if (ret < 0) {
  		dev_err(dev, "RTC_STATUS read failed, err = %d
  ", ret);
  		return ret;
  	}
  
  	ret = palmas_write(palmas, PALMAS_RTC_BASE, PALMAS_RTC_STATUS_REG,
  			rtc_reg);
  	if (ret < 0) {
  		dev_err(dev, "RTC_STATUS write failed, err = %d
  ", ret);
  		return ret;
  	}
  	return 0;
  }
  
  static irqreturn_t palmas_rtc_interrupt(int irq, void *context)
  {
  	struct palmas_rtc *palmas_rtc = context;
  	struct device *dev = palmas_rtc->dev;
  	int ret;
  
  	ret = palmas_clear_interrupts(dev);
  	if (ret < 0) {
  		dev_err(dev, "RTC interrupt clear failed, err = %d
  ", ret);
  		return IRQ_NONE;
  	}
  
  	rtc_update_irq(palmas_rtc->rtc, 1, RTC_IRQF | RTC_AF);
  	return IRQ_HANDLED;
  }
  
  static struct rtc_class_ops palmas_rtc_ops = {
  	.read_time	= palmas_rtc_read_time,
  	.set_time	= palmas_rtc_set_time,
  	.read_alarm	= palmas_rtc_read_alarm,
  	.set_alarm	= palmas_rtc_set_alarm,
  	.alarm_irq_enable = palmas_rtc_alarm_irq_enable,
  };
  
  static int palmas_rtc_probe(struct platform_device *pdev)
  {
  	struct palmas *palmas = dev_get_drvdata(pdev->dev.parent);
  	struct palmas_rtc *palmas_rtc = NULL;
  	int ret;
  	bool enable_bb_charging = false;
  	bool high_bb_charging;
  
  	if (pdev->dev.of_node) {
  		enable_bb_charging = of_property_read_bool(pdev->dev.of_node,
  					"ti,backup-battery-chargeable");
  		high_bb_charging = of_property_read_bool(pdev->dev.of_node,
  					"ti,backup-battery-charge-high-current");
  	}
  
  	palmas_rtc = devm_kzalloc(&pdev->dev, sizeof(struct palmas_rtc),
  			GFP_KERNEL);
  	if (!palmas_rtc)
  		return -ENOMEM;
  
  	/* Clear pending interrupts */
  	ret = palmas_clear_interrupts(&pdev->dev);
  	if (ret < 0) {
  		dev_err(&pdev->dev, "clear RTC int failed, err = %d
  ", ret);
  		return ret;
  	}
  
  	palmas_rtc->dev = &pdev->dev;
  	platform_set_drvdata(pdev, palmas_rtc);
  
  	if (enable_bb_charging) {
  		unsigned reg = PALMAS_BACKUP_BATTERY_CTRL_BBS_BBC_LOW_ICHRG;
  
  		if (high_bb_charging)
  			reg = 0;
  
  		ret = palmas_update_bits(palmas, PALMAS_PMU_CONTROL_BASE,
  			PALMAS_BACKUP_BATTERY_CTRL,
  			PALMAS_BACKUP_BATTERY_CTRL_BBS_BBC_LOW_ICHRG, reg);
  		if (ret < 0) {
  			dev_err(&pdev->dev,
  				"BACKUP_BATTERY_CTRL update failed, %d
  ", ret);
  			return ret;
  		}
  
  		ret = palmas_update_bits(palmas, PALMAS_PMU_CONTROL_BASE,
  			PALMAS_BACKUP_BATTERY_CTRL,
  			PALMAS_BACKUP_BATTERY_CTRL_BB_CHG_EN,
  			PALMAS_BACKUP_BATTERY_CTRL_BB_CHG_EN);
  		if (ret < 0) {
  			dev_err(&pdev->dev,
  				"BACKUP_BATTERY_CTRL update failed, %d
  ", ret);
  			return ret;
  		}
  	}
  
  	/* Start RTC */
  	ret = palmas_update_bits(palmas, PALMAS_RTC_BASE, PALMAS_RTC_CTRL_REG,
  			PALMAS_RTC_CTRL_REG_STOP_RTC,
  			PALMAS_RTC_CTRL_REG_STOP_RTC);
  	if (ret < 0) {
  		dev_err(&pdev->dev, "RTC_CTRL write failed, err = %d
  ", ret);
  		return ret;
  	}
  
  	palmas_rtc->irq = platform_get_irq(pdev, 0);
  
  	device_init_wakeup(&pdev->dev, 1);
  	palmas_rtc->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,
  				&palmas_rtc_ops, THIS_MODULE);
  	if (IS_ERR(palmas_rtc->rtc)) {
  		ret = PTR_ERR(palmas_rtc->rtc);
  		dev_err(&pdev->dev, "RTC register failed, err = %d
  ", ret);
  		return ret;
  	}
  
  	ret = devm_request_threaded_irq(&pdev->dev, palmas_rtc->irq, NULL,
  			palmas_rtc_interrupt,
  			IRQF_TRIGGER_LOW | IRQF_ONESHOT |
  			IRQF_EARLY_RESUME,
  			dev_name(&pdev->dev), palmas_rtc);
  	if (ret < 0) {
  		dev_err(&pdev->dev, "IRQ request failed, err = %d
  ", ret);
  		return ret;
  	}
  
  	return 0;
  }
  
  static int palmas_rtc_remove(struct platform_device *pdev)
  {
  	palmas_rtc_alarm_irq_enable(&pdev->dev, 0);
  	return 0;
  }
  
  #ifdef CONFIG_PM_SLEEP
  static int palmas_rtc_suspend(struct device *dev)
  {
  	struct palmas_rtc *palmas_rtc = dev_get_drvdata(dev);
  
  	if (device_may_wakeup(dev))
  		enable_irq_wake(palmas_rtc->irq);
  	return 0;
  }
  
  static int palmas_rtc_resume(struct device *dev)
  {
  	struct palmas_rtc *palmas_rtc = dev_get_drvdata(dev);
  
  	if (device_may_wakeup(dev))
  		disable_irq_wake(palmas_rtc->irq);
  	return 0;
  }
  #endif
  
  static const struct dev_pm_ops palmas_rtc_pm_ops = {
  	SET_SYSTEM_SLEEP_PM_OPS(palmas_rtc_suspend, palmas_rtc_resume)
  };
  
  #ifdef CONFIG_OF
  static struct of_device_id of_palmas_rtc_match[] = {
  	{ .compatible = "ti,palmas-rtc"},
  	{ },
  };
  MODULE_DEVICE_TABLE(of, of_palmas_rtc_match);
  #endif
  
  static struct platform_driver palmas_rtc_driver = {
  	.probe		= palmas_rtc_probe,
  	.remove		= palmas_rtc_remove,
  	.driver		= {
  		.owner	= THIS_MODULE,
  		.name	= "palmas-rtc",
  		.pm	= &palmas_rtc_pm_ops,
  		.of_match_table = of_match_ptr(of_palmas_rtc_match),
  	},
  };
  
  module_platform_driver(palmas_rtc_driver);
  
  MODULE_ALIAS("platform:palmas_rtc");
  MODULE_DESCRIPTION("TI PALMAS series RTC driver");
  MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
  MODULE_LICENSE("GPL v2");