/*
   * rtc-tps6586x.c: RTC driver for TI PMIC TPS6586X
   *
   * 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/device.h>
  #include <linux/err.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/mfd/tps6586x.h>
  #include <linux/module.h>
  #include <linux/platform_device.h>
  #include <linux/pm_runtime.h>
  #include <linux/rtc.h>
  #include <linux/slab.h>
  
  #define RTC_CTRL			0xc0
  #define POR_RESET_N			BIT(7)
  #define OSC_SRC_SEL			BIT(6)
  #define RTC_ENABLE			BIT(5)	/* enables alarm */
  #define RTC_BUF_ENABLE			BIT(4)	/* 32 KHz buffer enable */
  #define PRE_BYPASS			BIT(3)	/* 0=1KHz or 1=32KHz updates */
  #define CL_SEL_MASK			(BIT(2)|BIT(1))
  #define CL_SEL_POS			1
  #define RTC_ALARM1_HI			0xc1
  #define RTC_COUNT4			0xc6
  
  /* start a PMU RTC access by reading the register prior to the RTC_COUNT4 */
  #define RTC_COUNT4_DUMMYREAD		0xc5
  
  /*only 14-bits width in second*/
  #define ALM1_VALID_RANGE_IN_SEC		0x3FFF
  
  #define TPS6586X_RTC_CL_SEL_1_5PF	0x0
  #define TPS6586X_RTC_CL_SEL_6_5PF	0x1
  #define TPS6586X_RTC_CL_SEL_7_5PF	0x2
  #define TPS6586X_RTC_CL_SEL_12_5PF	0x3
  
  struct tps6586x_rtc {
  	struct device		*dev;
  	struct rtc_device	*rtc;
  	int			irq;
  	bool			irq_en;
  	unsigned long long	epoch_start;
  };
  
  static inline struct device *to_tps6586x_dev(struct device *dev)
  {
  	return dev->parent;
  }
  
  static int tps6586x_rtc_read_time(struct device *dev, struct rtc_time *tm)
  {
  	struct tps6586x_rtc *rtc = dev_get_drvdata(dev);
  	struct device *tps_dev = to_tps6586x_dev(dev);
  	unsigned long long ticks = 0;
  	unsigned long seconds;
  	u8 buff[6];
  	int ret;
  	int i;
  
  	ret = tps6586x_reads(tps_dev, RTC_COUNT4_DUMMYREAD, sizeof(buff), buff);
  	if (ret < 0) {
  		dev_err(dev, "read counter failed with err %d
  ", ret);
  		return ret;
  	}
  
  	for (i = 1; i < sizeof(buff); i++) {
  		ticks <<= 8;
  		ticks |= buff[i];
  	}
  
  	seconds = ticks >> 10;
  	seconds += rtc->epoch_start;
  	rtc_time_to_tm(seconds, tm);
  	return rtc_valid_tm(tm);
  }
  
  static int tps6586x_rtc_set_time(struct device *dev, struct rtc_time *tm)
  {
  	struct tps6586x_rtc *rtc = dev_get_drvdata(dev);
  	struct device *tps_dev = to_tps6586x_dev(dev);
  	unsigned long long ticks;
  	unsigned long seconds;
  	u8 buff[5];
  	int ret;
  
  	rtc_tm_to_time(tm, &seconds);
  	if (seconds < rtc->epoch_start) {
  		dev_err(dev, "requested time unsupported
  ");
  		return -EINVAL;
  	}
  	seconds -= rtc->epoch_start;
  
  	ticks = (unsigned long long)seconds << 10;
  	buff[0] = (ticks >> 32) & 0xff;
  	buff[1] = (ticks >> 24) & 0xff;
  	buff[2] = (ticks >> 16) & 0xff;
  	buff[3] = (ticks >> 8) & 0xff;
  	buff[4] = ticks & 0xff;
  
  	/* Disable RTC before changing time */
  	ret = tps6586x_clr_bits(tps_dev, RTC_CTRL, RTC_ENABLE);
  	if (ret < 0) {
  		dev_err(dev, "failed to clear RTC_ENABLE
  ");
  		return ret;
  	}
  
  	ret = tps6586x_writes(tps_dev, RTC_COUNT4, sizeof(buff), buff);
  	if (ret < 0) {
  		dev_err(dev, "failed to program new time
  ");
  		return ret;
  	}
  
  	/* Enable RTC */
  	ret = tps6586x_set_bits(tps_dev, RTC_CTRL, RTC_ENABLE);
  	if (ret < 0) {
  		dev_err(dev, "failed to set RTC_ENABLE
  ");
  		return ret;
  	}
  	return 0;
  }
  
  static int tps6586x_rtc_alarm_irq_enable(struct device *dev,
  			 unsigned int enabled)
  {
  	struct tps6586x_rtc *rtc = dev_get_drvdata(dev);
  
  	if (enabled && !rtc->irq_en) {
  		enable_irq(rtc->irq);
  		rtc->irq_en = true;
  	} else if (!enabled && rtc->irq_en)  {
  		disable_irq(rtc->irq);
  		rtc->irq_en = false;
  	}
  	return 0;
  }
  
  static int tps6586x_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	struct tps6586x_rtc *rtc = dev_get_drvdata(dev);
  	struct device *tps_dev = to_tps6586x_dev(dev);
  	unsigned long seconds;
  	unsigned long ticks;
  	unsigned long rtc_current_time;
  	unsigned long long rticks = 0;
  	u8 buff[3];
  	u8 rbuff[6];
  	int ret;
  	int i;
  
  	rtc_tm_to_time(&alrm->time, &seconds);
  
  	if (alrm->enabled && (seconds < rtc->epoch_start)) {
  		dev_err(dev, "can't set alarm to requested time
  ");
  		return -EINVAL;
  	}
  
  	ret = tps6586x_rtc_alarm_irq_enable(dev, alrm->enabled);
  	if (ret < 0) {
  		dev_err(dev, "can't set alarm irq, err %d
  ", ret);
  		return ret;
  	}
  
  	seconds -= rtc->epoch_start;
  	ret = tps6586x_reads(tps_dev, RTC_COUNT4_DUMMYREAD,
  			sizeof(rbuff), rbuff);
  	if (ret < 0) {
  		dev_err(dev, "read counter failed with err %d
  ", ret);
  		return ret;
  	}
  
  	for (i = 1; i < sizeof(rbuff); i++) {
  		rticks <<= 8;
  		rticks |= rbuff[i];
  	}
  
  	rtc_current_time = rticks >> 10;
  	if ((seconds - rtc_current_time) > ALM1_VALID_RANGE_IN_SEC)
  		seconds = rtc_current_time - 1;
  
  	ticks = (unsigned long long)seconds << 10;
  	buff[0] = (ticks >> 16) & 0xff;
  	buff[1] = (ticks >> 8) & 0xff;
  	buff[2] = ticks & 0xff;
  
  	ret = tps6586x_writes(tps_dev, RTC_ALARM1_HI, sizeof(buff), buff);
  	if (ret)
  		dev_err(dev, "programming alarm failed with err %d
  ", ret);
  
  	return ret;
  }
  
  static int tps6586x_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	struct tps6586x_rtc *rtc = dev_get_drvdata(dev);
  	struct device *tps_dev = to_tps6586x_dev(dev);
  	unsigned long ticks;
  	unsigned long seconds;
  	u8 buff[3];
  	int ret;
  
  	ret = tps6586x_reads(tps_dev, RTC_ALARM1_HI, sizeof(buff), buff);
  	if (ret) {
  		dev_err(dev, "read RTC_ALARM1_HI failed with err %d
  ", ret);
  		return ret;
  	}
  
  	ticks = (buff[0] << 16) | (buff[1] << 8) | buff[2];
  	seconds = ticks >> 10;
  	seconds += rtc->epoch_start;
  
  	rtc_time_to_tm(seconds, &alrm->time);
  	return 0;
  }
  
  static const struct rtc_class_ops tps6586x_rtc_ops = {
  	.read_time	= tps6586x_rtc_read_time,
  	.set_time	= tps6586x_rtc_set_time,
  	.set_alarm	= tps6586x_rtc_set_alarm,
  	.read_alarm	= tps6586x_rtc_read_alarm,
  	.alarm_irq_enable = tps6586x_rtc_alarm_irq_enable,
  };
  
  static irqreturn_t tps6586x_rtc_irq(int irq, void *data)
  {
  	struct tps6586x_rtc *rtc = data;
  
  	rtc_update_irq(rtc->rtc, 1, RTC_IRQF | RTC_AF);
  	return IRQ_HANDLED;
  }
  
  static int tps6586x_rtc_probe(struct platform_device *pdev)
  {
  	struct device *tps_dev = to_tps6586x_dev(&pdev->dev);
  	struct tps6586x_rtc *rtc;
  	int ret;
  
  	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
  	if (!rtc)
  		return -ENOMEM;
  
  	rtc->dev = &pdev->dev;
  	rtc->irq = platform_get_irq(pdev, 0);
  
  	/* Set epoch start as 00:00:00:01:01:2009 */
  	rtc->epoch_start = mktime(2009, 1, 1, 0, 0, 0);
  
  	/* 1 kHz tick mode, enable tick counting */
  	ret = tps6586x_update(tps_dev, RTC_CTRL,
  		RTC_ENABLE | OSC_SRC_SEL |
  		((TPS6586X_RTC_CL_SEL_1_5PF << CL_SEL_POS) & CL_SEL_MASK),
  		RTC_ENABLE | OSC_SRC_SEL | PRE_BYPASS | CL_SEL_MASK);
  	if (ret < 0) {
  		dev_err(&pdev->dev, "unable to start counter
  ");
  		return ret;
  	}
  
  	device_init_wakeup(&pdev->dev, 1);
  
  	platform_set_drvdata(pdev, rtc);
  	rtc->rtc = devm_rtc_device_register(&pdev->dev, dev_name(&pdev->dev),
  				       &tps6586x_rtc_ops, THIS_MODULE);
  	if (IS_ERR(rtc->rtc)) {
  		ret = PTR_ERR(rtc->rtc);
  		dev_err(&pdev->dev, "RTC device register: ret %d
  ", ret);
  		goto fail_rtc_register;
  	}
  
  	ret = devm_request_threaded_irq(&pdev->dev, rtc->irq, NULL,
  				tps6586x_rtc_irq,
  				IRQF_ONESHOT | IRQF_EARLY_RESUME,
  				dev_name(&pdev->dev), rtc);
  	if (ret < 0) {
  		dev_err(&pdev->dev, "request IRQ(%d) failed with ret %d
  ",
  				rtc->irq, ret);
  		goto fail_rtc_register;
  	}
  	disable_irq(rtc->irq);
  	return 0;
  
  fail_rtc_register:
  	tps6586x_update(tps_dev, RTC_CTRL, 0,
  		RTC_ENABLE | OSC_SRC_SEL | PRE_BYPASS | CL_SEL_MASK);
  	return ret;
  };
  
  static int tps6586x_rtc_remove(struct platform_device *pdev)
  {
  	struct device *tps_dev = to_tps6586x_dev(&pdev->dev);
  
  	tps6586x_update(tps_dev, RTC_CTRL, 0,
  		RTC_ENABLE | OSC_SRC_SEL | PRE_BYPASS | CL_SEL_MASK);
  	return 0;
  }
  
  #ifdef CONFIG_PM_SLEEP
  static int tps6586x_rtc_suspend(struct device *dev)
  {
  	struct tps6586x_rtc *rtc = dev_get_drvdata(dev);
  
  	if (device_may_wakeup(dev))
  		enable_irq_wake(rtc->irq);
  	return 0;
  }
  
  static int tps6586x_rtc_resume(struct device *dev)
  {
  	struct tps6586x_rtc *rtc = dev_get_drvdata(dev);
  
  	if (device_may_wakeup(dev))
  		disable_irq_wake(rtc->irq);
  	return 0;
  }
  #endif
  
  static SIMPLE_DEV_PM_OPS(tps6586x_pm_ops, tps6586x_rtc_suspend,
  			tps6586x_rtc_resume);
  
  static struct platform_driver tps6586x_rtc_driver = {
  	.driver	= {
  		.name	= "tps6586x-rtc",
  		.owner	= THIS_MODULE,
  		.pm	= &tps6586x_pm_ops,
  	},
  	.probe	= tps6586x_rtc_probe,
  	.remove	= tps6586x_rtc_remove,
  };
  module_platform_driver(tps6586x_rtc_driver);
  
  MODULE_ALIAS("platform:rtc-tps6586x");
  MODULE_DESCRIPTION("TI TPS6586x RTC driver");
  MODULE_AUTHOR("Laxman dewangan <ldewangan@nvidia.com>");
  MODULE_LICENSE("GPL v2");