/*
   * Freescale STMP37XX/STMP378X Real Time Clock driver
   *
   * Copyright (c) 2007 Sigmatel, Inc.
   * Peter Hartley, <peter.hartley@sigmatel.com>
   *
   * Copyright 2008 Freescale Semiconductor, Inc. All Rights Reserved.
   * Copyright 2008 Embedded Alley Solutions, Inc All Rights Reserved.

   * Copyright 2011 Wolfram Sang, Pengutronix e.K.

   */
  
  /*
   * The code contained herein is licensed under the GNU General Public
   * License. You may obtain a copy of the GNU General Public License
   * Version 2 or later at the following locations:
   *
   * http://www.opensource.org/licenses/gpl-license.html
   * http://www.gnu.org/copyleft/gpl.html
   */
  #include <linux/kernel.h>
  #include <linux/module.h>

  #include <linux/io.h>

  #include <linux/init.h>
  #include <linux/platform_device.h>
  #include <linux/interrupt.h>
  #include <linux/rtc.h>

  #include <linux/slab.h>

  #include <linux/of_device.h>

  #include <linux/of.h>

  #include <linux/stmp_device.h>
  #include <linux/stmp3xxx_rtc_wdt.h>

  #include <mach/common.h>

  
  #define STMP3XXX_RTC_CTRL			0x0

  #define STMP3XXX_RTC_CTRL_SET			0x4
  #define STMP3XXX_RTC_CTRL_CLR			0x8

  #define STMP3XXX_RTC_CTRL_ALARM_IRQ_EN		0x00000001
  #define STMP3XXX_RTC_CTRL_ONEMSEC_IRQ_EN	0x00000002
  #define STMP3XXX_RTC_CTRL_ALARM_IRQ		0x00000004

  #define STMP3XXX_RTC_CTRL_WATCHDOGEN		0x00000010

  
  #define STMP3XXX_RTC_STAT			0x10
  #define STMP3XXX_RTC_STAT_STALE_SHIFT		16
  #define STMP3XXX_RTC_STAT_RTC_PRESENT		0x80000000
  
  #define STMP3XXX_RTC_SECONDS			0x30
  
  #define STMP3XXX_RTC_ALARM			0x40

  #define STMP3XXX_RTC_WATCHDOG			0x50

  #define STMP3XXX_RTC_PERSISTENT0		0x60

  #define STMP3XXX_RTC_PERSISTENT0_SET		0x64
  #define STMP3XXX_RTC_PERSISTENT0_CLR		0x68

  #define STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE_EN	0x00000002
  #define STMP3XXX_RTC_PERSISTENT0_ALARM_EN	0x00000004
  #define STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE	0x00000080

  #define STMP3XXX_RTC_PERSISTENT1		0x70
  /* missing bitmask in headers */
  #define STMP3XXX_RTC_PERSISTENT1_FORCE_UPDATER	0x80000000

  struct stmp3xxx_rtc_data {
  	struct rtc_device *rtc;

  	void __iomem *io;

  	int irq_alarm;

  };

  #if IS_ENABLED(CONFIG_STMP3XXX_RTC_WATCHDOG)
  /**
   * stmp3xxx_wdt_set_timeout - configure the watchdog inside the STMP3xxx RTC
   * @dev: the parent device of the watchdog (= the RTC)
   * @timeout: the desired value for the timeout register of the watchdog.
   *           0 disables the watchdog
   *
   * The watchdog needs one register and two bits which are in the RTC domain.
   * To handle the resource conflict, the RTC driver will create another
   * platform_device for the watchdog driver as a child of the RTC device.
   * The watchdog driver is passed the below accessor function via platform_data
   * to configure the watchdog. Locking is not needed because accessing SET/CLR
   * registers is atomic.
   */
  
  static void stmp3xxx_wdt_set_timeout(struct device *dev, u32 timeout)
  {
  	struct stmp3xxx_rtc_data *rtc_data = dev_get_drvdata(dev);
  
  	if (timeout) {
  		writel(timeout, rtc_data->io + STMP3XXX_RTC_WATCHDOG);
  		writel(STMP3XXX_RTC_CTRL_WATCHDOGEN,
  		       rtc_data->io + STMP3XXX_RTC_CTRL + STMP_OFFSET_REG_SET);
  		writel(STMP3XXX_RTC_PERSISTENT1_FORCE_UPDATER,
  		       rtc_data->io + STMP3XXX_RTC_PERSISTENT1 + STMP_OFFSET_REG_SET);
  	} else {
  		writel(STMP3XXX_RTC_CTRL_WATCHDOGEN,
  		       rtc_data->io + STMP3XXX_RTC_CTRL + STMP_OFFSET_REG_CLR);
  		writel(STMP3XXX_RTC_PERSISTENT1_FORCE_UPDATER,
  		       rtc_data->io + STMP3XXX_RTC_PERSISTENT1 + STMP_OFFSET_REG_CLR);
  	}
  }
  
  static struct stmp3xxx_wdt_pdata wdt_pdata = {
  	.wdt_set_timeout = stmp3xxx_wdt_set_timeout,
  };
  
  static void stmp3xxx_wdt_register(struct platform_device *rtc_pdev)
  {
  	struct platform_device *wdt_pdev =
  		platform_device_alloc("stmp3xxx_rtc_wdt", rtc_pdev->id);
  
  	if (wdt_pdev) {
  		wdt_pdev->dev.parent = &rtc_pdev->dev;
  		wdt_pdev->dev.platform_data = &wdt_pdata;
  		platform_device_add(wdt_pdev);
  	}
  }
  #else
  static void stmp3xxx_wdt_register(struct platform_device *rtc_pdev)
  {
  }
  #endif /* CONFIG_STMP3XXX_RTC_WATCHDOG */

  static void stmp3xxx_wait_time(struct stmp3xxx_rtc_data *rtc_data)
  {
  	/*
  	 * The datasheet doesn't say which way round the
  	 * NEW_REGS/STALE_REGS bitfields go. In fact it's 0x1=P0,
  	 * 0x2=P1, .., 0x20=P5, 0x40=ALARM, 0x80=SECONDS
  	 */

  	while (readl(rtc_data->io + STMP3XXX_RTC_STAT) &

  			(0x80 << STMP3XXX_RTC_STAT_STALE_SHIFT))

  		cpu_relax();
  }
  
  /* Time read/write */
  static int stmp3xxx_rtc_gettime(struct device *dev, struct rtc_time *rtc_tm)
  {
  	struct stmp3xxx_rtc_data *rtc_data = dev_get_drvdata(dev);
  
  	stmp3xxx_wait_time(rtc_data);

  	rtc_time_to_tm(readl(rtc_data->io + STMP3XXX_RTC_SECONDS), rtc_tm);

  	return 0;
  }
  
  static int stmp3xxx_rtc_set_mmss(struct device *dev, unsigned long t)
  {
  	struct stmp3xxx_rtc_data *rtc_data = dev_get_drvdata(dev);

  	writel(t, rtc_data->io + STMP3XXX_RTC_SECONDS);

  	stmp3xxx_wait_time(rtc_data);
  	return 0;
  }
  
  /* interrupt(s) handler */
  static irqreturn_t stmp3xxx_rtc_interrupt(int irq, void *dev_id)
  {
  	struct stmp3xxx_rtc_data *rtc_data = dev_get_drvdata(dev_id);

  	u32 status = readl(rtc_data->io + STMP3XXX_RTC_CTRL);

  	if (status & STMP3XXX_RTC_CTRL_ALARM_IRQ) {

  		writel(STMP3XXX_RTC_CTRL_ALARM_IRQ,
  				rtc_data->io + STMP3XXX_RTC_CTRL_CLR);

  		rtc_update_irq(rtc_data->rtc, 1, RTC_AF | RTC_IRQF);
  		return IRQ_HANDLED;

  	}

  	return IRQ_NONE;

  }
  
  static int stmp3xxx_alarm_irq_enable(struct device *dev, unsigned int enabled)
  {
  	struct stmp3xxx_rtc_data *rtc_data = dev_get_drvdata(dev);

  
  	if (enabled) {

  		writel(STMP3XXX_RTC_PERSISTENT0_ALARM_EN |
  				STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE_EN,
  				rtc_data->io + STMP3XXX_RTC_PERSISTENT0_SET);
  		writel(STMP3XXX_RTC_CTRL_ALARM_IRQ_EN,
  				rtc_data->io + STMP3XXX_RTC_CTRL_SET);

  	} else {

  		writel(STMP3XXX_RTC_PERSISTENT0_ALARM_EN |
  				STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE_EN,
  				rtc_data->io + STMP3XXX_RTC_PERSISTENT0_CLR);
  		writel(STMP3XXX_RTC_CTRL_ALARM_IRQ_EN,
  				rtc_data->io + STMP3XXX_RTC_CTRL_CLR);

  	}
  	return 0;
  }

  static int stmp3xxx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
  {
  	struct stmp3xxx_rtc_data *rtc_data = dev_get_drvdata(dev);

  	rtc_time_to_tm(readl(rtc_data->io + STMP3XXX_RTC_ALARM), &alm->time);

  	return 0;
  }
  
  static int stmp3xxx_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
  {
  	unsigned long t;
  	struct stmp3xxx_rtc_data *rtc_data = dev_get_drvdata(dev);
  
  	rtc_tm_to_time(&alm->time, &t);

  	writel(t, rtc_data->io + STMP3XXX_RTC_ALARM);

  
  	stmp3xxx_alarm_irq_enable(dev, alm->enabled);

  	return 0;
  }
  
  static struct rtc_class_ops stmp3xxx_rtc_ops = {
  	.alarm_irq_enable =
  			  stmp3xxx_alarm_irq_enable,

  	.read_time	= stmp3xxx_rtc_gettime,
  	.set_mmss	= stmp3xxx_rtc_set_mmss,
  	.read_alarm	= stmp3xxx_rtc_read_alarm,
  	.set_alarm	= stmp3xxx_rtc_set_alarm,
  };
  
  static int stmp3xxx_rtc_remove(struct platform_device *pdev)
  {
  	struct stmp3xxx_rtc_data *rtc_data = platform_get_drvdata(pdev);
  
  	if (!rtc_data)
  		return 0;

  	writel(STMP3XXX_RTC_CTRL_ALARM_IRQ_EN,

  			rtc_data->io + STMP3XXX_RTC_CTRL_CLR);

  	free_irq(rtc_data->irq_alarm, &pdev->dev);

  	rtc_device_unregister(rtc_data->rtc);

  	platform_set_drvdata(pdev, NULL);

  	iounmap(rtc_data->io);
  	kfree(rtc_data);
  
  	return 0;
  }
  
  static int stmp3xxx_rtc_probe(struct platform_device *pdev)
  {
  	struct stmp3xxx_rtc_data *rtc_data;
  	struct resource *r;
  	int err;
  
  	rtc_data = kzalloc(sizeof *rtc_data, GFP_KERNEL);
  	if (!rtc_data)
  		return -ENOMEM;
  
  	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!r) {
  		dev_err(&pdev->dev, "failed to get resource
  ");
  		err = -ENXIO;
  		goto out_free;
  	}
  
  	rtc_data->io = ioremap(r->start, resource_size(r));
  	if (!rtc_data->io) {
  		dev_err(&pdev->dev, "ioremap failed
  ");
  		err = -EIO;
  		goto out_free;
  	}
  
  	rtc_data->irq_alarm = platform_get_irq(pdev, 0);

  	if (!(readl(STMP3XXX_RTC_STAT + rtc_data->io) &

  			STMP3XXX_RTC_STAT_RTC_PRESENT)) {

  		dev_err(&pdev->dev, "no device onboard
  ");
  		err = -ENODEV;
  		goto out_remap;
  	}

  	platform_set_drvdata(pdev, rtc_data);

  	mxs_reset_block(rtc_data->io);

  	writel(STMP3XXX_RTC_PERSISTENT0_ALARM_EN |

  			STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE_EN |
  			STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE,

  			rtc_data->io + STMP3XXX_RTC_PERSISTENT0_CLR);

  	writel(STMP3XXX_RTC_CTRL_ONEMSEC_IRQ_EN |
  			STMP3XXX_RTC_CTRL_ALARM_IRQ_EN,
  			rtc_data->io + STMP3XXX_RTC_CTRL_CLR);

  	rtc_data->rtc = rtc_device_register(pdev->name, &pdev->dev,
  				&stmp3xxx_rtc_ops, THIS_MODULE);
  	if (IS_ERR(rtc_data->rtc)) {
  		err = PTR_ERR(rtc_data->rtc);
  		goto out_remap;
  	}

  	err = request_irq(rtc_data->irq_alarm, stmp3xxx_rtc_interrupt, 0,
  			"RTC alarm", &pdev->dev);

  	if (err) {
  		dev_err(&pdev->dev, "Cannot claim IRQ%d
  ",
  			rtc_data->irq_alarm);
  		goto out_irq_alarm;
  	}

  	stmp3xxx_wdt_register(pdev);

  	return 0;

  out_irq_alarm:

  	rtc_device_unregister(rtc_data->rtc);
  out_remap:

  	platform_set_drvdata(pdev, NULL);

  	iounmap(rtc_data->io);
  out_free:
  	kfree(rtc_data);
  	return err;
  }
  
  #ifdef CONFIG_PM
  static int stmp3xxx_rtc_suspend(struct platform_device *dev, pm_message_t state)
  {
  	return 0;
  }
  
  static int stmp3xxx_rtc_resume(struct platform_device *dev)
  {
  	struct stmp3xxx_rtc_data *rtc_data = platform_get_drvdata(dev);

  	mxs_reset_block(rtc_data->io);

  	writel(STMP3XXX_RTC_PERSISTENT0_ALARM_EN |

  			STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE_EN |
  			STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE,

  			rtc_data->io + STMP3XXX_RTC_PERSISTENT0_CLR);

  	return 0;
  }
  #else
  #define stmp3xxx_rtc_suspend	NULL
  #define stmp3xxx_rtc_resume	NULL
  #endif

  static const struct of_device_id rtc_dt_ids[] = {
  	{ .compatible = "fsl,stmp3xxx-rtc", },
  	{ /* sentinel */ }
  };
  MODULE_DEVICE_TABLE(of, rtc_dt_ids);

  static struct platform_driver stmp3xxx_rtcdrv = {
  	.probe		= stmp3xxx_rtc_probe,
  	.remove		= stmp3xxx_rtc_remove,
  	.suspend	= stmp3xxx_rtc_suspend,
  	.resume		= stmp3xxx_rtc_resume,
  	.driver		= {
  		.name	= "stmp3xxx-rtc",
  		.owner	= THIS_MODULE,

  		.of_match_table = of_match_ptr(rtc_dt_ids),

  	},
  };

  module_platform_driver(stmp3xxx_rtcdrv);

  
  MODULE_DESCRIPTION("STMP3xxx RTC Driver");

  MODULE_AUTHOR("dmitry pervushin <dpervushin@embeddedalley.com> and "
  		"Wolfram Sang <w.sang@pengutronix.de>");

  MODULE_LICENSE("GPL");