/*
   *  Gemini OnChip RTC
   *
   *  Copyright (C) 2009 Janos Laube <janos.dev@gmail.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; either version 2 of the License, or
   * (at your option) any later version.
   *
   * 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.
   *
   * Original code for older kernel 2.6.15 are from Stormlinksemi
   * first update from Janos Laube for > 2.6.29 kernels
   *
   * checkpatch fixes and usage of rtc-lib code
   * Hans Ulli Kroll <ulli.kroll@googlemail.com>
   */
  
  #include <linux/rtc.h>
  #include <linux/io.h>
  #include <linux/slab.h>
  #include <linux/platform_device.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  
  #define DRV_NAME        "rtc-gemini"

  
  MODULE_AUTHOR("Hans Ulli Kroll <ulli.kroll@googlemail.com>");
  MODULE_DESCRIPTION("RTC driver for Gemini SoC");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("platform:" DRV_NAME);
  
  struct gemini_rtc {
  	struct rtc_device	*rtc_dev;
  	void __iomem		*rtc_base;
  	int			rtc_irq;
  };
  
  enum gemini_rtc_offsets {
  	GEMINI_RTC_SECOND	= 0x00,
  	GEMINI_RTC_MINUTE	= 0x04,
  	GEMINI_RTC_HOUR		= 0x08,
  	GEMINI_RTC_DAYS		= 0x0C,
  	GEMINI_RTC_ALARM_SECOND	= 0x10,
  	GEMINI_RTC_ALARM_MINUTE	= 0x14,
  	GEMINI_RTC_ALARM_HOUR	= 0x18,
  	GEMINI_RTC_RECORD	= 0x1C,
  	GEMINI_RTC_CR		= 0x20
  };
  
  static irqreturn_t gemini_rtc_interrupt(int irq, void *dev)
  {
  	return IRQ_HANDLED;
  }
  
  /*
   * Looks like the RTC in the Gemini SoC is (totaly) broken
   * We can't read/write directly the time from RTC registers.
   * We must do some "offset" calculation to get the real time
   *
   * This FIX works pretty fine and Stormlinksemi aka Cortina-Networks does
   * the same thing, without the rtc-lib.c calls.
   */
  
  static int gemini_rtc_read_time(struct device *dev, struct rtc_time *tm)
  {
  	struct gemini_rtc *rtc = dev_get_drvdata(dev);
  
  	unsigned int  days, hour, min, sec;
  	unsigned long offset, time;
  
  	sec  = readl(rtc->rtc_base + GEMINI_RTC_SECOND);
  	min  = readl(rtc->rtc_base + GEMINI_RTC_MINUTE);
  	hour = readl(rtc->rtc_base + GEMINI_RTC_HOUR);
  	days = readl(rtc->rtc_base + GEMINI_RTC_DAYS);
  	offset = readl(rtc->rtc_base + GEMINI_RTC_RECORD);
  
  	time = offset + days * 86400 + hour * 3600 + min * 60 + sec;
  
  	rtc_time_to_tm(time, tm);
  
  	return 0;
  }
  
  static int gemini_rtc_set_time(struct device *dev, struct rtc_time *tm)
  {
  	struct gemini_rtc *rtc = dev_get_drvdata(dev);
  	unsigned int sec, min, hour, day;
  	unsigned long offset, time;
  
  	if (tm->tm_year >= 2148)	/* EPOCH Year + 179 */
  		return -EINVAL;
  
  	rtc_tm_to_time(tm, &time);
  
  	sec = readl(rtc->rtc_base + GEMINI_RTC_SECOND);
  	min = readl(rtc->rtc_base + GEMINI_RTC_MINUTE);
  	hour = readl(rtc->rtc_base + GEMINI_RTC_HOUR);
  	day = readl(rtc->rtc_base + GEMINI_RTC_DAYS);
  
  	offset = time - (day * 86400 + hour * 3600 + min * 60 + sec);
  
  	writel(offset, rtc->rtc_base + GEMINI_RTC_RECORD);
  	writel(0x01, rtc->rtc_base + GEMINI_RTC_CR);
  
  	return 0;
  }
  
  static struct rtc_class_ops gemini_rtc_ops = {
  	.read_time     = gemini_rtc_read_time,
  	.set_time      = gemini_rtc_set_time,
  };
  
  static int gemini_rtc_probe(struct platform_device *pdev)
  {
  	struct gemini_rtc *rtc;
  	struct device *dev = &pdev->dev;
  	struct resource *res;
  	int ret;
  
  	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
  	if (unlikely(!rtc))
  		return -ENOMEM;
  	platform_set_drvdata(pdev, rtc);
  
  	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
  	if (!res)
  		return -ENODEV;
  
  	rtc->rtc_irq = res->start;
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!res)
  		return -ENODEV;
  
  	rtc->rtc_base = devm_ioremap(dev, res->start,

  				     resource_size(res));

  
  	ret = devm_request_irq(dev, rtc->rtc_irq, gemini_rtc_interrupt,
  			       IRQF_SHARED, pdev->name, dev);
  	if (unlikely(ret))
  		return ret;
  
  	rtc->rtc_dev = rtc_device_register(pdev->name, dev,
  					   &gemini_rtc_ops, THIS_MODULE);

  	return PTR_ERR_OR_ZERO(rtc->rtc_dev);

  }
  
  static int gemini_rtc_remove(struct platform_device *pdev)
  {
  	struct gemini_rtc *rtc = platform_get_drvdata(pdev);
  
  	rtc_device_unregister(rtc->rtc_dev);

  
  	return 0;
  }
  
  static struct platform_driver gemini_rtc_driver = {
  	.driver		= {
  		.name	= DRV_NAME,

  	},
  	.probe		= gemini_rtc_probe,
  	.remove		= gemini_rtc_remove,
  };
  
  module_platform_driver_probe(gemini_rtc_driver, gemini_rtc_probe);