/*
   *	Real Time Clock interface for Linux on Atmel AT91RM9200
   *
   *	Copyright (C) 2002 Rick Bronson
   *
   *	Converted to RTC class model by Andrew Victor
   *
   *	Ported to Linux 2.6 by Steven Scholz
   *	Based on s3c2410-rtc.c Simtec Electronics
   *
   *	Based on sa1100-rtc.c by Nils Faerber
   *	Based on rtc.c by Paul Gortmaker
   *
   *	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.
   *
   */
  
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/platform_device.h>
  #include <linux/time.h>
  #include <linux/rtc.h>
  #include <linux/bcd.h>
  #include <linux/interrupt.h>
  #include <linux/ioctl.h>
  #include <linux/completion.h>
  
  #include <asm/uaccess.h>

  #include <mach/at91_rtc.h>

  #define at91_rtc_read(field) \
  	__raw_readl(at91_rtc_regs + field)
  #define at91_rtc_write(field, val) \
  	__raw_writel((val), at91_rtc_regs + field)

  #define AT91_RTC_EPOCH		1900UL	/* just like arch/arm/common/rtctime.c */
  
  static DECLARE_COMPLETION(at91_rtc_updated);
  static unsigned int at91_alarm_year = AT91_RTC_EPOCH;

  static void __iomem *at91_rtc_regs;
  static int irq;

  /*
   * Decode time/date into rtc_time structure
   */

  static void at91_rtc_decodetime(unsigned int timereg, unsigned int calreg,
  				struct rtc_time *tm)

  {
  	unsigned int time, date;
  
  	/* must read twice in case it changes */
  	do {

  		time = at91_rtc_read(timereg);
  		date = at91_rtc_read(calreg);
  	} while ((time != at91_rtc_read(timereg)) ||
  			(date != at91_rtc_read(calreg)));

  	tm->tm_sec  = bcd2bin((time & AT91_RTC_SEC) >> 0);
  	tm->tm_min  = bcd2bin((time & AT91_RTC_MIN) >> 8);
  	tm->tm_hour = bcd2bin((time & AT91_RTC_HOUR) >> 16);

  
  	/*
  	 * The Calendar Alarm register does not have a field for
  	 * the year - so these will return an invalid value.  When an

  	 * alarm is set, at91_alarm_year will store the current year.

  	 */

  	tm->tm_year  = bcd2bin(date & AT91_RTC_CENT) * 100;	/* century */
  	tm->tm_year += bcd2bin((date & AT91_RTC_YEAR) >> 8);	/* year */

  	tm->tm_wday = bcd2bin((date & AT91_RTC_DAY) >> 21) - 1;	/* day of the week [0-6], Sunday=0 */
  	tm->tm_mon  = bcd2bin((date & AT91_RTC_MONTH) >> 16) - 1;
  	tm->tm_mday = bcd2bin((date & AT91_RTC_DATE) >> 24);

  }
  
  /*
   * Read current time and date in RTC
   */
  static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm)
  {
  	at91_rtc_decodetime(AT91_RTC_TIMR, AT91_RTC_CALR, tm);
  	tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
  	tm->tm_year = tm->tm_year - 1900;

  	pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d
  ", __func__,

  		1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
  		tm->tm_hour, tm->tm_min, tm->tm_sec);

  
  	return 0;
  }
  
  /*
   * Set current time and date in RTC
   */
  static int at91_rtc_settime(struct device *dev, struct rtc_time *tm)
  {
  	unsigned long cr;

  	pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d
  ", __func__,

  		1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
  		tm->tm_hour, tm->tm_min, tm->tm_sec);

  
  	/* Stop Time/Calendar from counting */

  	cr = at91_rtc_read(AT91_RTC_CR);
  	at91_rtc_write(AT91_RTC_CR, cr | AT91_RTC_UPDCAL | AT91_RTC_UPDTIM);

  	at91_rtc_write(AT91_RTC_IER, AT91_RTC_ACKUPD);

  	wait_for_completion(&at91_rtc_updated);	/* wait for ACKUPD interrupt */

  	at91_rtc_write(AT91_RTC_IDR, AT91_RTC_ACKUPD);

  	at91_rtc_write(AT91_RTC_TIMR,

  			  bin2bcd(tm->tm_sec) << 0
  			| bin2bcd(tm->tm_min) << 8
  			| bin2bcd(tm->tm_hour) << 16);

  	at91_rtc_write(AT91_RTC_CALR,

  			  bin2bcd((tm->tm_year + 1900) / 100)	/* century */
  			| bin2bcd(tm->tm_year % 100) << 8	/* year */
  			| bin2bcd(tm->tm_mon + 1) << 16		/* tm_mon starts at zero */
  			| bin2bcd(tm->tm_wday + 1) << 21	/* day of the week [0-6], Sunday=0 */
  			| bin2bcd(tm->tm_mday) << 24);

  
  	/* Restart Time/Calendar */

  	cr = at91_rtc_read(AT91_RTC_CR);
  	at91_rtc_write(AT91_RTC_CR, cr & ~(AT91_RTC_UPDCAL | AT91_RTC_UPDTIM));

  
  	return 0;
  }
  
  /*
   * Read alarm time and date in RTC
   */
  static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	struct rtc_time *tm = &alrm->time;
  
  	at91_rtc_decodetime(AT91_RTC_TIMALR, AT91_RTC_CALALR, tm);
  	tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
  	tm->tm_year = at91_alarm_year - 1900;

  	alrm->enabled = (at91_rtc_read(AT91_RTC_IMR) & AT91_RTC_ALARM)

  			? 1 : 0;

  	pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d
  ", __func__,

  		1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
  		tm->tm_hour, tm->tm_min, tm->tm_sec);

  
  	return 0;
  }
  
  /*
   * Set alarm time and date in RTC
   */
  static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
  {
  	struct rtc_time tm;
  
  	at91_rtc_decodetime(AT91_RTC_TIMR, AT91_RTC_CALR, &tm);
  
  	at91_alarm_year = tm.tm_year;
  
  	tm.tm_hour = alrm->time.tm_hour;
  	tm.tm_min = alrm->time.tm_min;
  	tm.tm_sec = alrm->time.tm_sec;

  	at91_rtc_write(AT91_RTC_IDR, AT91_RTC_ALARM);
  	at91_rtc_write(AT91_RTC_TIMALR,

  		  bin2bcd(tm.tm_sec) << 0
  		| bin2bcd(tm.tm_min) << 8
  		| bin2bcd(tm.tm_hour) << 16

  		| AT91_RTC_HOUREN | AT91_RTC_MINEN | AT91_RTC_SECEN);

  	at91_rtc_write(AT91_RTC_CALALR,

  		  bin2bcd(tm.tm_mon + 1) << 16		/* tm_mon starts at zero */
  		| bin2bcd(tm.tm_mday) << 24

  		| AT91_RTC_DATEEN | AT91_RTC_MTHEN);

  	if (alrm->enabled) {

  		at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
  		at91_rtc_write(AT91_RTC_IER, AT91_RTC_ALARM);

  	}

  	pr_debug("%s(): %4d-%02d-%02d %02d:%02d:%02d
  ", __func__,

  		at91_alarm_year, tm.tm_mon, tm.tm_mday, tm.tm_hour,
  		tm.tm_min, tm.tm_sec);

  
  	return 0;
  }

  static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
  {
  	pr_debug("%s(): cmd=%08x
  ", __func__, enabled);
  
  	if (enabled) {

  		at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
  		at91_rtc_write(AT91_RTC_IER, AT91_RTC_ALARM);

  	} else

  		at91_rtc_write(AT91_RTC_IDR, AT91_RTC_ALARM);

  
  	return 0;
  }

  /*
   * Provide additional RTC information in /proc/driver/rtc
   */
  static int at91_rtc_proc(struct device *dev, struct seq_file *seq)
  {

  	unsigned long imr = at91_rtc_read(AT91_RTC_IMR);

  	seq_printf(seq, "update_IRQ\t: %s
  ",
  			(imr & AT91_RTC_ACKUPD) ? "yes" : "no");
  	seq_printf(seq, "periodic_IRQ\t: %s
  ",
  			(imr & AT91_RTC_SECEV) ? "yes" : "no");

  
  	return 0;
  }
  
  /*
   * IRQ handler for the RTC
   */

  static irqreturn_t at91_rtc_interrupt(int irq, void *dev_id)

  {

  	struct platform_device *pdev = dev_id;

  	struct rtc_device *rtc = platform_get_drvdata(pdev);
  	unsigned int rtsr;
  	unsigned long events = 0;

  	rtsr = at91_rtc_read(AT91_RTC_SR) & at91_rtc_read(AT91_RTC_IMR);

  	if (rtsr) {		/* this interrupt is shared!  Is it ours? */
  		if (rtsr & AT91_RTC_ALARM)
  			events |= (RTC_AF | RTC_IRQF);
  		if (rtsr & AT91_RTC_SECEV)
  			events |= (RTC_UF | RTC_IRQF);
  		if (rtsr & AT91_RTC_ACKUPD)
  			complete(&at91_rtc_updated);

  		at91_rtc_write(AT91_RTC_SCCR, rtsr);	/* clear status reg */

  		rtc_update_irq(rtc, 1, events);

  		pr_debug("%s(): num=%ld, events=0x%02lx
  ", __func__,

  			events >> 8, events & 0x000000FF);
  
  		return IRQ_HANDLED;
  	}
  	return IRQ_NONE;		/* not handled */
  }

  static const struct rtc_class_ops at91_rtc_ops = {

  	.read_time	= at91_rtc_readtime,
  	.set_time	= at91_rtc_settime,
  	.read_alarm	= at91_rtc_readalarm,
  	.set_alarm	= at91_rtc_setalarm,
  	.proc		= at91_rtc_proc,

  	.alarm_irq_enable = at91_rtc_alarm_irq_enable,

  };
  
  /*
   * Initialize and install RTC driver
   */
  static int __init at91_rtc_probe(struct platform_device *pdev)
  {
  	struct rtc_device *rtc;

  	struct resource *regs;
  	int ret = 0;

  	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!regs) {
  		dev_err(&pdev->dev, "no mmio resource defined
  ");
  		return -ENXIO;
  	}
  
  	irq = platform_get_irq(pdev, 0);
  	if (irq < 0) {
  		dev_err(&pdev->dev, "no irq resource defined
  ");
  		return -ENXIO;
  	}
  
  	at91_rtc_regs = ioremap(regs->start, resource_size(regs));
  	if (!at91_rtc_regs) {
  		dev_err(&pdev->dev, "failed to map registers, aborting.
  ");
  		return -ENOMEM;
  	}
  
  	at91_rtc_write(AT91_RTC_CR, 0);
  	at91_rtc_write(AT91_RTC_MR, 0);		/* 24 hour mode */

  
  	/* Disable all interrupts */

  	at91_rtc_write(AT91_RTC_IDR, AT91_RTC_ACKUPD | AT91_RTC_ALARM |

  					AT91_RTC_SECEV | AT91_RTC_TIMEV |
  					AT91_RTC_CALEV);

  	ret = request_irq(irq, at91_rtc_interrupt,

  				IRQF_SHARED,

  				"at91_rtc", pdev);

  	if (ret) {

  		printk(KERN_ERR "at91_rtc: IRQ %d already in use.
  ",

  				irq);

  		return ret;
  	}

  	/* cpu init code should really have flagged this device as
  	 * being wake-capable; if it didn't, do that here.
  	 */
  	if (!device_can_wakeup(&pdev->dev))
  		device_init_wakeup(&pdev->dev, 1);

  	rtc = rtc_device_register(pdev->name, &pdev->dev,
  				&at91_rtc_ops, THIS_MODULE);

  	if (IS_ERR(rtc)) {

  		free_irq(irq, pdev);

  		return PTR_ERR(rtc);
  	}
  	platform_set_drvdata(pdev, rtc);
  
  	printk(KERN_INFO "AT91 Real Time Clock driver.
  ");
  	return 0;
  }
  
  /*
   * Disable and remove the RTC driver
   */

  static int __exit at91_rtc_remove(struct platform_device *pdev)

  {
  	struct rtc_device *rtc = platform_get_drvdata(pdev);
  
  	/* Disable all interrupts */

  	at91_rtc_write(AT91_RTC_IDR, AT91_RTC_ACKUPD | AT91_RTC_ALARM |

  					AT91_RTC_SECEV | AT91_RTC_TIMEV |
  					AT91_RTC_CALEV);

  	free_irq(irq, pdev);

  
  	rtc_device_unregister(rtc);
  	platform_set_drvdata(pdev, NULL);
  
  	return 0;
  }
  
  #ifdef CONFIG_PM
  
  /* AT91RM9200 RTC Power management control */

  static u32 at91_rtc_imr;

  static int at91_rtc_suspend(struct device *dev)

  {

  	/* this IRQ is shared with DBGU and other hardware which isn't
  	 * necessarily doing PM like we are...
  	 */

  	at91_rtc_imr = at91_rtc_read(AT91_RTC_IMR)

  			& (AT91_RTC_ALARM|AT91_RTC_SECEV);
  	if (at91_rtc_imr) {

  		if (device_may_wakeup(dev))

  			enable_irq_wake(irq);

  		else

  			at91_rtc_write(AT91_RTC_IDR, at91_rtc_imr);

  	}

  	return 0;
  }

  static int at91_rtc_resume(struct device *dev)

  {

  	if (at91_rtc_imr) {

  		if (device_may_wakeup(dev))

  			disable_irq_wake(irq);

  		else

  			at91_rtc_write(AT91_RTC_IER, at91_rtc_imr);

  	}

  	return 0;
  }

  
  static const struct dev_pm_ops at91_rtc_pm = {
  	.suspend =	at91_rtc_suspend,
  	.resume =	at91_rtc_resume,
  };
  
  #define at91_rtc_pm_ptr	&at91_rtc_pm

  #else

  #define at91_rtc_pm_ptr	NULL

  #endif
  
  static struct platform_driver at91_rtc_driver = {

  	.remove		= __exit_p(at91_rtc_remove),

  	.driver		= {
  		.name	= "at91_rtc",
  		.owner	= THIS_MODULE,

  		.pm	= at91_rtc_pm_ptr,

  	},
  };
  
  static int __init at91_rtc_init(void)
  {

  	return platform_driver_probe(&at91_rtc_driver, at91_rtc_probe);

  }
  
  static void __exit at91_rtc_exit(void)
  {
  	platform_driver_unregister(&at91_rtc_driver);
  }

  module_init(at91_rtc_init);
  module_exit(at91_rtc_exit);
  
  MODULE_AUTHOR("Rick Bronson");
  MODULE_DESCRIPTION("RTC driver for Atmel AT91RM9200");
  MODULE_LICENSE("GPL");

  MODULE_ALIAS("platform:at91_rtc");