/*
 * Real Time Clock interface for StrongARM SA1x00 and XScale PXA2xx
 *
 * Copyright (c) 2000 Nils Faerber
 *
 * Based on rtc.c by Paul Gortmaker
 *
 * Original Driver by Nils Faerber <nils@kernelconcepts.de>
 *
 * Modifications from:
 *   CIH <cih@coventive.com>
 *   Nicolas Pitre <nico@cam.org>
 *   Andrew Christian <andrew.christian@hp.com>
 *
 * Converted to the RTC subsystem and Driver Model
 *   by Richard Purdie <rpurdie@rpsys.net>
 *
 * 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/platform_device.h>
#include <linux/module.h>
#include <linux/rtc.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/interrupt.h>
#include <linux/string.h>
#include <linux/pm.h>

#include <asm/bitops.h>
#include <asm/hardware.h>
#include <asm/irq.h>
#include <asm/rtc.h>

#ifdef CONFIG_ARCH_PXA
#include <asm/arch/pxa-regs.h>
#endif

#define TIMER_FREQ		CLOCK_TICK_RATE
#define RTC_DEF_DIVIDER		32768 - 1
#define RTC_DEF_TRIM		0

static unsigned long rtc_freq = 1024;
static struct rtc_time rtc_alarm;
static DEFINE_SPINLOCK(sa1100_rtc_lock);

static int rtc_update_alarm(struct rtc_time *alrm)
{
	struct rtc_time alarm_tm, now_tm;
	unsigned long now, time;
	int ret;

	do {
		now = RCNR;
		rtc_time_to_tm(now, &now_tm);
		rtc_next_alarm_time(&alarm_tm, &now_tm, alrm);
		ret = rtc_tm_to_time(&alarm_tm, &time);
		if (ret != 0)
			break;

		RTSR = RTSR & (RTSR_HZE|RTSR_ALE|RTSR_AL);
		RTAR = time;
	} while (now != RCNR);

	return ret;
}

static irqreturn_t sa1100_rtc_interrupt(int irq, void *dev_id,
		struct pt_regs *regs)
{
	struct platform_device *pdev = to_platform_device(dev_id);
	struct rtc_device *rtc = platform_get_drvdata(pdev);
	unsigned int rtsr;
	unsigned long events = 0;

	spin_lock(&sa1100_rtc_lock);

	rtsr = RTSR;
	/* clear interrupt sources */
	RTSR = 0;
	RTSR = (RTSR_AL | RTSR_HZ) & (rtsr >> 2);

	/* clear alarm interrupt if it has occurred */
	if (rtsr & RTSR_AL)
		rtsr &= ~RTSR_ALE;
	RTSR = rtsr & (RTSR_ALE | RTSR_HZE);

	/* update irq data & counter */
	if (rtsr & RTSR_AL)
		events |= RTC_AF | RTC_IRQF;
	if (rtsr & RTSR_HZ)
		events |= RTC_UF | RTC_IRQF;

	rtc_update_irq(&rtc->class_dev, 1, events);

	if (rtsr & RTSR_AL && rtc_periodic_alarm(&rtc_alarm))
		rtc_update_alarm(&rtc_alarm);

	spin_unlock(&sa1100_rtc_lock);

	return IRQ_HANDLED;
}

static int rtc_timer1_count;

static irqreturn_t timer1_interrupt(int irq, void *dev_id,
		struct pt_regs *regs)
{
	struct platform_device *pdev = to_platform_device(dev_id);
	struct rtc_device *rtc = platform_get_drvdata(pdev);

	/*
	 * If we match for the first time, rtc_timer1_count will be 1.
	 * Otherwise, we wrapped around (very unlikely but
	 * still possible) so compute the amount of missed periods.
	 * The match reg is updated only when the data is actually retrieved
	 * to avoid unnecessary interrupts.
	 */
	OSSR = OSSR_M1;	/* clear match on timer1 */

	rtc_update_irq(&rtc->class_dev, rtc_timer1_count, RTC_PF | RTC_IRQF);

	if (rtc_timer1_count == 1)
		rtc_timer1_count = (rtc_freq * ((1<<30)/(TIMER_FREQ>>2)));

	return IRQ_HANDLED;
}

static int sa1100_rtc_read_callback(struct device *dev, int data)
{
	if (data & RTC_PF) {
		/* interpolate missed periods and set match for the next */
		unsigned long period = TIMER_FREQ/rtc_freq;
		unsigned long oscr = OSCR;
		unsigned long osmr1 = OSMR1;
		unsigned long missed = (oscr - osmr1)/period;
		data += missed << 8;
		OSSR = OSSR_M1;	/* clear match on timer 1 */
		OSMR1 = osmr1 + (missed + 1)*period;
		/* Ensure we didn't miss another match in the mean time.
		 * Here we compare (match - OSCR) 8 instead of 0 --
		 * see comment in pxa_timer_interrupt() for explanation.
		 */
		while( (signed long)((osmr1 = OSMR1) - OSCR) <= 8 ) {
			data += 0x100;
			OSSR = OSSR_M1;	/* clear match on timer 1 */
			OSMR1 = osmr1 + period;
		}
	}
	return data;
}

static int sa1100_rtc_open(struct device *dev)
{
	int ret;

	ret = request_irq(IRQ_RTC1Hz, sa1100_rtc_interrupt, IRQF_DISABLED,
				"rtc 1Hz", dev);
	if (ret) {
		dev_err(dev, "IRQ %d already in use.\n", IRQ_RTC1Hz);
		goto fail_ui;
	}
	ret = request_irq(IRQ_RTCAlrm, sa1100_rtc_interrupt, IRQF_DISABLED,
				"rtc Alrm", dev);
	if (ret) {
		dev_err(dev, "IRQ %d already in use.\n", IRQ_RTCAlrm);
		goto fail_ai;
	}
	ret = request_irq(IRQ_OST1, timer1_interrupt, IRQF_DISABLED,
				"rtc timer", dev);
	if (ret) {
		dev_err(dev, "IRQ %d already in use.\n", IRQ_OST1);
		goto fail_pi;
	}
	return 0;

 fail_pi:
	free_irq(IRQ_RTCAlrm, dev);
 fail_ai:
	free_irq(IRQ_RTC1Hz, dev);
 fail_ui:
	return ret;
}

static void sa1100_rtc_release(struct device *dev)
{
	spin_lock_irq(&sa1100_rtc_lock);
	RTSR = 0;
	OIER &= ~OIER_E1;
	OSSR = OSSR_M1;
	spin_unlock_irq(&sa1100_rtc_lock);

	free_irq(IRQ_OST1, dev);
	free_irq(IRQ_RTCAlrm, dev);
	free_irq(IRQ_RTC1Hz, dev);
}


static int sa1100_rtc_ioctl(struct device *dev, unsigned int cmd,
		unsigned long arg)
{
	switch(cmd) {
	case RTC_AIE_OFF:
		spin_lock_irq(&sa1100_rtc_lock);
		RTSR &= ~RTSR_ALE;
		spin_unlock_irq(&sa1100_rtc_lock);
		return 0;
	case RTC_AIE_ON:
		spin_lock_irq(&sa1100_rtc_lock);
		RTSR |= RTSR_ALE;
		spin_unlock_irq(&sa1100_rtc_lock);
		return 0;
	case RTC_UIE_OFF:
		spin_lock_irq(&sa1100_rtc_lock);
		RTSR &= ~RTSR_HZE;
		spin_unlock_irq(&sa1100_rtc_lock);
		return 0;
	case RTC_UIE_ON:
		spin_lock_irq(&sa1100_rtc_lock);
		RTSR |= RTSR_HZE;
		spin_unlock_irq(&sa1100_rtc_lock);
		return 0;
	case RTC_PIE_OFF:
		spin_lock_irq(&sa1100_rtc_lock);
		OIER &= ~OIER_E1;
		spin_unlock_irq(&sa1100_rtc_lock);
		return 0;
	case RTC_PIE_ON:
		spin_lock_irq(&sa1100_rtc_lock);
		OSMR1 = TIMER_FREQ/rtc_freq + OSCR;
		OIER |= OIER_E1;
		rtc_timer1_count = 1;
		spin_unlock_irq(&sa1100_rtc_lock);
		return 0;
	case RTC_IRQP_READ:
		return put_user(rtc_freq, (unsigned long *)arg);
	case RTC_IRQP_SET:
		if (arg < 1 || arg > TIMER_FREQ)
			return -EINVAL;
		rtc_freq = arg;
		return 0;
	}
	return -ENOIOCTLCMD;
}

static int sa1100_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	rtc_time_to_tm(RCNR, tm);
	return 0;
}

static int sa1100_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	unsigned long time;
	int ret;

	ret = rtc_tm_to_time(tm, &time);
	if (ret == 0)
		RCNR = time;
	return ret;
}

static int sa1100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	memcpy(&alrm->time, &rtc_alarm, sizeof(struct rtc_time));
	alrm->pending = RTSR & RTSR_AL ? 1 : 0;
	return 0;
}

static int sa1100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	int ret;

	spin_lock_irq(&sa1100_rtc_lock);
	ret = rtc_update_alarm(&alrm->time);
	if (ret == 0) {
		memcpy(&rtc_alarm, &alrm->time, sizeof(struct rtc_time));

		if (alrm->enabled)
			enable_irq_wake(IRQ_RTCAlrm);
		else
			disable_irq_wake(IRQ_RTCAlrm);
	}
	spin_unlock_irq(&sa1100_rtc_lock);

	return ret;
}

static int sa1100_rtc_proc(struct device *dev, struct seq_file *seq)
{
	seq_printf(seq, "trim/divider\t: 0x%08lx\n", RTTR);
	seq_printf(seq, "alarm_IRQ\t: %s\n",
			(RTSR & RTSR_ALE) ? "yes" : "no" );
	seq_printf(seq, "update_IRQ\t: %s\n",
			(RTSR & RTSR_HZE) ? "yes" : "no");
	seq_printf(seq, "periodic_IRQ\t: %s\n",
			(OIER & OIER_E1) ? "yes" : "no");
	seq_printf(seq, "periodic_freq\t: %ld\n", rtc_freq);

	return 0;
}

static struct rtc_class_ops sa1100_rtc_ops = {
	.open = sa1100_rtc_open,
	.read_callback = sa1100_rtc_read_callback,
	.release = sa1100_rtc_release,
	.ioctl = sa1100_rtc_ioctl,
	.read_time = sa1100_rtc_read_time,
	.set_time = sa1100_rtc_set_time,
	.read_alarm = sa1100_rtc_read_alarm,
	.set_alarm = sa1100_rtc_set_alarm,
	.proc = sa1100_rtc_proc,
};

static int sa1100_rtc_probe(struct platform_device *pdev)
{
	struct rtc_device *rtc;

	/*
	 * According to the manual we should be able to let RTTR be zero
	 * and then a default diviser for a 32.768KHz clock is used.
	 * Apparently this doesn't work, at least for my SA1110 rev 5.
	 * If the clock divider is uninitialized then reset it to the
	 * default value to get the 1Hz clock.
	 */
	if (RTTR == 0) {
		RTTR = RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16);
		dev_warn(&pdev->dev, "warning: initializing default clock divider/trim value\n");
		/* The current RTC value probably doesn't make sense either */
		RCNR = 0;
	}

	rtc = rtc_device_register(pdev->name, &pdev->dev, &sa1100_rtc_ops,
				THIS_MODULE);

	if (IS_ERR(rtc))
		return PTR_ERR(rtc);

	platform_set_drvdata(pdev, rtc);

	return 0;
}

static int sa1100_rtc_remove(struct platform_device *pdev)
{
	struct rtc_device *rtc = platform_get_drvdata(pdev);

 	if (rtc)
		rtc_device_unregister(rtc);

	return 0;
}

static struct platform_driver sa1100_rtc_driver = {
	.probe		= sa1100_rtc_probe,
	.remove		= sa1100_rtc_remove,
	.driver		= {
		.name		= "sa1100-rtc",
	},
};

static int __init sa1100_rtc_init(void)
{
	return platform_driver_register(&sa1100_rtc_driver);
}

static void __exit sa1100_rtc_exit(void)
{
	platform_driver_unregister(&sa1100_rtc_driver);
}

module_init(sa1100_rtc_init);
module_exit(sa1100_rtc_exit);

MODULE_AUTHOR("Richard Purdie <rpurdie@rpsys.net>");
MODULE_DESCRIPTION("SA11x0/PXA2xx Realtime Clock Driver (RTC)");
MODULE_LICENSE("GPL");