/*
 * Real Time Clock driver for Marvell 88PM860x PMIC
 *
 * Copyright (c) 2010 Marvell International Ltd.
 * Author:	Haojian Zhuang <haojian.zhuang@marvell.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/rtc.h>
#include <linux/delay.h>
#include <linux/mfd/core.h>
#include <linux/mfd/88pm860x.h>

#define VRTC_CALIBRATION

struct pm860x_rtc_info {
	struct pm860x_chip	*chip;
	struct i2c_client	*i2c;
	struct rtc_device	*rtc_dev;
	struct device		*dev;
	struct delayed_work	calib_work;

	int			irq;
	int			vrtc;
	int			(*sync)(unsigned int ticks);
};

#define REG_VRTC_MEAS1		0x7D

#define REG0_ADDR		0xB0
#define REG1_ADDR		0xB2
#define REG2_ADDR		0xB4
#define REG3_ADDR		0xB6

#define REG0_DATA		0xB1
#define REG1_DATA		0xB3
#define REG2_DATA		0xB5
#define REG3_DATA		0xB7

/* bit definitions of Measurement Enable Register 2 (0x51) */
#define MEAS2_VRTC		(1 << 0)

/* bit definitions of RTC Register 1 (0xA0) */
#define ALARM_EN		(1 << 3)
#define ALARM_WAKEUP		(1 << 4)
#define ALARM			(1 << 5)
#define RTC1_USE_XO		(1 << 7)

#define VRTC_CALIB_INTERVAL	(HZ * 60 * 10)		/* 10 minutes */

static irqreturn_t rtc_update_handler(int irq, void *data)
{
	struct pm860x_rtc_info *info = (struct pm860x_rtc_info *)data;
	int mask;

	mask = ALARM | ALARM_WAKEUP;
	pm860x_set_bits(info->i2c, PM8607_RTC1, mask | ALARM_EN, mask);
	rtc_update_irq(info->rtc_dev, 1, RTC_AF);
	return IRQ_HANDLED;
}

static int pm860x_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
	struct pm860x_rtc_info *info = dev_get_drvdata(dev);

	if (enabled)
		pm860x_set_bits(info->i2c, PM8607_RTC1, ALARM, ALARM);
	else
		pm860x_set_bits(info->i2c, PM8607_RTC1, ALARM, 0);
	return 0;
}

/*
 * Calculate the next alarm time given the requested alarm time mask
 * and the current time.
 */
static void rtc_next_alarm_time(struct rtc_time *next, struct rtc_time *now,
				struct rtc_time *alrm)
{
	unsigned long next_time;
	unsigned long now_time;

	next->tm_year = now->tm_year;
	next->tm_mon = now->tm_mon;
	next->tm_mday = now->tm_mday;
	next->tm_hour = alrm->tm_hour;
	next->tm_min = alrm->tm_min;
	next->tm_sec = alrm->tm_sec;

	rtc_tm_to_time(now, &now_time);
	rtc_tm_to_time(next, &next_time);

	if (next_time < now_time) {
		/* Advance one day */
		next_time += 60 * 60 * 24;
		rtc_time_to_tm(next_time, next);
	}
}

static int pm860x_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
	struct pm860x_rtc_info *info = dev_get_drvdata(dev);
	unsigned char buf[8];
	unsigned long ticks, base, data;

	pm860x_page_bulk_read(info->i2c, REG0_ADDR, 8, buf);
	dev_dbg(info->dev, "%x-%x-%x-%x-%x-%x-%x-%x\n", buf[0], buf[1],
		buf[2], buf[3], buf[4], buf[5], buf[6], buf[7]);
	base = (buf[1] << 24) | (buf[3] << 16) | (buf[5] << 8) | buf[7];

	/* load 32-bit read-only counter */
	pm860x_bulk_read(info->i2c, PM8607_RTC_COUNTER1, 4, buf);
	data = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
	ticks = base + data;
	dev_dbg(info->dev, "get base:0x%lx, RO count:0x%lx, ticks:0x%lx\n",
		base, data, ticks);

	rtc_time_to_tm(ticks, tm);

	return 0;
}

static int pm860x_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
	struct pm860x_rtc_info *info = dev_get_drvdata(dev);
	unsigned char buf[4];
	unsigned long ticks, base, data;

	if ((tm->tm_year < 70) || (tm->tm_year > 138)) {
		dev_dbg(info->dev, "Set time %d out of range. "
			"Please set time between 1970 to 2038.\n",
			1900 + tm->tm_year);
		return -EINVAL;
	}
	rtc_tm_to_time(tm, &ticks);

	/* load 32-bit read-only counter */
	pm860x_bulk_read(info->i2c, PM8607_RTC_COUNTER1, 4, buf);
	data = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
	base = ticks - data;
	dev_dbg(info->dev, "set base:0x%lx, RO count:0x%lx, ticks:0x%lx\n",
		base, data, ticks);

	pm860x_page_reg_write(info->i2c, REG0_DATA, (base >> 24) & 0xFF);
	pm860x_page_reg_write(info->i2c, REG1_DATA, (base >> 16) & 0xFF);
	pm860x_page_reg_write(info->i2c, REG2_DATA, (base >> 8) & 0xFF);
	pm860x_page_reg_write(info->i2c, REG3_DATA, base & 0xFF);

	if (info->sync)
		info->sync(ticks);
	return 0;
}

static int pm860x_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct pm860x_rtc_info *info = dev_get_drvdata(dev);
	unsigned char buf[8];
	unsigned long ticks, base, data;
	int ret;

	pm860x_page_bulk_read(info->i2c, REG0_ADDR, 8, buf);
	dev_dbg(info->dev, "%x-%x-%x-%x-%x-%x-%x-%x\n", buf[0], buf[1],
		buf[2], buf[3], buf[4], buf[5], buf[6], buf[7]);
	base = (buf[1] << 24) | (buf[3] << 16) | (buf[5] << 8) | buf[7];

	pm860x_bulk_read(info->i2c, PM8607_RTC_EXPIRE1, 4, buf);
	data = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
	ticks = base + data;
	dev_dbg(info->dev, "get base:0x%lx, RO count:0x%lx, ticks:0x%lx\n",
		base, data, ticks);

	rtc_time_to_tm(ticks, &alrm->time);
	ret = pm860x_reg_read(info->i2c, PM8607_RTC1);
	alrm->enabled = (ret & ALARM_EN) ? 1 : 0;
	alrm->pending = (ret & (ALARM | ALARM_WAKEUP)) ? 1 : 0;
	return 0;
}

static int pm860x_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
	struct pm860x_rtc_info *info = dev_get_drvdata(dev);
	struct rtc_time now_tm, alarm_tm;
	unsigned long ticks, base, data;
	unsigned char buf[8];
	int mask;

	pm860x_set_bits(info->i2c, PM8607_RTC1, ALARM_EN, 0);

	pm860x_page_bulk_read(info->i2c, REG0_ADDR, 8, buf);
	dev_dbg(info->dev, "%x-%x-%x-%x-%x-%x-%x-%x\n", buf[0], buf[1],
		buf[2], buf[3], buf[4], buf[5], buf[6], buf[7]);
	base = (buf[1] << 24) | (buf[3] << 16) | (buf[5] << 8) | buf[7];

	/* load 32-bit read-only counter */
	pm860x_bulk_read(info->i2c, PM8607_RTC_COUNTER1, 4, buf);
	data = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
	ticks = base + data;
	dev_dbg(info->dev, "get base:0x%lx, RO count:0x%lx, ticks:0x%lx\n",
		base, data, ticks);

	rtc_time_to_tm(ticks, &now_tm);
	rtc_next_alarm_time(&alarm_tm, &now_tm, &alrm->time);
	/* get new ticks for alarm in 24 hours */
	rtc_tm_to_time(&alarm_tm, &ticks);
	data = ticks - base;

	buf[0] = data & 0xff;
	buf[1] = (data >> 8) & 0xff;
	buf[2] = (data >> 16) & 0xff;
	buf[3] = (data >> 24) & 0xff;
	pm860x_bulk_write(info->i2c, PM8607_RTC_EXPIRE1, 4, buf);
	if (alrm->enabled) {
		mask = ALARM | ALARM_WAKEUP | ALARM_EN;
		pm860x_set_bits(info->i2c, PM8607_RTC1, mask, mask);
	} else {
		mask = ALARM | ALARM_WAKEUP | ALARM_EN;
		pm860x_set_bits(info->i2c, PM8607_RTC1, mask,
				ALARM | ALARM_WAKEUP);
	}
	return 0;
}

static const struct rtc_class_ops pm860x_rtc_ops = {
	.read_time	= pm860x_rtc_read_time,
	.set_time	= pm860x_rtc_set_time,
	.read_alarm	= pm860x_rtc_read_alarm,
	.set_alarm	= pm860x_rtc_set_alarm,
	.alarm_irq_enable = pm860x_rtc_alarm_irq_enable,
};

#ifdef VRTC_CALIBRATION
static void calibrate_vrtc_work(struct work_struct *work)
{
	struct pm860x_rtc_info *info = container_of(work,
		struct pm860x_rtc_info, calib_work.work);
	unsigned char buf[2];
	unsigned int sum, data, mean, vrtc_set;
	int i;

	for (i = 0, sum = 0; i < 16; i++) {
		msleep(100);
		pm860x_bulk_read(info->i2c, REG_VRTC_MEAS1, 2, buf);
		data = (buf[0] << 4) | buf[1];
		data = (data * 5400) >> 12;	/* convert to mv */
		sum += data;
	}
	mean = sum >> 4;
	vrtc_set = 2700 + (info->vrtc & 0x3) * 200;
	dev_dbg(info->dev, "mean:%d, vrtc_set:%d\n", mean, vrtc_set);

	sum = pm860x_reg_read(info->i2c, PM8607_RTC_MISC1);
	data = sum & 0x3;
	if ((mean + 200) < vrtc_set) {
		/* try higher voltage */
		if (++data == 4)
			goto out;
		data = (sum & 0xf8) | (data & 0x3);
		pm860x_reg_write(info->i2c, PM8607_RTC_MISC1, data);
	} else if ((mean - 200) > vrtc_set) {
		/* try lower voltage */
		if (data-- == 0)
			goto out;
		data = (sum & 0xf8) | (data & 0x3);
		pm860x_reg_write(info->i2c, PM8607_RTC_MISC1, data);
	} else
		goto out;
	dev_dbg(info->dev, "set 0x%x to RTC_MISC1\n", data);
	/* trigger next calibration since VRTC is updated */
	schedule_delayed_work(&info->calib_work, VRTC_CALIB_INTERVAL);
	return;
out:
	/* disable measurement */
	pm860x_set_bits(info->i2c, PM8607_MEAS_EN2, MEAS2_VRTC, 0);
	dev_dbg(info->dev, "finish VRTC calibration\n");
	return;
}
#endif

static int __devinit pm860x_rtc_probe(struct platform_device *pdev)
{
	struct pm860x_chip *chip = dev_get_drvdata(pdev->dev.parent);
	struct pm860x_rtc_pdata *pdata = NULL;
	struct pm860x_rtc_info *info;
	struct rtc_time tm;
	unsigned long ticks = 0;
	int ret;

	pdata = pdev->dev.platform_data;
	if (pdata == NULL)
		dev_warn(&pdev->dev, "No platform data!\n");

	info = kzalloc(sizeof(struct pm860x_rtc_info), GFP_KERNEL);
	if (!info)
		return -ENOMEM;
	info->irq = platform_get_irq(pdev, 0);
	if (info->irq < 0) {
		dev_err(&pdev->dev, "No IRQ resource!\n");
		ret = -EINVAL;
		goto out;
	}

	info->chip = chip;
	info->i2c = (chip->id == CHIP_PM8607) ? chip->client : chip->companion;
	info->dev = &pdev->dev;
	dev_set_drvdata(&pdev->dev, info);

	ret = request_threaded_irq(info->irq, NULL, rtc_update_handler,
				   IRQF_ONESHOT, "rtc", info);
	if (ret < 0) {
		dev_err(chip->dev, "Failed to request IRQ: #%d: %d\n",
			info->irq, ret);
		goto out;
	}

	/* set addresses of 32-bit base value for RTC time */
	pm860x_page_reg_write(info->i2c, REG0_ADDR, REG0_DATA);
	pm860x_page_reg_write(info->i2c, REG1_ADDR, REG1_DATA);
	pm860x_page_reg_write(info->i2c, REG2_ADDR, REG2_DATA);
	pm860x_page_reg_write(info->i2c, REG3_ADDR, REG3_DATA);

	ret = pm860x_rtc_read_time(&pdev->dev, &tm);
	if (ret < 0) {
		dev_err(&pdev->dev, "Failed to read initial time.\n");
		goto out_rtc;
	}
	if ((tm.tm_year < 70) || (tm.tm_year > 138)) {
		tm.tm_year = 70;
		tm.tm_mon = 0;
		tm.tm_mday = 1;
		tm.tm_hour = 0;
		tm.tm_min = 0;
		tm.tm_sec = 0;
		ret = pm860x_rtc_set_time(&pdev->dev, &tm);
		if (ret < 0) {
			dev_err(&pdev->dev, "Failed to set initial time.\n");
			goto out_rtc;
		}
	}
	rtc_tm_to_time(&tm, &ticks);
	if (pdata && pdata->sync) {
		pdata->sync(ticks);
		info->sync = pdata->sync;
	}

	info->rtc_dev = rtc_device_register("88pm860x-rtc", &pdev->dev,
					    &pm860x_rtc_ops, THIS_MODULE);
	ret = PTR_ERR(info->rtc_dev);
	if (IS_ERR(info->rtc_dev)) {
		dev_err(&pdev->dev, "Failed to register RTC device: %d\n", ret);
		goto out_rtc;
	}

	/*
	 * enable internal XO instead of internal 3.25MHz clock since it can
	 * free running in PMIC power-down state.
	 */
	pm860x_set_bits(info->i2c, PM8607_RTC1, RTC1_USE_XO, RTC1_USE_XO);

#ifdef VRTC_CALIBRATION
	/* <00> -- 2.7V, <01> -- 2.9V, <10> -- 3.1V, <11> -- 3.3V */
	if (pdata && pdata->vrtc)
		info->vrtc = pdata->vrtc & 0x3;
	else
		info->vrtc = 1;
	pm860x_set_bits(info->i2c, PM8607_MEAS_EN2, MEAS2_VRTC, MEAS2_VRTC);

	/* calibrate VRTC */
	INIT_DELAYED_WORK(&info->calib_work, calibrate_vrtc_work);
	schedule_delayed_work(&info->calib_work, VRTC_CALIB_INTERVAL);
#endif	/* VRTC_CALIBRATION */
	return 0;
out_rtc:
	free_irq(info->irq, info);
out:
	kfree(info);
	return ret;
}

static int __devexit pm860x_rtc_remove(struct platform_device *pdev)
{
	struct pm860x_rtc_info *info = platform_get_drvdata(pdev);

#ifdef VRTC_CALIBRATION
	flush_scheduled_work();
	/* disable measurement */
	pm860x_set_bits(info->i2c, PM8607_MEAS_EN2, MEAS2_VRTC, 0);
#endif	/* VRTC_CALIBRATION */

	platform_set_drvdata(pdev, NULL);
	rtc_device_unregister(info->rtc_dev);
	free_irq(info->irq, info);
	kfree(info);
	return 0;
}

static struct platform_driver pm860x_rtc_driver = {
	.driver		= {
		.name	= "88pm860x-rtc",
		.owner	= THIS_MODULE,
	},
	.probe		= pm860x_rtc_probe,
	.remove		= __devexit_p(pm860x_rtc_remove),
};

module_platform_driver(pm860x_rtc_driver);

MODULE_DESCRIPTION("Marvell 88PM860x RTC driver");
MODULE_AUTHOR("Haojian Zhuang <haojian.zhuang@marvell.com>");
MODULE_LICENSE("GPL");