/*
 * Driver for Epson's RTC module RX-8025 SA/NB
 *
 * Copyright (C) 2009 Wolfgang Grandegger <wg@grandegger.com>
 *
 * Copyright (C) 2005 by Digi International Inc.
 * All rights reserved.
 *
 * Modified by fengjh at rising.com.cn
 * <http://lists.lm-sensors.org/mailman/listinfo/lm-sensors>
 * 2006.11
 *
 * Code cleanup by Sergei Poselenov, <sposelenov@emcraft.com>
 * Converted to new style by Wolfgang Grandegger <wg@grandegger.com>
 * Alarm and periodic interrupt added by Dmitry Rakhchev <rda@emcraft.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/slab.h>
#include <linux/init.h>
#include <linux/bcd.h>
#include <linux/i2c.h>
#include <linux/list.h>
#include <linux/rtc.h>

/* Register definitions */
#define RX8025_REG_SEC		0x00
#define RX8025_REG_MIN		0x01
#define RX8025_REG_HOUR		0x02
#define RX8025_REG_WDAY		0x03
#define RX8025_REG_MDAY		0x04
#define RX8025_REG_MONTH	0x05
#define RX8025_REG_YEAR		0x06
#define RX8025_REG_DIGOFF	0x07
#define RX8025_REG_ALWMIN	0x08
#define RX8025_REG_ALWHOUR	0x09
#define RX8025_REG_ALWWDAY	0x0a
#define RX8025_REG_ALDMIN	0x0b
#define RX8025_REG_ALDHOUR	0x0c
/* 0x0d is reserved */
#define RX8025_REG_CTRL1	0x0e
#define RX8025_REG_CTRL2	0x0f

#define RX8025_BIT_CTRL1_CT	(7 << 0)
/* 1 Hz periodic level irq */
#define RX8025_BIT_CTRL1_CT_1HZ	4
#define RX8025_BIT_CTRL1_TEST	(1 << 3)
#define RX8025_BIT_CTRL1_1224	(1 << 5)
#define RX8025_BIT_CTRL1_DALE	(1 << 6)
#define RX8025_BIT_CTRL1_WALE	(1 << 7)

#define RX8025_BIT_CTRL2_DAFG	(1 << 0)
#define RX8025_BIT_CTRL2_WAFG	(1 << 1)
#define RX8025_BIT_CTRL2_CTFG	(1 << 2)
#define RX8025_BIT_CTRL2_PON	(1 << 4)
#define RX8025_BIT_CTRL2_XST	(1 << 5)
#define RX8025_BIT_CTRL2_VDET	(1 << 6)

/* Clock precision adjustment */
#define RX8025_ADJ_RESOLUTION	3050 /* in ppb */
#define RX8025_ADJ_DATA_MAX	62
#define RX8025_ADJ_DATA_MIN	-62

static const struct i2c_device_id rx8025_id[] = {
	{ "rx8025", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, rx8025_id);

struct rx8025_data {
	struct i2c_client *client;
	struct rtc_device *rtc;
	struct work_struct work;
	u8 ctrl1;
	unsigned exiting:1;
};

static int rx8025_read_reg(struct i2c_client *client, int number, u8 *value)
{
	int ret = i2c_smbus_read_byte_data(client, (number << 4) | 0x08);

	if (ret < 0) {
		dev_err(&client->dev, "Unable to read register #%d\n", number);
		return ret;
	}

	*value = ret;
	return 0;
}

static int rx8025_read_regs(struct i2c_client *client,
			    int number, u8 length, u8 *values)
{
	int ret = i2c_smbus_read_i2c_block_data(client, (number << 4) | 0x08,
						length, values);

	if (ret != length) {
		dev_err(&client->dev, "Unable to read registers #%d..#%d\n",
			number, number + length - 1);
		return ret < 0 ? ret : -EIO;
	}

	return 0;
}

static int rx8025_write_reg(struct i2c_client *client, int number, u8 value)
{
	int ret = i2c_smbus_write_byte_data(client, number << 4, value);

	if (ret)
		dev_err(&client->dev, "Unable to write register #%d\n",
			number);

	return ret;
}

static int rx8025_write_regs(struct i2c_client *client,
			     int number, u8 length, u8 *values)
{
	int ret = i2c_smbus_write_i2c_block_data(client, (number << 4) | 0x08,
						 length, values);

	if (ret)
		dev_err(&client->dev, "Unable to write registers #%d..#%d\n",
			number, number + length - 1);

	return ret;
}

static irqreturn_t rx8025_irq(int irq, void *dev_id)
{
	struct i2c_client *client = dev_id;
	struct rx8025_data *rx8025 = i2c_get_clientdata(client);

	disable_irq_nosync(irq);
	schedule_work(&rx8025->work);
	return IRQ_HANDLED;
}

static void rx8025_work(struct work_struct *work)
{
	struct rx8025_data *rx8025 = container_of(work, struct rx8025_data,
						  work);
	struct i2c_client *client = rx8025->client;
	struct mutex *lock = &rx8025->rtc->ops_lock;
	u8 status;

	mutex_lock(lock);

	if (rx8025_read_reg(client, RX8025_REG_CTRL2, &status))
		goto out;

	if (!(status & RX8025_BIT_CTRL2_XST))
		dev_warn(&client->dev, "Oscillation stop was detected,"
			 "you may have to readjust the clock\n");

	if (status & RX8025_BIT_CTRL2_CTFG) {
		/* periodic */
		status &= ~RX8025_BIT_CTRL2_CTFG;
		local_irq_disable();
		rtc_update_irq(rx8025->rtc, 1, RTC_PF | RTC_IRQF);
		local_irq_enable();
	}

	if (status & RX8025_BIT_CTRL2_DAFG) {
		/* alarm */
		status &= RX8025_BIT_CTRL2_DAFG;
		if (rx8025_write_reg(client, RX8025_REG_CTRL1,
				     rx8025->ctrl1 & ~RX8025_BIT_CTRL1_DALE))
			goto out;
		local_irq_disable();
		rtc_update_irq(rx8025->rtc, 1, RTC_AF | RTC_IRQF);
		local_irq_enable();
	}

	/* acknowledge IRQ */
	rx8025_write_reg(client, RX8025_REG_CTRL2,
			 status | RX8025_BIT_CTRL2_XST);

out:
	if (!rx8025->exiting)
		enable_irq(client->irq);

	mutex_unlock(lock);
}

static int rx8025_get_time(struct device *dev, struct rtc_time *dt)
{
	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
	u8 date[7];
	int err;

	err = rx8025_read_regs(rx8025->client, RX8025_REG_SEC, 7, date);
	if (err)
		return err;

	dev_dbg(dev, "%s: read 0x%02x 0x%02x "
		"0x%02x 0x%02x 0x%02x 0x%02x 0x%02x\n", __func__,
		date[0], date[1], date[2], date[3], date[4],
		date[5], date[6]);

	dt->tm_sec = bcd2bin(date[RX8025_REG_SEC] & 0x7f);
	dt->tm_min = bcd2bin(date[RX8025_REG_MIN] & 0x7f);
	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_1224)
		dt->tm_hour = bcd2bin(date[RX8025_REG_HOUR] & 0x3f);
	else
		dt->tm_hour = bcd2bin(date[RX8025_REG_HOUR] & 0x1f) % 12
			+ (date[RX8025_REG_HOUR] & 0x20 ? 12 : 0);

	dt->tm_mday = bcd2bin(date[RX8025_REG_MDAY] & 0x3f);
	dt->tm_mon = bcd2bin(date[RX8025_REG_MONTH] & 0x1f) - 1;
	dt->tm_year = bcd2bin(date[RX8025_REG_YEAR]);

	if (dt->tm_year < 70)
		dt->tm_year += 100;

	dev_dbg(dev, "%s: date %ds %dm %dh %dmd %dm %dy\n", __func__,
		dt->tm_sec, dt->tm_min, dt->tm_hour,
		dt->tm_mday, dt->tm_mon, dt->tm_year);

	return rtc_valid_tm(dt);
}

static int rx8025_set_time(struct device *dev, struct rtc_time *dt)
{
	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
	u8 date[7];

	/*
	 * BUG: The HW assumes every year that is a multiple of 4 to be a leap
	 * year.  Next time this is wrong is 2100, which will not be a leap
	 * year.
	 */

	/*
	 * Here the read-only bits are written as "0".  I'm not sure if that
	 * is sound.
	 */
	date[RX8025_REG_SEC] = bin2bcd(dt->tm_sec);
	date[RX8025_REG_MIN] = bin2bcd(dt->tm_min);
	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_1224)
		date[RX8025_REG_HOUR] = bin2bcd(dt->tm_hour);
	else
		date[RX8025_REG_HOUR] = (dt->tm_hour >= 12 ? 0x20 : 0)
			| bin2bcd((dt->tm_hour + 11) % 12 + 1);

	date[RX8025_REG_WDAY] = bin2bcd(dt->tm_wday);
	date[RX8025_REG_MDAY] = bin2bcd(dt->tm_mday);
	date[RX8025_REG_MONTH] = bin2bcd(dt->tm_mon + 1);
	date[RX8025_REG_YEAR] = bin2bcd(dt->tm_year % 100);

	dev_dbg(dev,
		"%s: write 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x\n",
		__func__,
		date[0], date[1], date[2], date[3], date[4], date[5], date[6]);

	return rx8025_write_regs(rx8025->client, RX8025_REG_SEC, 7, date);
}

static int rx8025_init_client(struct i2c_client *client, int *need_reset)
{
	struct rx8025_data *rx8025 = i2c_get_clientdata(client);
	u8 ctrl[2], ctrl2;
	int need_clear = 0;
	int err;

	err = rx8025_read_regs(rx8025->client, RX8025_REG_CTRL1, 2, ctrl);
	if (err)
		goto out;

	/* Keep test bit zero ! */
	rx8025->ctrl1 = ctrl[0] & ~RX8025_BIT_CTRL1_TEST;

	if (ctrl[1] & RX8025_BIT_CTRL2_PON) {
		dev_warn(&client->dev, "power-on reset was detected, "
			 "you may have to readjust the clock\n");
		*need_reset = 1;
	}

	if (ctrl[1] & RX8025_BIT_CTRL2_VDET) {
		dev_warn(&client->dev, "a power voltage drop was detected, "
			 "you may have to readjust the clock\n");
		*need_reset = 1;
	}

	if (!(ctrl[1] & RX8025_BIT_CTRL2_XST)) {
		dev_warn(&client->dev, "Oscillation stop was detected,"
			 "you may have to readjust the clock\n");
		*need_reset = 1;
	}

	if (ctrl[1] & (RX8025_BIT_CTRL2_DAFG | RX8025_BIT_CTRL2_WAFG)) {
		dev_warn(&client->dev, "Alarm was detected\n");
		need_clear = 1;
	}

	if (!(ctrl[1] & RX8025_BIT_CTRL2_CTFG))
		need_clear = 1;

	if (*need_reset || need_clear) {
		ctrl2 = ctrl[0];
		ctrl2 &= ~(RX8025_BIT_CTRL2_PON | RX8025_BIT_CTRL2_VDET |
			   RX8025_BIT_CTRL2_CTFG | RX8025_BIT_CTRL2_WAFG |
			   RX8025_BIT_CTRL2_DAFG);
		ctrl2 |= RX8025_BIT_CTRL2_XST;

		err = rx8025_write_reg(client, RX8025_REG_CTRL2, ctrl2);
	}
out:
	return err;
}

/* Alarm support */
static int rx8025_read_alarm(struct device *dev, struct rtc_wkalrm *t)
{
	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
	struct i2c_client *client = rx8025->client;
	u8 ctrl2, ald[2];
	int err;

	if (client->irq <= 0)
		return -EINVAL;

	err = rx8025_read_regs(client, RX8025_REG_ALDMIN, 2, ald);
	if (err)
		return err;

	err = rx8025_read_reg(client, RX8025_REG_CTRL2, &ctrl2);
	if (err)
		return err;

	dev_dbg(dev, "%s: read alarm 0x%02x 0x%02x ctrl2 %02x\n",
		__func__, ald[0], ald[1], ctrl2);

	/* Hardware alarms precision is 1 minute! */
	t->time.tm_sec = 0;
	t->time.tm_min = bcd2bin(ald[0] & 0x7f);
	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_1224)
		t->time.tm_hour = bcd2bin(ald[1] & 0x3f);
	else
		t->time.tm_hour = bcd2bin(ald[1] & 0x1f) % 12
			+ (ald[1] & 0x20 ? 12 : 0);

	t->time.tm_wday = -1;
	t->time.tm_mday = -1;
	t->time.tm_mon = -1;
	t->time.tm_year = -1;

	dev_dbg(dev, "%s: date: %ds %dm %dh %dmd %dm %dy\n",
		__func__,
		t->time.tm_sec, t->time.tm_min, t->time.tm_hour,
		t->time.tm_mday, t->time.tm_mon, t->time.tm_year);
	t->enabled = !!(rx8025->ctrl1 & RX8025_BIT_CTRL1_DALE);
	t->pending = (ctrl2 & RX8025_BIT_CTRL2_DAFG) && t->enabled;

	return err;
}

static int rx8025_set_alarm(struct device *dev, struct rtc_wkalrm *t)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
	u8 ald[2];
	int err;

	if (client->irq <= 0)
		return -EINVAL;

	/* Hardware alarm precision is 1 minute! */
	ald[0] = bin2bcd(t->time.tm_min);
	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_1224)
		ald[1] = bin2bcd(t->time.tm_hour);
	else
		ald[1] = (t->time.tm_hour >= 12 ? 0x20 : 0)
			| bin2bcd((t->time.tm_hour + 11) % 12 + 1);

	dev_dbg(dev, "%s: write 0x%02x 0x%02x\n", __func__, ald[0], ald[1]);

	if (rx8025->ctrl1 & RX8025_BIT_CTRL1_DALE) {
		rx8025->ctrl1 &= ~RX8025_BIT_CTRL1_DALE;
		err = rx8025_write_reg(rx8025->client, RX8025_REG_CTRL1,
				       rx8025->ctrl1);
		if (err)
			return err;
	}
	err = rx8025_write_regs(rx8025->client, RX8025_REG_ALDMIN, 2, ald);
	if (err)
		return err;

	if (t->enabled) {
		rx8025->ctrl1 |= RX8025_BIT_CTRL1_DALE;
		err = rx8025_write_reg(rx8025->client, RX8025_REG_CTRL1,
				       rx8025->ctrl1);
		if (err)
			return err;
	}

	return 0;
}

static int rx8025_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
	struct rx8025_data *rx8025 = dev_get_drvdata(dev);
	u8 ctrl1;
	int err;

	ctrl1 = rx8025->ctrl1;
	if (enabled)
		ctrl1 |= RX8025_BIT_CTRL1_DALE;
	else
		ctrl1 &= ~RX8025_BIT_CTRL1_DALE;

	if (ctrl1 != rx8025->ctrl1) {
		rx8025->ctrl1 = ctrl1;
		err = rx8025_write_reg(rx8025->client, RX8025_REG_CTRL1,
				       rx8025->ctrl1);
		if (err)
			return err;
	}
	return 0;
}

static struct rtc_class_ops rx8025_rtc_ops = {
	.read_time = rx8025_get_time,
	.set_time = rx8025_set_time,
	.read_alarm = rx8025_read_alarm,
	.set_alarm = rx8025_set_alarm,
	.alarm_irq_enable = rx8025_alarm_irq_enable,
};

/*
 * Clock precision adjustment support
 *
 * According to the RX8025 SA/NB application manual the frequency and
 * temperature characteristics can be approximated using the following
 * equation:
 *
 *   df = a * (ut - t)**2
 *
 *   df: Frequency deviation in any temperature
 *   a : Coefficient = (-35 +-5) * 10**-9
 *   ut: Ultimate temperature in degree = +25 +-5 degree
 *   t : Any temperature in degree
 *
 * Note that the clock adjustment in ppb must be entered (which is
 * the negative value of the deviation).
 */
static int rx8025_get_clock_adjust(struct device *dev, int *adj)
{
	struct i2c_client *client = to_i2c_client(dev);
	u8 digoff;
	int err;

	err = rx8025_read_reg(client, RX8025_REG_DIGOFF, &digoff);
	if (err)
		return err;

	*adj = digoff >= 64 ? digoff - 128 : digoff;
	if (*adj > 0)
		(*adj)--;
	*adj *= -RX8025_ADJ_RESOLUTION;

	return 0;
}

static int rx8025_set_clock_adjust(struct device *dev, int adj)
{
	struct i2c_client *client = to_i2c_client(dev);
	u8 digoff;
	int err;

	adj /= -RX8025_ADJ_RESOLUTION;
	if (adj > RX8025_ADJ_DATA_MAX)
		adj = RX8025_ADJ_DATA_MAX;
	else if (adj < RX8025_ADJ_DATA_MIN)
		adj = RX8025_ADJ_DATA_MIN;
	else if (adj > 0)
		adj++;
	else if (adj < 0)
		adj += 128;
	digoff = adj;

	err = rx8025_write_reg(client, RX8025_REG_DIGOFF, digoff);
	if (err)
		return err;

	dev_dbg(dev, "%s: write 0x%02x\n", __func__, digoff);

	return 0;
}

static ssize_t rx8025_sysfs_show_clock_adjust(struct device *dev,
					      struct device_attribute *attr,
					      char *buf)
{
	int err, adj;

	err = rx8025_get_clock_adjust(dev, &adj);
	if (err)
		return err;

	return sprintf(buf, "%d\n", adj);
}

static ssize_t rx8025_sysfs_store_clock_adjust(struct device *dev,
					       struct device_attribute *attr,
					       const char *buf, size_t count)
{
	int adj, err;

	if (sscanf(buf, "%i", &adj) != 1)
		return -EINVAL;

	err = rx8025_set_clock_adjust(dev, adj);

	return err ? err : count;
}

static DEVICE_ATTR(clock_adjust_ppb, S_IRUGO | S_IWUSR,
		   rx8025_sysfs_show_clock_adjust,
		   rx8025_sysfs_store_clock_adjust);

static int rx8025_sysfs_register(struct device *dev)
{
	return device_create_file(dev, &dev_attr_clock_adjust_ppb);
}

static void rx8025_sysfs_unregister(struct device *dev)
{
	device_remove_file(dev, &dev_attr_clock_adjust_ppb);
}

static int rx8025_probe(struct i2c_client *client,
			const struct i2c_device_id *id)
{
	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
	struct rx8025_data *rx8025;
	int err, need_reset = 0;

	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA
				     | I2C_FUNC_SMBUS_I2C_BLOCK)) {
		dev_err(&adapter->dev,
			"doesn't support required functionality\n");
		err = -EIO;
		goto errout;
	}

	rx8025 = devm_kzalloc(&client->dev, sizeof(*rx8025), GFP_KERNEL);
	if (!rx8025) {
		dev_err(&adapter->dev, "failed to alloc memory\n");
		err = -ENOMEM;
		goto errout;
	}

	rx8025->client = client;
	i2c_set_clientdata(client, rx8025);
	INIT_WORK(&rx8025->work, rx8025_work);

	err = rx8025_init_client(client, &need_reset);
	if (err)
		goto errout;

	if (need_reset) {
		struct rtc_time tm;
		dev_info(&client->dev,
			 "bad conditions detected, resetting date\n");
		rtc_time_to_tm(0, &tm);	/* 1970/1/1 */
		rx8025_set_time(&client->dev, &tm);
	}

	rx8025->rtc = devm_rtc_device_register(&client->dev, client->name,
					  &rx8025_rtc_ops, THIS_MODULE);
	if (IS_ERR(rx8025->rtc)) {
		err = PTR_ERR(rx8025->rtc);
		dev_err(&client->dev, "unable to register the class device\n");
		goto errout;
	}

	if (client->irq > 0) {
		dev_info(&client->dev, "IRQ %d supplied\n", client->irq);
		err = request_irq(client->irq, rx8025_irq,
				  0, "rx8025", client);
		if (err) {
			dev_err(&client->dev, "unable to request IRQ\n");
			goto errout;
		}
	}

	rx8025->rtc->irq_freq = 1;
	rx8025->rtc->max_user_freq = 1;

	err = rx8025_sysfs_register(&client->dev);
	if (err)
		goto errout_irq;

	return 0;

errout_irq:
	if (client->irq > 0)
		free_irq(client->irq, client);

errout:
	dev_err(&adapter->dev, "probing for rx8025 failed\n");
	return err;
}

static int rx8025_remove(struct i2c_client *client)
{
	struct rx8025_data *rx8025 = i2c_get_clientdata(client);
	struct mutex *lock = &rx8025->rtc->ops_lock;

	if (client->irq > 0) {
		mutex_lock(lock);
		rx8025->exiting = 1;
		mutex_unlock(lock);

		free_irq(client->irq, client);
		cancel_work_sync(&rx8025->work);
	}

	rx8025_sysfs_unregister(&client->dev);
	return 0;
}

static struct i2c_driver rx8025_driver = {
	.driver = {
		.name = "rtc-rx8025",
		.owner = THIS_MODULE,
	},
	.probe		= rx8025_probe,
	.remove		= rx8025_remove,
	.id_table	= rx8025_id,
};

module_i2c_driver(rx8025_driver);

MODULE_AUTHOR("Wolfgang Grandegger <wg@grandegger.com>");
MODULE_DESCRIPTION("RX-8025 SA/NB RTC driver");
MODULE_LICENSE("GPL");