/*
 * Copyright 2010 Freescale Semiconductor, Inc.
 *
 * Author:	Priyanka Jain <Priyanka.Jain@freescale.com>
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

/*
 * This file provides Date & Time support (no alarms) for PT7C4338 chip.
 *
 * This file is based on drivers/rtc/rtc-ds1307.c
 *
 * PT7C4338 chip is manufactured by Pericom Technology Inc.
 * It is a serial real-time clock which provides
 * 1)Low-power clock/calendar.
 * 2)Programmable square-wave output.
 * It has 56 bytes of nonvolatile RAM.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/rtc.h>
#include <linux/bcd.h>

/* RTC register addresses */
#define PT7C4338_REG_SECONDS          0x00
#define PT7C4338_REG_MINUTES          0x01
#define PT7C4338_REG_HOURS            0x02
#define PT7C4338_REG_AMPM             0x02
#define PT7C4338_REG_DAY              0x03
#define PT7C4338_REG_DATE             0x04
#define PT7C4338_REG_MONTH            0x05
#define PT7C4338_REG_YEAR             0x06
#define PT7C4338_REG_CTRL_STAT        0x07

/* RTC second register address bit */
#define PT7C4338_SEC_BIT_CH           0x80	/*Clock Halt (in Register 0)*/

/* RTC control and status register bits */
#define PT7C4338_CTRL_STAT_BIT_RS0    0x1	/*Rate select 0*/
#define PT7C4338_CTRL_STAT_BIT_RS1    0x2	/*Rate select 1*/
#define PT7C4338_CTRL_STAT_BIT_SQWE   0x10	/*Square Wave Enable*/
#define PT7C4338_CTRL_STAT_BIT_OSF    0x20	/*Oscillator Stop Flag*/
#define PT7C4338_CTRL_STAT_BIT_OUT    0x80	/*Output Level Control*/

static const struct i2c_device_id pt7c4338_id[] = {
	{ "pt7c4338", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, pt7c4338_id);

struct pt7c4338{
	struct i2c_client *client;
	struct rtc_device *rtc;
};

static int pt7c4338_read_time(struct device *dev, struct rtc_time *time)
{
	struct i2c_client *client = to_i2c_client(dev);
	int ret;
	u8 buf[7];
	u8 year, month, day, hour, minute, second;
	u8 week, twelve_hr, am_pm;

	ret = i2c_smbus_read_i2c_block_data(client,
			PT7C4338_REG_SECONDS, 7, buf);
	if (ret < 0)
		return ret;
	if (ret < 7)
		return -EIO;

	second = buf[0];
	minute = buf[1];
	hour = buf[2];
	week = buf[3];
	day = buf[4];
	month = buf[5];
	year = buf[6];

	/* Extract additional information for AM/PM */
	twelve_hr = hour & 0x40;
	am_pm = hour & 0x20;

	/* Write to rtc_time structure */
	time->tm_sec = bcd2bin(second & 0x7f);
	time->tm_min = bcd2bin(minute & 0x7f);
	if (twelve_hr) {
		/* Convert to 24 hr */
		if (am_pm)
			time->tm_hour = bcd2bin(hour & 0x10) + 12;
		else
			time->tm_hour = bcd2bin(hour & 0xBF);
	} else {
		time->tm_hour = bcd2bin(hour);
	}

	time->tm_wday = bcd2bin(week & 0x07) - 1;
	time->tm_mday = bcd2bin(day & 0x3f);
	time->tm_mon = bcd2bin(month & 0x1F) - 1;
	/* assume 20YY not 19YY */
	time->tm_year = bcd2bin(year) + 100;

	return 0;
}

static int pt7c4338_set_time(struct device *dev, struct rtc_time *time)
{
	struct i2c_client *client = to_i2c_client(dev);
	u8 buf[7];

	/* Extract time from rtc_time and load into pt7c4338*/
	buf[0] = bin2bcd(time->tm_sec);
	buf[1] = bin2bcd(time->tm_min);
	buf[2] = bin2bcd(time->tm_hour);
	buf[3] = bin2bcd(time->tm_wday + 1); /* Day of the week */
	buf[4] = bin2bcd(time->tm_mday); /* Date */
	buf[5] = bin2bcd(time->tm_mon + 1);

	/* assume 20YY not 19YY */
	if (time->tm_year >= 100)
		buf[6] = bin2bcd(time->tm_year - 100);
	else
		buf[6] = bin2bcd(time->tm_year);

	return i2c_smbus_write_i2c_block_data(client,
					PT7C4338_REG_SECONDS, 7, buf);
}

static const struct rtc_class_ops pt7c4338_rtc_ops = {
	.read_time = pt7c4338_read_time,
	.set_time = pt7c4338_set_time,
};

static int pt7c4338_probe(struct i2c_client *client,
		const struct i2c_device_id *id)
{
	struct pt7c4338 *pt7c4338;
	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
	int ret;

	pt7c4338 = kzalloc(sizeof(struct pt7c4338), GFP_KERNEL);
	if (!pt7c4338)
		return -ENOMEM;

	pt7c4338->client = client;
	i2c_set_clientdata(client, pt7c4338);
	pt7c4338->rtc = rtc_device_register(client->name, &client->dev,
					&pt7c4338_rtc_ops, THIS_MODULE);
	if (IS_ERR(pt7c4338->rtc)) {
		ret = PTR_ERR(pt7c4338->rtc);
		dev_err(&client->dev, "unable to register the class device\n");
		goto out_free;
	}

	return 0;
out_free:
	i2c_set_clientdata(client, NULL);
	kfree(pt7c4338);
	return ret;
}

static int pt7c4338_remove(struct i2c_client *client)
{
	struct pt7c4338 *pt7c4338 = i2c_get_clientdata(client);

	rtc_device_unregister(pt7c4338->rtc);
	i2c_set_clientdata(client, NULL);
	kfree(pt7c4338);
	return 0;
}

static struct i2c_driver pt7c4338_driver = {
	.driver = {
		.name = "rtc-pt7c4338",
		.owner = THIS_MODULE,
	},
	.probe = pt7c4338_probe,
	.remove = pt7c4338_remove,
	.id_table = pt7c4338_id,
};

static int __init pt7c4338_init(void)
{
	return i2c_add_driver(&pt7c4338_driver);
}

static void __exit pt7c4338_exit(void)
{
	i2c_del_driver(&pt7c4338_driver);
}

module_init(pt7c4338_init);
module_exit(pt7c4338_exit);

MODULE_AUTHOR("Priyanka Jain <Priyanka.Jain@freescale.com>");
MODULE_DESCRIPTION("pericom Technology Inc. PT7C4338 RTC Driver");
MODULE_LICENSE("GPL");