Commit a7fa9851 authored by Martyn Welch's avatar Martyn Welch Committed by Linus Torvalds
Browse files

rtc: basic implementation of Epson RX-8581 I2C Real Time Clock 



Provide the basic "get" and "set" functionality for the Epson RX-8581 I2C
RTC.  It currently does not support the RTC's Alarm or Fixed-cycle timer.

[akpm@linux-foundation.org: need log2.h for ilog2(), remove unneeded initialisation]
Signed-off-by: default avatarMartyn Welch <martyn.welch@gefanuc.com>
Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 077eaf5b

drivers/rtc/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -277,6 +277,14 @@ config RTC_DRV_FM3130 
	  This driver can also be built as a module. If so the module

	  will be called rtc-fm3130.



config RTC_DRV_RX8581

	tristate "Epson RX-8581"

	help

	  If you say yes here you will get support for the Epson RX-8581.



	  This driver can also be built as a module. If so the module

	  will be called rtc-rx8581.



endif # I2C



comment "SPI RTC drivers"

drivers/rtc/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -57,6 +57,7 @@ obj-$(CONFIG_RTC_DRV_R9701) += rtc-r9701.o 
obj-$(CONFIG_RTC_DRV_RS5C313)	+= rtc-rs5c313.o

obj-$(CONFIG_RTC_DRV_RS5C348)	+= rtc-rs5c348.o

obj-$(CONFIG_RTC_DRV_RS5C372)	+= rtc-rs5c372.o

obj-$(CONFIG_RTC_DRV_RX8581)	+= rtc-rx8581.o

obj-$(CONFIG_RTC_DRV_S35390A)	+= rtc-s35390a.o

obj-$(CONFIG_RTC_DRV_S3C)	+= rtc-s3c.o

obj-$(CONFIG_RTC_DRV_SA1100)	+= rtc-sa1100.o

drivers/rtc/rtc-rx8581.c

0 → 100644
+281 −0
Original line number Diff line number Diff line 
/*

 * An I2C driver for the Epson RX8581 RTC

 *

 * Author: Martyn Welch <martyn.welch@gefanuc.com>

 * Copyright 2008 GE Fanuc Intelligent Platforms Embedded Systems, Inc.

 *

 * 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.

 *

 * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC)

 * Copyright 2005-06 Tower Technologies

 */



#include <linux/module.h>

#include <linux/i2c.h>

#include <linux/bcd.h>

#include <linux/rtc.h>

#include <linux/log2.h>



#define DRV_VERSION "0.1"



#define RX8581_REG_SC		0x00 /* Second in BCD */

#define RX8581_REG_MN		0x01 /* Minute in BCD */

#define RX8581_REG_HR		0x02 /* Hour in BCD */

#define RX8581_REG_DW		0x03 /* Day of Week */

#define RX8581_REG_DM		0x04 /* Day of Month in BCD */

#define RX8581_REG_MO		0x05 /* Month in BCD */

#define RX8581_REG_YR		0x06 /* Year in BCD */

#define RX8581_REG_RAM		0x07 /* RAM */

#define RX8581_REG_AMN		0x08 /* Alarm Min in BCD*/

#define RX8581_REG_AHR		0x09 /* Alarm Hour in BCD */

#define RX8581_REG_ADM		0x0A

#define RX8581_REG_ADW		0x0A

#define RX8581_REG_TMR0		0x0B

#define RX8581_REG_TMR1		0x0C

#define RX8581_REG_EXT		0x0D /* Extension Register */

#define RX8581_REG_FLAG		0x0E /* Flag Register */

#define RX8581_REG_CTRL		0x0F /* Control Register */





/* Flag Register bit definitions */

#define RX8581_FLAG_UF		0x20 /* Update */

#define RX8581_FLAG_TF		0x10 /* Timer */

#define RX8581_FLAG_AF		0x08 /* Alarm */

#define RX8581_FLAG_VLF		0x02 /* Voltage Low */



/* Control Register bit definitions */

#define RX8581_CTRL_UIE		0x20 /* Update Interrupt Enable */

#define RX8581_CTRL_TIE		0x10 /* Timer Interrupt Enable */

#define RX8581_CTRL_AIE		0x08 /* Alarm Interrupt Enable */

#define RX8581_CTRL_STOP	0x02 /* STOP bit */

#define RX8581_CTRL_RESET	0x01 /* RESET bit */



static struct i2c_driver rx8581_driver;



/*

 * In the routines that deal directly with the rx8581 hardware, we use

 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.

 */

static int rx8581_get_datetime(struct i2c_client *client, struct rtc_time *tm)

{

	unsigned char date[7];

	int data, err;



	/* First we ensure that the "update flag" is not set, we read the

	 * time and date then re-read the "update flag". If the update flag

	 * has been set, we know that the time has changed during the read so

	 * we repeat the whole process again.

	 */

	data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);

	if (data < 0) {

		dev_err(&client->dev, "Unable to read device flags\n");

		return -EIO;

	}



	do {

		/* If update flag set, clear it */

		if (data & RX8581_FLAG_UF) {

			err = i2c_smbus_write_byte_data(client,

				RX8581_REG_FLAG, (data & ~RX8581_FLAG_UF));

			if (err != 0) {

				dev_err(&client->dev, "Unable to write device "

					"flags\n");

				return -EIO;

			}

		}



		/* Now read time and date */

		err = i2c_smbus_read_i2c_block_data(client, RX8581_REG_SC,

			7, date);

		if (err < 0) {

			dev_err(&client->dev, "Unable to read date\n");

			return -EIO;

		}



		/* Check flag register */

		data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);

		if (data < 0) {

			dev_err(&client->dev, "Unable to read device flags\n");

			return -EIO;

		}

	} while (data & RX8581_FLAG_UF);



	if (data & RX8581_FLAG_VLF)

		dev_info(&client->dev,

			"low voltage detected, date/time is not reliable.\n");



	dev_dbg(&client->dev,

		"%s: raw data is sec=%02x, min=%02x, hr=%02x, "

		"wday=%02x, mday=%02x, mon=%02x, year=%02x\n",

		__func__,

		date[0], date[1], date[2], date[3], date[4], date[5], date[6]);



	tm->tm_sec = bcd2bin(date[RX8581_REG_SC] & 0x7F);

	tm->tm_min = bcd2bin(date[RX8581_REG_MN] & 0x7F);

	tm->tm_hour = bcd2bin(date[RX8581_REG_HR] & 0x3F); /* rtc hr 0-23 */

	tm->tm_wday = ilog2(date[RX8581_REG_DW] & 0x7F);

	tm->tm_mday = bcd2bin(date[RX8581_REG_DM] & 0x3F);

	tm->tm_mon = bcd2bin(date[RX8581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */

	tm->tm_year = bcd2bin(date[RX8581_REG_YR]);

	if (tm->tm_year < 70)

		tm->tm_year += 100;	/* assume we are in 1970...2069 */





	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "

		"mday=%d, mon=%d, year=%d, wday=%d\n",

		__func__,

		tm->tm_sec, tm->tm_min, tm->tm_hour,

		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);



	err = rtc_valid_tm(tm);

	if (err < 0)

		dev_err(&client->dev, "retrieved date/time is not valid.\n");



	return err;

}



static int rx8581_set_datetime(struct i2c_client *client, struct rtc_time *tm)

{

	int data, err;

	unsigned char buf[7];



	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "

		"mday=%d, mon=%d, year=%d, wday=%d\n",

		__func__,

		tm->tm_sec, tm->tm_min, tm->tm_hour,

		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);



	/* hours, minutes and seconds */

	buf[RX8581_REG_SC] = bin2bcd(tm->tm_sec);

	buf[RX8581_REG_MN] = bin2bcd(tm->tm_min);

	buf[RX8581_REG_HR] = bin2bcd(tm->tm_hour);



	buf[RX8581_REG_DM] = bin2bcd(tm->tm_mday);



	/* month, 1 - 12 */

	buf[RX8581_REG_MO] = bin2bcd(tm->tm_mon + 1);



	/* year and century */

	buf[RX8581_REG_YR] = bin2bcd(tm->tm_year % 100);

	buf[RX8581_REG_DW] = (0x1 << tm->tm_wday);



	/* Stop the clock */

	data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL);

	if (data < 0) {

		dev_err(&client->dev, "Unable to read control register\n");

		return -EIO;

	}



	err = i2c_smbus_write_byte_data(client, RX8581_REG_FLAG,

		(data | RX8581_CTRL_STOP));

	if (err < 0) {

		dev_err(&client->dev, "Unable to write control register\n");

		return -EIO;

	}



	/* write register's data */

	err = i2c_smbus_write_i2c_block_data(client, RX8581_REG_SC, 7, buf);

	if (err < 0) {

		dev_err(&client->dev, "Unable to write to date registers\n");

		return -EIO;

	}



	/* Restart the clock */

	data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL);

	if (data < 0) {

		dev_err(&client->dev, "Unable to read control register\n");

		return -EIO;

	}



	err = i2c_smbus_write_byte_data(client, RX8581_REG_FLAG,

		(data | ~(RX8581_CTRL_STOP)));

	if (err != 0) {

		dev_err(&client->dev, "Unable to write control register\n");

		return -EIO;

	}



	return 0;

}



static int rx8581_rtc_read_time(struct device *dev, struct rtc_time *tm)

{

	return rx8581_get_datetime(to_i2c_client(dev), tm);

}



static int rx8581_rtc_set_time(struct device *dev, struct rtc_time *tm)

{

	return rx8581_set_datetime(to_i2c_client(dev), tm);

}



static const struct rtc_class_ops rx8581_rtc_ops = {

	.read_time	= rx8581_rtc_read_time,

	.set_time	= rx8581_rtc_set_time,

};



static int __devinit rx8581_probe(struct i2c_client *client,

				const struct i2c_device_id *id)

{

	struct rtc_device *rtc;



	dev_dbg(&client->dev, "%s\n", __func__);



	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))

		return -ENODEV;



	dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");



	rtc = rtc_device_register(rx8581_driver.driver.name,

				&client->dev, &rx8581_rtc_ops, THIS_MODULE);



	if (IS_ERR(rtc))

		return PTR_ERR(rtc);



	i2c_set_clientdata(client, rtc);



	return 0;

}



static int __devexit rx8581_remove(struct i2c_client *client)

{

	struct rtc_device *rtc = i2c_get_clientdata(client);



	rtc_device_unregister(rtc);



	return 0;

}



static const struct i2c_device_id rx8581_id[] = {

	{ "rx8581", 0 },

	{ }

};

MODULE_DEVICE_TABLE(i2c, rx8581_id);



static struct i2c_driver rx8581_driver = {

	.driver		= {

		.name	= "rtc-rx8581",

		.owner	= THIS_MODULE,

	},

	.probe		= rx8581_probe,

	.remove		= __devexit_p(rx8581_remove),

	.id_table	= rx8581_id,

};



static int __init rx8581_init(void)

{

	return i2c_add_driver(&rx8581_driver);

}



static void __exit rx8581_exit(void)

{

	i2c_del_driver(&rx8581_driver);

}



MODULE_AUTHOR("Martyn Welch <martyn.welch@gefanuc.com>");

MODULE_DESCRIPTION("Epson RX-8581 RTC driver");

MODULE_LICENSE("GPL");

MODULE_VERSION(DRV_VERSION);



module_init(rx8581_init);

module_exit(rx8581_exit);

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