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/*
* An I2C driver for the Epson RX8581 RTC
*
* Author: Martyn Welch <martyn.welch@ge.com>
* Copyright 2008 GE 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_CTRL,
(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;
}
/* get VLF and clear it */
data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
if (data < 0) {
dev_err(&client->dev, "Unable to read flag register\n");
return -EIO;
}
err = i2c_smbus_write_byte_data(client, RX8581_REG_FLAG,
(data & ~(RX8581_FLAG_VLF)));
if (err != 0) {
dev_err(&client->dev, "Unable to write flag register\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_CTRL,
(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 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 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 = rx8581_remove,
.id_table = rx8581_id,
};
module_i2c_driver(rx8581_driver);
MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
MODULE_DESCRIPTION("Epson RX-8581 RTC driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);
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