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linux/drivers/rtc/rtc-rx8581.c
Rudolf Marek 2884fce165 drivers/rtc/rtc-rx8581.c: fix setdatetime 
Fix the logic while writing new date/time to the chip.  The driver
incorrectly wrote back register values to different registers and even
with wrong mask.  The patch adds clearing of the VLF register, which
should be cleared if all date/time values are set.

Signed-off-by: Rudolf Marek <rudolf.marek@sysgo.com>
Acked-by: Wan ZongShun <mcuos.com@gmail.com>
Cc: Martyn Welch <martyn.welch@gefanuc.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-07-27 14:32:06 -07:00

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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 __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@ge.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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