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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: Martyn Welch <martyn.welch@gefanuc.com> Signed-off-by: Alessandro Zummo <a.zummo@towertech.it> Cc: David Brownell <david-b@pacbell.net> Cc: Jean Delvare <khali@linux-fr.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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/* | ||
* 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 | ||
*/ | ||
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#include <linux/module.h> | ||
#include <linux/i2c.h> | ||
#include <linux/bcd.h> | ||
#include <linux/rtc.h> | ||
#include <linux/log2.h> | ||
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#define DRV_VERSION "0.1" | ||
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#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 */ | ||
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/* 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 */ | ||
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/* 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 */ | ||
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static struct i2c_driver rx8581_driver; | ||
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/* | ||
* 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; | ||
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/* 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; | ||
} | ||
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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; | ||
} | ||
} | ||
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/* 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; | ||
} | ||
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/* 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); | ||
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if (data & RX8581_FLAG_VLF) | ||
dev_info(&client->dev, | ||
"low voltage detected, date/time is not reliable.\n"); | ||
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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]); | ||
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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 */ | ||
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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); | ||
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err = rtc_valid_tm(tm); | ||
if (err < 0) | ||
dev_err(&client->dev, "retrieved date/time is not valid.\n"); | ||
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return err; | ||
} | ||
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static int rx8581_set_datetime(struct i2c_client *client, struct rtc_time *tm) | ||
{ | ||
int data, err; | ||
unsigned char buf[7]; | ||
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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); | ||
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/* 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); | ||
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buf[RX8581_REG_DM] = bin2bcd(tm->tm_mday); | ||
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/* month, 1 - 12 */ | ||
buf[RX8581_REG_MO] = bin2bcd(tm->tm_mon + 1); | ||
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/* year and century */ | ||
buf[RX8581_REG_YR] = bin2bcd(tm->tm_year % 100); | ||
buf[RX8581_REG_DW] = (0x1 << tm->tm_wday); | ||
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/* 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; | ||
} | ||
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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; | ||
} | ||
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/* 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; | ||
} | ||
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/* 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; | ||
} | ||
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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; | ||
} | ||
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return 0; | ||
} | ||
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static int rx8581_rtc_read_time(struct device *dev, struct rtc_time *tm) | ||
{ | ||
return rx8581_get_datetime(to_i2c_client(dev), tm); | ||
} | ||
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static int rx8581_rtc_set_time(struct device *dev, struct rtc_time *tm) | ||
{ | ||
return rx8581_set_datetime(to_i2c_client(dev), tm); | ||
} | ||
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static const struct rtc_class_ops rx8581_rtc_ops = { | ||
.read_time = rx8581_rtc_read_time, | ||
.set_time = rx8581_rtc_set_time, | ||
}; | ||
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static int __devinit rx8581_probe(struct i2c_client *client, | ||
const struct i2c_device_id *id) | ||
{ | ||
struct rtc_device *rtc; | ||
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dev_dbg(&client->dev, "%s\n", __func__); | ||
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if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) | ||
return -ENODEV; | ||
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dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n"); | ||
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rtc = rtc_device_register(rx8581_driver.driver.name, | ||
&client->dev, &rx8581_rtc_ops, THIS_MODULE); | ||
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if (IS_ERR(rtc)) | ||
return PTR_ERR(rtc); | ||
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i2c_set_clientdata(client, rtc); | ||
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return 0; | ||
} | ||
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static int __devexit rx8581_remove(struct i2c_client *client) | ||
{ | ||
struct rtc_device *rtc = i2c_get_clientdata(client); | ||
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rtc_device_unregister(rtc); | ||
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return 0; | ||
} | ||
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static const struct i2c_device_id rx8581_id[] = { | ||
{ "rx8581", 0 }, | ||
{ } | ||
}; | ||
MODULE_DEVICE_TABLE(i2c, rx8581_id); | ||
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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, | ||
}; | ||
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static int __init rx8581_init(void) | ||
{ | ||
return i2c_add_driver(&rx8581_driver); | ||
} | ||
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static void __exit rx8581_exit(void) | ||
{ | ||
i2c_del_driver(&rx8581_driver); | ||
} | ||
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MODULE_AUTHOR("Martyn Welch <martyn.welch@gefanuc.com>"); | ||
MODULE_DESCRIPTION("Epson RX-8581 RTC driver"); | ||
MODULE_LICENSE("GPL"); | ||
MODULE_VERSION(DRV_VERSION); | ||
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module_init(rx8581_init); | ||
module_exit(rx8581_exit); |