/* drivers/rtc/rtc-rx4581.c
*
* written by Torben Hohn <torbenh@linutronix.de>
*
* Based on:
* drivers/rtc/rtc-max6902.c
*
* Copyright (C) 2006 8D Technologies inc.
* Copyright (C) 2004 Compulab Ltd.
*
* 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.
*
* Driver for MAX6902 spi RTC
*
* and based on:
* drivers/rtc/rtc-rx8581.c
*
* 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/kernel.h>
#include <linux/platform_device.h>
#include <linux/init.h>
#include <linux/rtc.h>
#include <linux/spi/spi.h>
#include <linux/bcd.h>
#define RX4581_REG_SC 0x00 /* Second in BCD */
#define RX4581_REG_MN 0x01 /* Minute in BCD */
#define RX4581_REG_HR 0x02 /* Hour in BCD */
#define RX4581_REG_DW 0x03 /* Day of Week */
#define RX4581_REG_DM 0x04 /* Day of Month in BCD */
#define RX4581_REG_MO 0x05 /* Month in BCD */
#define RX4581_REG_YR 0x06 /* Year in BCD */
#define RX4581_REG_RAM 0x07 /* RAM */
#define RX4581_REG_AMN 0x08 /* Alarm Min in BCD*/
#define RX4581_REG_AHR 0x09 /* Alarm Hour in BCD */
#define RX4581_REG_ADM 0x0A
#define RX4581_REG_ADW 0x0A
#define RX4581_REG_TMR0 0x0B
#define RX4581_REG_TMR1 0x0C
#define RX4581_REG_EXT 0x0D /* Extension Register */
#define RX4581_REG_FLAG 0x0E /* Flag Register */
#define RX4581_REG_CTRL 0x0F /* Control Register */
/* Flag Register bit definitions */
#define RX4581_FLAG_UF 0x20 /* Update */
#define RX4581_FLAG_TF 0x10 /* Timer */
#define RX4581_FLAG_AF 0x08 /* Alarm */
#define RX4581_FLAG_VLF 0x02 /* Voltage Low */
/* Control Register bit definitions */
#define RX4581_CTRL_UIE 0x20 /* Update Interrupt Enable */
#define RX4581_CTRL_TIE 0x10 /* Timer Interrupt Enable */
#define RX4581_CTRL_AIE 0x08 /* Alarm Interrupt Enable */
#define RX4581_CTRL_STOP 0x02 /* STOP bit */
#define RX4581_CTRL_RESET 0x01 /* RESET bit */
static int rx4581_set_reg(struct device *dev, unsigned char address,
unsigned char data)
{
struct spi_device *spi = to_spi_device(dev);
unsigned char buf[2];
/* high nibble must be '0' to write */
buf[0] = address & 0x0f;
buf[1] = data;
return spi_write_then_read(spi, buf, 2, NULL, 0);
}
static int rx4581_get_reg(struct device *dev, unsigned char address,
unsigned char *data)
{
struct spi_device *spi = to_spi_device(dev);
/* Set MSB to indicate read */
*data = address | 0x80;
return spi_write_then_read(spi, data, 1, data, 1);
}
/*
* 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 rx4581_get_datetime(struct device *dev, struct rtc_time *tm)
{
struct spi_device *spi = to_spi_device(dev);
unsigned char date[7];
unsigned char data;
int 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.
*/
err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
if (err != 0) {
dev_err(dev, "Unable to read device flags\n");
return -EIO;
}
do {
/* If update flag set, clear it */
if (data & RX4581_FLAG_UF) {
err = rx4581_set_reg(dev,
RX4581_REG_FLAG, (data & ~RX4581_FLAG_UF));
if (err != 0) {
dev_err(dev, "Unable to write device "
"flags\n");
return -EIO;
}
}
/* Now read time and date */
date[0] = 0x80;
err = spi_write_then_read(spi, date, 1, date, 7);
if (err < 0) {
dev_err(dev, "Unable to read date\n");
return -EIO;
}
/* Check flag register */
err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
if (err != 0) {
dev_err(dev, "Unable to read device flags\n");
return -EIO;
}
} while (data & RX4581_FLAG_UF);
if (data & RX4581_FLAG_VLF)
dev_info(dev,
"low voltage detected, date/time is not reliable.\n");
dev_dbg(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[RX4581_REG_SC] & 0x7F);
tm->tm_min = bcd2bin(date[RX4581_REG_MN] & 0x7F);
tm->tm_hour = bcd2bin(date[RX4581_REG_HR] & 0x3F); /* rtc hr 0-23 */
tm->tm_wday = ilog2(date[RX4581_REG_DW] & 0x7F);
tm->tm_mday = bcd2bin(date[RX4581_REG_DM] & 0x3F);
tm->tm_mon = bcd2bin(date[RX4581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
tm->tm_year = bcd2bin(date[RX4581_REG_YR]);
if (tm->tm_year < 70)
tm->tm_year += 100; /* assume we are in 1970...2069 */
dev_dbg(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(dev, "retrieved date/time is not valid.\n");
return err;
}
static int rx4581_set_datetime(struct device *dev, struct rtc_time *tm)
{
struct spi_device *spi = to_spi_device(dev);
int err;
unsigned char buf[8], data;
dev_dbg(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);
buf[0] = 0x00;
/* hours, minutes and seconds */
buf[RX4581_REG_SC+1] = bin2bcd(tm->tm_sec);
buf[RX4581_REG_MN+1] = bin2bcd(tm->tm_min);
buf[RX4581_REG_HR+1] = bin2bcd(tm->tm_hour);
buf[RX4581_REG_DM+1] = bin2bcd(tm->tm_mday);
/* month, 1 - 12 */
buf[RX4581_REG_MO+1] = bin2bcd(tm->tm_mon + 1);
/* year and century */
buf[RX4581_REG_YR+1] = bin2bcd(tm->tm_year % 100);
buf[RX4581_REG_DW+1] = (0x1 << tm->tm_wday);
/* Stop the clock */
err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
if (err != 0) {
dev_err(dev, "Unable to read control register\n");
return -EIO;
}
err = rx4581_set_reg(dev, RX4581_REG_CTRL,
(data | RX4581_CTRL_STOP));
if (err != 0) {
dev_err(dev, "Unable to write control register\n");
return -EIO;
}
/* write register's data */
err = spi_write_then_read(spi, buf, 8, NULL, 0);
if (err != 0) {
dev_err(dev, "Unable to write to date registers\n");
return -EIO;
}
/* get VLF and clear it */
err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
if (err != 0) {
dev_err(dev, "Unable to read flag register\n");
return -EIO;
}
err = rx4581_set_reg(dev, RX4581_REG_FLAG,
(data & ~(RX4581_FLAG_VLF)));
if (err != 0) {
dev_err(dev, "Unable to write flag register\n");
return -EIO;
}
/* Restart the clock */
err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
if (err != 0) {
dev_err(dev, "Unable to read control register\n");
return -EIO;
}
err = rx4581_set_reg(dev, RX4581_REG_CTRL,
(data & ~(RX4581_CTRL_STOP)));
if (err != 0) {
dev_err(dev, "Unable to write control register\n");
return -EIO;
}
return 0;
}
static const struct rtc_class_ops rx4581_rtc_ops = {
.read_time = rx4581_get_datetime,
.set_time = rx4581_set_datetime,
};
static int rx4581_probe(struct spi_device *spi)
{
struct rtc_device *rtc;
unsigned char tmp;
int res;
res = rx4581_get_reg(&spi->dev, RX4581_REG_SC, &tmp);
if (res != 0)
return res;
rtc = devm_rtc_device_register(&spi->dev, "rx4581",
&rx4581_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
spi_set_drvdata(spi, rtc);
return 0;
}
static int rx4581_remove(struct spi_device *spi)
{
return 0;
}
static const struct spi_device_id rx4581_id[] = {
{ "rx4581", 0 },
{ }
};
MODULE_DEVICE_TABLE(spi, rx4581_id);
static struct spi_driver rx4581_driver = {
.driver = {
.name = "rtc-rx4581",
.owner = THIS_MODULE,
},
.probe = rx4581_probe,
.remove = rx4581_remove,
.id_table = rx4581_id,
};
module_spi_driver(rx4581_driver);
MODULE_DESCRIPTION("rx4581 spi RTC driver");
MODULE_AUTHOR("Torben Hohn");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:rtc-rx4581");
