rtc-ds3234.c
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/* rtc-ds3234.c
*
* Driver for Dallas Semiconductor (DS3234) SPI RTC with Integrated Crystal
* and SRAM.
*
* Copyright (C) 2008 MIMOMax Wireless 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.
*
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/spi/spi.h>
#include <linux/bcd.h>
#define DS3234_REG_SECONDS 0x00
#define DS3234_REG_MINUTES 0x01
#define DS3234_REG_HOURS 0x02
#define DS3234_REG_DAY 0x03
#define DS3234_REG_DATE 0x04
#define DS3234_REG_MONTH 0x05
#define DS3234_REG_YEAR 0x06
#define DS3234_REG_CENTURY (1 << 7) /* Bit 7 of the Month register */
#define DS3234_REG_CONTROL 0x0E
#define DS3234_REG_CONT_STAT 0x0F
static int ds3234_set_reg(struct device *dev, unsigned char address,
unsigned char data)
{
struct spi_device *spi = to_spi_device(dev);
unsigned char buf[2];
/* MSB must be '1' to indicate write */
buf[0] = address | 0x80;
buf[1] = data;
return spi_write_then_read(spi, buf, 2, NULL, 0);
}
static int ds3234_get_reg(struct device *dev, unsigned char address,
unsigned char *data)
{
struct spi_device *spi = to_spi_device(dev);
*data = address & 0x7f;
return spi_write_then_read(spi, data, 1, data, 1);
}
static int ds3234_read_time(struct device *dev, struct rtc_time *dt)
{
int err;
unsigned char buf[8];
struct spi_device *spi = to_spi_device(dev);
buf[0] = 0x00; /* Start address */
err = spi_write_then_read(spi, buf, 1, buf, 8);
if (err != 0)
return err;
/* Seconds, Minutes, Hours, Day, Date, Month, Year */
dt->tm_sec = bcd2bin(buf[0]);
dt->tm_min = bcd2bin(buf[1]);
dt->tm_hour = bcd2bin(buf[2] & 0x3f);
dt->tm_wday = bcd2bin(buf[3]) - 1; /* 0 = Sun */
dt->tm_mday = bcd2bin(buf[4]);
dt->tm_mon = bcd2bin(buf[5] & 0x1f) - 1; /* 0 = Jan */
dt->tm_year = bcd2bin(buf[6] & 0xff) + 100; /* Assume 20YY */
return rtc_valid_tm(dt);
}
static int ds3234_set_time(struct device *dev, struct rtc_time *dt)
{
ds3234_set_reg(dev, DS3234_REG_SECONDS, bin2bcd(dt->tm_sec));
ds3234_set_reg(dev, DS3234_REG_MINUTES, bin2bcd(dt->tm_min));
ds3234_set_reg(dev, DS3234_REG_HOURS, bin2bcd(dt->tm_hour) & 0x3f);
/* 0 = Sun */
ds3234_set_reg(dev, DS3234_REG_DAY, bin2bcd(dt->tm_wday + 1));
ds3234_set_reg(dev, DS3234_REG_DATE, bin2bcd(dt->tm_mday));
/* 0 = Jan */
ds3234_set_reg(dev, DS3234_REG_MONTH, bin2bcd(dt->tm_mon + 1));
/* Assume 20YY although we just want to make sure not to go negative. */
if (dt->tm_year > 100)
dt->tm_year -= 100;
ds3234_set_reg(dev, DS3234_REG_YEAR, bin2bcd(dt->tm_year));
return 0;
}
static const struct rtc_class_ops ds3234_rtc_ops = {
.read_time = ds3234_read_time,
.set_time = ds3234_set_time,
};
static int ds3234_probe(struct spi_device *spi)
{
struct rtc_device *rtc;
unsigned char tmp;
int res;
spi->mode = SPI_MODE_3;
spi->bits_per_word = 8;
spi_setup(spi);
res = ds3234_get_reg(&spi->dev, DS3234_REG_SECONDS, &tmp);
if (res != 0)
return res;
/* Control settings
*
* CONTROL_REG
* BIT 7 6 5 4 3 2 1 0
* EOSC BBSQW CONV RS2 RS1 INTCN A2IE A1IE
*
* 0 0 0 1 1 1 0 0
*
* CONTROL_STAT_REG
* BIT 7 6 5 4 3 2 1 0
* OSF BB32kHz CRATE1 CRATE0 EN32kHz BSY A2F A1F
*
* 1 0 0 0 1 0 0 0
*/
ds3234_get_reg(&spi->dev, DS3234_REG_CONTROL, &tmp);
ds3234_set_reg(&spi->dev, DS3234_REG_CONTROL, tmp & 0x1c);
ds3234_get_reg(&spi->dev, DS3234_REG_CONT_STAT, &tmp);
ds3234_set_reg(&spi->dev, DS3234_REG_CONT_STAT, tmp & 0x88);
/* Print our settings */
ds3234_get_reg(&spi->dev, DS3234_REG_CONTROL, &tmp);
dev_info(&spi->dev, "Control Reg: 0x%02x\n", tmp);
ds3234_get_reg(&spi->dev, DS3234_REG_CONT_STAT, &tmp);
dev_info(&spi->dev, "Ctrl/Stat Reg: 0x%02x\n", tmp);
rtc = devm_rtc_device_register(&spi->dev, "ds3234",
&ds3234_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
spi_set_drvdata(spi, rtc);
return 0;
}
static struct spi_driver ds3234_driver = {
.driver = {
.name = "ds3234",
.owner = THIS_MODULE,
},
.probe = ds3234_probe,
};
module_spi_driver(ds3234_driver);
MODULE_DESCRIPTION("DS3234 SPI RTC driver");
MODULE_AUTHOR("Dennis Aberilla <denzzzhome@yahoo.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:ds3234");