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linux/drivers/rtc/rtc-ds3234.c
Dennis Aberilla 2f9b75e09e rtc: add device driver for Dallas DS3234 SPI RTC chip 
Add support for the Dallas DS3234 chip - extremely accurate SPI bus RTC
with integrated crystal and SRAM.

[akpm@linux-foundation.org: don't use BIN2BCD/BCD2BIN]
Signed-off-by: Dennis Aberilla <denzzzhome@yahoo.com>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-16 11:21:39 -07:00

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/* drivers/rtc/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.
*
* Changelog:
*
* 07-May-2008: Dennis Aberilla <denzzzhome@yahoo.com>
* - Created based on the max6902 code. Only implements the
* date/time keeping functions; no SRAM yet.
*/
#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
#undef DS3234_DEBUG
struct ds3234 {
struct rtc_device *rtc;
u8 buf[8]; /* Burst read: addr + 7 regs */
u8 tx_buf[2];
u8 rx_buf[2];
};
static void 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;
spi_write(spi, buf, 2);
}
static int ds3234_get_reg(struct device *dev, unsigned char address,
unsigned char *data)
{
struct spi_device *spi = to_spi_device(dev);
struct ds3234 *chip = dev_get_drvdata(dev);
struct spi_message message;
struct spi_transfer xfer;
int status;
if (!data)
return -EINVAL;
/* Build our spi message */
spi_message_init(&message);
memset(&xfer, 0, sizeof(xfer));
/* Address + dummy tx byte */
xfer.len = 2;
xfer.tx_buf = chip->tx_buf;
xfer.rx_buf = chip->rx_buf;
chip->tx_buf[0] = address;
chip->tx_buf[1] = 0xff;
spi_message_add_tail(&xfer, &message);
/* do the i/o */
status = spi_sync(spi, &message);
if (status == 0)
status = message.status;
else
return status;
*data = chip->rx_buf[1];
return status;
}
static int ds3234_get_datetime(struct device *dev, struct rtc_time *dt)
{
struct spi_device *spi = to_spi_device(dev);
struct ds3234 *chip = dev_get_drvdata(dev);
struct spi_message message;
struct spi_transfer xfer;
int status;
/* build the message */
spi_message_init(&message);
memset(&xfer, 0, sizeof(xfer));
xfer.len = 1 + 7; /* Addr + 7 registers */
xfer.tx_buf = chip->buf;
xfer.rx_buf = chip->buf;
chip->buf[0] = 0x00; /* Start address */
spi_message_add_tail(&xfer, &message);
/* do the i/o */
status = spi_sync(spi, &message);
if (status == 0)
status = message.status;
else
return status;
/* Seconds, Minutes, Hours, Day, Date, Month, Year */
dt->tm_sec = bcd2bin(chip->buf[1]);
dt->tm_min = bcd2bin(chip->buf[2]);
dt->tm_hour = bcd2bin(chip->buf[3] & 0x3f);
dt->tm_wday = bcd2bin(chip->buf[4]) - 1; /* 0 = Sun */
dt->tm_mday = bcd2bin(chip->buf[5]);
dt->tm_mon = bcd2bin(chip->buf[6] & 0x1f) - 1; /* 0 = Jan */
dt->tm_year = bcd2bin(chip->buf[7] & 0xff) + 100; /* Assume 20YY */
#ifdef DS3234_DEBUG
dev_dbg(dev, "\n%s : Read RTC values\n", __func__);
dev_dbg(dev, "tm_hour: %i\n", dt->tm_hour);
dev_dbg(dev, "tm_min : %i\n", dt->tm_min);
dev_dbg(dev, "tm_sec : %i\n", dt->tm_sec);
dev_dbg(dev, "tm_wday: %i\n", dt->tm_wday);
dev_dbg(dev, "tm_mday: %i\n", dt->tm_mday);
dev_dbg(dev, "tm_mon : %i\n", dt->tm_mon);
dev_dbg(dev, "tm_year: %i\n", dt->tm_year);
#endif
return 0;
}
static int ds3234_set_datetime(struct device *dev, struct rtc_time *dt)
{
#ifdef DS3234_DEBUG
dev_dbg(dev, "\n%s : Setting RTC values\n", __func__);
dev_dbg(dev, "tm_sec : %i\n", dt->tm_sec);
dev_dbg(dev, "tm_min : %i\n", dt->tm_min);
dev_dbg(dev, "tm_hour: %i\n", dt->tm_hour);
dev_dbg(dev, "tm_wday: %i\n", dt->tm_wday);
dev_dbg(dev, "tm_mday: %i\n", dt->tm_mday);
dev_dbg(dev, "tm_mon : %i\n", dt->tm_mon);
dev_dbg(dev, "tm_year: %i\n", dt->tm_year);
#endif
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 int ds3234_read_time(struct device *dev, struct rtc_time *tm)
{
return ds3234_get_datetime(dev, tm);
}
static int ds3234_set_time(struct device *dev, struct rtc_time *tm)
{
return ds3234_set_datetime(dev, tm);
}
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;
struct ds3234 *chip;
int res;
rtc = rtc_device_register("ds3234",
&spi->dev, &ds3234_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
spi->mode = SPI_MODE_3;
spi->bits_per_word = 8;
spi_setup(spi);
chip = kzalloc(sizeof(struct ds3234), GFP_KERNEL);
if (!chip) {
rtc_device_unregister(rtc);
return -ENOMEM;
}
chip->rtc = rtc;
dev_set_drvdata(&spi->dev, chip);
res = ds3234_get_reg(&spi->dev, DS3234_REG_SECONDS, &tmp);
if (res) {
rtc_device_unregister(rtc);
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);
return 0;
}
static int __exit ds3234_remove(struct spi_device *spi)
{
struct ds3234 *chip = platform_get_drvdata(spi);
struct rtc_device *rtc = chip->rtc;
if (rtc)
rtc_device_unregister(rtc);
kfree(chip);
return 0;
}
static struct spi_driver ds3234_driver = {
.driver = {
.name = "ds3234",
.bus = &spi_bus_type,
.owner = THIS_MODULE,
},
.probe = ds3234_probe,
.remove = __devexit_p(ds3234_remove),
};
static __init int ds3234_init(void)
{
printk(KERN_INFO "DS3234 SPI RTC Driver\n");
return spi_register_driver(&ds3234_driver);
}
module_init(ds3234_init);
static __exit void ds3234_exit(void)
{
spi_unregister_driver(&ds3234_driver);
}
module_exit(ds3234_exit);
MODULE_DESCRIPTION("DS3234 SPI RTC driver");
MODULE_AUTHOR("Dennis Aberilla <denzzzhome@yahoo.com>");
MODULE_LICENSE("GPL");
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