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Commit 2f9b75e0 authored by Dennis Aberilla's avatar Dennis Aberilla Committed by Linus Torvalds
Browse files

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: default avatarDennis Aberilla <denzzzhome@yahoo.com>
Signed-off-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 986e36a5

drivers/rtc/Kconfig

+9 −0
Original line number Diff line number Diff line
@@ -319,6 +319,15 @@ config RTC_DRV_RS5C348 
	  This driver can also be built as a module. If so, the module

	  will be called rtc-rs5c348.



config RTC_DRV_DS3234

	tristate "Maxim/Dallas DS3234"

	help

	  If you say yes here you get support for the

	  Maxim/Dallas DS3234 SPI RTC chip.



	  This driver can also be built as a module. If so, the module

	  will be called rtc-ds3234.



endif # SPI_MASTER



comment "Platform RTC drivers"

drivers/rtc/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ obj-$(CONFIG_RTC_DRV_DS1511) += rtc-ds1511.o 
obj-$(CONFIG_RTC_DRV_DS1553)	+= rtc-ds1553.o

obj-$(CONFIG_RTC_DRV_DS1672)	+= rtc-ds1672.o

obj-$(CONFIG_RTC_DRV_DS1742)	+= rtc-ds1742.o

obj-$(CONFIG_RTC_DRV_DS3234)	+= rtc-ds3234.o

obj-$(CONFIG_RTC_DRV_EP93XX)	+= rtc-ep93xx.o

obj-$(CONFIG_RTC_DRV_FM3130)	+= rtc-fm3130.o

obj-$(CONFIG_RTC_DRV_ISL1208)	+= rtc-isl1208.o

drivers/rtc/rtc-ds3234.c

0 → 100644
+290 −0
Original line number Diff line number Diff line 
/* 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");