[linux.git] / drivers / rtc / rtc-m41t94.c

/*
 * Driver for ST M41T94 SPI RTC
 *
 * Copyright (C) 2008 Kim B. Heino
 *
 * 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/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/spi/spi.h>
#include <linux/bcd.h>

#define M41T94_REG_SECONDS	0x01
#define M41T94_REG_MINUTES	0x02
#define M41T94_REG_HOURS	0x03
#define M41T94_REG_WDAY		0x04
#define M41T94_REG_DAY		0x05
#define M41T94_REG_MONTH	0x06
#define M41T94_REG_YEAR		0x07
#define M41T94_REG_HT		0x0c

#define M41T94_BIT_HALT		0x40
#define M41T94_BIT_STOP		0x80
#define M41T94_BIT_CB		0x40
#define M41T94_BIT_CEB		0x80

static int m41t94_set_time(struct device *dev, struct rtc_time *tm)
{
	struct spi_device *spi = to_spi_device(dev);
	u8 buf[8]; /* write cmd + 7 registers */

	dev_dbg(dev, "%s secs=%d, mins=%d, "
		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
		"write", tm->tm_sec, tm->tm_min,
		tm->tm_hour, tm->tm_mday,
		tm->tm_mon, tm->tm_year, tm->tm_wday);

	buf[0] = 0x80 | M41T94_REG_SECONDS; /* write time + date */
	buf[M41T94_REG_SECONDS] = bin2bcd(tm->tm_sec);
	buf[M41T94_REG_MINUTES] = bin2bcd(tm->tm_min);
	buf[M41T94_REG_HOURS]   = bin2bcd(tm->tm_hour);
	buf[M41T94_REG_WDAY]    = bin2bcd(tm->tm_wday + 1);
	buf[M41T94_REG_DAY]     = bin2bcd(tm->tm_mday);
	buf[M41T94_REG_MONTH]   = bin2bcd(tm->tm_mon + 1);

	buf[M41T94_REG_HOURS] |= M41T94_BIT_CEB;
	if (tm->tm_year >= 100)
		buf[M41T94_REG_HOURS] |= M41T94_BIT_CB;
	buf[M41T94_REG_YEAR] = bin2bcd(tm->tm_year % 100);

	return spi_write(spi, buf, 8);
}

static int m41t94_read_time(struct device *dev, struct rtc_time *tm)
{
	struct spi_device *spi = to_spi_device(dev);
	u8 buf[2];
	int ret, hour;

	/* clear halt update bit */
	ret = spi_w8r8(spi, M41T94_REG_HT);
	if (ret < 0)
		return ret;
	if (ret & M41T94_BIT_HALT) {
		buf[0] = 0x80 | M41T94_REG_HT;
		buf[1] = ret & ~M41T94_BIT_HALT;
		spi_write(spi, buf, 2);
	}

	/* clear stop bit */
	ret = spi_w8r8(spi, M41T94_REG_SECONDS);
	if (ret < 0)
		return ret;
	if (ret & M41T94_BIT_STOP) {
		buf[0] = 0x80 | M41T94_REG_SECONDS;
		buf[1] = ret & ~M41T94_BIT_STOP;
		spi_write(spi, buf, 2);
	}

	tm->tm_sec  = bcd2bin(spi_w8r8(spi, M41T94_REG_SECONDS));
	tm->tm_min  = bcd2bin(spi_w8r8(spi, M41T94_REG_MINUTES));
	hour = spi_w8r8(spi, M41T94_REG_HOURS);
	tm->tm_hour = bcd2bin(hour & 0x3f);
	tm->tm_wday = bcd2bin(spi_w8r8(spi, M41T94_REG_WDAY)) - 1;
	tm->tm_mday = bcd2bin(spi_w8r8(spi, M41T94_REG_DAY));
	tm->tm_mon  = bcd2bin(spi_w8r8(spi, M41T94_REG_MONTH)) - 1;
	tm->tm_year = bcd2bin(spi_w8r8(spi, M41T94_REG_YEAR));
	if ((hour & M41T94_BIT_CB) || !(hour & M41T94_BIT_CEB))
		tm->tm_year += 100;

	dev_dbg(dev, "%s secs=%d, mins=%d, "
		"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
		"read", tm->tm_sec, tm->tm_min,
		tm->tm_hour, tm->tm_mday,
		tm->tm_mon, tm->tm_year, tm->tm_wday);

	/* initial clock setting can be undefined */
	return rtc_valid_tm(tm);
}

static const struct rtc_class_ops m41t94_rtc_ops = {
	.read_time	= m41t94_read_time,
	.set_time	= m41t94_set_time,
};

static struct spi_driver m41t94_driver;

static int __devinit m41t94_probe(struct spi_device *spi)
{
	struct rtc_device *rtc;
	int res;

	spi->bits_per_word = 8;
	spi_setup(spi);

	res = spi_w8r8(spi, M41T94_REG_SECONDS);
	if (res < 0) {
		dev_err(&spi->dev, "not found.\n");
		return res;
	}

	rtc = rtc_device_register(m41t94_driver.driver.name,
		&spi->dev, &m41t94_rtc_ops, THIS_MODULE);
	if (IS_ERR(rtc))
		return PTR_ERR(rtc);

	dev_set_drvdata(&spi->dev, rtc);

	return 0;
}

static int __devexit m41t94_remove(struct spi_device *spi)
{
	struct rtc_device *rtc = spi_get_drvdata(spi);

	if (rtc)
		rtc_device_unregister(rtc);

	return 0;
}

static struct spi_driver m41t94_driver = {
	.driver = {
		.name	= "rtc-m41t94",
		.owner	= THIS_MODULE,
	},
	.probe	= m41t94_probe,
	.remove = __devexit_p(m41t94_remove),
};

module_spi_driver(m41t94_driver);

MODULE_AUTHOR("Kim B. Heino <[email protected]>");
MODULE_DESCRIPTION("Driver for ST M41T94 SPI RTC");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:rtc-m41t94");
Commit	Line	Data
8fc2c767 KH	1	/*
	2	* Driver for ST M41T94 SPI RTC
	3	*
	4	* Copyright (C) 2008 Kim B. Heino
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2 as
	8	* published by the Free Software Foundation.
	9	*/
	10
	11	#include <linux/module.h>
	12	#include <linux/kernel.h>
	13	#include <linux/platform_device.h>
	14	#include <linux/rtc.h>
	15	#include <linux/spi/spi.h>
	16	#include <linux/bcd.h>
	17
	18	#define M41T94_REG_SECONDS 0x01
	19	#define M41T94_REG_MINUTES 0x02
	20	#define M41T94_REG_HOURS 0x03
	21	#define M41T94_REG_WDAY 0x04
	22	#define M41T94_REG_DAY 0x05
	23	#define M41T94_REG_MONTH 0x06
	24	#define M41T94_REG_YEAR 0x07
	25	#define M41T94_REG_HT 0x0c
	26
	27	#define M41T94_BIT_HALT 0x40
	28	#define M41T94_BIT_STOP 0x80
	29	#define M41T94_BIT_CB 0x40
	30	#define M41T94_BIT_CEB 0x80
	31
	32	static int m41t94_set_time(struct device dev, struct rtc_time tm)
	33	{
	34	struct spi_device *spi = to_spi_device(dev);
	35	u8 buf[8]; /* write cmd + 7 registers */
	36
	37	dev_dbg(dev, "%s secs=%d, mins=%d, "
	38	"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
	39	"write", tm->tm_sec, tm->tm_min,
	40	tm->tm_hour, tm->tm_mday,
	41	tm->tm_mon, tm->tm_year, tm->tm_wday);
	42
	43	buf[0] = 0x80 \| M41T94_REG_SECONDS; /* write time + date */
fe20ba70 AB	44	buf[M41T94_REG_SECONDS] = bin2bcd(tm->tm_sec);
	45	buf[M41T94_REG_MINUTES] = bin2bcd(tm->tm_min);
	46	buf[M41T94_REG_HOURS] = bin2bcd(tm->tm_hour);
	47	buf[M41T94_REG_WDAY] = bin2bcd(tm->tm_wday + 1);
	48	buf[M41T94_REG_DAY] = bin2bcd(tm->tm_mday);
	49	buf[M41T94_REG_MONTH] = bin2bcd(tm->tm_mon + 1);
8fc2c767 KH	50
	51	buf[M41T94_REG_HOURS] \|= M41T94_BIT_CEB;
	52	if (tm->tm_year >= 100)
	53	buf[M41T94_REG_HOURS] \|= M41T94_BIT_CB;
fe20ba70	54	buf[M41T94_REG_YEAR] = bin2bcd(tm->tm_year % 100);
8fc2c767 KH	55
	56	return spi_write(spi, buf, 8);
	57	}
	58
	59	static int m41t94_read_time(struct device dev, struct rtc_time tm)
	60	{
	61	struct spi_device *spi = to_spi_device(dev);
	62	u8 buf[2];
	63	int ret, hour;
	64
	65	/* clear halt update bit */
	66	ret = spi_w8r8(spi, M41T94_REG_HT);
	67	if (ret < 0)
	68	return ret;
	69	if (ret & M41T94_BIT_HALT) {
	70	buf[0] = 0x80 \| M41T94_REG_HT;
	71	buf[1] = ret & ~M41T94_BIT_HALT;
	72	spi_write(spi, buf, 2);
	73	}
	74
	75	/* clear stop bit */
	76	ret = spi_w8r8(spi, M41T94_REG_SECONDS);
	77	if (ret < 0)
	78	return ret;
	79	if (ret & M41T94_BIT_STOP) {
	80	buf[0] = 0x80 \| M41T94_REG_SECONDS;
	81	buf[1] = ret & ~M41T94_BIT_STOP;
	82	spi_write(spi, buf, 2);
	83	}
	84
fe20ba70 AB	85	tm->tm_sec = bcd2bin(spi_w8r8(spi, M41T94_REG_SECONDS));
fe20ba70 AB	86	tm->tm_min = bcd2bin(spi_w8r8(spi, M41T94_REG_MINUTES));
8fc2c767	87	hour = spi_w8r8(spi, M41T94_REG_HOURS);
fe20ba70 AB	88	tm->tm_hour = bcd2bin(hour & 0x3f);
	89	tm->tm_wday = bcd2bin(spi_w8r8(spi, M41T94_REG_WDAY)) - 1;
	90	tm->tm_mday = bcd2bin(spi_w8r8(spi, M41T94_REG_DAY));
	91	tm->tm_mon = bcd2bin(spi_w8r8(spi, M41T94_REG_MONTH)) - 1;
	92	tm->tm_year = bcd2bin(spi_w8r8(spi, M41T94_REG_YEAR));
8fc2c767 KH	93	if ((hour & M41T94_BIT_CB) \|\| !(hour & M41T94_BIT_CEB))
	94	tm->tm_year += 100;
	95
	96	dev_dbg(dev, "%s secs=%d, mins=%d, "
	97	"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
	98	"read", tm->tm_sec, tm->tm_min,
	99	tm->tm_hour, tm->tm_mday,
	100	tm->tm_mon, tm->tm_year, tm->tm_wday);
	101
	102	/* initial clock setting can be undefined */
	103	return rtc_valid_tm(tm);
	104	}
	105
	106	static const struct rtc_class_ops m41t94_rtc_ops = {
	107	.read_time = m41t94_read_time,
	108	.set_time = m41t94_set_time,
	109	};
	110
	111	static struct spi_driver m41t94_driver;
	112
	113	static int __devinit m41t94_probe(struct spi_device *spi)
	114	{
	115	struct rtc_device *rtc;
	116	int res;
	117
	118	spi->bits_per_word = 8;
	119	spi_setup(spi);
	120
	121	res = spi_w8r8(spi, M41T94_REG_SECONDS);
	122	if (res < 0) {
	123	dev_err(&spi->dev, "not found.\n");
	124	return res;
	125	}
	126
	127	rtc = rtc_device_register(m41t94_driver.driver.name,
	128	&spi->dev, &m41t94_rtc_ops, THIS_MODULE);
	129	if (IS_ERR(rtc))
	130	return PTR_ERR(rtc);
	131
	132	dev_set_drvdata(&spi->dev, rtc);
	133
	134	return 0;
	135	}
	136
	137	static int __devexit m41t94_remove(struct spi_device *spi)
	138	{
42fea15d	139	struct rtc_device *rtc = spi_get_drvdata(spi);
8fc2c767 KH	140
	141	if (rtc)
	142	rtc_device_unregister(rtc);
	143
	144	return 0;
	145	}
	146
	147	static struct spi_driver m41t94_driver = {
	148	.driver = {
	149	.name = "rtc-m41t94",
8fc2c767 KH	150	.owner = THIS_MODULE,
	151	},
	152	.probe = m41t94_probe,
	153	.remove = __devexit_p(m41t94_remove),
	154	};
	155
109e9418	156	module_spi_driver(m41t94_driver);
8fc2c767 KH	157
	158	MODULE_AUTHOR("Kim B. Heino <[email protected]>");
	159	MODULE_DESCRIPTION("Driver for ST M41T94 SPI RTC");
	160	MODULE_LICENSE("GPL");
e0626e38	161	MODULE_ALIAS("spi:rtc-m41t94");