1/* rtc-ds3234.c
  2 *
  3 * Driver for Dallas Semiconductor (DS3234) SPI RTC with Integrated Crystal
  4 * and SRAM.
  5 *
  6 * Copyright (C) 2008 MIMOMax Wireless Ltd.
  7 *
  8 * This program is free software; you can redistribute it and/or modify
  9 * it under the terms of the GNU General Public License version 2 as
 10 * published by the Free Software Foundation.
 11 *
 12 */
 13
 14#include <linux/init.h>
 15#include <linux/module.h>
 16#include <linux/device.h>
 17#include <linux/platform_device.h>
 18#include <linux/rtc.h>
 19#include <linux/spi/spi.h>
 20#include <linux/bcd.h>
 21
 22#define DS3234_REG_SECONDS	0x00
 23#define DS3234_REG_MINUTES	0x01
 24#define DS3234_REG_HOURS	0x02
 25#define DS3234_REG_DAY		0x03
 26#define DS3234_REG_DATE		0x04
 27#define DS3234_REG_MONTH	0x05
 28#define DS3234_REG_YEAR		0x06
 29#define DS3234_REG_CENTURY	(1 << 7) /* Bit 7 of the Month register */
 30
 31#define DS3234_REG_CONTROL	0x0E
 32#define DS3234_REG_CONT_STAT	0x0F
 33
 34static int ds3234_set_reg(struct device *dev, unsigned char address,
 35				unsigned char data)
 36{
 37	struct spi_device *spi = to_spi_device(dev);
 38	unsigned char buf[2];
 39
 40	/* MSB must be '1' to indicate write */
 41	buf[0] = address | 0x80;
 42	buf[1] = data;
 43
 44	return spi_write_then_read(spi, buf, 2, NULL, 0);
 45}
 46
 47static int ds3234_get_reg(struct device *dev, unsigned char address,
 48				unsigned char *data)
 49{
 50	struct spi_device *spi = to_spi_device(dev);
 51
 52	*data = address & 0x7f;
 53
 54	return spi_write_then_read(spi, data, 1, data, 1);
 55}
 56
 57static int ds3234_read_time(struct device *dev, struct rtc_time *dt)
 58{
 59	int err;
 60	unsigned char buf[8];
 61	struct spi_device *spi = to_spi_device(dev);
 62
 63	buf[0] = 0x00; /* Start address */
 64
 65	err = spi_write_then_read(spi, buf, 1, buf, 8);
 66	if (err != 0)
 67		return err;
 68
 69	/* Seconds, Minutes, Hours, Day, Date, Month, Year */
 70	dt->tm_sec	= bcd2bin(buf[0]);
 71	dt->tm_min	= bcd2bin(buf[1]);
 72	dt->tm_hour	= bcd2bin(buf[2] & 0x3f);
 73	dt->tm_wday	= bcd2bin(buf[3]) - 1; /* 0 = Sun */
 74	dt->tm_mday	= bcd2bin(buf[4]);
 75	dt->tm_mon	= bcd2bin(buf[5] & 0x1f) - 1; /* 0 = Jan */
 76	dt->tm_year 	= bcd2bin(buf[6] & 0xff) + 100; /* Assume 20YY */
 77
 78	return rtc_valid_tm(dt);
 79}
 80
 81static int ds3234_set_time(struct device *dev, struct rtc_time *dt)
 82{
 83	ds3234_set_reg(dev, DS3234_REG_SECONDS, bin2bcd(dt->tm_sec));
 84	ds3234_set_reg(dev, DS3234_REG_MINUTES, bin2bcd(dt->tm_min));
 85	ds3234_set_reg(dev, DS3234_REG_HOURS, bin2bcd(dt->tm_hour) & 0x3f);
 86
 87	/* 0 = Sun */
 88	ds3234_set_reg(dev, DS3234_REG_DAY, bin2bcd(dt->tm_wday + 1));
 89	ds3234_set_reg(dev, DS3234_REG_DATE, bin2bcd(dt->tm_mday));
 90
 91	/* 0 = Jan */
 92	ds3234_set_reg(dev, DS3234_REG_MONTH, bin2bcd(dt->tm_mon + 1));
 93
 94	/* Assume 20YY although we just want to make sure not to go negative. */
 95	if (dt->tm_year > 100)
 96		dt->tm_year -= 100;
 97
 98	ds3234_set_reg(dev, DS3234_REG_YEAR, bin2bcd(dt->tm_year));
 99
100	return 0;
101}
102
103static const struct rtc_class_ops ds3234_rtc_ops = {
104	.read_time	= ds3234_read_time,
105	.set_time	= ds3234_set_time,
106};
107
108static int __devinit ds3234_probe(struct spi_device *spi)
109{
110	struct rtc_device *rtc;
111	unsigned char tmp;
112	int res;
113
114	spi->mode = SPI_MODE_3;
115	spi->bits_per_word = 8;
116	spi_setup(spi);
117
118	res = ds3234_get_reg(&spi->dev, DS3234_REG_SECONDS, &tmp);
119	if (res != 0)
120		return res;
121
122	/* Control settings
123	 *
124	 * CONTROL_REG
125	 * BIT 7	6	5	4	3	2	1	0
126	 *     EOSC	BBSQW	CONV	RS2	RS1	INTCN	A2IE	A1IE
127	 *
128	 *     0	0	0	1	1	1	0	0
129	 *
130	 * CONTROL_STAT_REG
131	 * BIT 7	6	5	4	3	2	1	0
132	 *     OSF	BB32kHz	CRATE1	CRATE0	EN32kHz	BSY	A2F	A1F
133	 *
134	 *     1	0	0	0	1	0	0	0
135	 */
136	ds3234_get_reg(&spi->dev, DS3234_REG_CONTROL, &tmp);
137	ds3234_set_reg(&spi->dev, DS3234_REG_CONTROL, tmp & 0x1c);
138
139	ds3234_get_reg(&spi->dev, DS3234_REG_CONT_STAT, &tmp);
140	ds3234_set_reg(&spi->dev, DS3234_REG_CONT_STAT, tmp & 0x88);
141
142	/* Print our settings */
143	ds3234_get_reg(&spi->dev, DS3234_REG_CONTROL, &tmp);
144	dev_info(&spi->dev, "Control Reg: 0x%02x\n", tmp);
145
146	ds3234_get_reg(&spi->dev, DS3234_REG_CONT_STAT, &tmp);
147	dev_info(&spi->dev, "Ctrl/Stat Reg: 0x%02x\n", tmp);
148
149	rtc = rtc_device_register("ds3234",
150				&spi->dev, &ds3234_rtc_ops, THIS_MODULE);
151	if (IS_ERR(rtc))
152		return PTR_ERR(rtc);
153
154	dev_set_drvdata(&spi->dev, rtc);
155
156	return 0;
157}
158
159static int __devexit ds3234_remove(struct spi_device *spi)
160{
161	struct rtc_device *rtc = spi_get_drvdata(spi);
162
163	rtc_device_unregister(rtc);
164	return 0;
165}
166
167static struct spi_driver ds3234_driver = {
168	.driver = {
169		.name	 = "ds3234",
170		.owner	= THIS_MODULE,
171	},
172	.probe	 = ds3234_probe,
173	.remove = __devexit_p(ds3234_remove),
174};
175
176static __init int ds3234_init(void)
177{
178	return spi_register_driver(&ds3234_driver);
179}
180module_init(ds3234_init);
181
182static __exit void ds3234_exit(void)
183{
184	spi_unregister_driver(&ds3234_driver);
185}
186module_exit(ds3234_exit);
187
188MODULE_DESCRIPTION("DS3234 SPI RTC driver");
189MODULE_AUTHOR("Dennis Aberilla <denzzzhome@yahoo.com>");
190MODULE_LICENSE("GPL");
191MODULE_ALIAS("spi:ds3234");