aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/rtc/rtc-ds1390.c
blob: be9d8c0a7e3a9297f093522087a04c1d82d2d335 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
/*
 * rtc-ds1390.c -- driver for the Dallas/Maxim DS1390/93/94 SPI RTC
 *
 * Copyright (C) 2008 Mercury IMC Ltd
 * Written by Mark Jackson <mpfj@mimc.co.uk>
 *
 * 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.
 *
 * NOTE: Currently this driver only supports the bare minimum for read
 * and write the RTC. The extra features provided by the chip family
 * (alarms, trickle charger, different control registers) are unavailable.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/spi/spi.h>
#include <linux/bcd.h>
#include <linux/slab.h>

#define DS1390_REG_100THS		0x00
#define DS1390_REG_SECONDS		0x01
#define DS1390_REG_MINUTES		0x02
#define DS1390_REG_HOURS		0x03
#define DS1390_REG_DAY			0x04
#define DS1390_REG_DATE			0x05
#define DS1390_REG_MONTH_CENT		0x06
#define DS1390_REG_YEAR			0x07

#define DS1390_REG_ALARM_100THS		0x08
#define DS1390_REG_ALARM_SECONDS	0x09
#define DS1390_REG_ALARM_MINUTES	0x0A
#define DS1390_REG_ALARM_HOURS		0x0B
#define DS1390_REG_ALARM_DAY_DATE	0x0C

#define DS1390_REG_CONTROL		0x0D
#define DS1390_REG_STATUS		0x0E
#define DS1390_REG_TRICKLE		0x0F

struct ds1390 {
	struct rtc_device *rtc;
	u8 txrx_buf[9];	/* cmd + 8 registers */
};

static int ds1390_get_reg(struct device *dev, unsigned char address,
				unsigned char *data)
{
	struct spi_device *spi = to_spi_device(dev);
	struct ds1390 *chip = dev_get_drvdata(dev);
	int status;

	if (!data)
		return -EINVAL;

	/* Clear MSB to indicate read */
	chip->txrx_buf[0] = address & 0x7f;
	/* do the i/o */
	status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 1);
	if (status != 0)
		return status;

	*data = chip->txrx_buf[1];

	return 0;
}

static int ds1390_read_time(struct device *dev, struct rtc_time *dt)
{
	struct spi_device *spi = to_spi_device(dev);
	struct ds1390 *chip = dev_get_drvdata(dev);
	int status;

	/* build the message */
	chip->txrx_buf[0] = DS1390_REG_SECONDS;

	/* do the i/o */
	status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 8);
	if (status != 0)
		return status;

	/* The chip sends data in this order:
	 * Seconds, Minutes, Hours, Day, Date, Month / Century, Year */
	dt->tm_sec	= bcd2bin(chip->txrx_buf[0]);
	dt->tm_min	= bcd2bin(chip->txrx_buf[1]);
	dt->tm_hour	= bcd2bin(chip->txrx_buf[2]);
	dt->tm_wday	= bcd2bin(chip->txrx_buf[3]);
	dt->tm_mday	= bcd2bin(chip->txrx_buf[4]);
	/* mask off century bit */
	dt->tm_mon	= bcd2bin(chip->txrx_buf[5] & 0x7f) - 1;
	/* adjust for century bit */
	dt->tm_year = bcd2bin(chip->txrx_buf[6]) + ((chip->txrx_buf[5] & 0x80) ? 100 : 0);

	return rtc_valid_tm(dt);
}

static int ds1390_set_time(struct device *dev, struct rtc_time *dt)
{
	struct spi_device *spi = to_spi_device(dev);
	struct ds1390 *chip = dev_get_drvdata(dev);

	/* build the message */
	chip->txrx_buf[0] = DS1390_REG_SECONDS | 0x80;
	chip->txrx_buf[1] = bin2bcd(dt->tm_sec);
	chip->txrx_buf[2] = bin2bcd(dt->tm_min);
	chip->txrx_buf[3] = bin2bcd(dt->tm_hour);
	chip->txrx_buf[4] = bin2bcd(dt->tm_wday);
	chip->txrx_buf[5] = bin2bcd(dt->tm_mday);
	chip->txrx_buf[6] = bin2bcd(dt->tm_mon + 1) |
				((dt->tm_year > 99) ? 0x80 : 0x00);
	chip->txrx_buf[7] = bin2bcd(dt->tm_year % 100);

	/* do the i/o */
	return spi_write_then_read(spi, chip->txrx_buf, 8, NULL, 0);
}

static const struct rtc_class_ops ds1390_rtc_ops = {
	.read_time	= ds1390_read_time,
	.set_time	= ds1390_set_time,
};

static int ds1390_probe(struct spi_device *spi)
{
	unsigned char tmp;
	struct ds1390 *chip;
	int res;

	spi->mode = SPI_MODE_3;
	spi->bits_per_word = 8;
	spi_setup(spi);

	chip = devm_kzalloc(&spi->dev, sizeof(*chip), GFP_KERNEL);
	if (!chip) {
		dev_err(&spi->dev, "unable to allocate device memory\n");
		return -ENOMEM;
	}
	spi_set_drvdata(spi, chip);

	res = ds1390_get_reg(&spi->dev, DS1390_REG_SECONDS, &tmp);
	if (res != 0) {
		dev_err(&spi->dev, "unable to read device\n");
		return res;
	}

	chip->rtc = devm_rtc_device_register(&spi->dev, "ds1390",
					&ds1390_rtc_ops, THIS_MODULE);
	if (IS_ERR(chip->rtc)) {
		dev_err(&spi->dev, "unable to register device\n");
		res = PTR_ERR(chip->rtc);
	}

	return res;
}

static struct spi_driver ds1390_driver = {
	.driver = {
		.name	= "rtc-ds1390",
		.owner	= THIS_MODULE,
	},
	.probe	= ds1390_probe,
};

module_spi_driver(ds1390_driver);

MODULE_DESCRIPTION("Dallas/Maxim DS1390/93/94 SPI RTC driver");
MODULE_AUTHOR("Mark Jackson <mpfj@mimc.co.uk>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:rtc-ds1390");