Root/drivers/rtc/rtc-ds1390.c

1/*
2 * rtc-ds1390.c -- driver for the Dallas/Maxim DS1390/93/94 SPI RTC
3 *
4 * Copyright (C) 2008 Mercury IMC Ltd
5 * Written by Mark Jackson <mpfj@mimc.co.uk>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 * NOTE: Currently this driver only supports the bare minimum for read
12 * and write the RTC. The extra features provided by the chip family
13 * (alarms, trickle charger, different control registers) are unavailable.
14 */
15
16#include <linux/init.h>
17#include <linux/module.h>
18#include <linux/platform_device.h>
19#include <linux/rtc.h>
20#include <linux/spi/spi.h>
21#include <linux/bcd.h>
22#include <linux/slab.h>
23
24#define DS1390_REG_100THS 0x00
25#define DS1390_REG_SECONDS 0x01
26#define DS1390_REG_MINUTES 0x02
27#define DS1390_REG_HOURS 0x03
28#define DS1390_REG_DAY 0x04
29#define DS1390_REG_DATE 0x05
30#define DS1390_REG_MONTH_CENT 0x06
31#define DS1390_REG_YEAR 0x07
32
33#define DS1390_REG_ALARM_100THS 0x08
34#define DS1390_REG_ALARM_SECONDS 0x09
35#define DS1390_REG_ALARM_MINUTES 0x0A
36#define DS1390_REG_ALARM_HOURS 0x0B
37#define DS1390_REG_ALARM_DAY_DATE 0x0C
38
39#define DS1390_REG_CONTROL 0x0D
40#define DS1390_REG_STATUS 0x0E
41#define DS1390_REG_TRICKLE 0x0F
42
43struct ds1390 {
44    struct rtc_device *rtc;
45    u8 txrx_buf[9]; /* cmd + 8 registers */
46};
47
48static int ds1390_get_reg(struct device *dev, unsigned char address,
49                unsigned char *data)
50{
51    struct spi_device *spi = to_spi_device(dev);
52    struct ds1390 *chip = dev_get_drvdata(dev);
53    int status;
54
55    if (!data)
56        return -EINVAL;
57
58    /* Clear MSB to indicate read */
59    chip->txrx_buf[0] = address & 0x7f;
60    /* do the i/o */
61    status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 1);
62    if (status != 0)
63        return status;
64
65    *data = chip->txrx_buf[1];
66
67    return 0;
68}
69
70static int ds1390_read_time(struct device *dev, struct rtc_time *dt)
71{
72    struct spi_device *spi = to_spi_device(dev);
73    struct ds1390 *chip = dev_get_drvdata(dev);
74    int status;
75
76    /* build the message */
77    chip->txrx_buf[0] = DS1390_REG_SECONDS;
78
79    /* do the i/o */
80    status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 8);
81    if (status != 0)
82        return status;
83
84    /* The chip sends data in this order:
85     * Seconds, Minutes, Hours, Day, Date, Month / Century, Year */
86    dt->tm_sec = bcd2bin(chip->txrx_buf[0]);
87    dt->tm_min = bcd2bin(chip->txrx_buf[1]);
88    dt->tm_hour = bcd2bin(chip->txrx_buf[2]);
89    dt->tm_wday = bcd2bin(chip->txrx_buf[3]);
90    dt->tm_mday = bcd2bin(chip->txrx_buf[4]);
91    /* mask off century bit */
92    dt->tm_mon = bcd2bin(chip->txrx_buf[5] & 0x7f) - 1;
93    /* adjust for century bit */
94    dt->tm_year = bcd2bin(chip->txrx_buf[6]) + ((chip->txrx_buf[5] & 0x80) ? 100 : 0);
95
96    return rtc_valid_tm(dt);
97}
98
99static int ds1390_set_time(struct device *dev, struct rtc_time *dt)
100{
101    struct spi_device *spi = to_spi_device(dev);
102    struct ds1390 *chip = dev_get_drvdata(dev);
103
104    /* build the message */
105    chip->txrx_buf[0] = DS1390_REG_SECONDS | 0x80;
106    chip->txrx_buf[1] = bin2bcd(dt->tm_sec);
107    chip->txrx_buf[2] = bin2bcd(dt->tm_min);
108    chip->txrx_buf[3] = bin2bcd(dt->tm_hour);
109    chip->txrx_buf[4] = bin2bcd(dt->tm_wday);
110    chip->txrx_buf[5] = bin2bcd(dt->tm_mday);
111    chip->txrx_buf[6] = bin2bcd(dt->tm_mon + 1) |
112                ((dt->tm_year > 99) ? 0x80 : 0x00);
113    chip->txrx_buf[7] = bin2bcd(dt->tm_year % 100);
114
115    /* do the i/o */
116    return spi_write_then_read(spi, chip->txrx_buf, 8, NULL, 0);
117}
118
119static const struct rtc_class_ops ds1390_rtc_ops = {
120    .read_time = ds1390_read_time,
121    .set_time = ds1390_set_time,
122};
123
124static int __devinit ds1390_probe(struct spi_device *spi)
125{
126    unsigned char tmp;
127    struct ds1390 *chip;
128    int res;
129
130    spi->mode = SPI_MODE_3;
131    spi->bits_per_word = 8;
132    spi_setup(spi);
133
134    chip = kzalloc(sizeof *chip, GFP_KERNEL);
135    if (!chip) {
136        dev_err(&spi->dev, "unable to allocate device memory\n");
137        return -ENOMEM;
138    }
139    dev_set_drvdata(&spi->dev, chip);
140
141    res = ds1390_get_reg(&spi->dev, DS1390_REG_SECONDS, &tmp);
142    if (res != 0) {
143        dev_err(&spi->dev, "unable to read device\n");
144        kfree(chip);
145        return res;
146    }
147
148    chip->rtc = rtc_device_register("ds1390",
149                &spi->dev, &ds1390_rtc_ops, THIS_MODULE);
150    if (IS_ERR(chip->rtc)) {
151        dev_err(&spi->dev, "unable to register device\n");
152        res = PTR_ERR(chip->rtc);
153        kfree(chip);
154    }
155
156    return res;
157}
158
159static int __devexit ds1390_remove(struct spi_device *spi)
160{
161    struct ds1390 *chip = spi_get_drvdata(spi);
162
163    rtc_device_unregister(chip->rtc);
164    kfree(chip);
165
166    return 0;
167}
168
169static struct spi_driver ds1390_driver = {
170    .driver = {
171        .name = "rtc-ds1390",
172        .owner = THIS_MODULE,
173    },
174    .probe = ds1390_probe,
175    .remove = __devexit_p(ds1390_remove),
176};
177
178module_spi_driver(ds1390_driver);
179
180MODULE_DESCRIPTION("Dallas/Maxim DS1390/93/94 SPI RTC driver");
181MODULE_AUTHOR("Mark Jackson <mpfj@mimc.co.uk>");
182MODULE_LICENSE("GPL");
183MODULE_ALIAS("spi:rtc-ds1390");
184

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