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Mark Jackson06de1802008-11-12 13:27:07 -08001/*
Alessandro Zummo7b9b2ef2009-01-06 14:42:16 -08002 * rtc-ds1390.c -- driver for the Dallas/Maxim DS1390/93/94 SPI RTC
Mark Jackson06de1802008-11-12 13:27:07 -08003 *
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 *
Alessandro Zummo7b9b2ef2009-01-06 14:42:16 -080011 * NOTE: Currently this driver only supports the bare minimum for read
12 * and write the RTC. The extra features provided by the chip family
Mark Jackson06de1802008-11-12 13:27:07 -080013 * (alarms, trickle charger, different control registers) are unavailable.
14 */
15
Alessandro Zummo7b9b2ef2009-01-06 14:42:16 -080016#include <linux/init.h>
17#include <linux/module.h>
Mark Jackson06de1802008-11-12 13:27:07 -080018#include <linux/platform_device.h>
19#include <linux/rtc.h>
20#include <linux/spi/spi.h>
21#include <linux/bcd.h>
22
23#define DS1390_REG_100THS 0x00
24#define DS1390_REG_SECONDS 0x01
25#define DS1390_REG_MINUTES 0x02
26#define DS1390_REG_HOURS 0x03
27#define DS1390_REG_DAY 0x04
28#define DS1390_REG_DATE 0x05
29#define DS1390_REG_MONTH_CENT 0x06
30#define DS1390_REG_YEAR 0x07
31
32#define DS1390_REG_ALARM_100THS 0x08
33#define DS1390_REG_ALARM_SECONDS 0x09
34#define DS1390_REG_ALARM_MINUTES 0x0A
35#define DS1390_REG_ALARM_HOURS 0x0B
36#define DS1390_REG_ALARM_DAY_DATE 0x0C
37
38#define DS1390_REG_CONTROL 0x0D
39#define DS1390_REG_STATUS 0x0E
40#define DS1390_REG_TRICKLE 0x0F
41
42struct ds1390 {
43 struct rtc_device *rtc;
44 u8 txrx_buf[9]; /* cmd + 8 registers */
45};
46
Mark Jackson06de1802008-11-12 13:27:07 -080047static int ds1390_get_reg(struct device *dev, unsigned char address,
48 unsigned char *data)
49{
50 struct spi_device *spi = to_spi_device(dev);
51 struct ds1390 *chip = dev_get_drvdata(dev);
52 int status;
53
54 if (!data)
55 return -EINVAL;
56
57 /* Clear MSB to indicate read */
58 chip->txrx_buf[0] = address & 0x7f;
59 /* do the i/o */
60 status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 1);
61 if (status != 0)
62 return status;
63
64 *data = chip->txrx_buf[1];
65
66 return 0;
67}
68
Alessandro Zummo7b9b2ef2009-01-06 14:42:16 -080069static int ds1390_read_time(struct device *dev, struct rtc_time *dt)
Mark Jackson06de1802008-11-12 13:27:07 -080070{
71 struct spi_device *spi = to_spi_device(dev);
72 struct ds1390 *chip = dev_get_drvdata(dev);
73 int status;
74
75 /* build the message */
76 chip->txrx_buf[0] = DS1390_REG_SECONDS;
77
78 /* do the i/o */
79 status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 8);
80 if (status != 0)
81 return status;
82
83 /* The chip sends data in this order:
84 * Seconds, Minutes, Hours, Day, Date, Month / Century, Year */
85 dt->tm_sec = bcd2bin(chip->txrx_buf[0]);
86 dt->tm_min = bcd2bin(chip->txrx_buf[1]);
87 dt->tm_hour = bcd2bin(chip->txrx_buf[2]);
88 dt->tm_wday = bcd2bin(chip->txrx_buf[3]);
89 dt->tm_mday = bcd2bin(chip->txrx_buf[4]);
90 /* mask off century bit */
91 dt->tm_mon = bcd2bin(chip->txrx_buf[5] & 0x7f) - 1;
92 /* adjust for century bit */
93 dt->tm_year = bcd2bin(chip->txrx_buf[6]) + ((chip->txrx_buf[5] & 0x80) ? 100 : 0);
94
95 return rtc_valid_tm(dt);
96}
97
Alessandro Zummo7b9b2ef2009-01-06 14:42:16 -080098static int ds1390_set_time(struct device *dev, struct rtc_time *dt)
Mark Jackson06de1802008-11-12 13:27:07 -080099{
100 struct spi_device *spi = to_spi_device(dev);
101 struct ds1390 *chip = dev_get_drvdata(dev);
102
103 /* build the message */
104 chip->txrx_buf[0] = DS1390_REG_SECONDS | 0x80;
105 chip->txrx_buf[1] = bin2bcd(dt->tm_sec);
106 chip->txrx_buf[2] = bin2bcd(dt->tm_min);
107 chip->txrx_buf[3] = bin2bcd(dt->tm_hour);
108 chip->txrx_buf[4] = bin2bcd(dt->tm_wday);
109 chip->txrx_buf[5] = bin2bcd(dt->tm_mday);
110 chip->txrx_buf[6] = bin2bcd(dt->tm_mon + 1) |
111 ((dt->tm_year > 99) ? 0x80 : 0x00);
112 chip->txrx_buf[7] = bin2bcd(dt->tm_year % 100);
113
114 /* do the i/o */
115 return spi_write_then_read(spi, chip->txrx_buf, 8, NULL, 0);
116}
117
Mark Jackson06de1802008-11-12 13:27:07 -0800118static const struct rtc_class_ops ds1390_rtc_ops = {
119 .read_time = ds1390_read_time,
120 .set_time = ds1390_set_time,
121};
122
123static int __devinit ds1390_probe(struct spi_device *spi)
124{
Mark Jackson06de1802008-11-12 13:27:07 -0800125 unsigned char tmp;
126 struct ds1390 *chip;
127 int res;
128
Mark Jackson06de1802008-11-12 13:27:07 -0800129 spi->mode = SPI_MODE_3;
130 spi->bits_per_word = 8;
131 spi_setup(spi);
132
133 chip = kzalloc(sizeof *chip, GFP_KERNEL);
134 if (!chip) {
Alessandro Zummo7b9b2ef2009-01-06 14:42:16 -0800135 dev_err(&spi->dev, "unable to allocate device memory\n");
Mark Jackson06de1802008-11-12 13:27:07 -0800136 return -ENOMEM;
137 }
Mark Jackson06de1802008-11-12 13:27:07 -0800138 dev_set_drvdata(&spi->dev, chip);
139
140 res = ds1390_get_reg(&spi->dev, DS1390_REG_SECONDS, &tmp);
Alessandro Zummo7b9b2ef2009-01-06 14:42:16 -0800141 if (res != 0) {
142 dev_err(&spi->dev, "unable to read device\n");
143 kfree(chip);
Mark Jackson06de1802008-11-12 13:27:07 -0800144 return res;
145 }
146
Alessandro Zummo7b9b2ef2009-01-06 14:42:16 -0800147 chip->rtc = rtc_device_register("ds1390",
148 &spi->dev, &ds1390_rtc_ops, THIS_MODULE);
149 if (IS_ERR(chip->rtc)) {
150 dev_err(&spi->dev, "unable to register device\n");
151 res = PTR_ERR(chip->rtc);
152 kfree(chip);
153 }
154
155 return res;
Mark Jackson06de1802008-11-12 13:27:07 -0800156}
157
158static int __devexit ds1390_remove(struct spi_device *spi)
159{
160 struct ds1390 *chip = platform_get_drvdata(spi);
Mark Jackson06de1802008-11-12 13:27:07 -0800161
Alessandro Zummo7b9b2ef2009-01-06 14:42:16 -0800162 rtc_device_unregister(chip->rtc);
Mark Jackson06de1802008-11-12 13:27:07 -0800163 kfree(chip);
164
165 return 0;
166}
167
168static struct spi_driver ds1390_driver = {
169 .driver = {
170 .name = "rtc-ds1390",
171 .owner = THIS_MODULE,
172 },
173 .probe = ds1390_probe,
174 .remove = __devexit_p(ds1390_remove),
175};
176
177static __init int ds1390_init(void)
178{
179 return spi_register_driver(&ds1390_driver);
180}
181module_init(ds1390_init);
182
183static __exit void ds1390_exit(void)
184{
185 spi_unregister_driver(&ds1390_driver);
186}
187module_exit(ds1390_exit);
188
Alessandro Zummo7b9b2ef2009-01-06 14:42:16 -0800189MODULE_DESCRIPTION("Dallas/Maxim DS1390/93/94 SPI RTC driver");
Mark Jackson06de1802008-11-12 13:27:07 -0800190MODULE_AUTHOR("Mark Jackson <mpfj@mimc.co.uk>");
191MODULE_LICENSE("GPL");