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
ds3234_set_reg(struct device * dev,unsigned char address,unsigned char data)34 static 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
ds3234_get_reg(struct device * dev,unsigned char address,unsigned char * data)47 static 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
ds3234_read_time(struct device * dev,struct rtc_time * dt)57 static 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
ds3234_set_time(struct device * dev,struct rtc_time * dt)81 static 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
103 static const struct rtc_class_ops ds3234_rtc_ops = {
104 .read_time = ds3234_read_time,
105 .set_time = ds3234_set_time,
106 };
107
ds3234_probe(struct spi_device * spi)108 static 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
ds3234_remove(struct spi_device * spi)159 static 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
167 static 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
176 module_spi_driver(ds3234_driver);
177
178 MODULE_DESCRIPTION("DS3234 SPI RTC driver");
179 MODULE_AUTHOR("Dennis Aberilla <denzzzhome@yahoo.com>");
180 MODULE_LICENSE("GPL");
181 MODULE_ALIAS("spi:ds3234");
182