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
171
172
173
174
175
176
177
178
179
|
/* drivers/rtc/rtc-max6902.c
*
* Copyright (C) 2006 8D Technologies inc.
* Copyright (C) 2004 Compulab Ltd.
*
* 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.
*
* Driver for MAX6902 spi RTC
*
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/init.h>
#include <linux/rtc.h>
#include <linux/spi/spi.h>
#include <linux/bcd.h>
#define MAX6902_REG_SECONDS 0x01
#define MAX6902_REG_MINUTES 0x03
#define MAX6902_REG_HOURS 0x05
#define MAX6902_REG_DATE 0x07
#define MAX6902_REG_MONTH 0x09
#define MAX6902_REG_DAY 0x0B
#define MAX6902_REG_YEAR 0x0D
#define MAX6902_REG_CONTROL 0x0F
#define MAX6902_REG_CENTURY 0x13
static int max6902_set_reg(struct device *dev, unsigned char address,
unsigned char data)
{
struct spi_device *spi = to_spi_device(dev);
unsigned char buf[2];
/* MSB must be '0' to write */
buf[0] = address & 0x7f;
buf[1] = data;
return spi_write_then_read(spi, buf, 2, NULL, 0);
}
static int max6902_get_reg(struct device *dev, unsigned char address,
unsigned char *data)
{
struct spi_device *spi = to_spi_device(dev);
/* Set MSB to indicate read */
*data = address | 0x80;
return spi_write_then_read(spi, data, 1, data, 1);
}
static int max6902_read_time(struct device *dev, struct rtc_time *dt)
{
int err, century;
struct spi_device *spi = to_spi_device(dev);
unsigned char buf[8];
buf[0] = 0xbf; /* Burst read */
err = spi_write_then_read(spi, buf, 1, buf, 8);
if (err != 0)
return err;
/* The chip sends data in this order:
* Seconds, Minutes, Hours, Date, Month, Day, Year */
dt->tm_sec = bcd2bin(buf[0]);
dt->tm_min = bcd2bin(buf[1]);
dt->tm_hour = bcd2bin(buf[2]);
dt->tm_mday = bcd2bin(buf[3]);
dt->tm_mon = bcd2bin(buf[4]) - 1;
dt->tm_wday = bcd2bin(buf[5]);
dt->tm_year = bcd2bin(buf[6]);
/* Read century */
err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &buf[0]);
if (err != 0)
return err;
century = bcd2bin(buf[0]) * 100;
dt->tm_year += century;
dt->tm_year -= 1900;
return rtc_valid_tm(dt);
}
static int max6902_set_time(struct device *dev, struct rtc_time *dt)
{
dt->tm_year = dt->tm_year + 1900;
/* Remove write protection */
max6902_set_reg(dev, 0xF, 0);
max6902_set_reg(dev, 0x01, bin2bcd(dt->tm_sec));
max6902_set_reg(dev, 0x03, bin2bcd(dt->tm_min));
max6902_set_reg(dev, 0x05, bin2bcd(dt->tm_hour));
max6902_set_reg(dev, 0x07, bin2bcd(dt->tm_mday));
max6902_set_reg(dev, 0x09, bin2bcd(dt->tm_mon + 1));
max6902_set_reg(dev, 0x0B, bin2bcd(dt->tm_wday));
max6902_set_reg(dev, 0x0D, bin2bcd(dt->tm_year % 100));
max6902_set_reg(dev, 0x13, bin2bcd(dt->tm_year / 100));
/* Compulab used a delay here. However, the datasheet
* does not mention a delay being required anywhere... */
/* delay(2000); */
/* Write protect */
max6902_set_reg(dev, 0xF, 0x80);
return 0;
}
static const struct rtc_class_ops max6902_rtc_ops = {
.read_time = max6902_read_time,
.set_time = max6902_set_time,
};
static int __devinit max6902_probe(struct spi_device *spi)
{
struct rtc_device *rtc;
unsigned char tmp;
int res;
spi->mode = SPI_MODE_3;
spi->bits_per_word = 8;
spi_setup(spi);
res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp);
if (res != 0)
return res;
rtc = rtc_device_register("max6902",
&spi->dev, &max6902_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
dev_set_drvdata(&spi->dev, rtc);
return 0;
}
static int __devexit max6902_remove(struct spi_device *spi)
{
struct rtc_device *rtc = dev_get_drvdata(&spi->dev);
rtc_device_unregister(rtc);
return 0;
}
static struct spi_driver max6902_driver = {
.driver = {
.name = "rtc-max6902",
.bus = &spi_bus_type,
.owner = THIS_MODULE,
},
.probe = max6902_probe,
.remove = __devexit_p(max6902_remove),
};
static __init int max6902_init(void)
{
return spi_register_driver(&max6902_driver);
}
module_init(max6902_init);
static __exit void max6902_exit(void)
{
spi_unregister_driver(&max6902_driver);
}
module_exit(max6902_exit);
MODULE_DESCRIPTION ("max6902 spi RTC driver");
MODULE_AUTHOR ("Raphael Assenat");
MODULE_LICENSE ("GPL");
MODULE_ALIAS("spi:rtc-max6902");
|
