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
|
/*
* Driver for ST M41T94 SPI RTC
*
* Copyright (C) 2008 Kim B. Heino
*
* 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.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/spi/spi.h>
#include <linux/bcd.h>
#define M41T94_REG_SECONDS 0x01
#define M41T94_REG_MINUTES 0x02
#define M41T94_REG_HOURS 0x03
#define M41T94_REG_WDAY 0x04
#define M41T94_REG_DAY 0x05
#define M41T94_REG_MONTH 0x06
#define M41T94_REG_YEAR 0x07
#define M41T94_REG_HT 0x0c
#define M41T94_BIT_HALT 0x40
#define M41T94_BIT_STOP 0x80
#define M41T94_BIT_CB 0x40
#define M41T94_BIT_CEB 0x80
static int m41t94_set_time(struct device *dev, struct rtc_time *tm)
{
struct spi_device *spi = to_spi_device(dev);
u8 buf[8]; /* write cmd + 7 registers */
dev_dbg(dev, "%s secs=%d, mins=%d, "
"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
"write", tm->tm_sec, tm->tm_min,
tm->tm_hour, tm->tm_mday,
tm->tm_mon, tm->tm_year, tm->tm_wday);
buf[0] = 0x80 | M41T94_REG_SECONDS; /* write time + date */
buf[M41T94_REG_SECONDS] = bin2bcd(tm->tm_sec);
buf[M41T94_REG_MINUTES] = bin2bcd(tm->tm_min);
buf[M41T94_REG_HOURS] = bin2bcd(tm->tm_hour);
buf[M41T94_REG_WDAY] = bin2bcd(tm->tm_wday + 1);
buf[M41T94_REG_DAY] = bin2bcd(tm->tm_mday);
buf[M41T94_REG_MONTH] = bin2bcd(tm->tm_mon + 1);
buf[M41T94_REG_HOURS] |= M41T94_BIT_CEB;
if (tm->tm_year >= 100)
buf[M41T94_REG_HOURS] |= M41T94_BIT_CB;
buf[M41T94_REG_YEAR] = bin2bcd(tm->tm_year % 100);
return spi_write(spi, buf, 8);
}
static int m41t94_read_time(struct device *dev, struct rtc_time *tm)
{
struct spi_device *spi = to_spi_device(dev);
u8 buf[2];
int ret, hour;
/* clear halt update bit */
ret = spi_w8r8(spi, M41T94_REG_HT);
if (ret < 0)
return ret;
if (ret & M41T94_BIT_HALT) {
buf[0] = 0x80 | M41T94_REG_HT;
buf[1] = ret & ~M41T94_BIT_HALT;
spi_write(spi, buf, 2);
}
/* clear stop bit */
ret = spi_w8r8(spi, M41T94_REG_SECONDS);
if (ret < 0)
return ret;
if (ret & M41T94_BIT_STOP) {
buf[0] = 0x80 | M41T94_REG_SECONDS;
buf[1] = ret & ~M41T94_BIT_STOP;
spi_write(spi, buf, 2);
}
tm->tm_sec = bcd2bin(spi_w8r8(spi, M41T94_REG_SECONDS));
tm->tm_min = bcd2bin(spi_w8r8(spi, M41T94_REG_MINUTES));
hour = spi_w8r8(spi, M41T94_REG_HOURS);
tm->tm_hour = bcd2bin(hour & 0x3f);
tm->tm_wday = bcd2bin(spi_w8r8(spi, M41T94_REG_WDAY)) - 1;
tm->tm_mday = bcd2bin(spi_w8r8(spi, M41T94_REG_DAY));
tm->tm_mon = bcd2bin(spi_w8r8(spi, M41T94_REG_MONTH)) - 1;
tm->tm_year = bcd2bin(spi_w8r8(spi, M41T94_REG_YEAR));
if ((hour & M41T94_BIT_CB) || !(hour & M41T94_BIT_CEB))
tm->tm_year += 100;
dev_dbg(dev, "%s secs=%d, mins=%d, "
"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
"read", tm->tm_sec, tm->tm_min,
tm->tm_hour, tm->tm_mday,
tm->tm_mon, tm->tm_year, tm->tm_wday);
/* initial clock setting can be undefined */
return rtc_valid_tm(tm);
}
static const struct rtc_class_ops m41t94_rtc_ops = {
.read_time = m41t94_read_time,
.set_time = m41t94_set_time,
};
static struct spi_driver m41t94_driver;
static int m41t94_probe(struct spi_device *spi)
{
struct rtc_device *rtc;
int res;
spi->bits_per_word = 8;
spi_setup(spi);
res = spi_w8r8(spi, M41T94_REG_SECONDS);
if (res < 0) {
dev_err(&spi->dev, "not found.\n");
return res;
}
rtc = devm_rtc_device_register(&spi->dev, m41t94_driver.driver.name,
&m41t94_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
spi_set_drvdata(spi, rtc);
return 0;
}
static struct spi_driver m41t94_driver = {
.driver = {
.name = "rtc-m41t94",
},
.probe = m41t94_probe,
};
module_spi_driver(m41t94_driver);
MODULE_AUTHOR("Kim B. Heino <Kim.Heino@bluegiga.com>");
MODULE_DESCRIPTION("Driver for ST M41T94 SPI RTC");
MODULE_LICENSE("GPL");
MODULE_ALIAS("spi:rtc-m41t94");
|
