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
|
/* rtc-ds1347.c
*
* Driver for Dallas Semiconductor DS1347 Low Current, SPI Compatible
* Real Time Clock
*
* Author : Raghavendra Chandra Ganiga <ravi23ganiga@gmail.com>
*
* 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/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/spi/spi.h>
#include <linux/bcd.h>
/* Registers in ds1347 rtc */
#define DS1347_SECONDS_REG 0x01
#define DS1347_MINUTES_REG 0x03
#define DS1347_HOURS_REG 0x05
#define DS1347_DATE_REG 0x07
#define DS1347_MONTH_REG 0x09
#define DS1347_DAY_REG 0x0B
#define DS1347_YEAR_REG 0x0D
#define DS1347_CONTROL_REG 0x0F
#define DS1347_STATUS_REG 0x17
#define DS1347_CLOCK_BURST 0x3F
static int ds1347_read_reg(struct device *dev, unsigned char address,
unsigned char *data)
{
struct spi_device *spi = to_spi_device(dev);
*data = address | 0x80;
return spi_write_then_read(spi, data, 1, data, 1);
}
static int ds1347_write_reg(struct device *dev, unsigned char address,
unsigned char data)
{
struct spi_device *spi = to_spi_device(dev);
unsigned char buf[2];
buf[0] = address & 0x7F;
buf[1] = data;
return spi_write_then_read(spi, buf, 2, NULL, 0);
}
static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
{
struct spi_device *spi = to_spi_device(dev);
int err;
unsigned char buf[8];
buf[0] = DS1347_CLOCK_BURST | 0x80;
err = spi_write_then_read(spi, buf, 1, buf, 8);
if (err)
return err;
dt->tm_sec = bcd2bin(buf[0]);
dt->tm_min = bcd2bin(buf[1]);
dt->tm_hour = bcd2bin(buf[2] & 0x3F);
dt->tm_mday = bcd2bin(buf[3]);
dt->tm_mon = bcd2bin(buf[4]) - 1;
dt->tm_wday = bcd2bin(buf[5]) - 1;
dt->tm_year = bcd2bin(buf[6]) + 100;
return rtc_valid_tm(dt);
}
static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
{
struct spi_device *spi = to_spi_device(dev);
unsigned char buf[9];
buf[0] = DS1347_CLOCK_BURST & 0x7F;
buf[1] = bin2bcd(dt->tm_sec);
buf[2] = bin2bcd(dt->tm_min);
buf[3] = (bin2bcd(dt->tm_hour) & 0x3F);
buf[4] = bin2bcd(dt->tm_mday);
buf[5] = bin2bcd(dt->tm_mon + 1);
buf[6] = bin2bcd(dt->tm_wday + 1);
/* year in linux is from 1900 i.e in range of 100
in rtc it is from 00 to 99 */
dt->tm_year = dt->tm_year % 100;
buf[7] = bin2bcd(dt->tm_year);
buf[8] = bin2bcd(0x00);
/* write the rtc settings */
return spi_write_then_read(spi, buf, 9, NULL, 0);
}
static const struct rtc_class_ops ds1347_rtc_ops = {
.read_time = ds1347_read_time,
.set_time = ds1347_set_time,
};
static int ds1347_probe(struct spi_device *spi)
{
struct rtc_device *rtc;
unsigned char data;
int res;
/* spi setup with ds1347 in mode 3 and bits per word as 8 */
spi->mode = SPI_MODE_3;
spi->bits_per_word = 8;
spi_setup(spi);
/* RTC Settings */
res = ds1347_read_reg(&spi->dev, DS1347_SECONDS_REG, &data);
if (res)
return res;
/* Disable the write protect of rtc */
ds1347_read_reg(&spi->dev, DS1347_CONTROL_REG, &data);
data = data & ~(1<<7);
ds1347_write_reg(&spi->dev, DS1347_CONTROL_REG, data);
/* Enable the oscillator , disable the oscillator stop flag,
and glitch filter to reduce current consumption */
ds1347_read_reg(&spi->dev, DS1347_STATUS_REG, &data);
data = data & 0x1B;
ds1347_write_reg(&spi->dev, DS1347_STATUS_REG, data);
/* display the settings */
ds1347_read_reg(&spi->dev, DS1347_CONTROL_REG, &data);
dev_info(&spi->dev, "DS1347 RTC CTRL Reg = 0x%02x\n", data);
ds1347_read_reg(&spi->dev, DS1347_STATUS_REG, &data);
dev_info(&spi->dev, "DS1347 RTC Status Reg = 0x%02x\n", data);
rtc = devm_rtc_device_register(&spi->dev, "ds1347",
&ds1347_rtc_ops, THIS_MODULE);
if (IS_ERR(rtc))
return PTR_ERR(rtc);
spi_set_drvdata(spi, rtc);
return 0;
}
static struct spi_driver ds1347_driver = {
.driver = {
.name = "ds1347",
},
.probe = ds1347_probe,
};
module_spi_driver(ds1347_driver);
MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");
MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>");
MODULE_LICENSE("GPL v2");
|
