GNU Linux-libre 4.4.289-gnu1
[releases.git] / drivers / rtc / rtc-ds1347.c
1 /* rtc-ds1347.c
2  *
3  * Driver for Dallas Semiconductor DS1347 Low Current, SPI Compatible
4  * Real Time Clock
5  *
6  * Author : Raghavendra Chandra Ganiga <ravi23ganiga@gmail.com>
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 /* Registers in ds1347 rtc */
23
24 #define DS1347_SECONDS_REG      0x01
25 #define DS1347_MINUTES_REG      0x03
26 #define DS1347_HOURS_REG        0x05
27 #define DS1347_DATE_REG         0x07
28 #define DS1347_MONTH_REG        0x09
29 #define DS1347_DAY_REG          0x0B
30 #define DS1347_YEAR_REG         0x0D
31 #define DS1347_CONTROL_REG      0x0F
32 #define DS1347_STATUS_REG       0x17
33 #define DS1347_CLOCK_BURST      0x3F
34
35 static int ds1347_read_reg(struct device *dev, unsigned char address,
36                                 unsigned char *data)
37 {
38         struct spi_device *spi = to_spi_device(dev);
39
40         *data = address | 0x80;
41
42         return spi_write_then_read(spi, data, 1, data, 1);
43 }
44
45 static int ds1347_write_reg(struct device *dev, unsigned char address,
46                                 unsigned char data)
47 {
48         struct spi_device *spi = to_spi_device(dev);
49         unsigned char buf[2];
50
51         buf[0] = address & 0x7F;
52         buf[1] = data;
53
54         return spi_write_then_read(spi, buf, 2, NULL, 0);
55 }
56
57 static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
58 {
59         struct spi_device *spi = to_spi_device(dev);
60         int err;
61         unsigned char buf[8];
62
63         buf[0] = DS1347_CLOCK_BURST | 0x80;
64
65         err = spi_write_then_read(spi, buf, 1, buf, 8);
66         if (err)
67                 return err;
68
69         dt->tm_sec = bcd2bin(buf[0]);
70         dt->tm_min = bcd2bin(buf[1]);
71         dt->tm_hour = bcd2bin(buf[2] & 0x3F);
72         dt->tm_mday = bcd2bin(buf[3]);
73         dt->tm_mon = bcd2bin(buf[4]) - 1;
74         dt->tm_wday = bcd2bin(buf[5]) - 1;
75         dt->tm_year = bcd2bin(buf[6]) + 100;
76
77         return rtc_valid_tm(dt);
78 }
79
80 static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
81 {
82         struct spi_device *spi = to_spi_device(dev);
83         unsigned char buf[9];
84
85         buf[0] = DS1347_CLOCK_BURST & 0x7F;
86         buf[1] = bin2bcd(dt->tm_sec);
87         buf[2] = bin2bcd(dt->tm_min);
88         buf[3] = (bin2bcd(dt->tm_hour) & 0x3F);
89         buf[4] = bin2bcd(dt->tm_mday);
90         buf[5] = bin2bcd(dt->tm_mon + 1);
91         buf[6] = bin2bcd(dt->tm_wday + 1);
92
93         /* year in linux is from 1900 i.e in range of 100
94         in rtc it is from 00 to 99 */
95         dt->tm_year = dt->tm_year % 100;
96
97         buf[7] = bin2bcd(dt->tm_year);
98         buf[8] = bin2bcd(0x00);
99
100         /* write the rtc settings */
101         return spi_write_then_read(spi, buf, 9, NULL, 0);
102 }
103
104 static const struct rtc_class_ops ds1347_rtc_ops = {
105         .read_time = ds1347_read_time,
106         .set_time = ds1347_set_time,
107 };
108
109 static int ds1347_probe(struct spi_device *spi)
110 {
111         struct rtc_device *rtc;
112         unsigned char data;
113         int res;
114
115         /* spi setup with ds1347 in mode 3 and bits per word as 8 */
116         spi->mode = SPI_MODE_3;
117         spi->bits_per_word = 8;
118         spi_setup(spi);
119
120         /* RTC Settings */
121         res = ds1347_read_reg(&spi->dev, DS1347_SECONDS_REG, &data);
122         if (res)
123                 return res;
124
125         /* Disable the write protect of rtc */
126         ds1347_read_reg(&spi->dev, DS1347_CONTROL_REG, &data);
127         data = data & ~(1<<7);
128         ds1347_write_reg(&spi->dev, DS1347_CONTROL_REG, data);
129
130         /* Enable the oscillator , disable the oscillator stop flag,
131          and glitch filter to reduce current consumption */
132         ds1347_read_reg(&spi->dev, DS1347_STATUS_REG, &data);
133         data = data & 0x1B;
134         ds1347_write_reg(&spi->dev, DS1347_STATUS_REG, data);
135
136         /* display the settings */
137         ds1347_read_reg(&spi->dev, DS1347_CONTROL_REG, &data);
138         dev_info(&spi->dev, "DS1347 RTC CTRL Reg = 0x%02x\n", data);
139
140         ds1347_read_reg(&spi->dev, DS1347_STATUS_REG, &data);
141         dev_info(&spi->dev, "DS1347 RTC Status Reg = 0x%02x\n", data);
142
143         rtc = devm_rtc_device_register(&spi->dev, "ds1347",
144                                 &ds1347_rtc_ops, THIS_MODULE);
145
146         if (IS_ERR(rtc))
147                 return PTR_ERR(rtc);
148
149         spi_set_drvdata(spi, rtc);
150
151         return 0;
152 }
153
154 static struct spi_driver ds1347_driver = {
155         .driver = {
156                 .name = "ds1347",
157         },
158         .probe = ds1347_probe,
159 };
160
161 module_spi_driver(ds1347_driver);
162
163 MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");
164 MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>");
165 MODULE_LICENSE("GPL v2");