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617b26a0 RG |
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", | |
617b26a0 RG |
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"); |