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f30c2269 | 1 | /* drivers/rtc/rtc-max6902.c |
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2 | * |
3 | * Copyright (C) 2006 8D Technologies inc. | |
4 | * Copyright (C) 2004 Compulab Ltd. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License version 2 as | |
8 | * published by the Free Software Foundation. | |
9 | * | |
10 | * Driver for MAX6902 spi RTC | |
11 | * | |
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12 | */ |
13 | ||
8e12ecc2 | 14 | #include <linux/module.h> |
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15 | #include <linux/kernel.h> |
16 | #include <linux/platform_device.h> | |
17 | #include <linux/init.h> | |
18 | #include <linux/rtc.h> | |
19 | #include <linux/spi/spi.h> | |
20 | #include <linux/bcd.h> | |
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21 | |
22 | #define MAX6902_REG_SECONDS 0x01 | |
23 | #define MAX6902_REG_MINUTES 0x03 | |
24 | #define MAX6902_REG_HOURS 0x05 | |
25 | #define MAX6902_REG_DATE 0x07 | |
26 | #define MAX6902_REG_MONTH 0x09 | |
27 | #define MAX6902_REG_DAY 0x0B | |
28 | #define MAX6902_REG_YEAR 0x0D | |
29 | #define MAX6902_REG_CONTROL 0x0F | |
30 | #define MAX6902_REG_CENTURY 0x13 | |
31 | ||
a5771c6c | 32 | static int max6902_set_reg(struct device *dev, unsigned char address, |
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33 | unsigned char data) |
34 | { | |
35 | struct spi_device *spi = to_spi_device(dev); | |
36 | unsigned char buf[2]; | |
37 | ||
38 | /* MSB must be '0' to write */ | |
39 | buf[0] = address & 0x7f; | |
40 | buf[1] = data; | |
41 | ||
a5771c6c | 42 | return spi_write_then_read(spi, buf, 2, NULL, 0); |
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43 | } |
44 | ||
45 | static int max6902_get_reg(struct device *dev, unsigned char address, | |
46 | unsigned char *data) | |
47 | { | |
48 | struct spi_device *spi = to_spi_device(dev); | |
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49 | |
50 | /* Set MSB to indicate read */ | |
a5771c6c | 51 | *data = address | 0x80; |
8e12ecc2 | 52 | |
a5771c6c | 53 | return spi_write_then_read(spi, data, 1, data, 1); |
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54 | } |
55 | ||
a5771c6c | 56 | static int max6902_read_time(struct device *dev, struct rtc_time *dt) |
8e12ecc2 | 57 | { |
a5771c6c | 58 | int err, century; |
8e12ecc2 | 59 | struct spi_device *spi = to_spi_device(dev); |
a5771c6c | 60 | unsigned char buf[8]; |
8e12ecc2 | 61 | |
a5771c6c | 62 | buf[0] = 0xbf; /* Burst read */ |
8e12ecc2 | 63 | |
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64 | err = spi_write_then_read(spi, buf, 1, buf, 8); |
65 | if (err != 0) | |
66 | return err; | |
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67 | |
68 | /* The chip sends data in this order: | |
69 | * Seconds, Minutes, Hours, Date, Month, Day, Year */ | |
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70 | dt->tm_sec = bcd2bin(buf[0]); |
71 | dt->tm_min = bcd2bin(buf[1]); | |
72 | dt->tm_hour = bcd2bin(buf[2]); | |
73 | dt->tm_mday = bcd2bin(buf[3]); | |
74 | dt->tm_mon = bcd2bin(buf[4]) - 1; | |
75 | dt->tm_wday = bcd2bin(buf[5]); | |
76 | dt->tm_year = bcd2bin(buf[6]); | |
77 | ||
78 | /* Read century */ | |
79 | err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &buf[0]); | |
80 | if (err != 0) | |
81 | return err; | |
8e12ecc2 | 82 | |
a5771c6c | 83 | century = bcd2bin(buf[0]) * 100; |
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84 | |
85 | dt->tm_year += century; | |
86 | dt->tm_year -= 1900; | |
87 | ||
a5771c6c | 88 | return rtc_valid_tm(dt); |
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89 | } |
90 | ||
a5771c6c | 91 | static int max6902_set_time(struct device *dev, struct rtc_time *dt) |
8e12ecc2 | 92 | { |
a5771c6c | 93 | dt->tm_year = dt->tm_year + 1900; |
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94 | |
95 | /* Remove write protection */ | |
96 | max6902_set_reg(dev, 0xF, 0); | |
97 | ||
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98 | max6902_set_reg(dev, 0x01, bin2bcd(dt->tm_sec)); |
99 | max6902_set_reg(dev, 0x03, bin2bcd(dt->tm_min)); | |
100 | max6902_set_reg(dev, 0x05, bin2bcd(dt->tm_hour)); | |
8e12ecc2 | 101 | |
fe20ba70 | 102 | max6902_set_reg(dev, 0x07, bin2bcd(dt->tm_mday)); |
a5771c6c | 103 | max6902_set_reg(dev, 0x09, bin2bcd(dt->tm_mon + 1)); |
fe20ba70 | 104 | max6902_set_reg(dev, 0x0B, bin2bcd(dt->tm_wday)); |
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105 | max6902_set_reg(dev, 0x0D, bin2bcd(dt->tm_year % 100)); |
106 | max6902_set_reg(dev, 0x13, bin2bcd(dt->tm_year / 100)); | |
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107 | |
108 | /* Compulab used a delay here. However, the datasheet | |
109 | * does not mention a delay being required anywhere... */ | |
110 | /* delay(2000); */ | |
111 | ||
112 | /* Write protect */ | |
113 | max6902_set_reg(dev, 0xF, 0x80); | |
114 | ||
115 | return 0; | |
116 | } | |
117 | ||
ff8371ac | 118 | static const struct rtc_class_ops max6902_rtc_ops = { |
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119 | .read_time = max6902_read_time, |
120 | .set_time = max6902_set_time, | |
121 | }; | |
122 | ||
123 | static int __devinit max6902_probe(struct spi_device *spi) | |
124 | { | |
125 | struct rtc_device *rtc; | |
126 | unsigned char tmp; | |
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127 | int res; |
128 | ||
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129 | spi->mode = SPI_MODE_3; |
130 | spi->bits_per_word = 8; | |
131 | spi_setup(spi); | |
132 | ||
8e12ecc2 | 133 | res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp); |
a5771c6c | 134 | if (res != 0) |
8e12ecc2 | 135 | return res; |
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136 | |
137 | rtc = rtc_device_register("max6902", | |
138 | &spi->dev, &max6902_rtc_ops, THIS_MODULE); | |
139 | if (IS_ERR(rtc)) | |
140 | return PTR_ERR(rtc); | |
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141 | |
142 | return 0; | |
143 | } | |
144 | ||
145 | static int __devexit max6902_remove(struct spi_device *spi) | |
146 | { | |
a5771c6c | 147 | struct rtc_device *rtc = platform_get_drvdata(spi); |
8e12ecc2 | 148 | |
a5771c6c | 149 | rtc_device_unregister(rtc); |
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150 | return 0; |
151 | } | |
152 | ||
153 | static struct spi_driver max6902_driver = { | |
154 | .driver = { | |
5c076fce | 155 | .name = "rtc-max6902", |
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156 | .bus = &spi_bus_type, |
157 | .owner = THIS_MODULE, | |
158 | }, | |
5c076fce | 159 | .probe = max6902_probe, |
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160 | .remove = __devexit_p(max6902_remove), |
161 | }; | |
162 | ||
163 | static __init int max6902_init(void) | |
164 | { | |
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165 | return spi_register_driver(&max6902_driver); |
166 | } | |
167 | module_init(max6902_init); | |
168 | ||
169 | static __exit void max6902_exit(void) | |
170 | { | |
171 | spi_unregister_driver(&max6902_driver); | |
172 | } | |
173 | module_exit(max6902_exit); | |
174 | ||
175 | MODULE_DESCRIPTION ("max6902 spi RTC driver"); | |
176 | MODULE_AUTHOR ("Raphael Assenat"); | |
177 | MODULE_LICENSE ("GPL"); |