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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
f30c2269 | 2 | /* drivers/rtc/rtc-max6902.c |
8e12ecc2 RA |
3 | * |
4 | * Copyright (C) 2006 8D Technologies inc. | |
5 | * Copyright (C) 2004 Compulab Ltd. | |
6 | * | |
8e12ecc2 | 7 | * Driver for MAX6902 spi RTC |
8e12ecc2 RA |
8 | */ |
9 | ||
8e12ecc2 | 10 | #include <linux/module.h> |
8e12ecc2 RA |
11 | #include <linux/kernel.h> |
12 | #include <linux/platform_device.h> | |
13 | #include <linux/init.h> | |
14 | #include <linux/rtc.h> | |
15 | #include <linux/spi/spi.h> | |
16 | #include <linux/bcd.h> | |
8e12ecc2 RA |
17 | |
18 | #define MAX6902_REG_SECONDS 0x01 | |
19 | #define MAX6902_REG_MINUTES 0x03 | |
20 | #define MAX6902_REG_HOURS 0x05 | |
21 | #define MAX6902_REG_DATE 0x07 | |
22 | #define MAX6902_REG_MONTH 0x09 | |
23 | #define MAX6902_REG_DAY 0x0B | |
24 | #define MAX6902_REG_YEAR 0x0D | |
25 | #define MAX6902_REG_CONTROL 0x0F | |
26 | #define MAX6902_REG_CENTURY 0x13 | |
27 | ||
a5771c6c | 28 | static int max6902_set_reg(struct device *dev, unsigned char address, |
8e12ecc2 RA |
29 | unsigned char data) |
30 | { | |
31 | struct spi_device *spi = to_spi_device(dev); | |
32 | unsigned char buf[2]; | |
33 | ||
34 | /* MSB must be '0' to write */ | |
35 | buf[0] = address & 0x7f; | |
36 | buf[1] = data; | |
37 | ||
a5771c6c | 38 | return spi_write_then_read(spi, buf, 2, NULL, 0); |
8e12ecc2 RA |
39 | } |
40 | ||
41 | static int max6902_get_reg(struct device *dev, unsigned char address, | |
42 | unsigned char *data) | |
43 | { | |
44 | struct spi_device *spi = to_spi_device(dev); | |
8e12ecc2 RA |
45 | |
46 | /* Set MSB to indicate read */ | |
a5771c6c | 47 | *data = address | 0x80; |
8e12ecc2 | 48 | |
a5771c6c | 49 | return spi_write_then_read(spi, data, 1, data, 1); |
8e12ecc2 RA |
50 | } |
51 | ||
a5771c6c | 52 | static int max6902_read_time(struct device *dev, struct rtc_time *dt) |
8e12ecc2 | 53 | { |
a5771c6c | 54 | int err, century; |
8e12ecc2 | 55 | struct spi_device *spi = to_spi_device(dev); |
a5771c6c | 56 | unsigned char buf[8]; |
8e12ecc2 | 57 | |
a5771c6c | 58 | buf[0] = 0xbf; /* Burst read */ |
8e12ecc2 | 59 | |
a5771c6c AZ |
60 | err = spi_write_then_read(spi, buf, 1, buf, 8); |
61 | if (err != 0) | |
62 | return err; | |
8e12ecc2 RA |
63 | |
64 | /* The chip sends data in this order: | |
65 | * Seconds, Minutes, Hours, Date, Month, Day, Year */ | |
a5771c6c AZ |
66 | dt->tm_sec = bcd2bin(buf[0]); |
67 | dt->tm_min = bcd2bin(buf[1]); | |
68 | dt->tm_hour = bcd2bin(buf[2]); | |
69 | dt->tm_mday = bcd2bin(buf[3]); | |
70 | dt->tm_mon = bcd2bin(buf[4]) - 1; | |
71 | dt->tm_wday = bcd2bin(buf[5]); | |
72 | dt->tm_year = bcd2bin(buf[6]); | |
73 | ||
74 | /* Read century */ | |
75 | err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &buf[0]); | |
76 | if (err != 0) | |
77 | return err; | |
8e12ecc2 | 78 | |
a5771c6c | 79 | century = bcd2bin(buf[0]) * 100; |
8e12ecc2 RA |
80 | |
81 | dt->tm_year += century; | |
82 | dt->tm_year -= 1900; | |
83 | ||
22652ba7 | 84 | return 0; |
8e12ecc2 RA |
85 | } |
86 | ||
a5771c6c | 87 | static int max6902_set_time(struct device *dev, struct rtc_time *dt) |
8e12ecc2 | 88 | { |
a5771c6c | 89 | dt->tm_year = dt->tm_year + 1900; |
8e12ecc2 RA |
90 | |
91 | /* Remove write protection */ | |
08348d2f | 92 | max6902_set_reg(dev, MAX6902_REG_CONTROL, 0); |
8e12ecc2 | 93 | |
08348d2f AL |
94 | max6902_set_reg(dev, MAX6902_REG_SECONDS, bin2bcd(dt->tm_sec)); |
95 | max6902_set_reg(dev, MAX6902_REG_MINUTES, bin2bcd(dt->tm_min)); | |
96 | max6902_set_reg(dev, MAX6902_REG_HOURS, bin2bcd(dt->tm_hour)); | |
8e12ecc2 | 97 | |
08348d2f AL |
98 | max6902_set_reg(dev, MAX6902_REG_DATE, bin2bcd(dt->tm_mday)); |
99 | max6902_set_reg(dev, MAX6902_REG_MONTH, bin2bcd(dt->tm_mon + 1)); | |
100 | max6902_set_reg(dev, MAX6902_REG_DAY, bin2bcd(dt->tm_wday)); | |
101 | max6902_set_reg(dev, MAX6902_REG_YEAR, bin2bcd(dt->tm_year % 100)); | |
102 | max6902_set_reg(dev, MAX6902_REG_CENTURY, bin2bcd(dt->tm_year / 100)); | |
8e12ecc2 RA |
103 | |
104 | /* Compulab used a delay here. However, the datasheet | |
105 | * does not mention a delay being required anywhere... */ | |
106 | /* delay(2000); */ | |
107 | ||
108 | /* Write protect */ | |
08348d2f | 109 | max6902_set_reg(dev, MAX6902_REG_CONTROL, 0x80); |
8e12ecc2 RA |
110 | |
111 | return 0; | |
112 | } | |
113 | ||
ff8371ac | 114 | static const struct rtc_class_ops max6902_rtc_ops = { |
8e12ecc2 RA |
115 | .read_time = max6902_read_time, |
116 | .set_time = max6902_set_time, | |
117 | }; | |
118 | ||
5a167f45 | 119 | static int max6902_probe(struct spi_device *spi) |
8e12ecc2 RA |
120 | { |
121 | struct rtc_device *rtc; | |
122 | unsigned char tmp; | |
8e12ecc2 RA |
123 | int res; |
124 | ||
8e12ecc2 RA |
125 | spi->mode = SPI_MODE_3; |
126 | spi->bits_per_word = 8; | |
127 | spi_setup(spi); | |
128 | ||
8e12ecc2 | 129 | res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp); |
a5771c6c | 130 | if (res != 0) |
8e12ecc2 | 131 | return res; |
a5771c6c | 132 | |
04353a73 JH |
133 | rtc = devm_rtc_device_register(&spi->dev, "max6902", |
134 | &max6902_rtc_ops, THIS_MODULE); | |
a5771c6c AZ |
135 | if (IS_ERR(rtc)) |
136 | return PTR_ERR(rtc); | |
8e12ecc2 | 137 | |
a5ef73f0 | 138 | spi_set_drvdata(spi, rtc); |
8e12ecc2 RA |
139 | return 0; |
140 | } | |
141 | ||
8e12ecc2 RA |
142 | static struct spi_driver max6902_driver = { |
143 | .driver = { | |
5c076fce | 144 | .name = "rtc-max6902", |
8e12ecc2 | 145 | }, |
5c076fce | 146 | .probe = max6902_probe, |
8e12ecc2 RA |
147 | }; |
148 | ||
109e9418 | 149 | module_spi_driver(max6902_driver); |
8e12ecc2 | 150 | |
83246a16 SK |
151 | MODULE_DESCRIPTION("max6902 spi RTC driver"); |
152 | MODULE_AUTHOR("Raphael Assenat"); | |
153 | MODULE_LICENSE("GPL"); | |
e0626e38 | 154 | MODULE_ALIAS("spi:rtc-max6902"); |