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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 | /* drivers/rtc/rtc-max6902.c * * Copyright (C) 2006 8D Technologies inc. * Copyright (C) 2004 Compulab Ltd. * * 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. * * Driver for MAX6902 spi RTC * */ #include <linux/module.h> #include <linux/kernel.h> #include <linux/platform_device.h> #include <linux/init.h> #include <linux/rtc.h> #include <linux/spi/spi.h> #include <linux/bcd.h> #define MAX6902_REG_SECONDS 0x01 #define MAX6902_REG_MINUTES 0x03 #define MAX6902_REG_HOURS 0x05 #define MAX6902_REG_DATE 0x07 #define MAX6902_REG_MONTH 0x09 #define MAX6902_REG_DAY 0x0B #define MAX6902_REG_YEAR 0x0D #define MAX6902_REG_CONTROL 0x0F #define MAX6902_REG_CENTURY 0x13 static int max6902_set_reg(struct device *dev, unsigned char address, unsigned char data) { struct spi_device *spi = to_spi_device(dev); unsigned char buf[2]; /* MSB must be '0' to write */ buf[0] = address & 0x7f; buf[1] = data; return spi_write_then_read(spi, buf, 2, NULL, 0); } static int max6902_get_reg(struct device *dev, unsigned char address, unsigned char *data) { struct spi_device *spi = to_spi_device(dev); /* Set MSB to indicate read */ *data = address | 0x80; return spi_write_then_read(spi, data, 1, data, 1); } static int max6902_read_time(struct device *dev, struct rtc_time *dt) { int err, century; struct spi_device *spi = to_spi_device(dev); unsigned char buf[8]; buf[0] = 0xbf; /* Burst read */ err = spi_write_then_read(spi, buf, 1, buf, 8); if (err != 0) return err; /* The chip sends data in this order: * Seconds, Minutes, Hours, Date, Month, Day, Year */ dt->tm_sec = bcd2bin(buf[0]); dt->tm_min = bcd2bin(buf[1]); dt->tm_hour = bcd2bin(buf[2]); dt->tm_mday = bcd2bin(buf[3]); dt->tm_mon = bcd2bin(buf[4]) - 1; dt->tm_wday = bcd2bin(buf[5]); dt->tm_year = bcd2bin(buf[6]); /* Read century */ err = max6902_get_reg(dev, MAX6902_REG_CENTURY, &buf[0]); if (err != 0) return err; century = bcd2bin(buf[0]) * 100; dt->tm_year += century; dt->tm_year -= 1900; return rtc_valid_tm(dt); } static int max6902_set_time(struct device *dev, struct rtc_time *dt) { dt->tm_year = dt->tm_year + 1900; /* Remove write protection */ max6902_set_reg(dev, MAX6902_REG_CONTROL, 0); max6902_set_reg(dev, MAX6902_REG_SECONDS, bin2bcd(dt->tm_sec)); max6902_set_reg(dev, MAX6902_REG_MINUTES, bin2bcd(dt->tm_min)); max6902_set_reg(dev, MAX6902_REG_HOURS, bin2bcd(dt->tm_hour)); max6902_set_reg(dev, MAX6902_REG_DATE, bin2bcd(dt->tm_mday)); max6902_set_reg(dev, MAX6902_REG_MONTH, bin2bcd(dt->tm_mon + 1)); max6902_set_reg(dev, MAX6902_REG_DAY, bin2bcd(dt->tm_wday)); max6902_set_reg(dev, MAX6902_REG_YEAR, bin2bcd(dt->tm_year % 100)); max6902_set_reg(dev, MAX6902_REG_CENTURY, bin2bcd(dt->tm_year / 100)); /* Compulab used a delay here. However, the datasheet * does not mention a delay being required anywhere... */ /* delay(2000); */ /* Write protect */ max6902_set_reg(dev, MAX6902_REG_CONTROL, 0x80); return 0; } static const struct rtc_class_ops max6902_rtc_ops = { .read_time = max6902_read_time, .set_time = max6902_set_time, }; static int max6902_probe(struct spi_device *spi) { struct rtc_device *rtc; unsigned char tmp; int res; spi->mode = SPI_MODE_3; spi->bits_per_word = 8; spi_setup(spi); res = max6902_get_reg(&spi->dev, MAX6902_REG_SECONDS, &tmp); if (res != 0) return res; rtc = devm_rtc_device_register(&spi->dev, "max6902", &max6902_rtc_ops, THIS_MODULE); if (IS_ERR(rtc)) return PTR_ERR(rtc); spi_set_drvdata(spi, rtc); return 0; } static struct spi_driver max6902_driver = { .driver = { .name = "rtc-max6902", .owner = THIS_MODULE, }, .probe = max6902_probe, }; module_spi_driver(max6902_driver); MODULE_DESCRIPTION("max6902 spi RTC driver"); MODULE_AUTHOR("Raphael Assenat"); MODULE_LICENSE("GPL"); MODULE_ALIAS("spi:rtc-max6902"); |