/* 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", }, .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");