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