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154 lines
3.7 KiB
154 lines
3.7 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* 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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* Driver for MAX6902 spi RTC |
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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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