// SPDX-License-Identifier: GPL-2.0-only/* drivers/rtc/rtc-max6902.c * * Copyright (C) 2006 8D Technologies inc. * Copyright (C) 2004 Compulab Ltd. * * 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 0;} 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");