// SPDX-License-Identifier: GPL-2.0-or-later/* * The Netronix embedded controller is a microcontroller found in some * e-book readers designed by the original design manufacturer Netronix, Inc. * It contains RTC, battery monitoring, system power management, and PWM * functionality. * * This driver implements access to the RTC time and date. * * Copyright 2020 Jonathan Neuschäfer <j.neuschaefer@gmx.net> */ #include <linux/mfd/ntxec.h>#include <linux/module.h>#include <linux/platform_device.h>#include <linux/regmap.h>#include <linux/rtc.h>#include <linux/types.h> struct ntxec_rtc {	struct device *dev;	struct ntxec *ec;}; #define NTXEC_REG_WRITE_YEAR	0x10#define NTXEC_REG_WRITE_MONTH	0x11#define NTXEC_REG_WRITE_DAY	0x12#define NTXEC_REG_WRITE_HOUR	0x13#define NTXEC_REG_WRITE_MINUTE	0x14#define NTXEC_REG_WRITE_SECOND	0x15 #define NTXEC_REG_READ_YEAR_MONTH	0x20#define NTXEC_REG_READ_MDAY_HOUR	0x21#define NTXEC_REG_READ_MINUTE_SECOND	0x23 static int ntxec_read_time(struct device *dev, struct rtc_time *tm){	struct ntxec_rtc *rtc = dev_get_drvdata(dev);	unsigned int value;	int res; retry:	res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_MINUTE_SECOND, &value);	if (res < 0)		return res; 	tm->tm_min = value >> 8;	tm->tm_sec = value & 0xff; 	res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_MDAY_HOUR, &value);	if (res < 0)		return res; 	tm->tm_mday = value >> 8;	tm->tm_hour = value & 0xff; 	res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_YEAR_MONTH, &value);	if (res < 0)		return res; 	tm->tm_year = (value >> 8) + 100;	tm->tm_mon = (value & 0xff) - 1; 	/*	 * Read the minutes/seconds field again. If it changed since the first	 * read, we can't assume that the values read so far are consistent,	 * and should start from the beginning.	 */	res = regmap_read(rtc->ec->regmap, NTXEC_REG_READ_MINUTE_SECOND, &value);	if (res < 0)		return res; 	if (tm->tm_min != value >> 8 || tm->tm_sec != (value & 0xff))		goto retry; 	return 0;} static int ntxec_set_time(struct device *dev, struct rtc_time *tm){	struct ntxec_rtc *rtc = dev_get_drvdata(dev); 	/*	 * To avoid time overflows while we're writing the full date/time,	 * set the seconds field to zero before doing anything else. For the	 * next 59 seconds (plus however long it takes until the RTC's next	 * update of the second field), the seconds field will not overflow	 * into the other fields.	 */	struct reg_sequence regs[] = {		{ NTXEC_REG_WRITE_SECOND, ntxec_reg8(0) },		{ NTXEC_REG_WRITE_YEAR, ntxec_reg8(tm->tm_year - 100) },		{ NTXEC_REG_WRITE_MONTH, ntxec_reg8(tm->tm_mon + 1) },		{ NTXEC_REG_WRITE_DAY, ntxec_reg8(tm->tm_mday) },		{ NTXEC_REG_WRITE_HOUR, ntxec_reg8(tm->tm_hour) },		{ NTXEC_REG_WRITE_MINUTE, ntxec_reg8(tm->tm_min) },		{ NTXEC_REG_WRITE_SECOND, ntxec_reg8(tm->tm_sec) },	}; 	return regmap_multi_reg_write(rtc->ec->regmap, regs, ARRAY_SIZE(regs));} static const struct rtc_class_ops ntxec_rtc_ops = {	.read_time = ntxec_read_time,	.set_time = ntxec_set_time,}; static int ntxec_rtc_probe(struct platform_device *pdev){	struct rtc_device *dev;	struct ntxec_rtc *rtc; 	device_set_of_node_from_dev(&pdev->dev, pdev->dev.parent); 	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);	if (!rtc)		return -ENOMEM; 	rtc->dev = &pdev->dev;	rtc->ec = dev_get_drvdata(pdev->dev.parent);	platform_set_drvdata(pdev, rtc); 	dev = devm_rtc_allocate_device(&pdev->dev);	if (IS_ERR(dev))		return PTR_ERR(dev); 	dev->ops = &ntxec_rtc_ops;	dev->range_min = RTC_TIMESTAMP_BEGIN_2000;	dev->range_max = 9025257599LL; /* 2255-12-31 23:59:59 */ 	return devm_rtc_register_device(dev);} static struct platform_driver ntxec_rtc_driver = {	.driver = {		.name = "ntxec-rtc",	},	.probe = ntxec_rtc_probe,};module_platform_driver(ntxec_rtc_driver); MODULE_AUTHOR("Jonathan Neuschäfer <j.neuschaefer@gmx.net>");MODULE_DESCRIPTION("RTC driver for Netronix EC");MODULE_LICENSE("GPL");MODULE_ALIAS("platform:ntxec-rtc");