// SPDX-License-Identifier: GPL-2.0-or-later/* * RTC driver for the SD2405AL Real-Time Clock * * Datasheet: * https://image.dfrobot.com/image/data/TOY0021/SD2405AL%20datasheet%20(Angelo%20v0.1).pdf * * I2C slave address: 0x32 * * Copyright (C) 2024-2025 Tóth János <gomba007@gmail.com> */ #include <linux/bcd.h>#include <linux/i2c.h>#include <linux/regmap.h>#include <linux/rtc.h> /* Real time clock registers */#define SD2405AL_REG_T_SEC	0x00#define SD2405AL_REG_T_MIN	0x01#define SD2405AL_REG_T_HOUR	0x02#	define SD2405AL_BIT_12H_PM	BIT(5)#	define SD2405AL_BIT_24H		BIT(7)#define SD2405AL_REG_T_WEEK	0x03#define SD2405AL_REG_T_DAY	0x04#define SD2405AL_REG_T_MON	0x05#define SD2405AL_REG_T_YEAR	0x06 #define SD2405AL_NUM_T_REGS	(SD2405AL_REG_T_YEAR - SD2405AL_REG_T_SEC + 1) /* Control registers */#define SD2405AL_REG_CTR1	0x0F#	define SD2405AL_BIT_WRTC2	BIT(2)#	define SD2405AL_BIT_WRTC3	BIT(7)#define SD2405AL_REG_CTR2	0x10#	define SD2405AL_BIT_WRTC1	BIT(7)#define SD2405AL_REG_CTR3	0x11#define SD2405AL_REG_TTF	0x12#define SD2405AL_REG_CNTDWN	0x13 /* General RAM */#define SD2405AL_REG_M_START	0x14#define SD2405AL_REG_M_END	0x1F struct sd2405al {	struct device		*dev;	struct regmap		*regmap;}; static int sd2405al_enable_reg_write(struct sd2405al *sd2405al){	int ret; 	/* order of writes is important */	ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR2,				 SD2405AL_BIT_WRTC1, SD2405AL_BIT_WRTC1);	if (ret < 0)		return ret; 	ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR1,				 SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3,				 SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3);	if (ret < 0)		return ret; 	return 0;} static int sd2405al_disable_reg_write(struct sd2405al *sd2405al){	int ret; 	/* order of writes is important */	ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR1,				 SD2405AL_BIT_WRTC2 | SD2405AL_BIT_WRTC3, 0x00);	if (ret < 0)		return ret; 	ret = regmap_update_bits(sd2405al->regmap, SD2405AL_REG_CTR2,				 SD2405AL_BIT_WRTC1, 0x00);	if (ret < 0)		return ret; 	return 0;} static int sd2405al_read_time(struct device *dev, struct rtc_time *time){	u8 data[SD2405AL_NUM_T_REGS] = { 0 };	struct sd2405al *sd2405al = dev_get_drvdata(dev);	int ret; 	ret = regmap_bulk_read(sd2405al->regmap, SD2405AL_REG_T_SEC, data,			       SD2405AL_NUM_T_REGS);	if (ret < 0)		return ret; 	time->tm_sec = bcd2bin(data[SD2405AL_REG_T_SEC] & 0x7F);	time->tm_min = bcd2bin(data[SD2405AL_REG_T_MIN] & 0x7F); 	if (data[SD2405AL_REG_T_HOUR] & SD2405AL_BIT_24H)		time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR] & 0x3F);	else		if (data[SD2405AL_REG_T_HOUR] & SD2405AL_BIT_12H_PM)			time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR]						& 0x1F) + 12;		else /* 12 hour mode, AM */			time->tm_hour = bcd2bin(data[SD2405AL_REG_T_HOUR]						& 0x1F); 	time->tm_wday = bcd2bin(data[SD2405AL_REG_T_WEEK] & 0x07);	time->tm_mday = bcd2bin(data[SD2405AL_REG_T_DAY] & 0x3F);	time->tm_mon = bcd2bin(data[SD2405AL_REG_T_MON] & 0x1F) - 1;	time->tm_year = bcd2bin(data[SD2405AL_REG_T_YEAR]) + 100; 	dev_dbg(sd2405al->dev, "read time: %ptR (%d)\n", time, time->tm_wday); 	return 0;} static int sd2405al_set_time(struct device *dev, struct rtc_time *time){	u8 data[SD2405AL_NUM_T_REGS];	struct sd2405al *sd2405al = dev_get_drvdata(dev);	int ret; 	data[SD2405AL_REG_T_SEC] = bin2bcd(time->tm_sec);	data[SD2405AL_REG_T_MIN] = bin2bcd(time->tm_min);	data[SD2405AL_REG_T_HOUR] = bin2bcd(time->tm_hour) | SD2405AL_BIT_24H;	data[SD2405AL_REG_T_DAY] = bin2bcd(time->tm_mday);	data[SD2405AL_REG_T_WEEK] = bin2bcd(time->tm_wday);	data[SD2405AL_REG_T_MON] = bin2bcd(time->tm_mon) + 1;	data[SD2405AL_REG_T_YEAR] = bin2bcd(time->tm_year - 100); 	ret = sd2405al_enable_reg_write(sd2405al);	if (ret < 0)		return ret; 	ret = regmap_bulk_write(sd2405al->regmap, SD2405AL_REG_T_SEC, data,				SD2405AL_NUM_T_REGS);	if (ret < 0)		return ret; 	ret = regmap_write(sd2405al->regmap, SD2405AL_REG_TTF, 0x00);	if (ret < 0)		return ret; 	ret = sd2405al_disable_reg_write(sd2405al);	if (ret < 0)		return ret; 	dev_dbg(sd2405al->dev, "set time: %ptR (%d)\n", time, time->tm_wday); 	return 0;} static const struct rtc_class_ops sd2405al_rtc_ops = {	.read_time = sd2405al_read_time,	.set_time = sd2405al_set_time,}; static const struct regmap_config sd2405al_regmap_conf = {	.reg_bits = 8,	.val_bits = 8,	.max_register = SD2405AL_REG_M_END,}; static int sd2405al_probe(struct i2c_client *client){	struct sd2405al *sd2405al;	struct rtc_device *rtc;	int ret; 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))		return -ENODEV; 	sd2405al = devm_kzalloc(&client->dev, sizeof(*sd2405al), GFP_KERNEL);	if (!sd2405al)		return -ENOMEM; 	sd2405al->dev = &client->dev; 	sd2405al->regmap = devm_regmap_init_i2c(client, &sd2405al_regmap_conf);	if (IS_ERR(sd2405al->regmap))		return PTR_ERR(sd2405al->regmap); 	rtc = devm_rtc_allocate_device(&client->dev);	if (IS_ERR(rtc))		return PTR_ERR(rtc); 	rtc->ops = &sd2405al_rtc_ops;	rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;	rtc->range_max = RTC_TIMESTAMP_END_2099; 	dev_set_drvdata(&client->dev, sd2405al); 	ret = devm_rtc_register_device(rtc);	if (ret < 0)		return ret; 	return 0;} static const struct i2c_device_id sd2405al_id[] = {	{ .name = "sd2405al" },	{ /* sentinel */ }};MODULE_DEVICE_TABLE(i2c, sd2405al_id); static const __maybe_unused struct of_device_id sd2405al_of_match[] = {	{ .compatible = "dfrobot,sd2405al" },	{ /* sentinel */ }};MODULE_DEVICE_TABLE(of, sd2405al_of_match); static struct i2c_driver sd2405al_driver = {	.driver = {		.name = "sd2405al",		.of_match_table = of_match_ptr(sd2405al_of_match),	},	.probe = sd2405al_probe,	.id_table = sd2405al_id,}; module_i2c_driver(sd2405al_driver); MODULE_AUTHOR("Tóth János <gomba007@gmail.com>");MODULE_LICENSE("GPL");MODULE_DESCRIPTION("SD2405AL RTC driver");