// SPDX-License-Identifier: GPL-2.0/* * An rtc/i2c driver for the Dallas DS1672 * Copyright 2005-06 Tower Technologies * * Author: Alessandro Zummo <a.zummo@towertech.it> */ #include <linux/i2c.h>#include <linux/rtc.h>#include <linux/module.h> /* Registers */ #define DS1672_REG_CNT_BASE	0#define DS1672_REG_CONTROL	4#define DS1672_REG_TRICKLE	5 #define DS1672_REG_CONTROL_EOSC	0x80 /* * In the routines that deal directly with the ds1672 hardware, we use * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch * Time is set to UTC. */static int ds1672_read_time(struct device *dev, struct rtc_time *tm){	struct i2c_client *client = to_i2c_client(dev);	unsigned long time;	unsigned char addr = DS1672_REG_CONTROL;	unsigned char buf[4]; 	struct i2c_msg msgs[] = {		{/* setup read ptr */			.addr = client->addr,			.len = 1,			.buf = &addr		},		{/* read date */			.addr = client->addr,			.flags = I2C_M_RD,			.len = 1,			.buf = buf		},	}; 	/* read control register */	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {		dev_warn(&client->dev, "Unable to read the control register\n");		return -EIO;	} 	if (buf[0] & DS1672_REG_CONTROL_EOSC) {		dev_warn(&client->dev, "Oscillator not enabled. Set time to enable.\n");		return -EINVAL;	} 	addr = DS1672_REG_CNT_BASE;	msgs[1].len = 4; 	/* read date registers */	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {		dev_err(&client->dev, "%s: read error\n", __func__);		return -EIO;	} 	dev_dbg(&client->dev,		"%s: raw read data - counters=%02x,%02x,%02x,%02x\n",		__func__, buf[0], buf[1], buf[2], buf[3]); 	time = ((unsigned long)buf[3] << 24) | (buf[2] << 16) |	       (buf[1] << 8) | buf[0]; 	rtc_time64_to_tm(time, tm); 	dev_dbg(&client->dev, "%s: tm is %ptR\n", __func__, tm); 	return 0;} static int ds1672_set_time(struct device *dev, struct rtc_time *tm){	struct i2c_client *client = to_i2c_client(dev);	int xfer;	unsigned char buf[6];	unsigned long secs = rtc_tm_to_time64(tm); 	buf[0] = DS1672_REG_CNT_BASE;	buf[1] = secs & 0x000000FF;	buf[2] = (secs & 0x0000FF00) >> 8;	buf[3] = (secs & 0x00FF0000) >> 16;	buf[4] = (secs & 0xFF000000) >> 24;	buf[5] = 0;		/* set control reg to enable counting */ 	xfer = i2c_master_send(client, buf, 6);	if (xfer != 6) {		dev_err(&client->dev, "%s: send: %d\n", __func__, xfer);		return -EIO;	} 	return 0;} static const struct rtc_class_ops ds1672_rtc_ops = {	.read_time = ds1672_read_time,	.set_time = ds1672_set_time,}; static int ds1672_probe(struct i2c_client *client){	int err = 0;	struct rtc_device *rtc; 	dev_dbg(&client->dev, "%s\n", __func__); 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))		return -ENODEV; 	rtc = devm_rtc_allocate_device(&client->dev);	if (IS_ERR(rtc))		return PTR_ERR(rtc); 	rtc->ops = &ds1672_rtc_ops;	rtc->range_max = U32_MAX; 	err = devm_rtc_register_device(rtc);	if (err)		return err; 	i2c_set_clientdata(client, rtc); 	return 0;} static const struct i2c_device_id ds1672_id[] = {	{ .name = "ds1672" },	{ }};MODULE_DEVICE_TABLE(i2c, ds1672_id); static const __maybe_unused struct of_device_id ds1672_of_match[] = {	{ .compatible = "dallas,ds1672" },	{ }};MODULE_DEVICE_TABLE(of, ds1672_of_match); static struct i2c_driver ds1672_driver = {	.driver = {		   .name = "rtc-ds1672",		   .of_match_table = of_match_ptr(ds1672_of_match),	},	.probe = ds1672_probe,	.id_table = ds1672_id,}; module_i2c_driver(ds1672_driver); MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");MODULE_LICENSE("GPL");