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// 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,
const struct i2c_device_id *id)
{
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[] = {
{ "ds1672", 0 },
{ }
};
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");
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