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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 <[email protected]>
- */
- #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[] = {
- { "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_new = ds1672_probe,
- .id_table = ds1672_id,
- };
- module_i2c_driver(ds1672_driver);
- MODULE_AUTHOR("Alessandro Zummo <[email protected]>");
- MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");
- MODULE_LICENSE("GPL");
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