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