LXR linux/drivers/rtc/rtc-ds1672.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * An rtc/i2c driver for the Dallas DS1672
   4 * Copyright 2005-06 Tower Technologies
   5 *
   6 * Author: Alessandro Zummo <a.zummo@towertech.it>
   7 */
   8
   9#include <linux/i2c.h>
  10#include <linux/rtc.h>
  11#include <linux/module.h>
  12
  13/* Registers */
  14
  15#define DS1672_REG_CNT_BASE     0
  16#define DS1672_REG_CONTROL      4
  17#define DS1672_REG_TRICKLE      5
  18
  19#define DS1672_REG_CONTROL_EOSC 0x80
  20
  21/*
  22 * In the routines that deal directly with the ds1672 hardware, we use
  23 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
  24 * Time is set to UTC.
  25 */
  26static int ds1672_read_time(struct device *dev, struct rtc_time *tm)
  27{
  28        struct i2c_client *client = to_i2c_client(dev);
  29        unsigned long time;
  30        unsigned char addr = DS1672_REG_CONTROL;
  31        unsigned char buf[4];
  32
  33        struct i2c_msg msgs[] = {
  34                {/* setup read ptr */
  35                        .addr = client->addr,
  36                        .len = 1,
  37                        .buf = &addr
  38                },
  39                {/* read date */
  40                        .addr = client->addr,
  41                        .flags = I2C_M_RD,
  42                        .len = 1,
  43                        .buf = buf
  44                },
  45        };
  46
  47        /* read control register */
  48        if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
  49                dev_warn(&client->dev, "Unable to read the control register\n");
  50                return -EIO;
  51        }
  52
  53        if (buf[0] & DS1672_REG_CONTROL_EOSC) {
  54                dev_warn(&client->dev, "Oscillator not enabled. Set time to enable.\n");
  55                return -EINVAL;
  56        }
  57
  58        addr = DS1672_REG_CNT_BASE;
  59        msgs[1].len = 4;
  60
  61        /* read date registers */
  62        if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
  63                dev_err(&client->dev, "%s: read error\n", __func__);
  64                return -EIO;
  65        }
  66
  67        dev_dbg(&client->dev,
  68                "%s: raw read data - counters=%02x,%02x,%02x,%02x\n",
  69                __func__, buf[0], buf[1], buf[2], buf[3]);
  70
  71        time = ((unsigned long)buf[3] << 24) | (buf[2] << 16) |
  72               (buf[1] << 8) | buf[0];
  73
  74        rtc_time64_to_tm(time, tm);
  75
  76        dev_dbg(&client->dev, "%s: tm is %ptR\n", __func__, tm);
  77
  78        return 0;
  79}
  80
  81static int ds1672_set_time(struct device *dev, struct rtc_time *tm)
  82{
  83        struct i2c_client *client = to_i2c_client(dev);
  84        int xfer;
  85        unsigned char buf[6];
  86        unsigned long secs = rtc_tm_to_time64(tm);
  87
  88        buf[0] = DS1672_REG_CNT_BASE;
  89        buf[1] = secs & 0x000000FF;
  90        buf[2] = (secs & 0x0000FF00) >> 8;
  91        buf[3] = (secs & 0x00FF0000) >> 16;
  92        buf[4] = (secs & 0xFF000000) >> 24;
  93        buf[5] = 0;             /* set control reg to enable counting */
  94
  95        xfer = i2c_master_send(client, buf, 6);
  96        if (xfer != 6) {
  97                dev_err(&client->dev, "%s: send: %d\n", __func__, xfer);
  98                return -EIO;
  99        }
 100
 101        return 0;
 102}
 103
 104static const struct rtc_class_ops ds1672_rtc_ops = {
 105        .read_time = ds1672_read_time,
 106        .set_time = ds1672_set_time,
 107};
 108
 109static int ds1672_probe(struct i2c_client *client,
 110                        const struct i2c_device_id *id)
 111{
 112        int err = 0;
 113        struct rtc_device *rtc;
 114
 115        dev_dbg(&client->dev, "%s\n", __func__);
 116
 117        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 118                return -ENODEV;
 119
 120        rtc = devm_rtc_allocate_device(&client->dev);
 121        if (IS_ERR(rtc))
 122                return PTR_ERR(rtc);
 123
 124        rtc->ops = &ds1672_rtc_ops;
 125        rtc->range_max = U32_MAX;
 126
 127        err = devm_rtc_register_device(rtc);
 128        if (err)
 129                return err;
 130
 131        i2c_set_clientdata(client, rtc);
 132
 133        return 0;
 134}
 135
 136static const struct i2c_device_id ds1672_id[] = {
 137        { "ds1672", 0 },
 138        { }
 139};
 140MODULE_DEVICE_TABLE(i2c, ds1672_id);
 141
 142static const __maybe_unused struct of_device_id ds1672_of_match[] = {
 143        { .compatible = "dallas,ds1672" },
 144        { }
 145};
 146MODULE_DEVICE_TABLE(of, ds1672_of_match);
 147
 148static struct i2c_driver ds1672_driver = {
 149        .driver = {
 150                   .name = "rtc-ds1672",
 151                   .of_match_table = of_match_ptr(ds1672_of_match),
 152        },
 153        .probe = &ds1672_probe,
 154        .id_table = ds1672_id,
 155};
 156
 157module_i2c_driver(ds1672_driver);
 158
 159MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 160MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");
 161MODULE_LICENSE("GPL");
 162