drivers/rtc/rtc-ds1672.c

   1 /*
   2  * An rtc/i2c driver for the Dallas DS1672
   3  * Copyright 2005-06 Tower Technologies
   4  *
   5  * Author: Alessandro Zummo <a.zummo@towertech.it>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/i2c.h>
  13 #include <linux/rtc.h>
  14 #include <linux/module.h>
  15
  16 /* Registers */
  17
  18 #define DS1672_REG_CNT_BASE     0
  19 #define DS1672_REG_CONTROL      4
  20 #define DS1672_REG_TRICKLE      5
  21
  22 #define DS1672_REG_CONTROL_EOSC 0x80
  23
  24 /*
  25  * In the routines that deal directly with the ds1672 hardware, we use
  26  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
  27  * Time is set to UTC.
  28  */
  29 static int ds1672_read_time(struct device *dev, struct rtc_time *tm)
  30 {
  31         struct i2c_client *client = to_i2c_client(dev);
  32         unsigned long time;
  33         unsigned char addr = DS1672_REG_CONTROL;
  34         unsigned char buf[4];
  35
  36         struct i2c_msg msgs[] = {
  37                 {/* setup read ptr */
  38                         .addr = client->addr,
  39                         .len = 1,
  40                         .buf = &addr
  41                 },
  42                 {/* read date */
  43                         .addr = client->addr,
  44                         .flags = I2C_M_RD,
  45                         .len = 1,
  46                         .buf = buf
  47                 },
  48         };
  49
  50         /* read control register */
  51         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
  52                 dev_warn(&client->dev, "Unable to read the control register\n");
  53                 return -EIO;
  54         }
  55
  56         if (buf[0] & DS1672_REG_CONTROL_EOSC) {
  57                 dev_warn(&client->dev, "Oscillator not enabled. Set time to enable.\n");
  58                 return -EINVAL;
  59         }
  60
  61         addr = DS1672_REG_CNT_BASE;
  62         msgs[1].len = 4;
  63
  64         /* read date registers */
  65         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
  66                 dev_err(&client->dev, "%s: read error\n", __func__);
  67                 return -EIO;
  68         }
  69
  70         dev_dbg(&client->dev,
  71                 "%s: raw read data - counters=%02x,%02x,%02x,%02x\n",
  72                 __func__, buf[0], buf[1], buf[2], buf[3]);
  73
  74         time = ((unsigned long)buf[3] << 24) | (buf[2] << 16) |
  75                (buf[1] << 8) | buf[0];
  76
  77         rtc_time64_to_tm(time, tm);
  78
  79         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
  80                 "mday=%d, mon=%d, year=%d, wday=%d\n",
  81                 __func__, tm->tm_sec, tm->tm_min, tm->tm_hour,
  82                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
  83
  84         return 0;
  85 }
  86
  87 static int ds1672_set_mmss(struct device *dev, unsigned long secs)
  88 {
  89         struct i2c_client *client = to_i2c_client(dev);
  90         int xfer;
  91         unsigned char buf[6];
  92
  93         buf[0] = DS1672_REG_CNT_BASE;
  94         buf[1] = secs & 0x000000FF;
  95         buf[2] = (secs & 0x0000FF00) >> 8;
  96         buf[3] = (secs & 0x00FF0000) >> 16;
  97         buf[4] = (secs & 0xFF000000) >> 24;
  98         buf[5] = 0;             /* set control reg to enable counting */
  99
 100         xfer = i2c_master_send(client, buf, 6);
 101         if (xfer != 6) {
 102                 dev_err(&client->dev, "%s: send: %d\n", __func__, xfer);
 103                 return -EIO;
 104         }
 105
 106         return 0;
 107 }
 108
 109 static const struct rtc_class_ops ds1672_rtc_ops = {
 110         .read_time = ds1672_read_time,
 111         .set_mmss = ds1672_set_mmss,
 112 };
 113
 114 static int ds1672_probe(struct i2c_client *client,
 115                         const struct i2c_device_id *id)
 116 {
 117         int err = 0;
 118         struct rtc_device *rtc;
 119
 120         dev_dbg(&client->dev, "%s\n", __func__);
 121
 122         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 123                 return -ENODEV;
 124
 125         rtc = devm_rtc_allocate_device(&client->dev);
 126         if (IS_ERR(rtc))
 127                 return PTR_ERR(rtc);
 128
 129         rtc->ops = &ds1672_rtc_ops;
 130         rtc->range_max = U32_MAX;
 131
 132         err = rtc_register_device(rtc);
 133         if (err)
 134                 return err;
 135
 136         if (IS_ERR(rtc))
 137                 return PTR_ERR(rtc);
 138
 139         i2c_set_clientdata(client, rtc);
 140
 141         return 0;
 142 }
 143
 144 static const struct i2c_device_id ds1672_id[] = {
 145         { "ds1672", 0 },
 146         { }
 147 };
 148 MODULE_DEVICE_TABLE(i2c, ds1672_id);
 149
 150 static const struct of_device_id ds1672_of_match[] = {
 151         { .compatible = "dallas,ds1672" },
 152         { }
 153 };
 154 MODULE_DEVICE_TABLE(of, ds1672_of_match);
 155
 156 static struct i2c_driver ds1672_driver = {
 157         .driver = {
 158                    .name = "rtc-ds1672",
 159                    .of_match_table = of_match_ptr(ds1672_of_match),
 160         },
 161         .probe = &ds1672_probe,
 162         .id_table = ds1672_id,
 163 };
 164
 165 module_i2c_driver(ds1672_driver);
 166
 167 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 168 MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");
 169 MODULE_LICENSE("GPL");