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 #define DRV_VERSION "0.4"
  17
  18 /* Registers */
  19
  20 #define DS1672_REG_CNT_BASE     0
  21 #define DS1672_REG_CONTROL      4
  22 #define DS1672_REG_TRICKLE      5
  23
  24 #define DS1672_REG_CONTROL_EOSC 0x80
  25
  26 static struct i2c_driver ds1672_driver;
  27
  28 /*
  29  * In the routines that deal directly with the ds1672 hardware, we use
  30  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
  31  * Epoch is initialized as 2000. Time is set to UTC.
  32  */
  33 static int ds1672_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  34 {
  35         unsigned long time;
  36         unsigned char addr = DS1672_REG_CNT_BASE;
  37         unsigned char buf[4];
  38
  39         struct i2c_msg msgs[] = {
  40                 {/* setup read ptr */
  41                         .addr = client->addr,
  42                         .len = 1,
  43                         .buf = &addr
  44                 },
  45                 {/* read date */
  46                         .addr = client->addr,
  47                         .flags = I2C_M_RD,
  48                         .len = 4,
  49                         .buf = buf
  50                 },
  51         };
  52
  53         /* read date registers */
  54         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
  55                 dev_err(&client->dev, "%s: read error\n", __func__);
  56                 return -EIO;
  57         }
  58
  59         dev_dbg(&client->dev,
  60                 "%s: raw read data - counters=%02x,%02x,%02x,%02x\n",
  61                 __func__, buf[0], buf[1], buf[2], buf[3]);
  62
  63         time = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
  64
  65         rtc_time_to_tm(time, tm);
  66
  67         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
  68                 "mday=%d, mon=%d, year=%d, wday=%d\n",
  69                 __func__, tm->tm_sec, tm->tm_min, tm->tm_hour,
  70                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
  71
  72         return 0;
  73 }
  74
  75 static int ds1672_set_mmss(struct i2c_client *client, unsigned long secs)
  76 {
  77         int xfer;
  78         unsigned char buf[6];
  79
  80         buf[0] = DS1672_REG_CNT_BASE;
  81         buf[1] = secs & 0x000000FF;
  82         buf[2] = (secs & 0x0000FF00) >> 8;
  83         buf[3] = (secs & 0x00FF0000) >> 16;
  84         buf[4] = (secs & 0xFF000000) >> 24;
  85         buf[5] = 0;             /* set control reg to enable counting */
  86
  87         xfer = i2c_master_send(client, buf, 6);
  88         if (xfer != 6) {
  89                 dev_err(&client->dev, "%s: send: %d\n", __func__, xfer);
  90                 return -EIO;
  91         }
  92
  93         return 0;
  94 }
  95
  96 static int ds1672_rtc_read_time(struct device *dev, struct rtc_time *tm)
  97 {
  98         return ds1672_get_datetime(to_i2c_client(dev), tm);
  99 }
 100
 101 static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs)
 102 {
 103         return ds1672_set_mmss(to_i2c_client(dev), secs);
 104 }
 105
 106 static int ds1672_get_control(struct i2c_client *client, u8 *status)
 107 {
 108         unsigned char addr = DS1672_REG_CONTROL;
 109
 110         struct i2c_msg msgs[] = {
 111                 {/* setup read ptr */
 112                         .addr = client->addr,
 113                         .len = 1,
 114                         .buf = &addr
 115                 },
 116                 {/* read control */
 117                         .addr = client->addr,
 118                         .flags = I2C_M_RD,
 119                         .len = 1,
 120                         .buf = status
 121                 },
 122         };
 123
 124         /* read control register */
 125         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
 126                 dev_err(&client->dev, "%s: read error\n", __func__);
 127                 return -EIO;
 128         }
 129
 130         return 0;
 131 }
 132
 133 /* following are the sysfs callback functions */
 134 static ssize_t show_control(struct device *dev, struct device_attribute *attr,
 135                             char *buf)
 136 {
 137         struct i2c_client *client = to_i2c_client(dev);
 138         u8 control;
 139         int err;
 140
 141         err = ds1672_get_control(client, &control);
 142         if (err)
 143                 return err;
 144
 145         return sprintf(buf, "%s\n", (control & DS1672_REG_CONTROL_EOSC)
 146                        ? "disabled" : "enabled");
 147 }
 148
 149 static DEVICE_ATTR(control, S_IRUGO, show_control, NULL);
 150
 151 static const struct rtc_class_ops ds1672_rtc_ops = {
 152         .read_time = ds1672_rtc_read_time,
 153         .set_mmss = ds1672_rtc_set_mmss,
 154 };
 155
 156 static int ds1672_probe(struct i2c_client *client,
 157                         const struct i2c_device_id *id)
 158 {
 159         int err = 0;
 160         u8 control;
 161         struct rtc_device *rtc;
 162
 163         dev_dbg(&client->dev, "%s\n", __func__);
 164
 165         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 166                 return -ENODEV;
 167
 168         dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 169
 170         rtc = devm_rtc_device_register(&client->dev, ds1672_driver.driver.name,
 171                                   &ds1672_rtc_ops, THIS_MODULE);
 172
 173         if (IS_ERR(rtc))
 174                 return PTR_ERR(rtc);
 175
 176         i2c_set_clientdata(client, rtc);
 177
 178         /* read control register */
 179         err = ds1672_get_control(client, &control);
 180         if (err) {
 181                 dev_warn(&client->dev, "Unable to read the control register\n");
 182         }
 183
 184         if (control & DS1672_REG_CONTROL_EOSC)
 185                 dev_warn(&client->dev, "Oscillator not enabled. "
 186                          "Set time to enable.\n");
 187
 188         /* Register sysfs hooks */
 189         err = device_create_file(&client->dev, &dev_attr_control);
 190         if (err)
 191                 dev_err(&client->dev, "Unable to create sysfs entry: %s\n",
 192                         dev_attr_control.attr.name);
 193
 194         return 0;
 195 }
 196
 197 static struct i2c_device_id ds1672_id[] = {
 198         { "ds1672", 0 },
 199         { }
 200 };
 201
 202 static struct i2c_driver ds1672_driver = {
 203         .driver = {
 204                    .name = "rtc-ds1672",
 205                    },
 206         .probe = &ds1672_probe,
 207         .id_table = ds1672_id,
 208 };
 209
 210 module_i2c_driver(ds1672_driver);
 211
 212 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 213 MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");
 214 MODULE_LICENSE("GPL");
 215 MODULE_VERSION(DRV_VERSION);