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 = ((unsigned long)buf[3] << 24) | (buf[2] << 16) |
  64                (buf[1] << 8) | buf[0];
  65
  66         rtc_time_to_tm(time, tm);
  67
  68         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
  69                 "mday=%d, mon=%d, year=%d, wday=%d\n",
  70                 __func__, tm->tm_sec, tm->tm_min, tm->tm_hour,
  71                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
  72
  73         return 0;
  74 }
  75
  76 static int ds1672_set_mmss(struct i2c_client *client, unsigned long secs)
  77 {
  78         int xfer;
  79         unsigned char buf[6];
  80
  81         buf[0] = DS1672_REG_CNT_BASE;
  82         buf[1] = secs & 0x000000FF;
  83         buf[2] = (secs & 0x0000FF00) >> 8;
  84         buf[3] = (secs & 0x00FF0000) >> 16;
  85         buf[4] = (secs & 0xFF000000) >> 24;
  86         buf[5] = 0;             /* set control reg to enable counting */
  87
  88         xfer = i2c_master_send(client, buf, 6);
  89         if (xfer != 6) {
  90                 dev_err(&client->dev, "%s: send: %d\n", __func__, xfer);
  91                 return -EIO;
  92         }
  93
  94         return 0;
  95 }
  96
  97 static int ds1672_rtc_read_time(struct device *dev, struct rtc_time *tm)
  98 {
  99         return ds1672_get_datetime(to_i2c_client(dev), tm);
 100 }
 101
 102 static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs)
 103 {
 104         return ds1672_set_mmss(to_i2c_client(dev), secs);
 105 }
 106
 107 static int ds1672_get_control(struct i2c_client *client, u8 *status)
 108 {
 109         unsigned char addr = DS1672_REG_CONTROL;
 110
 111         struct i2c_msg msgs[] = {
 112                 {/* setup read ptr */
 113                         .addr = client->addr,
 114                         .len = 1,
 115                         .buf = &addr
 116                 },
 117                 {/* read control */
 118                         .addr = client->addr,
 119                         .flags = I2C_M_RD,
 120                         .len = 1,
 121                         .buf = status
 122                 },
 123         };
 124
 125         /* read control register */
 126         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
 127                 dev_err(&client->dev, "%s: read error\n", __func__);
 128                 return -EIO;
 129         }
 130
 131         return 0;
 132 }
 133
 134 /* following are the sysfs callback functions */
 135 static ssize_t show_control(struct device *dev, struct device_attribute *attr,
 136                             char *buf)
 137 {
 138         struct i2c_client *client = to_i2c_client(dev);
 139         u8 control;
 140         int err;
 141
 142         err = ds1672_get_control(client, &control);
 143         if (err)
 144                 return err;
 145
 146         return sprintf(buf, "%s\n", (control & DS1672_REG_CONTROL_EOSC)
 147                        ? "disabled" : "enabled");
 148 }
 149
 150 static DEVICE_ATTR(control, S_IRUGO, show_control, NULL);
 151
 152 static const struct rtc_class_ops ds1672_rtc_ops = {
 153         .read_time = ds1672_rtc_read_time,
 154         .set_mmss = ds1672_rtc_set_mmss,
 155 };
 156
 157 static int ds1672_probe(struct i2c_client *client,
 158                         const struct i2c_device_id *id)
 159 {
 160         int err = 0;
 161         u8 control;
 162         struct rtc_device *rtc;
 163
 164         dev_dbg(&client->dev, "%s\n", __func__);
 165
 166         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 167                 return -ENODEV;
 168
 169         dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 170
 171         rtc = devm_rtc_device_register(&client->dev, ds1672_driver.driver.name,
 172                                   &ds1672_rtc_ops, THIS_MODULE);
 173
 174         if (IS_ERR(rtc))
 175                 return PTR_ERR(rtc);
 176
 177         i2c_set_clientdata(client, rtc);
 178
 179         /* read control register */
 180         err = ds1672_get_control(client, &control);
 181         if (err) {
 182                 dev_warn(&client->dev, "Unable to read the control register\n");
 183         }
 184
 185         if (control & DS1672_REG_CONTROL_EOSC)
 186                 dev_warn(&client->dev, "Oscillator not enabled. "
 187                          "Set time to enable.\n");
 188
 189         /* Register sysfs hooks */
 190         err = device_create_file(&client->dev, &dev_attr_control);
 191         if (err)
 192                 dev_err(&client->dev, "Unable to create sysfs entry: %s\n",
 193                         dev_attr_control.attr.name);
 194
 195         return 0;
 196 }
 197
 198 static struct i2c_device_id ds1672_id[] = {
 199         { "ds1672", 0 },
 200         { }
 201 };
 202 MODULE_DEVICE_TABLE(i2c, ds1672_id);
 203
 204 static struct i2c_driver ds1672_driver = {
 205         .driver = {
 206                    .name = "rtc-ds1672",
 207                    },
 208         .probe = &ds1672_probe,
 209         .id_table = ds1672_id,
 210 };
 211
 212 module_i2c_driver(ds1672_driver);
 213
 214 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 215 MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");
 216 MODULE_LICENSE("GPL");
 217 MODULE_VERSION(DRV_VERSION);