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                 {client->addr, 0, 1, &addr},    /* setup read ptr */
  41                 {client->addr, I2C_M_RD, 4, buf},       /* read date */
  42         };
  43
  44         /* read date registers */
  45         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
  46                 dev_err(&client->dev, "%s: read error\n", __func__);
  47                 return -EIO;
  48         }
  49
  50         dev_dbg(&client->dev,
  51                 "%s: raw read data - counters=%02x,%02x,%02x,%02x\n",
  52                 __func__, buf[0], buf[1], buf[2], buf[3]);
  53
  54         time = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
  55
  56         rtc_time_to_tm(time, tm);
  57
  58         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
  59                 "mday=%d, mon=%d, year=%d, wday=%d\n",
  60                 __func__, tm->tm_sec, tm->tm_min, tm->tm_hour,
  61                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
  62
  63         return 0;
  64 }
  65
  66 static int ds1672_set_mmss(struct i2c_client *client, unsigned long secs)
  67 {
  68         int xfer;
  69         unsigned char buf[6];
  70
  71         buf[0] = DS1672_REG_CNT_BASE;
  72         buf[1] = secs & 0x000000FF;
  73         buf[2] = (secs & 0x0000FF00) >> 8;
  74         buf[3] = (secs & 0x00FF0000) >> 16;
  75         buf[4] = (secs & 0xFF000000) >> 24;
  76         buf[5] = 0;             /* set control reg to enable counting */
  77
  78         xfer = i2c_master_send(client, buf, 6);
  79         if (xfer != 6) {
  80                 dev_err(&client->dev, "%s: send: %d\n", __func__, xfer);
  81                 return -EIO;
  82         }
  83
  84         return 0;
  85 }
  86
  87 static int ds1672_rtc_read_time(struct device *dev, struct rtc_time *tm)
  88 {
  89         return ds1672_get_datetime(to_i2c_client(dev), tm);
  90 }
  91
  92 static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs)
  93 {
  94         return ds1672_set_mmss(to_i2c_client(dev), secs);
  95 }
  96
  97 static int ds1672_get_control(struct i2c_client *client, u8 *status)
  98 {
  99         unsigned char addr = DS1672_REG_CONTROL;
 100
 101         struct i2c_msg msgs[] = {
 102                 {client->addr, 0, 1, &addr},    /* setup read ptr */
 103                 {client->addr, I2C_M_RD, 1, status},    /* read control */
 104         };
 105
 106         /* read control register */
 107         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
 108                 dev_err(&client->dev, "%s: read error\n", __func__);
 109                 return -EIO;
 110         }
 111
 112         return 0;
 113 }
 114
 115 /* following are the sysfs callback functions */
 116 static ssize_t show_control(struct device *dev, struct device_attribute *attr,
 117                             char *buf)
 118 {
 119         struct i2c_client *client = to_i2c_client(dev);
 120         u8 control;
 121         int err;
 122
 123         err = ds1672_get_control(client, &control);
 124         if (err)
 125                 return err;
 126
 127         return sprintf(buf, "%s\n", (control & DS1672_REG_CONTROL_EOSC)
 128                        ? "disabled" : "enabled");
 129 }
 130
 131 static DEVICE_ATTR(control, S_IRUGO, show_control, NULL);
 132
 133 static const struct rtc_class_ops ds1672_rtc_ops = {
 134         .read_time = ds1672_rtc_read_time,
 135         .set_mmss = ds1672_rtc_set_mmss,
 136 };
 137
 138 static int ds1672_remove(struct i2c_client *client)
 139 {
 140         struct rtc_device *rtc = i2c_get_clientdata(client);
 141
 142         if (rtc)
 143                 rtc_device_unregister(rtc);
 144
 145         return 0;
 146 }
 147
 148 static int ds1672_probe(struct i2c_client *client,
 149                         const struct i2c_device_id *id)
 150 {
 151         int err = 0;
 152         u8 control;
 153         struct rtc_device *rtc;
 154
 155         dev_dbg(&client->dev, "%s\n", __func__);
 156
 157         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 158                 return -ENODEV;
 159
 160         dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 161
 162         rtc = rtc_device_register(ds1672_driver.driver.name, &client->dev,
 163                                   &ds1672_rtc_ops, THIS_MODULE);
 164
 165         if (IS_ERR(rtc))
 166                 return PTR_ERR(rtc);
 167
 168         i2c_set_clientdata(client, rtc);
 169
 170         /* read control register */
 171         err = ds1672_get_control(client, &control);
 172         if (err)
 173                 goto exit_devreg;
 174
 175         if (control & DS1672_REG_CONTROL_EOSC)
 176                 dev_warn(&client->dev, "Oscillator not enabled. "
 177                          "Set time to enable.\n");
 178
 179         /* Register sysfs hooks */
 180         err = device_create_file(&client->dev, &dev_attr_control);
 181         if (err)
 182                 goto exit_devreg;
 183
 184         return 0;
 185
 186  exit_devreg:
 187         rtc_device_unregister(rtc);
 188         return err;
 189 }
 190
 191 static struct i2c_device_id ds1672_id[] = {
 192         { "ds1672", 0 },
 193         { }
 194 };
 195
 196 static struct i2c_driver ds1672_driver = {
 197         .driver = {
 198                    .name = "rtc-ds1672",
 199                    },
 200         .probe = &ds1672_probe,
 201         .remove = &ds1672_remove,
 202         .id_table = ds1672_id,
 203 };
 204
 205 static int __init ds1672_init(void)
 206 {
 207         return i2c_add_driver(&ds1672_driver);
 208 }
 209
 210 static void __exit ds1672_exit(void)
 211 {
 212         i2c_del_driver(&ds1672_driver);
 213 }
 214
 215 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 216 MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");
 217 MODULE_LICENSE("GPL");
 218 MODULE_VERSION(DRV_VERSION);
 219
 220 module_init(ds1672_init);
 221 module_exit(ds1672_exit);