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 static struct i2c_driver ds1672_driver;
  25
  26 /*
  27  * In the routines that deal directly with the ds1672 hardware, we use
  28  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
  29  * Epoch is initialized as 2000. Time is set to UTC.
  30  */
  31 static int ds1672_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  32 {
  33         unsigned long time;
  34         unsigned char addr = DS1672_REG_CNT_BASE;
  35         unsigned char buf[4];
  36
  37         struct i2c_msg msgs[] = {
  38                 {/* setup read ptr */
  39                         .addr = client->addr,
  40                         .len = 1,
  41                         .buf = &addr
  42                 },
  43                 {/* read date */
  44                         .addr = client->addr,
  45                         .flags = I2C_M_RD,
  46                         .len = 4,
  47                         .buf = buf
  48                 },
  49         };
  50
  51         /* read date registers */
  52         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
  53                 dev_err(&client->dev, "%s: read error\n", __func__);
  54                 return -EIO;
  55         }
  56
  57         dev_dbg(&client->dev,
  58                 "%s: raw read data - counters=%02x,%02x,%02x,%02x\n",
  59                 __func__, buf[0], buf[1], buf[2], buf[3]);
  60
  61         time = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
  62
  63         rtc_time_to_tm(time, tm);
  64
  65         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
  66                 "mday=%d, mon=%d, year=%d, wday=%d\n",
  67                 __func__, tm->tm_sec, tm->tm_min, tm->tm_hour,
  68                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
  69
  70         return 0;
  71 }
  72
  73 static int ds1672_set_mmss(struct i2c_client *client, unsigned long secs)
  74 {
  75         int xfer;
  76         unsigned char buf[6];
  77
  78         buf[0] = DS1672_REG_CNT_BASE;
  79         buf[1] = secs & 0x000000FF;
  80         buf[2] = (secs & 0x0000FF00) >> 8;
  81         buf[3] = (secs & 0x00FF0000) >> 16;
  82         buf[4] = (secs & 0xFF000000) >> 24;
  83         buf[5] = 0;             /* set control reg to enable counting */
  84
  85         xfer = i2c_master_send(client, buf, 6);
  86         if (xfer != 6) {
  87                 dev_err(&client->dev, "%s: send: %d\n", __func__, xfer);
  88                 return -EIO;
  89         }
  90
  91         return 0;
  92 }
  93
  94 static int ds1672_rtc_read_time(struct device *dev, struct rtc_time *tm)
  95 {
  96         return ds1672_get_datetime(to_i2c_client(dev), tm);
  97 }
  98
  99 static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs)
 100 {
 101         return ds1672_set_mmss(to_i2c_client(dev), secs);
 102 }
 103
 104 static int ds1672_get_control(struct i2c_client *client, u8 *status)
 105 {
 106         unsigned char addr = DS1672_REG_CONTROL;
 107
 108         struct i2c_msg msgs[] = {
 109                 {/* setup read ptr */
 110                         .addr = client->addr,
 111                         .len = 1,
 112                         .buf = &addr
 113                 },
 114                 {/* read control */
 115                         .addr = client->addr,
 116                         .flags = I2C_M_RD,
 117                         .len = 1,
 118                         .buf = status
 119                 },
 120         };
 121
 122         /* read control register */
 123         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
 124                 dev_err(&client->dev, "%s: read error\n", __func__);
 125                 return -EIO;
 126         }
 127
 128         return 0;
 129 }
 130
 131 /* following are the sysfs callback functions */
 132 static ssize_t show_control(struct device *dev, struct device_attribute *attr,
 133                             char *buf)
 134 {
 135         struct i2c_client *client = to_i2c_client(dev);
 136         u8 control;
 137         int err;
 138
 139         err = ds1672_get_control(client, &control);
 140         if (err)
 141                 return err;
 142
 143         return sprintf(buf, "%s\n", (control & DS1672_REG_CONTROL_EOSC)
 144                        ? "disabled" : "enabled");
 145 }
 146
 147 static DEVICE_ATTR(control, S_IRUGO, show_control, NULL);
 148
 149 static const struct rtc_class_ops ds1672_rtc_ops = {
 150         .read_time = ds1672_rtc_read_time,
 151         .set_mmss = ds1672_rtc_set_mmss,
 152 };
 153
 154 static int ds1672_probe(struct i2c_client *client,
 155                         const struct i2c_device_id *id)
 156 {
 157         int err = 0;
 158         u8 control;
 159         struct rtc_device *rtc;
 160
 161         dev_dbg(&client->dev, "%s\n", __func__);
 162
 163         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 164                 return -ENODEV;
 165
 166         rtc = devm_rtc_device_register(&client->dev, ds1672_driver.driver.name,
 167                                   &ds1672_rtc_ops, THIS_MODULE);
 168
 169         if (IS_ERR(rtc))
 170                 return PTR_ERR(rtc);
 171
 172         i2c_set_clientdata(client, rtc);
 173
 174         /* read control register */
 175         err = ds1672_get_control(client, &control);
 176         if (err) {
 177                 dev_warn(&client->dev, "Unable to read the control register\n");
 178         }
 179
 180         if (control & DS1672_REG_CONTROL_EOSC)
 181                 dev_warn(&client->dev, "Oscillator not enabled. "
 182                          "Set time to enable.\n");
 183
 184         /* Register sysfs hooks */
 185         err = device_create_file(&client->dev, &dev_attr_control);
 186         if (err)
 187                 dev_err(&client->dev, "Unable to create sysfs entry: %s\n",
 188                         dev_attr_control.attr.name);
 189
 190         return 0;
 191 }
 192
 193 static struct i2c_device_id ds1672_id[] = {
 194         { "ds1672", 0 },
 195         { }
 196 };
 197 MODULE_DEVICE_TABLE(i2c, ds1672_id);
 198
 199 static struct i2c_driver ds1672_driver = {
 200         .driver = {
 201                    .name = "rtc-ds1672",
 202                    },
 203         .probe = &ds1672_probe,
 204         .id_table = ds1672_id,
 205 };
 206
 207 module_i2c_driver(ds1672_driver);
 208
 209 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 210 MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");
 211 MODULE_LICENSE("GPL");