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_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  30 {
  31         unsigned long time;
  32         unsigned char addr = DS1672_REG_CNT_BASE;
  33         unsigned char buf[4];
  34
  35         struct i2c_msg msgs[] = {
  36                 {/* setup read ptr */
  37                         .addr = client->addr,
  38                         .len = 1,
  39                         .buf = &addr
  40                 },
  41                 {/* read date */
  42                         .addr = client->addr,
  43                         .flags = I2C_M_RD,
  44                         .len = 4,
  45                         .buf = buf
  46                 },
  47         };
  48
  49         /* read date registers */
  50         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
  51                 dev_err(&client->dev, "%s: read error\n", __func__);
  52                 return -EIO;
  53         }
  54
  55         dev_dbg(&client->dev,
  56                 "%s: raw read data - counters=%02x,%02x,%02x,%02x\n",
  57                 __func__, buf[0], buf[1], buf[2], buf[3]);
  58
  59         time = ((unsigned long)buf[3] << 24) | (buf[2] << 16) |
  60                (buf[1] << 8) | buf[0];
  61
  62         rtc_time_to_tm(time, tm);
  63
  64         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
  65                 "mday=%d, mon=%d, year=%d, wday=%d\n",
  66                 __func__, tm->tm_sec, tm->tm_min, tm->tm_hour,
  67                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
  68
  69         return 0;
  70 }
  71
  72 static int ds1672_set_mmss(struct i2c_client *client, unsigned long secs)
  73 {
  74         int xfer;
  75         unsigned char buf[6];
  76
  77         buf[0] = DS1672_REG_CNT_BASE;
  78         buf[1] = secs & 0x000000FF;
  79         buf[2] = (secs & 0x0000FF00) >> 8;
  80         buf[3] = (secs & 0x00FF0000) >> 16;
  81         buf[4] = (secs & 0xFF000000) >> 24;
  82         buf[5] = 0;             /* set control reg to enable counting */
  83
  84         xfer = i2c_master_send(client, buf, 6);
  85         if (xfer != 6) {
  86                 dev_err(&client->dev, "%s: send: %d\n", __func__, xfer);
  87                 return -EIO;
  88         }
  89
  90         return 0;
  91 }
  92
  93 static int ds1672_rtc_read_time(struct device *dev, struct rtc_time *tm)
  94 {
  95         return ds1672_get_datetime(to_i2c_client(dev), tm);
  96 }
  97
  98 static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs)
  99 {
 100         return ds1672_set_mmss(to_i2c_client(dev), secs);
 101 }
 102
 103 static int ds1672_get_control(struct i2c_client *client, u8 *status)
 104 {
 105         unsigned char addr = DS1672_REG_CONTROL;
 106
 107         struct i2c_msg msgs[] = {
 108                 {/* setup read ptr */
 109                         .addr = client->addr,
 110                         .len = 1,
 111                         .buf = &addr
 112                 },
 113                 {/* read control */
 114                         .addr = client->addr,
 115                         .flags = I2C_M_RD,
 116                         .len = 1,
 117                         .buf = status
 118                 },
 119         };
 120
 121         /* read control register */
 122         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
 123                 dev_err(&client->dev, "%s: read error\n", __func__);
 124                 return -EIO;
 125         }
 126
 127         return 0;
 128 }
 129
 130 /* following are the sysfs callback functions */
 131 static ssize_t show_control(struct device *dev, struct device_attribute *attr,
 132                             char *buf)
 133 {
 134         struct i2c_client *client = to_i2c_client(dev);
 135         u8 control;
 136         int err;
 137
 138         err = ds1672_get_control(client, &control);
 139         if (err)
 140                 return err;
 141
 142         return sprintf(buf, "%s\n", (control & DS1672_REG_CONTROL_EOSC)
 143                        ? "disabled" : "enabled");
 144 }
 145
 146 static DEVICE_ATTR(control, S_IRUGO, show_control, NULL);
 147
 148 static const struct rtc_class_ops ds1672_rtc_ops = {
 149         .read_time = ds1672_rtc_read_time,
 150         .set_mmss = ds1672_rtc_set_mmss,
 151 };
 152
 153 static int ds1672_probe(struct i2c_client *client,
 154                         const struct i2c_device_id *id)
 155 {
 156         int err = 0;
 157         u8 control;
 158         struct rtc_device *rtc;
 159
 160         dev_dbg(&client->dev, "%s\n", __func__);
 161
 162         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 163                 return -ENODEV;
 164
 165         rtc = devm_rtc_allocate_device(&client->dev);
 166         if (IS_ERR(rtc))
 167                 return PTR_ERR(rtc);
 168
 169         rtc->ops = &ds1672_rtc_ops;
 170         rtc->range_max = U32_MAX;
 171
 172         err = rtc_register_device(rtc);
 173         if (err)
 174                 return err;
 175
 176         if (IS_ERR(rtc))
 177                 return PTR_ERR(rtc);
 178
 179         i2c_set_clientdata(client, rtc);
 180
 181         /* read control register */
 182         err = ds1672_get_control(client, &control);
 183         if (err) {
 184                 dev_warn(&client->dev, "Unable to read the control register\n");
 185         }
 186
 187         if (control & DS1672_REG_CONTROL_EOSC)
 188                 dev_warn(&client->dev, "Oscillator not enabled. "
 189                          "Set time to enable.\n");
 190
 191         /* Register sysfs hooks */
 192         err = device_create_file(&client->dev, &dev_attr_control);
 193         if (err)
 194                 dev_err(&client->dev, "Unable to create sysfs entry: %s\n",
 195                         dev_attr_control.attr.name);
 196
 197         return 0;
 198 }
 199
 200 static const struct i2c_device_id ds1672_id[] = {
 201         { "ds1672", 0 },
 202         { }
 203 };
 204 MODULE_DEVICE_TABLE(i2c, ds1672_id);
 205
 206 static const struct of_device_id ds1672_of_match[] = {
 207         { .compatible = "dallas,ds1672" },
 208         { }
 209 };
 210 MODULE_DEVICE_TABLE(of, ds1672_of_match);
 211
 212 static struct i2c_driver ds1672_driver = {
 213         .driver = {
 214                    .name = "rtc-ds1672",
 215                    .of_match_table = of_match_ptr(ds1672_of_match),
 216         },
 217         .probe = &ds1672_probe,
 218         .id_table = ds1672_id,
 219 };
 220
 221 module_i2c_driver(ds1672_driver);
 222
 223 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 224 MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");
 225 MODULE_LICENSE("GPL");