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
  15 #define DRV_VERSION "0.4"
  16
  17 /* Registers */
  18
  19 #define DS1672_REG_CNT_BASE     0
  20 #define DS1672_REG_CONTROL      4
  21 #define DS1672_REG_TRICKLE      5
  22
  23 #define DS1672_REG_CONTROL_EOSC 0x80
  24
  25 static struct i2c_driver ds1672_driver;
  26
  27 /*
  28  * In the routines that deal directly with the ds1672 hardware, we use
  29  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
  30  * Epoch is initialized as 2000. Time is set to UTC.
  31  */
  32 static int ds1672_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  33 {
  34         unsigned long time;
  35         unsigned char addr = DS1672_REG_CNT_BASE;
  36         unsigned char buf[4];
  37
  38         struct i2c_msg msgs[] = {
  39                 {client->addr, 0, 1, &addr},    /* setup read ptr */
  40                 {client->addr, I2C_M_RD, 4, buf},       /* read date */
  41         };
  42
  43         /* read date registers */
  44         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
  45                 dev_err(&client->dev, "%s: read error\n", __func__);
  46                 return -EIO;
  47         }
  48
  49         dev_dbg(&client->dev,
  50                 "%s: raw read data - counters=%02x,%02x,%02x,%02x\n",
  51                 __func__, buf[0], buf[1], buf[2], buf[3]);
  52
  53         time = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
  54
  55         rtc_time_to_tm(time, tm);
  56
  57         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
  58                 "mday=%d, mon=%d, year=%d, wday=%d\n",
  59                 __func__, tm->tm_sec, tm->tm_min, tm->tm_hour,
  60                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
  61
  62         return 0;
  63 }
  64
  65 static int ds1672_set_mmss(struct i2c_client *client, unsigned long secs)
  66 {
  67         int xfer;
  68         unsigned char buf[6];
  69
  70         buf[0] = DS1672_REG_CNT_BASE;
  71         buf[1] = secs & 0x000000FF;
  72         buf[2] = (secs & 0x0000FF00) >> 8;
  73         buf[3] = (secs & 0x00FF0000) >> 16;
  74         buf[4] = (secs & 0xFF000000) >> 24;
  75         buf[5] = 0;             /* set control reg to enable counting */
  76
  77         xfer = i2c_master_send(client, buf, 6);
  78         if (xfer != 6) {
  79                 dev_err(&client->dev, "%s: send: %d\n", __func__, xfer);
  80                 return -EIO;
  81         }
  82
  83         return 0;
  84 }
  85
  86 static int ds1672_rtc_read_time(struct device *dev, struct rtc_time *tm)
  87 {
  88         return ds1672_get_datetime(to_i2c_client(dev), tm);
  89 }
  90
  91 static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs)
  92 {
  93         return ds1672_set_mmss(to_i2c_client(dev), secs);
  94 }
  95
  96 static int ds1672_get_control(struct i2c_client *client, u8 *status)
  97 {
  98         unsigned char addr = DS1672_REG_CONTROL;
  99
 100         struct i2c_msg msgs[] = {
 101                 {client->addr, 0, 1, &addr},    /* setup read ptr */
 102                 {client->addr, I2C_M_RD, 1, status},    /* read control */
 103         };
 104
 105         /* read control register */
 106         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
 107                 dev_err(&client->dev, "%s: read error\n", __func__);
 108                 return -EIO;
 109         }
 110
 111         return 0;
 112 }
 113
 114 /* following are the sysfs callback functions */
 115 static ssize_t show_control(struct device *dev, struct device_attribute *attr,
 116                             char *buf)
 117 {
 118         struct i2c_client *client = to_i2c_client(dev);
 119         u8 control;
 120         int err;
 121
 122         err = ds1672_get_control(client, &control);
 123         if (err)
 124                 return err;
 125
 126         return sprintf(buf, "%s\n", (control & DS1672_REG_CONTROL_EOSC)
 127                        ? "disabled" : "enabled");
 128 }
 129
 130 static DEVICE_ATTR(control, S_IRUGO, show_control, NULL);
 131
 132 static const struct rtc_class_ops ds1672_rtc_ops = {
 133         .read_time = ds1672_rtc_read_time,
 134         .set_mmss = ds1672_rtc_set_mmss,
 135 };
 136
 137 static int ds1672_remove(struct i2c_client *client)
 138 {
 139         struct rtc_device *rtc = i2c_get_clientdata(client);
 140
 141         if (rtc)
 142                 rtc_device_unregister(rtc);
 143
 144         return 0;
 145 }
 146
 147 static int ds1672_probe(struct i2c_client *client,
 148                         const struct i2c_device_id *id)
 149 {
 150         int err = 0;
 151         u8 control;
 152         struct rtc_device *rtc;
 153
 154         dev_dbg(&client->dev, "%s\n", __func__);
 155
 156         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 157                 return -ENODEV;
 158
 159         dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 160
 161         rtc = rtc_device_register(ds1672_driver.driver.name, &client->dev,
 162                                   &ds1672_rtc_ops, THIS_MODULE);
 163
 164         if (IS_ERR(rtc))
 165                 return PTR_ERR(rtc);
 166
 167         i2c_set_clientdata(client, rtc);
 168
 169         /* read control register */
 170         err = ds1672_get_control(client, &control);
 171         if (err)
 172                 goto exit_devreg;
 173
 174         if (control & DS1672_REG_CONTROL_EOSC)
 175                 dev_warn(&client->dev, "Oscillator not enabled. "
 176                          "Set time to enable.\n");
 177
 178         /* Register sysfs hooks */
 179         err = device_create_file(&client->dev, &dev_attr_control);
 180         if (err)
 181                 goto exit_devreg;
 182
 183         return 0;
 184
 185  exit_devreg:
 186         rtc_device_unregister(rtc);
 187         return err;
 188 }
 189
 190 static struct i2c_device_id ds1672_id[] = {
 191         { "ds1672", 0 },
 192         { }
 193 };
 194
 195 static struct i2c_driver ds1672_driver = {
 196         .driver = {
 197                    .name = "rtc-ds1672",
 198                    },
 199         .probe = &ds1672_probe,
 200         .remove = &ds1672_remove,
 201         .id_table = ds1672_id,
 202 };
 203
 204 static int __init ds1672_init(void)
 205 {
 206         return i2c_add_driver(&ds1672_driver);
 207 }
 208
 209 static void __exit ds1672_exit(void)
 210 {
 211         i2c_del_driver(&ds1672_driver);
 212 }
 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);
 218
 219 module_init(ds1672_init);
 220 module_exit(ds1672_exit);