linux/drivers/rtc/rtc-ds1672.c
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   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
  25static 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 */
  32static 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
  65static 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
  86static 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
  91static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs)
  92{
  93        return ds1672_set_mmss(to_i2c_client(dev), secs);
  94}
  95
  96static 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 */
 115static 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
 130static DEVICE_ATTR(control, S_IRUGO, show_control, NULL);
 131
 132static const struct rtc_class_ops ds1672_rtc_ops = {
 133        .read_time = ds1672_rtc_read_time,
 134        .set_mmss = ds1672_rtc_set_mmss,
 135};
 136
 137static 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
 147static 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
 190static struct i2c_device_id ds1672_id[] = {
 191        { "ds1672", 0 },
 192        { }
 193};
 194
 195static 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
 204static int __init ds1672_init(void)
 205{
 206        return i2c_add_driver(&ds1672_driver);
 207}
 208
 209static void __exit ds1672_exit(void)
 210{
 211        i2c_del_driver(&ds1672_driver);
 212}
 213
 214MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 215MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");
 216MODULE_LICENSE("GPL");
 217MODULE_VERSION(DRV_VERSION);
 218
 219module_init(ds1672_init);
 220module_exit(ds1672_exit);
 221