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#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
  26static 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 */
  33static 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
  66static 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
  87static 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
  92static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs)
  93{
  94        return ds1672_set_mmss(to_i2c_client(dev), secs);
  95}
  96
  97static 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 */
 116static 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
 131static DEVICE_ATTR(control, S_IRUGO, show_control, NULL);
 132
 133static const struct rtc_class_ops ds1672_rtc_ops = {
 134        .read_time = ds1672_rtc_read_time,
 135        .set_mmss = ds1672_rtc_set_mmss,
 136};
 137
 138static 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
 148static 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
 191static struct i2c_device_id ds1672_id[] = {
 192        { "ds1672", 0 },
 193        { }
 194};
 195
 196static 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
 205module_i2c_driver(ds1672_driver);
 206
 207MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 208MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");
 209MODULE_LICENSE("GPL");
 210MODULE_VERSION(DRV_VERSION);
 211
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