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