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/module.h>
  13 #include <linux/i2c.h>
  14 #include <linux/rtc.h>
  15
  16 #define DRV_VERSION "0.3"
  17
  18 /* Addresses to scan: none. This chip cannot be detected. */
  19 static const unsigned short normal_i2c[] = { I2C_CLIENT_END };
  20
  21 /* Insmod parameters */
  22 I2C_CLIENT_INSMOD;
  23
  24 /* Registers */
  25
  26 #define DS1672_REG_CNT_BASE     0
  27 #define DS1672_REG_CONTROL      4
  28 #define DS1672_REG_TRICKLE      5
  29
  30 #define DS1672_REG_CONTROL_EOSC 0x80
  31
  32 /* Prototypes */
  33 static int ds1672_probe(struct i2c_adapter *adapter, int address, int kind);
  34
  35 /*
  36  * In the routines that deal directly with the ds1672 hardware, we use
  37  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
  38  * Epoch is initialized as 2000. Time is set to UTC.
  39  */
  40 static int ds1672_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  41 {
  42         unsigned long time;
  43         unsigned char addr = DS1672_REG_CNT_BASE;
  44         unsigned char buf[4];
  45
  46         struct i2c_msg msgs[] = {
  47                 { client->addr, 0, 1, &addr },          /* setup read ptr */
  48                 { client->addr, I2C_M_RD, 4, buf },     /* read date */
  49         };
  50
  51         /* read date registers */
  52         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
  53                 dev_err(&client->dev, "%s: read error\n", __func__);
  54                 return -EIO;
  55         }
  56
  57         dev_dbg(&client->dev,
  58                 "%s: raw read data - counters=%02x,%02x,%02x,%02x\n",
  59                 __func__, buf[0], buf[1], buf[2], buf[3]);
  60
  61         time = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
  62
  63         rtc_time_to_tm(time, tm);
  64
  65         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
  66                 "mday=%d, mon=%d, year=%d, wday=%d\n",
  67                 __func__, tm->tm_sec, tm->tm_min, tm->tm_hour,
  68                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
  69
  70         return 0;
  71 }
  72
  73 static int ds1672_set_mmss(struct i2c_client *client, unsigned long secs)
  74 {
  75         int xfer;
  76         unsigned char buf[6];
  77
  78         buf[0] = DS1672_REG_CNT_BASE;
  79         buf[1] = secs & 0x000000FF;
  80         buf[2] = (secs & 0x0000FF00) >> 8;
  81         buf[3] = (secs & 0x00FF0000) >> 16;
  82         buf[4] = (secs & 0xFF000000) >> 24;
  83         buf[5] = 0;     /* set control reg to enable counting */
  84
  85         xfer = i2c_master_send(client, buf, 6);
  86         if (xfer != 6) {
  87                 dev_err(&client->dev, "%s: send: %d\n", __func__, xfer);
  88                 return -EIO;
  89         }
  90
  91         return 0;
  92 }
  93
  94 static int ds1672_set_datetime(struct i2c_client *client, struct rtc_time *tm)
  95 {
  96         unsigned long secs;
  97
  98         dev_dbg(&client->dev,
  99                 "%s: secs=%d, mins=%d, hours=%d, "
 100                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 101                 __func__,
 102                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 103                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 104
 105         rtc_tm_to_time(tm, &secs);
 106
 107         return ds1672_set_mmss(client, secs);
 108 }
 109
 110 static int ds1672_rtc_read_time(struct device *dev, struct rtc_time *tm)
 111 {
 112         return ds1672_get_datetime(to_i2c_client(dev), tm);
 113 }
 114
 115 static int ds1672_rtc_set_time(struct device *dev, struct rtc_time *tm)
 116 {
 117         return ds1672_set_datetime(to_i2c_client(dev), tm);
 118 }
 119
 120 static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs)
 121 {
 122         return ds1672_set_mmss(to_i2c_client(dev), secs);
 123 }
 124
 125 static int ds1672_get_control(struct i2c_client *client, u8 *status)
 126 {
 127         unsigned char addr = DS1672_REG_CONTROL;
 128
 129         struct i2c_msg msgs[] = {
 130                 { client->addr, 0, 1, &addr },          /* setup read ptr */
 131                 { client->addr, I2C_M_RD, 1, status },  /* read control */
 132         };
 133
 134         /* read control register */
 135         if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
 136                 dev_err(&client->dev, "%s: read error\n", __func__);
 137                 return -EIO;
 138         }
 139
 140         return 0;
 141 }
 142
 143 /* following are the sysfs callback functions */
 144 static ssize_t show_control(struct device *dev, struct device_attribute *attr, char *buf)
 145 {
 146         struct i2c_client *client = to_i2c_client(dev);
 147         u8 control;
 148         int err;
 149
 150         err = ds1672_get_control(client, &control);
 151         if (err)
 152                 return err;
 153
 154         return sprintf(buf, "%s\n", (control & DS1672_REG_CONTROL_EOSC)
 155                                         ? "disabled" : "enabled");
 156 }
 157 static DEVICE_ATTR(control, S_IRUGO, show_control, NULL);
 158
 159 static const struct rtc_class_ops ds1672_rtc_ops = {
 160         .read_time      = ds1672_rtc_read_time,
 161         .set_time       = ds1672_rtc_set_time,
 162         .set_mmss       = ds1672_rtc_set_mmss,
 163 };
 164
 165 static int ds1672_attach(struct i2c_adapter *adapter)
 166 {
 167         return i2c_probe(adapter, &addr_data, ds1672_probe);
 168 }
 169
 170 static int ds1672_detach(struct i2c_client *client)
 171 {
 172         int err;
 173         struct rtc_device *rtc = i2c_get_clientdata(client);
 174
 175         if (rtc)
 176                 rtc_device_unregister(rtc);
 177
 178         if ((err = i2c_detach_client(client)))
 179                 return err;
 180
 181         kfree(client);
 182
 183         return 0;
 184 }
 185
 186 static struct i2c_driver ds1672_driver = {
 187         .driver         = {
 188                 .name   = "ds1672",
 189         },
 190         .id             = I2C_DRIVERID_DS1672,
 191         .attach_adapter = &ds1672_attach,
 192         .detach_client  = &ds1672_detach,
 193 };
 194
 195 static int ds1672_probe(struct i2c_adapter *adapter, int address, int kind)
 196 {
 197         int err = 0;
 198         u8 control;
 199         struct i2c_client *client;
 200         struct rtc_device *rtc;
 201
 202         dev_dbg(&adapter->dev, "%s\n", __func__);
 203
 204         if (!i2c_check_functionality(adapter, I2C_FUNC_I2C)) {
 205                 err = -ENODEV;
 206                 goto exit;
 207         }
 208
 209         if (!(client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL))) {
 210                 err = -ENOMEM;
 211                 goto exit;
 212         }
 213
 214         /* I2C client */
 215         client->addr = address;
 216         client->driver = &ds1672_driver;
 217         client->adapter = adapter;
 218
 219         strlcpy(client->name, ds1672_driver.driver.name, I2C_NAME_SIZE);
 220
 221         /* Inform the i2c layer */
 222         if ((err = i2c_attach_client(client)))
 223                 goto exit_kfree;
 224
 225         dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 226
 227         rtc = rtc_device_register(ds1672_driver.driver.name, &client->dev,
 228                                 &ds1672_rtc_ops, THIS_MODULE);
 229
 230         if (IS_ERR(rtc)) {
 231                 err = PTR_ERR(rtc);
 232                 goto exit_detach;
 233         }
 234
 235         i2c_set_clientdata(client, rtc);
 236
 237         /* read control register */
 238         err = ds1672_get_control(client, &control);
 239         if (err)
 240                 goto exit_devreg;
 241
 242         if (control & DS1672_REG_CONTROL_EOSC)
 243                 dev_warn(&client->dev, "Oscillator not enabled. "
 244                                         "Set time to enable.\n");
 245
 246         /* Register sysfs hooks */
 247         err = device_create_file(&client->dev, &dev_attr_control);
 248         if (err)
 249                 goto exit_devreg;
 250
 251         return 0;
 252
 253 exit_devreg:
 254         rtc_device_unregister(rtc);
 255
 256 exit_detach:
 257         i2c_detach_client(client);
 258
 259 exit_kfree:
 260         kfree(client);
 261
 262 exit:
 263         return err;
 264 }
 265
 266 static int __init ds1672_init(void)
 267 {
 268         return i2c_add_driver(&ds1672_driver);
 269 }
 270
 271 static void __exit ds1672_exit(void)
 272 {
 273         i2c_del_driver(&ds1672_driver);
 274 }
 275
 276 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 277 MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");
 278 MODULE_LICENSE("GPL");
 279 MODULE_VERSION(DRV_VERSION);
 280
 281 module_init(ds1672_init);
 282 module_exit(ds1672_exit);