drivers/rtc/rtc-rx8581.c

   1 /*
   2  * An I2C driver for the Epson RX8581 RTC
   3  *
   4  * Author: Martyn Welch <martyn.welch@ge.com>
   5  * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
   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  * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC)
  12  * Copyright 2005-06 Tower Technologies
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/i2c.h>
  17 #include <linux/bcd.h>
  18 #include <linux/rtc.h>
  19 #include <linux/log2.h>
  20
  21 #define DRV_VERSION "0.1"
  22
  23 #define RX8581_REG_SC           0x00 /* Second in BCD */
  24 #define RX8581_REG_MN           0x01 /* Minute in BCD */
  25 #define RX8581_REG_HR           0x02 /* Hour in BCD */
  26 #define RX8581_REG_DW           0x03 /* Day of Week */
  27 #define RX8581_REG_DM           0x04 /* Day of Month in BCD */
  28 #define RX8581_REG_MO           0x05 /* Month in BCD */
  29 #define RX8581_REG_YR           0x06 /* Year in BCD */
  30 #define RX8581_REG_RAM          0x07 /* RAM */
  31 #define RX8581_REG_AMN          0x08 /* Alarm Min in BCD*/
  32 #define RX8581_REG_AHR          0x09 /* Alarm Hour in BCD */
  33 #define RX8581_REG_ADM          0x0A
  34 #define RX8581_REG_ADW          0x0A
  35 #define RX8581_REG_TMR0         0x0B
  36 #define RX8581_REG_TMR1         0x0C
  37 #define RX8581_REG_EXT          0x0D /* Extension Register */
  38 #define RX8581_REG_FLAG         0x0E /* Flag Register */
  39 #define RX8581_REG_CTRL         0x0F /* Control Register */
  40
  41
  42 /* Flag Register bit definitions */
  43 #define RX8581_FLAG_UF          0x20 /* Update */
  44 #define RX8581_FLAG_TF          0x10 /* Timer */
  45 #define RX8581_FLAG_AF          0x08 /* Alarm */
  46 #define RX8581_FLAG_VLF         0x02 /* Voltage Low */
  47
  48 /* Control Register bit definitions */
  49 #define RX8581_CTRL_UIE         0x20 /* Update Interrupt Enable */
  50 #define RX8581_CTRL_TIE         0x10 /* Timer Interrupt Enable */
  51 #define RX8581_CTRL_AIE         0x08 /* Alarm Interrupt Enable */
  52 #define RX8581_CTRL_STOP        0x02 /* STOP bit */
  53 #define RX8581_CTRL_RESET       0x01 /* RESET bit */
  54
  55 struct rx8581 {
  56         struct i2c_client       *client;
  57         struct rtc_device       *rtc;
  58         s32 (*read_block_data)(const struct i2c_client *client, u8 command,
  59                                 u8 length, u8 *values);
  60         s32 (*write_block_data)(const struct i2c_client *client, u8 command,
  61                                 u8 length, const u8 *values);
  62 };
  63
  64 static struct i2c_driver rx8581_driver;
  65
  66 static int rx8581_read_block_data(const struct i2c_client *client, u8 command,
  67                                         u8 length, u8 *values)
  68 {
  69         s32 i, data;
  70
  71         for (i = 0; i < length; i++) {
  72                 data = i2c_smbus_read_byte_data(client, command + i);
  73                 if (data < 0)
  74                         return data;
  75                 values[i] = data;
  76         }
  77         return i;
  78 }
  79
  80 static int rx8581_write_block_data(const struct i2c_client *client, u8 command,
  81                                         u8 length, const u8 *values)
  82 {
  83         s32 i, ret;
  84
  85         for (i = 0; i < length; i++) {
  86                 ret = i2c_smbus_write_byte_data(client, command + i,
  87                                                 values[i]);
  88                 if (ret < 0)
  89                         return ret;
  90         }
  91         return length;
  92 }
  93
  94 /*
  95  * In the routines that deal directly with the rx8581 hardware, we use
  96  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  97  */
  98 static int rx8581_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  99 {
 100         unsigned char date[7];
 101         int data, err;
 102         struct rx8581 *rx8581 = i2c_get_clientdata(client);
 103
 104         /* First we ensure that the "update flag" is not set, we read the
 105          * time and date then re-read the "update flag". If the update flag
 106          * has been set, we know that the time has changed during the read so
 107          * we repeat the whole process again.
 108          */
 109         data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
 110         if (data < 0) {
 111                 dev_err(&client->dev, "Unable to read device flags\n");
 112                 return -EIO;
 113         }
 114
 115         do {
 116                 /* If update flag set, clear it */
 117                 if (data & RX8581_FLAG_UF) {
 118                         err = i2c_smbus_write_byte_data(client,
 119                                 RX8581_REG_FLAG, (data & ~RX8581_FLAG_UF));
 120                         if (err != 0) {
 121                                 dev_err(&client->dev, "Unable to write device flags\n");
 122                                 return -EIO;
 123                         }
 124                 }
 125
 126                 /* Now read time and date */
 127                 err = rx8581->read_block_data(client, RX8581_REG_SC,
 128                         7, date);
 129                 if (err < 0) {
 130                         dev_err(&client->dev, "Unable to read date\n");
 131                         return -EIO;
 132                 }
 133
 134                 /* Check flag register */
 135                 data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
 136                 if (data < 0) {
 137                         dev_err(&client->dev, "Unable to read device flags\n");
 138                         return -EIO;
 139                 }
 140         } while (data & RX8581_FLAG_UF);
 141
 142         if (data & RX8581_FLAG_VLF)
 143                 dev_info(&client->dev,
 144                         "low voltage detected, date/time is not reliable.\n");
 145
 146         dev_dbg(&client->dev,
 147                 "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
 148                 "wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
 149                 __func__,
 150                 date[0], date[1], date[2], date[3], date[4], date[5], date[6]);
 151
 152         tm->tm_sec = bcd2bin(date[RX8581_REG_SC] & 0x7F);
 153         tm->tm_min = bcd2bin(date[RX8581_REG_MN] & 0x7F);
 154         tm->tm_hour = bcd2bin(date[RX8581_REG_HR] & 0x3F); /* rtc hr 0-23 */
 155         tm->tm_wday = ilog2(date[RX8581_REG_DW] & 0x7F);
 156         tm->tm_mday = bcd2bin(date[RX8581_REG_DM] & 0x3F);
 157         tm->tm_mon = bcd2bin(date[RX8581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
 158         tm->tm_year = bcd2bin(date[RX8581_REG_YR]);
 159         if (tm->tm_year < 70)
 160                 tm->tm_year += 100;     /* assume we are in 1970...2069 */
 161
 162
 163         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 164                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 165                 __func__,
 166                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 167                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 168
 169         err = rtc_valid_tm(tm);
 170         if (err < 0)
 171                 dev_err(&client->dev, "retrieved date/time is not valid.\n");
 172
 173         return err;
 174 }
 175
 176 static int rx8581_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 177 {
 178         int data, err;
 179         unsigned char buf[7];
 180         struct rx8581 *rx8581 = i2c_get_clientdata(client);
 181
 182         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 183                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 184                 __func__,
 185                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 186                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 187
 188         /* hours, minutes and seconds */
 189         buf[RX8581_REG_SC] = bin2bcd(tm->tm_sec);
 190         buf[RX8581_REG_MN] = bin2bcd(tm->tm_min);
 191         buf[RX8581_REG_HR] = bin2bcd(tm->tm_hour);
 192
 193         buf[RX8581_REG_DM] = bin2bcd(tm->tm_mday);
 194
 195         /* month, 1 - 12 */
 196         buf[RX8581_REG_MO] = bin2bcd(tm->tm_mon + 1);
 197
 198         /* year and century */
 199         buf[RX8581_REG_YR] = bin2bcd(tm->tm_year % 100);
 200         buf[RX8581_REG_DW] = (0x1 << tm->tm_wday);
 201
 202         /* Stop the clock */
 203         data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL);
 204         if (data < 0) {
 205                 dev_err(&client->dev, "Unable to read control register\n");
 206                 return -EIO;
 207         }
 208
 209         err = i2c_smbus_write_byte_data(client, RX8581_REG_CTRL,
 210                 (data | RX8581_CTRL_STOP));
 211         if (err < 0) {
 212                 dev_err(&client->dev, "Unable to write control register\n");
 213                 return -EIO;
 214         }
 215
 216         /* write register's data */
 217         err = rx8581->write_block_data(client, RX8581_REG_SC, 7, buf);
 218         if (err < 0) {
 219                 dev_err(&client->dev, "Unable to write to date registers\n");
 220                 return -EIO;
 221         }
 222
 223         /* get VLF and clear it */
 224         data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
 225         if (data < 0) {
 226                 dev_err(&client->dev, "Unable to read flag register\n");
 227                 return -EIO;
 228         }
 229
 230         err = i2c_smbus_write_byte_data(client, RX8581_REG_FLAG,
 231                 (data & ~(RX8581_FLAG_VLF)));
 232         if (err != 0) {
 233                 dev_err(&client->dev, "Unable to write flag register\n");
 234                 return -EIO;
 235         }
 236
 237         /* Restart the clock */
 238         data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL);
 239         if (data < 0) {
 240                 dev_err(&client->dev, "Unable to read control register\n");
 241                 return -EIO;
 242         }
 243
 244         err = i2c_smbus_write_byte_data(client, RX8581_REG_CTRL,
 245                 (data & ~(RX8581_CTRL_STOP)));
 246         if (err != 0) {
 247                 dev_err(&client->dev, "Unable to write control register\n");
 248                 return -EIO;
 249         }
 250
 251         return 0;
 252 }
 253
 254 static int rx8581_rtc_read_time(struct device *dev, struct rtc_time *tm)
 255 {
 256         return rx8581_get_datetime(to_i2c_client(dev), tm);
 257 }
 258
 259 static int rx8581_rtc_set_time(struct device *dev, struct rtc_time *tm)
 260 {
 261         return rx8581_set_datetime(to_i2c_client(dev), tm);
 262 }
 263
 264 static const struct rtc_class_ops rx8581_rtc_ops = {
 265         .read_time      = rx8581_rtc_read_time,
 266         .set_time       = rx8581_rtc_set_time,
 267 };
 268
 269 static int rx8581_probe(struct i2c_client *client,
 270                         const struct i2c_device_id *id)
 271 {
 272         struct rx8581     *rx8581;
 273
 274         dev_dbg(&client->dev, "%s\n", __func__);
 275
 276         if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA)
 277                 && !i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
 278                 return -EIO;
 279
 280         rx8581 = devm_kzalloc(&client->dev, sizeof(struct rx8581), GFP_KERNEL);
 281         if (!rx8581)
 282                 return -ENOMEM;
 283
 284         i2c_set_clientdata(client, rx8581);
 285         rx8581->client = client;
 286
 287         if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) {
 288                 rx8581->read_block_data = i2c_smbus_read_i2c_block_data;
 289                 rx8581->write_block_data = i2c_smbus_write_i2c_block_data;
 290         } else {
 291                 rx8581->read_block_data = rx8581_read_block_data;
 292                 rx8581->write_block_data = rx8581_write_block_data;
 293         }
 294
 295         dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 296
 297         rx8581->rtc = devm_rtc_device_register(&client->dev,
 298                 rx8581_driver.driver.name, &rx8581_rtc_ops, THIS_MODULE);
 299
 300         if (IS_ERR(rx8581->rtc)) {
 301                 dev_err(&client->dev,
 302                         "unable to register the class device\n");
 303                 return PTR_ERR(rx8581->rtc);
 304         }
 305
 306         return 0;
 307 }
 308
 309 static const struct i2c_device_id rx8581_id[] = {
 310         { "rx8581", 0 },
 311         { }
 312 };
 313 MODULE_DEVICE_TABLE(i2c, rx8581_id);
 314
 315 static struct i2c_driver rx8581_driver = {
 316         .driver         = {
 317                 .name   = "rtc-rx8581",
 318         },
 319         .probe          = rx8581_probe,
 320         .id_table       = rx8581_id,
 321 };
 322
 323 module_i2c_driver(rx8581_driver);
 324
 325 MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
 326 MODULE_DESCRIPTION("Epson RX-8581 RTC driver");
 327 MODULE_LICENSE("GPL");
 328 MODULE_VERSION(DRV_VERSION);