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