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 static struct i2c_driver rx8581_driver;
  56
  57 /*
  58  * In the routines that deal directly with the rx8581 hardware, we use
  59  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  60  */
  61 static int rx8581_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  62 {
  63         unsigned char date[7];
  64         int data, err;
  65
  66         /* First we ensure that the "update flag" is not set, we read the
  67          * time and date then re-read the "update flag". If the update flag
  68          * has been set, we know that the time has changed during the read so
  69          * we repeat the whole process again.
  70          */
  71         data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
  72         if (data < 0) {
  73                 dev_err(&client->dev, "Unable to read device flags\n");
  74                 return -EIO;
  75         }
  76
  77         do {
  78                 /* If update flag set, clear it */
  79                 if (data & RX8581_FLAG_UF) {
  80                         err = i2c_smbus_write_byte_data(client,
  81                                 RX8581_REG_FLAG, (data & ~RX8581_FLAG_UF));
  82                         if (err != 0) {
  83                                 dev_err(&client->dev, "Unable to write device "
  84                                         "flags\n");
  85                                 return -EIO;
  86                         }
  87                 }
  88
  89                 /* Now read time and date */
  90                 err = i2c_smbus_read_i2c_block_data(client, RX8581_REG_SC,
  91                         7, date);
  92                 if (err < 0) {
  93                         dev_err(&client->dev, "Unable to read date\n");
  94                         return -EIO;
  95                 }
  96
  97                 /* Check flag register */
  98                 data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
  99                 if (data < 0) {
 100                         dev_err(&client->dev, "Unable to read device flags\n");
 101                         return -EIO;
 102                 }
 103         } while (data & RX8581_FLAG_UF);
 104
 105         if (data & RX8581_FLAG_VLF)
 106                 dev_info(&client->dev,
 107                         "low voltage detected, date/time is not reliable.\n");
 108
 109         dev_dbg(&client->dev,
 110                 "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
 111                 "wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
 112                 __func__,
 113                 date[0], date[1], date[2], date[3], date[4], date[5], date[6]);
 114
 115         tm->tm_sec = bcd2bin(date[RX8581_REG_SC] & 0x7F);
 116         tm->tm_min = bcd2bin(date[RX8581_REG_MN] & 0x7F);
 117         tm->tm_hour = bcd2bin(date[RX8581_REG_HR] & 0x3F); /* rtc hr 0-23 */
 118         tm->tm_wday = ilog2(date[RX8581_REG_DW] & 0x7F);
 119         tm->tm_mday = bcd2bin(date[RX8581_REG_DM] & 0x3F);
 120         tm->tm_mon = bcd2bin(date[RX8581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
 121         tm->tm_year = bcd2bin(date[RX8581_REG_YR]);
 122         if (tm->tm_year < 70)
 123                 tm->tm_year += 100;     /* assume we are in 1970...2069 */
 124
 125
 126         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 127                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 128                 __func__,
 129                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 130                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 131
 132         err = rtc_valid_tm(tm);
 133         if (err < 0)
 134                 dev_err(&client->dev, "retrieved date/time is not valid.\n");
 135
 136         return err;
 137 }
 138
 139 static int rx8581_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 140 {
 141         int data, err;
 142         unsigned char buf[7];
 143
 144         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 145                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 146                 __func__,
 147                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 148                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 149
 150         /* hours, minutes and seconds */
 151         buf[RX8581_REG_SC] = bin2bcd(tm->tm_sec);
 152         buf[RX8581_REG_MN] = bin2bcd(tm->tm_min);
 153         buf[RX8581_REG_HR] = bin2bcd(tm->tm_hour);
 154
 155         buf[RX8581_REG_DM] = bin2bcd(tm->tm_mday);
 156
 157         /* month, 1 - 12 */
 158         buf[RX8581_REG_MO] = bin2bcd(tm->tm_mon + 1);
 159
 160         /* year and century */
 161         buf[RX8581_REG_YR] = bin2bcd(tm->tm_year % 100);
 162         buf[RX8581_REG_DW] = (0x1 << tm->tm_wday);
 163
 164         /* Stop the clock */
 165         data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL);
 166         if (data < 0) {
 167                 dev_err(&client->dev, "Unable to read control register\n");
 168                 return -EIO;
 169         }
 170
 171         err = i2c_smbus_write_byte_data(client, RX8581_REG_CTRL,
 172                 (data | RX8581_CTRL_STOP));
 173         if (err < 0) {
 174                 dev_err(&client->dev, "Unable to write control register\n");
 175                 return -EIO;
 176         }
 177
 178         /* write register's data */
 179         err = i2c_smbus_write_i2c_block_data(client, RX8581_REG_SC, 7, buf);
 180         if (err < 0) {
 181                 dev_err(&client->dev, "Unable to write to date registers\n");
 182                 return -EIO;
 183         }
 184
 185         /* get VLF and clear it */
 186         data = i2c_smbus_read_byte_data(client, RX8581_REG_FLAG);
 187         if (data < 0) {
 188                 dev_err(&client->dev, "Unable to read flag register\n");
 189                 return -EIO;
 190         }
 191
 192         err = i2c_smbus_write_byte_data(client, RX8581_REG_FLAG,
 193                 (data & ~(RX8581_FLAG_VLF)));
 194         if (err != 0) {
 195                 dev_err(&client->dev, "Unable to write flag register\n");
 196                 return -EIO;
 197         }
 198
 199         /* Restart the clock */
 200         data = i2c_smbus_read_byte_data(client, RX8581_REG_CTRL);
 201         if (data < 0) {
 202                 dev_err(&client->dev, "Unable to read control register\n");
 203                 return -EIO;
 204         }
 205
 206         err = i2c_smbus_write_byte_data(client, RX8581_REG_CTRL,
 207                 (data & ~(RX8581_CTRL_STOP)));
 208         if (err != 0) {
 209                 dev_err(&client->dev, "Unable to write control register\n");
 210                 return -EIO;
 211         }
 212
 213         return 0;
 214 }
 215
 216 static int rx8581_rtc_read_time(struct device *dev, struct rtc_time *tm)
 217 {
 218         return rx8581_get_datetime(to_i2c_client(dev), tm);
 219 }
 220
 221 static int rx8581_rtc_set_time(struct device *dev, struct rtc_time *tm)
 222 {
 223         return rx8581_set_datetime(to_i2c_client(dev), tm);
 224 }
 225
 226 static const struct rtc_class_ops rx8581_rtc_ops = {
 227         .read_time      = rx8581_rtc_read_time,
 228         .set_time       = rx8581_rtc_set_time,
 229 };
 230
 231 static int __devinit rx8581_probe(struct i2c_client *client,
 232                                 const struct i2c_device_id *id)
 233 {
 234         struct rtc_device *rtc;
 235
 236         dev_dbg(&client->dev, "%s\n", __func__);
 237
 238         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 239                 return -ENODEV;
 240
 241         dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 242
 243         rtc = rtc_device_register(rx8581_driver.driver.name,
 244                                 &client->dev, &rx8581_rtc_ops, THIS_MODULE);
 245
 246         if (IS_ERR(rtc))
 247                 return PTR_ERR(rtc);
 248
 249         i2c_set_clientdata(client, rtc);
 250
 251         return 0;
 252 }
 253
 254 static int __devexit rx8581_remove(struct i2c_client *client)
 255 {
 256         struct rtc_device *rtc = i2c_get_clientdata(client);
 257
 258         rtc_device_unregister(rtc);
 259
 260         return 0;
 261 }
 262
 263 static const struct i2c_device_id rx8581_id[] = {
 264         { "rx8581", 0 },
 265         { }
 266 };
 267 MODULE_DEVICE_TABLE(i2c, rx8581_id);
 268
 269 static struct i2c_driver rx8581_driver = {
 270         .driver         = {
 271                 .name   = "rtc-rx8581",
 272                 .owner  = THIS_MODULE,
 273         },
 274         .probe          = rx8581_probe,
 275         .remove         = __devexit_p(rx8581_remove),
 276         .id_table       = rx8581_id,
 277 };
 278
 279 static int __init rx8581_init(void)
 280 {
 281         return i2c_add_driver(&rx8581_driver);
 282 }
 283
 284 static void __exit rx8581_exit(void)
 285 {
 286         i2c_del_driver(&rx8581_driver);
 287 }
 288
 289 MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
 290 MODULE_DESCRIPTION("Epson RX-8581 RTC driver");
 291 MODULE_LICENSE("GPL");
 292 MODULE_VERSION(DRV_VERSION);
 293
 294 module_init(rx8581_init);
 295 module_exit(rx8581_exit);