drivers/rtc/rtc-rx4581.c

   1 /* drivers/rtc/rtc-rx4581.c
   2  *
   3  * written by Torben Hohn <torbenh@linutronix.de>
   4  *
   5  * Based on:
   6  * drivers/rtc/rtc-max6902.c
   7  *
   8  * Copyright (C) 2006 8D Technologies inc.
   9  * Copyright (C) 2004 Compulab Ltd.
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License version 2 as
  13  * published by the Free Software Foundation.
  14  *
  15  * Driver for MAX6902 spi RTC
  16  *
  17  * and based on:
  18  * drivers/rtc/rtc-rx8581.c
  19  *
  20  * An I2C driver for the Epson RX8581 RTC
  21  *
  22  * Author: Martyn Welch <martyn.welch@ge.com>
  23  * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
  24  *
  25  * This program is free software; you can redistribute it and/or modify
  26  * it under the terms of the GNU General Public License version 2 as
  27  * published by the Free Software Foundation.
  28  *
  29  * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC)
  30  * Copyright 2005-06 Tower Technologies
  31  *
  32  */
  33
  34 #include <linux/module.h>
  35 #include <linux/kernel.h>
  36 #include <linux/platform_device.h>
  37 #include <linux/init.h>
  38 #include <linux/rtc.h>
  39 #include <linux/spi/spi.h>
  40 #include <linux/bcd.h>
  41
  42 #define RX4581_REG_SC           0x00 /* Second in BCD */
  43 #define RX4581_REG_MN           0x01 /* Minute in BCD */
  44 #define RX4581_REG_HR           0x02 /* Hour in BCD */
  45 #define RX4581_REG_DW           0x03 /* Day of Week */
  46 #define RX4581_REG_DM           0x04 /* Day of Month in BCD */
  47 #define RX4581_REG_MO           0x05 /* Month in BCD */
  48 #define RX4581_REG_YR           0x06 /* Year in BCD */
  49 #define RX4581_REG_RAM          0x07 /* RAM */
  50 #define RX4581_REG_AMN          0x08 /* Alarm Min in BCD*/
  51 #define RX4581_REG_AHR          0x09 /* Alarm Hour in BCD */
  52 #define RX4581_REG_ADM          0x0A
  53 #define RX4581_REG_ADW          0x0A
  54 #define RX4581_REG_TMR0         0x0B
  55 #define RX4581_REG_TMR1         0x0C
  56 #define RX4581_REG_EXT          0x0D /* Extension Register */
  57 #define RX4581_REG_FLAG         0x0E /* Flag Register */
  58 #define RX4581_REG_CTRL         0x0F /* Control Register */
  59
  60
  61 /* Flag Register bit definitions */
  62 #define RX4581_FLAG_UF          0x20 /* Update */
  63 #define RX4581_FLAG_TF          0x10 /* Timer */
  64 #define RX4581_FLAG_AF          0x08 /* Alarm */
  65 #define RX4581_FLAG_VLF         0x02 /* Voltage Low */
  66
  67 /* Control Register bit definitions */
  68 #define RX4581_CTRL_UIE         0x20 /* Update Interrupt Enable */
  69 #define RX4581_CTRL_TIE         0x10 /* Timer Interrupt Enable */
  70 #define RX4581_CTRL_AIE         0x08 /* Alarm Interrupt Enable */
  71 #define RX4581_CTRL_STOP        0x02 /* STOP bit */
  72 #define RX4581_CTRL_RESET       0x01 /* RESET bit */
  73
  74 static int rx4581_set_reg(struct device *dev, unsigned char address,
  75                                 unsigned char data)
  76 {
  77         struct spi_device *spi = to_spi_device(dev);
  78         unsigned char buf[2];
  79
  80         /* high nibble must be '0' to write */
  81         buf[0] = address & 0x0f;
  82         buf[1] = data;
  83
  84         return spi_write_then_read(spi, buf, 2, NULL, 0);
  85 }
  86
  87 static int rx4581_get_reg(struct device *dev, unsigned char address,
  88                                 unsigned char *data)
  89 {
  90         struct spi_device *spi = to_spi_device(dev);
  91
  92         /* Set MSB to indicate read */
  93         *data = address | 0x80;
  94
  95         return spi_write_then_read(spi, data, 1, data, 1);
  96 }
  97
  98 /*
  99  * In the routines that deal directly with the rx8581 hardware, we use
 100  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
 101  */
 102 static int rx4581_get_datetime(struct device *dev, struct rtc_time *tm)
 103 {
 104         struct spi_device *spi = to_spi_device(dev);
 105         unsigned char date[7];
 106         unsigned char data;
 107         int err;
 108
 109         /* First we ensure that the "update flag" is not set, we read the
 110          * time and date then re-read the "update flag". If the update flag
 111          * has been set, we know that the time has changed during the read so
 112          * we repeat the whole process again.
 113          */
 114         err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
 115         if (err != 0) {
 116                 dev_err(dev, "Unable to read device flags\n");
 117                 return -EIO;
 118         }
 119
 120         do {
 121                 /* If update flag set, clear it */
 122                 if (data & RX4581_FLAG_UF) {
 123                         err = rx4581_set_reg(dev,
 124                                 RX4581_REG_FLAG, (data & ~RX4581_FLAG_UF));
 125                         if (err != 0) {
 126                                 dev_err(dev, "Unable to write device "
 127                                         "flags\n");
 128                                 return -EIO;
 129                         }
 130                 }
 131
 132                 /* Now read time and date */
 133                 date[0] = 0x80;
 134                 err = spi_write_then_read(spi, date, 1, date, 7);
 135                 if (err < 0) {
 136                         dev_err(dev, "Unable to read date\n");
 137                         return -EIO;
 138                 }
 139
 140                 /* Check flag register */
 141                 err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
 142                 if (err != 0) {
 143                         dev_err(dev, "Unable to read device flags\n");
 144                         return -EIO;
 145                 }
 146         } while (data & RX4581_FLAG_UF);
 147
 148         if (data & RX4581_FLAG_VLF)
 149                 dev_info(dev,
 150                         "low voltage detected, date/time is not reliable.\n");
 151
 152         dev_dbg(dev,
 153                 "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
 154                 "wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
 155                 __func__,
 156                 date[0], date[1], date[2], date[3], date[4], date[5], date[6]);
 157
 158         tm->tm_sec = bcd2bin(date[RX4581_REG_SC] & 0x7F);
 159         tm->tm_min = bcd2bin(date[RX4581_REG_MN] & 0x7F);
 160         tm->tm_hour = bcd2bin(date[RX4581_REG_HR] & 0x3F); /* rtc hr 0-23 */
 161         tm->tm_wday = ilog2(date[RX4581_REG_DW] & 0x7F);
 162         tm->tm_mday = bcd2bin(date[RX4581_REG_DM] & 0x3F);
 163         tm->tm_mon = bcd2bin(date[RX4581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
 164         tm->tm_year = bcd2bin(date[RX4581_REG_YR]);
 165         if (tm->tm_year < 70)
 166                 tm->tm_year += 100;     /* assume we are in 1970...2069 */
 167
 168
 169         dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 170                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 171                 __func__,
 172                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 173                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 174
 175         return 0;
 176 }
 177
 178 static int rx4581_set_datetime(struct device *dev, struct rtc_time *tm)
 179 {
 180         struct spi_device *spi = to_spi_device(dev);
 181         int err;
 182         unsigned char buf[8], data;
 183
 184         dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, "
 185                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 186                 __func__,
 187                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 188                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 189
 190         buf[0] = 0x00;
 191         /* hours, minutes and seconds */
 192         buf[RX4581_REG_SC+1] = bin2bcd(tm->tm_sec);
 193         buf[RX4581_REG_MN+1] = bin2bcd(tm->tm_min);
 194         buf[RX4581_REG_HR+1] = bin2bcd(tm->tm_hour);
 195
 196         buf[RX4581_REG_DM+1] = bin2bcd(tm->tm_mday);
 197
 198         /* month, 1 - 12 */
 199         buf[RX4581_REG_MO+1] = bin2bcd(tm->tm_mon + 1);
 200
 201         /* year and century */
 202         buf[RX4581_REG_YR+1] = bin2bcd(tm->tm_year % 100);
 203         buf[RX4581_REG_DW+1] = (0x1 << tm->tm_wday);
 204
 205         /* Stop the clock */
 206         err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
 207         if (err != 0) {
 208                 dev_err(dev, "Unable to read control register\n");
 209                 return -EIO;
 210         }
 211
 212         err = rx4581_set_reg(dev, RX4581_REG_CTRL,
 213                 (data | RX4581_CTRL_STOP));
 214         if (err != 0) {
 215                 dev_err(dev, "Unable to write control register\n");
 216                 return -EIO;
 217         }
 218
 219         /* write register's data */
 220         err = spi_write_then_read(spi, buf, 8, NULL, 0);
 221         if (err != 0) {
 222                 dev_err(dev, "Unable to write to date registers\n");
 223                 return -EIO;
 224         }
 225
 226         /* get VLF and clear it */
 227         err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
 228         if (err != 0) {
 229                 dev_err(dev, "Unable to read flag register\n");
 230                 return -EIO;
 231         }
 232
 233         err = rx4581_set_reg(dev, RX4581_REG_FLAG,
 234                 (data & ~(RX4581_FLAG_VLF)));
 235         if (err != 0) {
 236                 dev_err(dev, "Unable to write flag register\n");
 237                 return -EIO;
 238         }
 239
 240         /* Restart the clock */
 241         err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
 242         if (err != 0) {
 243                 dev_err(dev, "Unable to read control register\n");
 244                 return -EIO;
 245         }
 246
 247         err = rx4581_set_reg(dev, RX4581_REG_CTRL,
 248                 (data & ~(RX4581_CTRL_STOP)));
 249         if (err != 0) {
 250                 dev_err(dev, "Unable to write control register\n");
 251                 return -EIO;
 252         }
 253
 254         return 0;
 255 }
 256
 257 static const struct rtc_class_ops rx4581_rtc_ops = {
 258         .read_time      = rx4581_get_datetime,
 259         .set_time       = rx4581_set_datetime,
 260 };
 261
 262 static int rx4581_probe(struct spi_device *spi)
 263 {
 264         struct rtc_device *rtc;
 265         unsigned char tmp;
 266         int res;
 267
 268         res = rx4581_get_reg(&spi->dev, RX4581_REG_SC, &tmp);
 269         if (res != 0)
 270                 return res;
 271
 272         rtc = devm_rtc_device_register(&spi->dev, "rx4581",
 273                                 &rx4581_rtc_ops, THIS_MODULE);
 274         if (IS_ERR(rtc))
 275                 return PTR_ERR(rtc);
 276
 277         spi_set_drvdata(spi, rtc);
 278         return 0;
 279 }
 280
 281 static const struct spi_device_id rx4581_id[] = {
 282         { "rx4581", 0 },
 283         { }
 284 };
 285 MODULE_DEVICE_TABLE(spi, rx4581_id);
 286
 287 static struct spi_driver rx4581_driver = {
 288         .driver = {
 289                 .name   = "rtc-rx4581",
 290         },
 291         .probe  = rx4581_probe,
 292         .id_table = rx4581_id,
 293 };
 294
 295 module_spi_driver(rx4581_driver);
 296
 297 MODULE_DESCRIPTION("rx4581 spi RTC driver");
 298 MODULE_AUTHOR("Torben Hohn");
 299 MODULE_LICENSE("GPL");
 300 MODULE_ALIAS("spi:rtc-rx4581");