linux/drivers/rtc/rtc-rx4581.c
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   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
  74static 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
  87static 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 */
 102static 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        err = rtc_valid_tm(tm);
 176        if (err < 0)
 177                dev_err(dev, "retrieved date/time is not valid.\n");
 178
 179        return err;
 180}
 181
 182static int rx4581_set_datetime(struct device *dev, struct rtc_time *tm)
 183{
 184        struct spi_device *spi = to_spi_device(dev);
 185        int err;
 186        unsigned char buf[8], data;
 187
 188        dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, "
 189                "mday=%d, mon=%d, year=%d, wday=%d\n",
 190                __func__,
 191                tm->tm_sec, tm->tm_min, tm->tm_hour,
 192                tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 193
 194        buf[0] = 0x00;
 195        /* hours, minutes and seconds */
 196        buf[RX4581_REG_SC+1] = bin2bcd(tm->tm_sec);
 197        buf[RX4581_REG_MN+1] = bin2bcd(tm->tm_min);
 198        buf[RX4581_REG_HR+1] = bin2bcd(tm->tm_hour);
 199
 200        buf[RX4581_REG_DM+1] = bin2bcd(tm->tm_mday);
 201
 202        /* month, 1 - 12 */
 203        buf[RX4581_REG_MO+1] = bin2bcd(tm->tm_mon + 1);
 204
 205        /* year and century */
 206        buf[RX4581_REG_YR+1] = bin2bcd(tm->tm_year % 100);
 207        buf[RX4581_REG_DW+1] = (0x1 << tm->tm_wday);
 208
 209        /* Stop the clock */
 210        err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
 211        if (err != 0) {
 212                dev_err(dev, "Unable to read control register\n");
 213                return -EIO;
 214        }
 215
 216        err = rx4581_set_reg(dev, RX4581_REG_CTRL,
 217                (data | RX4581_CTRL_STOP));
 218        if (err != 0) {
 219                dev_err(dev, "Unable to write control register\n");
 220                return -EIO;
 221        }
 222
 223        /* write register's data */
 224        err = spi_write_then_read(spi, buf, 8, NULL, 0);
 225        if (err != 0) {
 226                dev_err(dev, "Unable to write to date registers\n");
 227                return -EIO;
 228        }
 229
 230        /* get VLF and clear it */
 231        err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
 232        if (err != 0) {
 233                dev_err(dev, "Unable to read flag register\n");
 234                return -EIO;
 235        }
 236
 237        err = rx4581_set_reg(dev, RX4581_REG_FLAG,
 238                (data & ~(RX4581_FLAG_VLF)));
 239        if (err != 0) {
 240                dev_err(dev, "Unable to write flag register\n");
 241                return -EIO;
 242        }
 243
 244        /* Restart the clock */
 245        err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
 246        if (err != 0) {
 247                dev_err(dev, "Unable to read control register\n");
 248                return -EIO;
 249        }
 250
 251        err = rx4581_set_reg(dev, RX4581_REG_CTRL,
 252                (data & ~(RX4581_CTRL_STOP)));
 253        if (err != 0) {
 254                dev_err(dev, "Unable to write control register\n");
 255                return -EIO;
 256        }
 257
 258        return 0;
 259}
 260
 261static const struct rtc_class_ops rx4581_rtc_ops = {
 262        .read_time      = rx4581_get_datetime,
 263        .set_time       = rx4581_set_datetime,
 264};
 265
 266static int rx4581_probe(struct spi_device *spi)
 267{
 268        struct rtc_device *rtc;
 269        unsigned char tmp;
 270        int res;
 271
 272        res = rx4581_get_reg(&spi->dev, RX4581_REG_SC, &tmp);
 273        if (res != 0)
 274                return res;
 275
 276        rtc = rtc_device_register("rx4581",
 277                                &spi->dev, &rx4581_rtc_ops, THIS_MODULE);
 278        if (IS_ERR(rtc))
 279                return PTR_ERR(rtc);
 280
 281        dev_set_drvdata(&spi->dev, rtc);
 282        return 0;
 283}
 284
 285static int rx4581_remove(struct spi_device *spi)
 286{
 287        struct rtc_device *rtc = dev_get_drvdata(&spi->dev);
 288
 289        rtc_device_unregister(rtc);
 290        return 0;
 291}
 292
 293static const struct spi_device_id rx4581_id[] = {
 294        { "rx4581", 0 },
 295        { }
 296};
 297MODULE_DEVICE_TABLE(spi, rx4581_id);
 298
 299static struct spi_driver rx4581_driver = {
 300        .driver = {
 301                .name   = "rtc-rx4581",
 302                .owner  = THIS_MODULE,
 303        },
 304        .probe  = rx4581_probe,
 305        .remove = rx4581_remove,
 306        .id_table = rx4581_id,
 307};
 308
 309module_spi_driver(rx4581_driver);
 310
 311MODULE_DESCRIPTION("rx4581 spi RTC driver");
 312MODULE_AUTHOR("Torben Hohn");
 313MODULE_LICENSE("GPL");
 314MODULE_ALIAS("spi:rtc-rx4581");
 315
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