linux/drivers/rtc/rtc-rx8581.c
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   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
  55static 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 */
  61static 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
 139static 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
 216static 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
 221static 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
 226static const struct rtc_class_ops rx8581_rtc_ops = {
 227        .read_time      = rx8581_rtc_read_time,
 228        .set_time       = rx8581_rtc_set_time,
 229};
 230
 231static int 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 = devm_rtc_device_register(&client->dev, rx8581_driver.driver.name,
 244                                        &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
 254static int rx8581_remove(struct i2c_client *client)
 255{
 256        return 0;
 257}
 258
 259static const struct i2c_device_id rx8581_id[] = {
 260        { "rx8581", 0 },
 261        { }
 262};
 263MODULE_DEVICE_TABLE(i2c, rx8581_id);
 264
 265static struct i2c_driver rx8581_driver = {
 266        .driver         = {
 267                .name   = "rtc-rx8581",
 268                .owner  = THIS_MODULE,
 269        },
 270        .probe          = rx8581_probe,
 271        .remove         = rx8581_remove,
 272        .id_table       = rx8581_id,
 273};
 274
 275module_i2c_driver(rx8581_driver);
 276
 277MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
 278MODULE_DESCRIPTION("Epson RX-8581 RTC driver");
 279MODULE_LICENSE("GPL");
 280MODULE_VERSION(DRV_VERSION);
 281
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