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/regmap.h>
  19#include <linux/rtc.h>
  20#include <linux/log2.h>
  21
  22#define RX8581_REG_SC           0x00 /* Second in BCD */
  23#define RX8581_REG_MN           0x01 /* Minute in BCD */
  24#define RX8581_REG_HR           0x02 /* Hour in BCD */
  25#define RX8581_REG_DW           0x03 /* Day of Week */
  26#define RX8581_REG_DM           0x04 /* Day of Month in BCD */
  27#define RX8581_REG_MO           0x05 /* Month in BCD */
  28#define RX8581_REG_YR           0x06 /* Year in BCD */
  29#define RX8581_REG_RAM          0x07 /* RAM */
  30#define RX8581_REG_AMN          0x08 /* Alarm Min in BCD*/
  31#define RX8581_REG_AHR          0x09 /* Alarm Hour in BCD */
  32#define RX8581_REG_ADM          0x0A
  33#define RX8581_REG_ADW          0x0A
  34#define RX8581_REG_TMR0         0x0B
  35#define RX8581_REG_TMR1         0x0C
  36#define RX8581_REG_EXT          0x0D /* Extension Register */
  37#define RX8581_REG_FLAG         0x0E /* Flag Register */
  38#define RX8581_REG_CTRL         0x0F /* Control Register */
  39
  40
  41/* Flag Register bit definitions */
  42#define RX8581_FLAG_UF          0x20 /* Update */
  43#define RX8581_FLAG_TF          0x10 /* Timer */
  44#define RX8581_FLAG_AF          0x08 /* Alarm */
  45#define RX8581_FLAG_VLF         0x02 /* Voltage Low */
  46
  47/* Control Register bit definitions */
  48#define RX8581_CTRL_UIE         0x20 /* Update Interrupt Enable */
  49#define RX8581_CTRL_TIE         0x10 /* Timer Interrupt Enable */
  50#define RX8581_CTRL_AIE         0x08 /* Alarm Interrupt Enable */
  51#define RX8581_CTRL_STOP        0x02 /* STOP bit */
  52#define RX8581_CTRL_RESET       0x01 /* RESET bit */
  53
  54struct rx8581 {
  55        struct regmap           *regmap;
  56        struct rtc_device       *rtc;
  57};
  58
  59/*
  60 * In the routines that deal directly with the rx8581 hardware, we use
  61 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  62 */
  63static int rx8581_rtc_read_time(struct device *dev, struct rtc_time *tm)
  64{
  65        struct i2c_client *client = to_i2c_client(dev);
  66        unsigned char date[7];
  67        unsigned int data;
  68        int err;
  69        struct rx8581 *rx8581 = i2c_get_clientdata(client);
  70
  71        /* First we ensure that the "update flag" is not set, we read the
  72         * time and date then re-read the "update flag". If the update flag
  73         * has been set, we know that the time has changed during the read so
  74         * we repeat the whole process again.
  75         */
  76        err = regmap_read(rx8581->regmap, RX8581_REG_FLAG, &data);
  77        if (err < 0)
  78                return err;
  79
  80        if (data & RX8581_FLAG_VLF) {
  81                dev_warn(dev,
  82                         "low voltage detected, date/time is not reliable.\n");
  83                return -EINVAL;
  84        }
  85
  86        do {
  87                /* If update flag set, clear it */
  88                if (data & RX8581_FLAG_UF) {
  89                        err = regmap_write(rx8581->regmap, RX8581_REG_FLAG,
  90                                          data & ~RX8581_FLAG_UF);
  91                        if (err < 0)
  92                                return err;
  93                }
  94
  95                /* Now read time and date */
  96                err = regmap_bulk_read(rx8581->regmap, RX8581_REG_SC, date,
  97                                       sizeof(date));
  98                if (err < 0)
  99                        return err;
 100
 101                /* Check flag register */
 102                err = regmap_read(rx8581->regmap, RX8581_REG_FLAG, &data);
 103                if (err < 0)
 104                        return err;
 105        } while (data & RX8581_FLAG_UF);
 106
 107        dev_dbg(dev, "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
 108                "wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
 109                __func__,
 110                date[0], date[1], date[2], date[3], date[4], date[5], date[6]);
 111
 112        tm->tm_sec = bcd2bin(date[RX8581_REG_SC] & 0x7F);
 113        tm->tm_min = bcd2bin(date[RX8581_REG_MN] & 0x7F);
 114        tm->tm_hour = bcd2bin(date[RX8581_REG_HR] & 0x3F); /* rtc hr 0-23 */
 115        tm->tm_wday = ilog2(date[RX8581_REG_DW] & 0x7F);
 116        tm->tm_mday = bcd2bin(date[RX8581_REG_DM] & 0x3F);
 117        tm->tm_mon = bcd2bin(date[RX8581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
 118        tm->tm_year = bcd2bin(date[RX8581_REG_YR]) + 100;
 119
 120        dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 121                "mday=%d, mon=%d, year=%d, wday=%d\n",
 122                __func__,
 123                tm->tm_sec, tm->tm_min, tm->tm_hour,
 124                tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 125
 126        return 0;
 127}
 128
 129static int rx8581_rtc_set_time(struct device *dev, struct rtc_time *tm)
 130{
 131        struct i2c_client *client = to_i2c_client(dev);
 132        int err;
 133        unsigned char buf[7];
 134        struct rx8581 *rx8581 = i2c_get_clientdata(client);
 135
 136        dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, "
 137                "mday=%d, mon=%d, year=%d, wday=%d\n",
 138                __func__,
 139                tm->tm_sec, tm->tm_min, tm->tm_hour,
 140                tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 141
 142        /* hours, minutes and seconds */
 143        buf[RX8581_REG_SC] = bin2bcd(tm->tm_sec);
 144        buf[RX8581_REG_MN] = bin2bcd(tm->tm_min);
 145        buf[RX8581_REG_HR] = bin2bcd(tm->tm_hour);
 146
 147        buf[RX8581_REG_DM] = bin2bcd(tm->tm_mday);
 148
 149        /* month, 1 - 12 */
 150        buf[RX8581_REG_MO] = bin2bcd(tm->tm_mon + 1);
 151
 152        /* year and century */
 153        buf[RX8581_REG_YR] = bin2bcd(tm->tm_year - 100);
 154        buf[RX8581_REG_DW] = (0x1 << tm->tm_wday);
 155
 156        /* Stop the clock */
 157        err = regmap_update_bits(rx8581->regmap, RX8581_REG_CTRL,
 158                                 RX8581_CTRL_STOP, RX8581_CTRL_STOP);
 159        if (err < 0)
 160                return err;
 161
 162        /* write register's data */
 163        err = regmap_bulk_write(rx8581->regmap, RX8581_REG_SC,
 164                                buf, sizeof(buf));
 165        if (err < 0)
 166                return err;
 167
 168        /* get VLF and clear it */
 169        err = regmap_update_bits(rx8581->regmap, RX8581_REG_FLAG,
 170                                 RX8581_FLAG_VLF, 0);
 171        if (err < 0)
 172                return err;
 173
 174        /* Restart the clock */
 175        return regmap_update_bits(rx8581->regmap, RX8581_REG_CTRL,
 176                                 RX8581_CTRL_STOP, 0);
 177}
 178
 179static const struct rtc_class_ops rx8581_rtc_ops = {
 180        .read_time      = rx8581_rtc_read_time,
 181        .set_time       = rx8581_rtc_set_time,
 182};
 183
 184static int rx8581_probe(struct i2c_client *client,
 185                        const struct i2c_device_id *id)
 186{
 187        struct rx8581     *rx8581;
 188        static const struct regmap_config config = {
 189                .reg_bits = 8,
 190                .val_bits = 8,
 191                .max_register = 0xf,
 192        };
 193
 194        dev_dbg(&client->dev, "%s\n", __func__);
 195
 196        rx8581 = devm_kzalloc(&client->dev, sizeof(struct rx8581), GFP_KERNEL);
 197        if (!rx8581)
 198                return -ENOMEM;
 199
 200        i2c_set_clientdata(client, rx8581);
 201
 202        rx8581->regmap = devm_regmap_init_i2c(client, &config);
 203        if (IS_ERR(rx8581->regmap))
 204                return PTR_ERR(rx8581->regmap);
 205
 206        rx8581->rtc = devm_rtc_allocate_device(&client->dev);
 207        if (IS_ERR(rx8581->rtc))
 208                return PTR_ERR(rx8581->rtc);
 209
 210        rx8581->rtc->ops = &rx8581_rtc_ops;
 211        rx8581->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
 212        rx8581->rtc->range_max = RTC_TIMESTAMP_END_2099;
 213        rx8581->rtc->start_secs = 0;
 214        rx8581->rtc->set_start_time = true;
 215
 216        return rtc_register_device(rx8581->rtc);
 217}
 218
 219static const struct i2c_device_id rx8581_id[] = {
 220        { "rx8581", 0 },
 221        { }
 222};
 223MODULE_DEVICE_TABLE(i2c, rx8581_id);
 224
 225static const struct of_device_id rx8581_of_match[] = {
 226        { .compatible = "epson,rx8581" },
 227        { }
 228};
 229MODULE_DEVICE_TABLE(of, rx8581_of_match);
 230
 231static struct i2c_driver rx8581_driver = {
 232        .driver         = {
 233                .name   = "rtc-rx8581",
 234                .of_match_table = of_match_ptr(rx8581_of_match),
 235        },
 236        .probe          = rx8581_probe,
 237        .id_table       = rx8581_id,
 238};
 239
 240module_i2c_driver(rx8581_driver);
 241
 242MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
 243MODULE_DESCRIPTION("Epson RX-8581 RTC driver");
 244MODULE_LICENSE("GPL");
 245
Hosted by Missing Link Electronics. The original LXR software by the LXR community, this experimental version by lxr@linux.no.