linux/drivers/rtc/rtc-pcf8563.c
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   1/*
   2 * An I2C driver for the Philips PCF8563 RTC
   3 * Copyright 2005-06 Tower Technologies
   4 *
   5 * Author: Alessandro Zummo <a.zummo@towertech.it>
   6 * Maintainers: http://www.nslu2-linux.org/
   7 *
   8 * based on the other drivers in this same directory.
   9 *
  10 * http://www.semiconductors.philips.com/acrobat/datasheets/PCF8563-04.pdf
  11 *
  12 * This program is free software; you can redistribute it and/or modify
  13 * it under the terms of the GNU General Public License version 2 as
  14 * published by the Free Software Foundation.
  15 */
  16
  17#include <linux/i2c.h>
  18#include <linux/bcd.h>
  19#include <linux/rtc.h>
  20#include <linux/slab.h>
  21#include <linux/module.h>
  22#include <linux/of.h>
  23#include <linux/err.h>
  24
  25#define DRV_VERSION "0.4.3"
  26
  27#define PCF8563_REG_ST1         0x00 /* status */
  28#define PCF8563_REG_ST2         0x01
  29
  30#define PCF8563_REG_SC          0x02 /* datetime */
  31#define PCF8563_REG_MN          0x03
  32#define PCF8563_REG_HR          0x04
  33#define PCF8563_REG_DM          0x05
  34#define PCF8563_REG_DW          0x06
  35#define PCF8563_REG_MO          0x07
  36#define PCF8563_REG_YR          0x08
  37
  38#define PCF8563_REG_AMN         0x09 /* alarm */
  39#define PCF8563_REG_AHR         0x0A
  40#define PCF8563_REG_ADM         0x0B
  41#define PCF8563_REG_ADW         0x0C
  42
  43#define PCF8563_REG_CLKO        0x0D /* clock out */
  44#define PCF8563_REG_TMRC        0x0E /* timer control */
  45#define PCF8563_REG_TMR         0x0F /* timer */
  46
  47#define PCF8563_SC_LV           0x80 /* low voltage */
  48#define PCF8563_MO_C            0x80 /* century */
  49
  50static struct i2c_driver pcf8563_driver;
  51
  52struct pcf8563 {
  53        struct rtc_device *rtc;
  54        /*
  55         * The meaning of MO_C bit varies by the chip type.
  56         * From PCF8563 datasheet: this bit is toggled when the years
  57         * register overflows from 99 to 00
  58         *   0 indicates the century is 20xx
  59         *   1 indicates the century is 19xx
  60         * From RTC8564 datasheet: this bit indicates change of
  61         * century. When the year digit data overflows from 99 to 00,
  62         * this bit is set. By presetting it to 0 while still in the
  63         * 20th century, it will be set in year 2000, ...
  64         * There seems no reliable way to know how the system use this
  65         * bit.  So let's do it heuristically, assuming we are live in
  66         * 1970...2069.
  67         */
  68        int c_polarity; /* 0: MO_C=1 means 19xx, otherwise MO_C=1 means 20xx */
  69        int voltage_low; /* incicates if a low_voltage was detected */
  70};
  71
  72/*
  73 * In the routines that deal directly with the pcf8563 hardware, we use
  74 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  75 */
  76static int pcf8563_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  77{
  78        struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
  79        unsigned char buf[13] = { PCF8563_REG_ST1 };
  80
  81        struct i2c_msg msgs[] = {
  82                {/* setup read ptr */
  83                        .addr = client->addr,
  84                        .len = 1,
  85                        .buf = buf
  86                },
  87                {/* read status + date */
  88                        .addr = client->addr,
  89                        .flags = I2C_M_RD,
  90                        .len = 13,
  91                        .buf = buf
  92                },
  93        };
  94
  95        /* read registers */
  96        if ((i2c_transfer(client->adapter, msgs, 2)) != 2) {
  97                dev_err(&client->dev, "%s: read error\n", __func__);
  98                return -EIO;
  99        }
 100
 101        if (buf[PCF8563_REG_SC] & PCF8563_SC_LV) {
 102                pcf8563->voltage_low = 1;
 103                dev_info(&client->dev,
 104                        "low voltage detected, date/time is not reliable.\n");
 105        }
 106
 107        dev_dbg(&client->dev,
 108                "%s: raw data is st1=%02x, st2=%02x, sec=%02x, min=%02x, hr=%02x, "
 109                "mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
 110                __func__,
 111                buf[0], buf[1], buf[2], buf[3],
 112                buf[4], buf[5], buf[6], buf[7],
 113                buf[8]);
 114
 115
 116        tm->tm_sec = bcd2bin(buf[PCF8563_REG_SC] & 0x7F);
 117        tm->tm_min = bcd2bin(buf[PCF8563_REG_MN] & 0x7F);
 118        tm->tm_hour = bcd2bin(buf[PCF8563_REG_HR] & 0x3F); /* rtc hr 0-23 */
 119        tm->tm_mday = bcd2bin(buf[PCF8563_REG_DM] & 0x3F);
 120        tm->tm_wday = buf[PCF8563_REG_DW] & 0x07;
 121        tm->tm_mon = bcd2bin(buf[PCF8563_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
 122        tm->tm_year = bcd2bin(buf[PCF8563_REG_YR]);
 123        if (tm->tm_year < 70)
 124                tm->tm_year += 100;     /* assume we are in 1970...2069 */
 125        /* detect the polarity heuristically. see note above. */
 126        pcf8563->c_polarity = (buf[PCF8563_REG_MO] & PCF8563_MO_C) ?
 127                (tm->tm_year >= 100) : (tm->tm_year < 100);
 128
 129        dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 130                "mday=%d, mon=%d, year=%d, wday=%d\n",
 131                __func__,
 132                tm->tm_sec, tm->tm_min, tm->tm_hour,
 133                tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 134
 135        /* the clock can give out invalid datetime, but we cannot return
 136         * -EINVAL otherwise hwclock will refuse to set the time on bootup.
 137         */
 138        if (rtc_valid_tm(tm) < 0)
 139                dev_err(&client->dev, "retrieved date/time is not valid.\n");
 140
 141        return 0;
 142}
 143
 144static int pcf8563_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 145{
 146        struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
 147        int i, err;
 148        unsigned char buf[9];
 149
 150        dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 151                "mday=%d, mon=%d, year=%d, wday=%d\n",
 152                __func__,
 153                tm->tm_sec, tm->tm_min, tm->tm_hour,
 154                tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 155
 156        /* hours, minutes and seconds */
 157        buf[PCF8563_REG_SC] = bin2bcd(tm->tm_sec);
 158        buf[PCF8563_REG_MN] = bin2bcd(tm->tm_min);
 159        buf[PCF8563_REG_HR] = bin2bcd(tm->tm_hour);
 160
 161        buf[PCF8563_REG_DM] = bin2bcd(tm->tm_mday);
 162
 163        /* month, 1 - 12 */
 164        buf[PCF8563_REG_MO] = bin2bcd(tm->tm_mon + 1);
 165
 166        /* year and century */
 167        buf[PCF8563_REG_YR] = bin2bcd(tm->tm_year % 100);
 168        if (pcf8563->c_polarity ? (tm->tm_year >= 100) : (tm->tm_year < 100))
 169                buf[PCF8563_REG_MO] |= PCF8563_MO_C;
 170
 171        buf[PCF8563_REG_DW] = tm->tm_wday & 0x07;
 172
 173        /* write register's data */
 174        for (i = 0; i < 7; i++) {
 175                unsigned char data[2] = { PCF8563_REG_SC + i,
 176                                                buf[PCF8563_REG_SC + i] };
 177
 178                err = i2c_master_send(client, data, sizeof(data));
 179                if (err != sizeof(data)) {
 180                        dev_err(&client->dev,
 181                                "%s: err=%d addr=%02x, data=%02x\n",
 182                                __func__, err, data[0], data[1]);
 183                        return -EIO;
 184                }
 185        }
 186
 187        return 0;
 188}
 189
 190#ifdef CONFIG_RTC_INTF_DEV
 191static int pcf8563_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 192{
 193        struct pcf8563 *pcf8563 = i2c_get_clientdata(to_i2c_client(dev));
 194        struct rtc_time tm;
 195
 196        switch (cmd) {
 197        case RTC_VL_READ:
 198                if (pcf8563->voltage_low)
 199                        dev_info(dev, "low voltage detected, date/time is not reliable.\n");
 200
 201                if (copy_to_user((void __user *)arg, &pcf8563->voltage_low,
 202                                        sizeof(int)))
 203                        return -EFAULT;
 204                return 0;
 205        case RTC_VL_CLR:
 206                /*
 207                 * Clear the VL bit in the seconds register in case
 208                 * the time has not been set already (which would
 209                 * have cleared it). This does not really matter
 210                 * because of the cached voltage_low value but do it
 211                 * anyway for consistency.
 212                 */
 213                if (pcf8563_get_datetime(to_i2c_client(dev), &tm))
 214                        pcf8563_set_datetime(to_i2c_client(dev), &tm);
 215
 216                /* Clear the cached value. */
 217                pcf8563->voltage_low = 0;
 218
 219                return 0;
 220        default:
 221                return -ENOIOCTLCMD;
 222        }
 223}
 224#else
 225#define pcf8563_rtc_ioctl NULL
 226#endif
 227
 228static int pcf8563_rtc_read_time(struct device *dev, struct rtc_time *tm)
 229{
 230        return pcf8563_get_datetime(to_i2c_client(dev), tm);
 231}
 232
 233static int pcf8563_rtc_set_time(struct device *dev, struct rtc_time *tm)
 234{
 235        return pcf8563_set_datetime(to_i2c_client(dev), tm);
 236}
 237
 238static const struct rtc_class_ops pcf8563_rtc_ops = {
 239        .ioctl          = pcf8563_rtc_ioctl,
 240        .read_time      = pcf8563_rtc_read_time,
 241        .set_time       = pcf8563_rtc_set_time,
 242};
 243
 244static int pcf8563_probe(struct i2c_client *client,
 245                                const struct i2c_device_id *id)
 246{
 247        struct pcf8563 *pcf8563;
 248
 249        dev_dbg(&client->dev, "%s\n", __func__);
 250
 251        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 252                return -ENODEV;
 253
 254        pcf8563 = devm_kzalloc(&client->dev, sizeof(struct pcf8563),
 255                                GFP_KERNEL);
 256        if (!pcf8563)
 257                return -ENOMEM;
 258
 259        dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 260
 261        i2c_set_clientdata(client, pcf8563);
 262
 263        pcf8563->rtc = devm_rtc_device_register(&client->dev,
 264                                pcf8563_driver.driver.name,
 265                                &pcf8563_rtc_ops, THIS_MODULE);
 266
 267        return PTR_RET(pcf8563->rtc);
 268}
 269
 270static const struct i2c_device_id pcf8563_id[] = {
 271        { "pcf8563", 0 },
 272        { "rtc8564", 0 },
 273        { }
 274};
 275MODULE_DEVICE_TABLE(i2c, pcf8563_id);
 276
 277#ifdef CONFIG_OF
 278static const struct of_device_id pcf8563_of_match[] = {
 279        { .compatible = "nxp,pcf8563" },
 280        {}
 281};
 282MODULE_DEVICE_TABLE(of, pcf8563_of_match);
 283#endif
 284
 285static struct i2c_driver pcf8563_driver = {
 286        .driver         = {
 287                .name   = "rtc-pcf8563",
 288                .owner  = THIS_MODULE,
 289                .of_match_table = of_match_ptr(pcf8563_of_match),
 290        },
 291        .probe          = pcf8563_probe,
 292        .id_table       = pcf8563_id,
 293};
 294
 295module_i2c_driver(pcf8563_driver);
 296
 297MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 298MODULE_DESCRIPTION("Philips PCF8563/Epson RTC8564 RTC driver");
 299MODULE_LICENSE("GPL");
 300MODULE_VERSION(DRV_VERSION);
 301
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