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
  24#define DRV_VERSION "0.4.3"
  25
  26#define PCF8563_REG_ST1         0x00 /* status */
  27#define PCF8563_REG_ST2         0x01
  28
  29#define PCF8563_REG_SC          0x02 /* datetime */
  30#define PCF8563_REG_MN          0x03
  31#define PCF8563_REG_HR          0x04
  32#define PCF8563_REG_DM          0x05
  33#define PCF8563_REG_DW          0x06
  34#define PCF8563_REG_MO          0x07
  35#define PCF8563_REG_YR          0x08
  36
  37#define PCF8563_REG_AMN         0x09 /* alarm */
  38#define PCF8563_REG_AHR         0x0A
  39#define PCF8563_REG_ADM         0x0B
  40#define PCF8563_REG_ADW         0x0C
  41
  42#define PCF8563_REG_CLKO        0x0D /* clock out */
  43#define PCF8563_REG_TMRC        0x0E /* timer control */
  44#define PCF8563_REG_TMR         0x0F /* timer */
  45
  46#define PCF8563_SC_LV           0x80 /* low voltage */
  47#define PCF8563_MO_C            0x80 /* century */
  48
  49static struct i2c_driver pcf8563_driver;
  50
  51struct pcf8563 {
  52        struct rtc_device *rtc;
  53        /*
  54         * The meaning of MO_C bit varies by the chip type.
  55         * From PCF8563 datasheet: this bit is toggled when the years
  56         * register overflows from 99 to 00
  57         *   0 indicates the century is 20xx
  58         *   1 indicates the century is 19xx
  59         * From RTC8564 datasheet: this bit indicates change of
  60         * century. When the year digit data overflows from 99 to 00,
  61         * this bit is set. By presetting it to 0 while still in the
  62         * 20th century, it will be set in year 2000, ...
  63         * There seems no reliable way to know how the system use this
  64         * bit.  So let's do it heuristically, assuming we are live in
  65         * 1970...2069.
  66         */
  67        int c_polarity; /* 0: MO_C=1 means 19xx, otherwise MO_C=1 means 20xx */
  68        int voltage_low; /* incicates if a low_voltage was detected */
  69};
  70
  71/*
  72 * In the routines that deal directly with the pcf8563 hardware, we use
  73 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  74 */
  75static int pcf8563_get_datetime(struct i2c_client *client, struct rtc_time *tm)
  76{
  77        struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
  78        unsigned char buf[13] = { PCF8563_REG_ST1 };
  79
  80        struct i2c_msg msgs[] = {
  81                {/* setup read ptr */
  82                        .addr = client->addr,
  83                        .len = 1,
  84                        .buf = buf
  85                },
  86                {/* read status + date */
  87                        .addr = client->addr,
  88                        .flags = I2C_M_RD,
  89                        .len = 13,
  90                        .buf = buf
  91                },
  92        };
  93
  94        /* read registers */
  95        if ((i2c_transfer(client->adapter, msgs, 2)) != 2) {
  96                dev_err(&client->dev, "%s: read error\n", __func__);
  97                return -EIO;
  98        }
  99
 100        if (buf[PCF8563_REG_SC] & PCF8563_SC_LV) {
 101                pcf8563->voltage_low = 1;
 102                dev_info(&client->dev,
 103                        "low voltage detected, date/time is not reliable.\n");
 104        }
 105
 106        dev_dbg(&client->dev,
 107                "%s: raw data is st1=%02x, st2=%02x, sec=%02x, min=%02x, hr=%02x, "
 108                "mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
 109                __func__,
 110                buf[0], buf[1], buf[2], buf[3],
 111                buf[4], buf[5], buf[6], buf[7],
 112                buf[8]);
 113
 114
 115        tm->tm_sec = bcd2bin(buf[PCF8563_REG_SC] & 0x7F);
 116        tm->tm_min = bcd2bin(buf[PCF8563_REG_MN] & 0x7F);
 117        tm->tm_hour = bcd2bin(buf[PCF8563_REG_HR] & 0x3F); /* rtc hr 0-23 */
 118        tm->tm_mday = bcd2bin(buf[PCF8563_REG_DM] & 0x3F);
 119        tm->tm_wday = buf[PCF8563_REG_DW] & 0x07;
 120        tm->tm_mon = bcd2bin(buf[PCF8563_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
 121        tm->tm_year = bcd2bin(buf[PCF8563_REG_YR]);
 122        if (tm->tm_year < 70)
 123                tm->tm_year += 100;     /* assume we are in 1970...2069 */
 124        /* detect the polarity heuristically. see note above. */
 125        pcf8563->c_polarity = (buf[PCF8563_REG_MO] & PCF8563_MO_C) ?
 126                (tm->tm_year >= 100) : (tm->tm_year < 100);
 127
 128        dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 129                "mday=%d, mon=%d, year=%d, wday=%d\n",
 130                __func__,
 131                tm->tm_sec, tm->tm_min, tm->tm_hour,
 132                tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 133
 134        /* the clock can give out invalid datetime, but we cannot return
 135         * -EINVAL otherwise hwclock will refuse to set the time on bootup.
 136         */
 137        if (rtc_valid_tm(tm) < 0)
 138                dev_err(&client->dev, "retrieved date/time is not valid.\n");
 139
 140        return 0;
 141}
 142
 143static int pcf8563_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 144{
 145        struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
 146        int i, err;
 147        unsigned char buf[9];
 148
 149        dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
 150                "mday=%d, mon=%d, year=%d, wday=%d\n",
 151                __func__,
 152                tm->tm_sec, tm->tm_min, tm->tm_hour,
 153                tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 154
 155        /* hours, minutes and seconds */
 156        buf[PCF8563_REG_SC] = bin2bcd(tm->tm_sec);
 157        buf[PCF8563_REG_MN] = bin2bcd(tm->tm_min);
 158        buf[PCF8563_REG_HR] = bin2bcd(tm->tm_hour);
 159
 160        buf[PCF8563_REG_DM] = bin2bcd(tm->tm_mday);
 161
 162        /* month, 1 - 12 */
 163        buf[PCF8563_REG_MO] = bin2bcd(tm->tm_mon + 1);
 164
 165        /* year and century */
 166        buf[PCF8563_REG_YR] = bin2bcd(tm->tm_year % 100);
 167        if (pcf8563->c_polarity ? (tm->tm_year >= 100) : (tm->tm_year < 100))
 168                buf[PCF8563_REG_MO] |= PCF8563_MO_C;
 169
 170        buf[PCF8563_REG_DW] = tm->tm_wday & 0x07;
 171
 172        /* write register's data */
 173        for (i = 0; i < 7; i++) {
 174                unsigned char data[2] = { PCF8563_REG_SC + i,
 175                                                buf[PCF8563_REG_SC + i] };
 176
 177                err = i2c_master_send(client, data, sizeof(data));
 178                if (err != sizeof(data)) {
 179                        dev_err(&client->dev,
 180                                "%s: err=%d addr=%02x, data=%02x\n",
 181                                __func__, err, data[0], data[1]);
 182                        return -EIO;
 183                }
 184        }
 185
 186        return 0;
 187}
 188
 189#ifdef CONFIG_RTC_INTF_DEV
 190static int pcf8563_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 191{
 192        struct pcf8563 *pcf8563 = i2c_get_clientdata(to_i2c_client(dev));
 193        struct rtc_time tm;
 194
 195        switch (cmd) {
 196        case RTC_VL_READ:
 197                if (pcf8563->voltage_low)
 198                        dev_info(dev, "low voltage detected, date/time is not reliable.\n");
 199
 200                if (copy_to_user((void __user *)arg, &pcf8563->voltage_low,
 201                                        sizeof(int)))
 202                        return -EFAULT;
 203                return 0;
 204        case RTC_VL_CLR:
 205                /*
 206                 * Clear the VL bit in the seconds register in case
 207                 * the time has not been set already (which would
 208                 * have cleared it). This does not really matter
 209                 * because of the cached voltage_low value but do it
 210                 * anyway for consistency.
 211                 */
 212                if (pcf8563_get_datetime(to_i2c_client(dev), &tm))
 213                        pcf8563_set_datetime(to_i2c_client(dev), &tm);
 214
 215                /* Clear the cached value. */
 216                pcf8563->voltage_low = 0;
 217
 218                return 0;
 219        default:
 220                return -ENOIOCTLCMD;
 221        }
 222}
 223#else
 224#define pcf8563_rtc_ioctl NULL
 225#endif
 226
 227static int pcf8563_rtc_read_time(struct device *dev, struct rtc_time *tm)
 228{
 229        return pcf8563_get_datetime(to_i2c_client(dev), tm);
 230}
 231
 232static int pcf8563_rtc_set_time(struct device *dev, struct rtc_time *tm)
 233{
 234        return pcf8563_set_datetime(to_i2c_client(dev), tm);
 235}
 236
 237static const struct rtc_class_ops pcf8563_rtc_ops = {
 238        .ioctl          = pcf8563_rtc_ioctl,
 239        .read_time      = pcf8563_rtc_read_time,
 240        .set_time       = pcf8563_rtc_set_time,
 241};
 242
 243static int pcf8563_probe(struct i2c_client *client,
 244                                const struct i2c_device_id *id)
 245{
 246        struct pcf8563 *pcf8563;
 247
 248        dev_dbg(&client->dev, "%s\n", __func__);
 249
 250        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 251                return -ENODEV;
 252
 253        pcf8563 = devm_kzalloc(&client->dev, sizeof(struct pcf8563),
 254                                GFP_KERNEL);
 255        if (!pcf8563)
 256                return -ENOMEM;
 257
 258        dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 259
 260        i2c_set_clientdata(client, pcf8563);
 261
 262        pcf8563->rtc = devm_rtc_device_register(&client->dev,
 263                                pcf8563_driver.driver.name,
 264                                &pcf8563_rtc_ops, THIS_MODULE);
 265
 266        if (IS_ERR(pcf8563->rtc))
 267                return PTR_ERR(pcf8563->rtc);
 268
 269        return 0;
 270}
 271
 272static int pcf8563_remove(struct i2c_client *client)
 273{
 274        return 0;
 275}
 276
 277static const struct i2c_device_id pcf8563_id[] = {
 278        { "pcf8563", 0 },
 279        { "rtc8564", 0 },
 280        { }
 281};
 282MODULE_DEVICE_TABLE(i2c, pcf8563_id);
 283
 284#ifdef CONFIG_OF
 285static const struct of_device_id pcf8563_of_match[] = {
 286        { .compatible = "nxp,pcf8563" },
 287        {}
 288};
 289MODULE_DEVICE_TABLE(of, pcf8563_of_match);
 290#endif
 291
 292static struct i2c_driver pcf8563_driver = {
 293        .driver         = {
 294                .name   = "rtc-pcf8563",
 295                .owner  = THIS_MODULE,
 296                .of_match_table = of_match_ptr(pcf8563_of_match),
 297        },
 298        .probe          = pcf8563_probe,
 299        .remove         = pcf8563_remove,
 300        .id_table       = pcf8563_id,
 301};
 302
 303module_i2c_driver(pcf8563_driver);
 304
 305MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 306MODULE_DESCRIPTION("Philips PCF8563/Epson RTC8564 RTC driver");
 307MODULE_LICENSE("GPL");
 308MODULE_VERSION(DRV_VERSION);
 309
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