drivers/rtc/rtc-pcf8563.c

   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
  50 static struct i2c_driver pcf8563_driver;
  51
  52 struct 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  */
  76 static 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
 144 static 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
 191 static 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
 228 static 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
 233 static 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
 238 static 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
 244 static 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_ERR_OR_ZERO(pcf8563->rtc);
 268 }
 269
 270 static const struct i2c_device_id pcf8563_id[] = {
 271         { "pcf8563", 0 },
 272         { "rtc8564", 0 },
 273         { }
 274 };
 275 MODULE_DEVICE_TABLE(i2c, pcf8563_id);
 276
 277 #ifdef CONFIG_OF
 278 static const struct of_device_id pcf8563_of_match[] = {
 279         { .compatible = "nxp,pcf8563" },
 280         {}
 281 };
 282 MODULE_DEVICE_TABLE(of, pcf8563_of_match);
 283 #endif
 284
 285 static 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
 295 module_i2c_driver(pcf8563_driver);
 296
 297 MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
 298 MODULE_DESCRIPTION("Philips PCF8563/Epson RTC8564 RTC driver");
 299 MODULE_LICENSE("GPL");
 300 MODULE_VERSION(DRV_VERSION);