drivers/rtc/rtc-rx8581.c

   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
  54 struct 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  */
  63 static 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
 129 static 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
 179 static const struct rtc_class_ops rx8581_rtc_ops = {
 180         .read_time      = rx8581_rtc_read_time,
 181         .set_time       = rx8581_rtc_set_time,
 182 };
 183
 184 static 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
 219 static const struct i2c_device_id rx8581_id[] = {
 220         { "rx8581", 0 },
 221         { }
 222 };
 223 MODULE_DEVICE_TABLE(i2c, rx8581_id);
 224
 225 static const struct of_device_id rx8581_of_match[] = {
 226         { .compatible = "epson,rx8581" },
 227         { }
 228 };
 229 MODULE_DEVICE_TABLE(of, rx8581_of_match);
 230
 231 static 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
 240 module_i2c_driver(rx8581_driver);
 241
 242 MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
 243 MODULE_DESCRIPTION("Epson RX-8581 RTC driver");
 244 MODULE_LICENSE("GPL");