drivers/rtc/rtc-rx4581.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* drivers/rtc/rtc-rx4581.c
   3  *
   4  * written by Torben Hohn <torbenh@linutronix.de>
   5  *
   6  * Based on:
   7  * drivers/rtc/rtc-max6902.c
   8  *
   9  * Copyright (C) 2006 8D Technologies inc.
  10  * Copyright (C) 2004 Compulab Ltd.
  11  *
  12  * Driver for MAX6902 spi RTC
  13  *
  14  * and based on:
  15  * drivers/rtc/rtc-rx8581.c
  16  *
  17  * An I2C driver for the Epson RX8581 RTC
  18  *
  19  * Author: Martyn Welch <martyn.welch@ge.com>
  20  * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
  21  *
  22  * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC)
  23  * Copyright 2005-06 Tower Technologies
  24  */
  25
  26 #include <linux/module.h>
  27 #include <linux/kernel.h>
  28 #include <linux/platform_device.h>
  29 #include <linux/init.h>
  30 #include <linux/rtc.h>
  31 #include <linux/spi/spi.h>
  32 #include <linux/bcd.h>
  33
  34 #define RX4581_REG_SC           0x00 /* Second in BCD */
  35 #define RX4581_REG_MN           0x01 /* Minute in BCD */
  36 #define RX4581_REG_HR           0x02 /* Hour in BCD */
  37 #define RX4581_REG_DW           0x03 /* Day of Week */
  38 #define RX4581_REG_DM           0x04 /* Day of Month in BCD */
  39 #define RX4581_REG_MO           0x05 /* Month in BCD */
  40 #define RX4581_REG_YR           0x06 /* Year in BCD */
  41 #define RX4581_REG_RAM          0x07 /* RAM */
  42 #define RX4581_REG_AMN          0x08 /* Alarm Min in BCD*/
  43 #define RX4581_REG_AHR          0x09 /* Alarm Hour in BCD */
  44 #define RX4581_REG_ADM          0x0A
  45 #define RX4581_REG_ADW          0x0A
  46 #define RX4581_REG_TMR0         0x0B
  47 #define RX4581_REG_TMR1         0x0C
  48 #define RX4581_REG_EXT          0x0D /* Extension Register */
  49 #define RX4581_REG_FLAG         0x0E /* Flag Register */
  50 #define RX4581_REG_CTRL         0x0F /* Control Register */
  51
  52
  53 /* Flag Register bit definitions */
  54 #define RX4581_FLAG_UF          0x20 /* Update */
  55 #define RX4581_FLAG_TF          0x10 /* Timer */
  56 #define RX4581_FLAG_AF          0x08 /* Alarm */
  57 #define RX4581_FLAG_VLF         0x02 /* Voltage Low */
  58
  59 /* Control Register bit definitions */
  60 #define RX4581_CTRL_UIE         0x20 /* Update Interrupt Enable */
  61 #define RX4581_CTRL_TIE         0x10 /* Timer Interrupt Enable */
  62 #define RX4581_CTRL_AIE         0x08 /* Alarm Interrupt Enable */
  63 #define RX4581_CTRL_STOP        0x02 /* STOP bit */
  64 #define RX4581_CTRL_RESET       0x01 /* RESET bit */
  65
  66 static int rx4581_set_reg(struct device *dev, unsigned char address,
  67                                 unsigned char data)
  68 {
  69         struct spi_device *spi = to_spi_device(dev);
  70         unsigned char buf[2];
  71
  72         /* high nibble must be '0' to write */
  73         buf[0] = address & 0x0f;
  74         buf[1] = data;
  75
  76         return spi_write_then_read(spi, buf, 2, NULL, 0);
  77 }
  78
  79 static int rx4581_get_reg(struct device *dev, unsigned char address,
  80                                 unsigned char *data)
  81 {
  82         struct spi_device *spi = to_spi_device(dev);
  83
  84         /* Set MSB to indicate read */
  85         *data = address | 0x80;
  86
  87         return spi_write_then_read(spi, data, 1, data, 1);
  88 }
  89
  90 /*
  91  * In the routines that deal directly with the rx8581 hardware, we use
  92  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
  93  */
  94 static int rx4581_get_datetime(struct device *dev, struct rtc_time *tm)
  95 {
  96         struct spi_device *spi = to_spi_device(dev);
  97         unsigned char date[7];
  98         unsigned char data;
  99         int err;
 100
 101         /* First we ensure that the "update flag" is not set, we read the
 102          * time and date then re-read the "update flag". If the update flag
 103          * has been set, we know that the time has changed during the read so
 104          * we repeat the whole process again.
 105          */
 106         err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
 107         if (err != 0) {
 108                 dev_err(dev, "Unable to read device flags\n");
 109                 return -EIO;
 110         }
 111
 112         do {
 113                 /* If update flag set, clear it */
 114                 if (data & RX4581_FLAG_UF) {
 115                         err = rx4581_set_reg(dev,
 116                                 RX4581_REG_FLAG, (data & ~RX4581_FLAG_UF));
 117                         if (err != 0) {
 118                                 dev_err(dev, "Unable to write device "
 119                                         "flags\n");
 120                                 return -EIO;
 121                         }
 122                 }
 123
 124                 /* Now read time and date */
 125                 date[0] = 0x80;
 126                 err = spi_write_then_read(spi, date, 1, date, 7);
 127                 if (err < 0) {
 128                         dev_err(dev, "Unable to read date\n");
 129                         return -EIO;
 130                 }
 131
 132                 /* Check flag register */
 133                 err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
 134                 if (err != 0) {
 135                         dev_err(dev, "Unable to read device flags\n");
 136                         return -EIO;
 137                 }
 138         } while (data & RX4581_FLAG_UF);
 139
 140         if (data & RX4581_FLAG_VLF)
 141                 dev_info(dev,
 142                         "low voltage detected, date/time is not reliable.\n");
 143
 144         dev_dbg(dev,
 145                 "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
 146                 "wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
 147                 __func__,
 148                 date[0], date[1], date[2], date[3], date[4], date[5], date[6]);
 149
 150         tm->tm_sec = bcd2bin(date[RX4581_REG_SC] & 0x7F);
 151         tm->tm_min = bcd2bin(date[RX4581_REG_MN] & 0x7F);
 152         tm->tm_hour = bcd2bin(date[RX4581_REG_HR] & 0x3F); /* rtc hr 0-23 */
 153         tm->tm_wday = ilog2(date[RX4581_REG_DW] & 0x7F);
 154         tm->tm_mday = bcd2bin(date[RX4581_REG_DM] & 0x3F);
 155         tm->tm_mon = bcd2bin(date[RX4581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
 156         tm->tm_year = bcd2bin(date[RX4581_REG_YR]);
 157         if (tm->tm_year < 70)
 158                 tm->tm_year += 100;     /* assume we are in 1970...2069 */
 159
 160
 161         dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 162                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 163                 __func__,
 164                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 165                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 166
 167         return 0;
 168 }
 169
 170 static int rx4581_set_datetime(struct device *dev, struct rtc_time *tm)
 171 {
 172         struct spi_device *spi = to_spi_device(dev);
 173         int err;
 174         unsigned char buf[8], data;
 175
 176         dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, "
 177                 "mday=%d, mon=%d, year=%d, wday=%d\n",
 178                 __func__,
 179                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 180                 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 181
 182         buf[0] = 0x00;
 183         /* hours, minutes and seconds */
 184         buf[RX4581_REG_SC+1] = bin2bcd(tm->tm_sec);
 185         buf[RX4581_REG_MN+1] = bin2bcd(tm->tm_min);
 186         buf[RX4581_REG_HR+1] = bin2bcd(tm->tm_hour);
 187
 188         buf[RX4581_REG_DM+1] = bin2bcd(tm->tm_mday);
 189
 190         /* month, 1 - 12 */
 191         buf[RX4581_REG_MO+1] = bin2bcd(tm->tm_mon + 1);
 192
 193         /* year and century */
 194         buf[RX4581_REG_YR+1] = bin2bcd(tm->tm_year % 100);
 195         buf[RX4581_REG_DW+1] = (0x1 << tm->tm_wday);
 196
 197         /* Stop the clock */
 198         err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
 199         if (err != 0) {
 200                 dev_err(dev, "Unable to read control register\n");
 201                 return -EIO;
 202         }
 203
 204         err = rx4581_set_reg(dev, RX4581_REG_CTRL,
 205                 (data | RX4581_CTRL_STOP));
 206         if (err != 0) {
 207                 dev_err(dev, "Unable to write control register\n");
 208                 return -EIO;
 209         }
 210
 211         /* write register's data */
 212         err = spi_write_then_read(spi, buf, 8, NULL, 0);
 213         if (err != 0) {
 214                 dev_err(dev, "Unable to write to date registers\n");
 215                 return -EIO;
 216         }
 217
 218         /* get VLF and clear it */
 219         err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
 220         if (err != 0) {
 221                 dev_err(dev, "Unable to read flag register\n");
 222                 return -EIO;
 223         }
 224
 225         err = rx4581_set_reg(dev, RX4581_REG_FLAG,
 226                 (data & ~(RX4581_FLAG_VLF)));
 227         if (err != 0) {
 228                 dev_err(dev, "Unable to write flag register\n");
 229                 return -EIO;
 230         }
 231
 232         /* Restart the clock */
 233         err = rx4581_get_reg(dev, RX4581_REG_CTRL, &data);
 234         if (err != 0) {
 235                 dev_err(dev, "Unable to read control register\n");
 236                 return -EIO;
 237         }
 238
 239         err = rx4581_set_reg(dev, RX4581_REG_CTRL,
 240                 (data & ~(RX4581_CTRL_STOP)));
 241         if (err != 0) {
 242                 dev_err(dev, "Unable to write control register\n");
 243                 return -EIO;
 244         }
 245
 246         return 0;
 247 }
 248
 249 static const struct rtc_class_ops rx4581_rtc_ops = {
 250         .read_time      = rx4581_get_datetime,
 251         .set_time       = rx4581_set_datetime,
 252 };
 253
 254 static int rx4581_probe(struct spi_device *spi)
 255 {
 256         struct rtc_device *rtc;
 257         unsigned char tmp;
 258         int res;
 259
 260         res = rx4581_get_reg(&spi->dev, RX4581_REG_SC, &tmp);
 261         if (res != 0)
 262                 return res;
 263
 264         rtc = devm_rtc_device_register(&spi->dev, "rx4581",
 265                                 &rx4581_rtc_ops, THIS_MODULE);
 266         if (IS_ERR(rtc))
 267                 return PTR_ERR(rtc);
 268
 269         spi_set_drvdata(spi, rtc);
 270         return 0;
 271 }
 272
 273 static const struct spi_device_id rx4581_id[] = {
 274         { "rx4581", 0 },
 275         { }
 276 };
 277 MODULE_DEVICE_TABLE(spi, rx4581_id);
 278
 279 static struct spi_driver rx4581_driver = {
 280         .driver = {
 281                 .name   = "rtc-rx4581",
 282         },
 283         .probe  = rx4581_probe,
 284         .id_table = rx4581_id,
 285 };
 286
 287 module_spi_driver(rx4581_driver);
 288
 289 MODULE_DESCRIPTION("rx4581 spi RTC driver");
 290 MODULE_AUTHOR("Torben Hohn");
 291 MODULE_LICENSE("GPL");
 292 MODULE_ALIAS("spi:rtc-rx4581");