LXR linux/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
  66static 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
  79static 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 */
  94static 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
 170static 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
 249static const struct rtc_class_ops rx4581_rtc_ops = {
 250        .read_time      = rx4581_get_datetime,
 251        .set_time       = rx4581_set_datetime,
 252};
 253
 254static 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
 273static const struct spi_device_id rx4581_id[] = {
 274        { "rx4581", 0 },
 275        { }
 276};
 277MODULE_DEVICE_TABLE(spi, rx4581_id);
 278
 279static struct spi_driver rx4581_driver = {
 280        .driver = {
 281                .name   = "rtc-rx4581",
 282        },
 283        .probe  = rx4581_probe,
 284        .id_table = rx4581_id,
 285};
 286
 287module_spi_driver(rx4581_driver);
 288
 289MODULE_DESCRIPTION("rx4581 spi RTC driver");
 290MODULE_AUTHOR("Torben Hohn");
 291MODULE_LICENSE("GPL");
 292MODULE_ALIAS("spi:rtc-rx4581");
 293