LXR linux/drivers/rtc/rtc-rx6110.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Driver for the Epson RTC module RX-6110 SA
   4 *
   5 * Copyright(C) 2015 Pengutronix, Steffen Trumtrar <kernel@pengutronix.de>
   6 * Copyright(C) SEIKO EPSON CORPORATION 2013. All rights reserved.
   7 */
   8
   9#include <linux/bcd.h>
  10#include <linux/init.h>
  11#include <linux/kernel.h>
  12#include <linux/module.h>
  13#include <linux/of_gpio.h>
  14#include <linux/regmap.h>
  15#include <linux/rtc.h>
  16#include <linux/of.h>
  17#include <linux/of_device.h>
  18#include <linux/spi/spi.h>
  19
  20/* RX-6110 Register definitions */
  21#define RX6110_REG_SEC          0x10
  22#define RX6110_REG_MIN          0x11
  23#define RX6110_REG_HOUR         0x12
  24#define RX6110_REG_WDAY         0x13
  25#define RX6110_REG_MDAY         0x14
  26#define RX6110_REG_MONTH        0x15
  27#define RX6110_REG_YEAR         0x16
  28#define RX6110_REG_RES1         0x17
  29#define RX6110_REG_ALMIN        0x18
  30#define RX6110_REG_ALHOUR       0x19
  31#define RX6110_REG_ALWDAY       0x1A
  32#define RX6110_REG_TCOUNT0      0x1B
  33#define RX6110_REG_TCOUNT1      0x1C
  34#define RX6110_REG_EXT          0x1D
  35#define RX6110_REG_FLAG         0x1E
  36#define RX6110_REG_CTRL         0x1F
  37#define RX6110_REG_USER0        0x20
  38#define RX6110_REG_USER1        0x21
  39#define RX6110_REG_USER2        0x22
  40#define RX6110_REG_USER3        0x23
  41#define RX6110_REG_USER4        0x24
  42#define RX6110_REG_USER5        0x25
  43#define RX6110_REG_USER6        0x26
  44#define RX6110_REG_USER7        0x27
  45#define RX6110_REG_USER8        0x28
  46#define RX6110_REG_USER9        0x29
  47#define RX6110_REG_USERA        0x2A
  48#define RX6110_REG_USERB        0x2B
  49#define RX6110_REG_USERC        0x2C
  50#define RX6110_REG_USERD        0x2D
  51#define RX6110_REG_USERE        0x2E
  52#define RX6110_REG_USERF        0x2F
  53#define RX6110_REG_RES2         0x30
  54#define RX6110_REG_RES3         0x31
  55#define RX6110_REG_IRQ          0x32
  56
  57#define RX6110_BIT_ALARM_EN             BIT(7)
  58
  59/* Extension Register (1Dh) bit positions */
  60#define RX6110_BIT_EXT_TSEL0            BIT(0)
  61#define RX6110_BIT_EXT_TSEL1            BIT(1)
  62#define RX6110_BIT_EXT_TSEL2            BIT(2)
  63#define RX6110_BIT_EXT_WADA             BIT(3)
  64#define RX6110_BIT_EXT_TE               BIT(4)
  65#define RX6110_BIT_EXT_USEL             BIT(5)
  66#define RX6110_BIT_EXT_FSEL0            BIT(6)
  67#define RX6110_BIT_EXT_FSEL1            BIT(7)
  68
  69/* Flag Register (1Eh) bit positions */
  70#define RX6110_BIT_FLAG_VLF             BIT(1)
  71#define RX6110_BIT_FLAG_AF              BIT(3)
  72#define RX6110_BIT_FLAG_TF              BIT(4)
  73#define RX6110_BIT_FLAG_UF              BIT(5)
  74
  75/* Control Register (1Fh) bit positions */
  76#define RX6110_BIT_CTRL_TBKE            BIT(0)
  77#define RX6110_BIT_CTRL_TBKON           BIT(1)
  78#define RX6110_BIT_CTRL_TSTP            BIT(2)
  79#define RX6110_BIT_CTRL_AIE             BIT(3)
  80#define RX6110_BIT_CTRL_TIE             BIT(4)
  81#define RX6110_BIT_CTRL_UIE             BIT(5)
  82#define RX6110_BIT_CTRL_STOP            BIT(6)
  83#define RX6110_BIT_CTRL_TEST            BIT(7)
  84
  85enum {
  86        RTC_SEC = 0,
  87        RTC_MIN,
  88        RTC_HOUR,
  89        RTC_WDAY,
  90        RTC_MDAY,
  91        RTC_MONTH,
  92        RTC_YEAR,
  93        RTC_NR_TIME
  94};
  95
  96#define RX6110_DRIVER_NAME              "rx6110"
  97
  98struct rx6110_data {
  99        struct rtc_device *rtc;
 100        struct regmap *regmap;
 101};
 102
 103/**
 104 * rx6110_rtc_tm_to_data - convert rtc_time to native time encoding
 105 *
 106 * @tm: holds date and time
 107 * @data: holds the encoding in rx6110 native form
 108 */
 109static int rx6110_rtc_tm_to_data(struct rtc_time *tm, u8 *data)
 110{
 111        pr_debug("%s: date %ptRr\n", __func__, tm);
 112
 113        /*
 114         * The year in the RTC is a value between 0 and 99.
 115         * Assume that this represents the current century
 116         * and disregard all other values.
 117         */
 118        if (tm->tm_year < 100 || tm->tm_year >= 200)
 119                return -EINVAL;
 120
 121        data[RTC_SEC] = bin2bcd(tm->tm_sec);
 122        data[RTC_MIN] = bin2bcd(tm->tm_min);
 123        data[RTC_HOUR] = bin2bcd(tm->tm_hour);
 124        data[RTC_WDAY] = BIT(bin2bcd(tm->tm_wday));
 125        data[RTC_MDAY] = bin2bcd(tm->tm_mday);
 126        data[RTC_MONTH] = bin2bcd(tm->tm_mon + 1);
 127        data[RTC_YEAR] = bin2bcd(tm->tm_year % 100);
 128
 129        return 0;
 130}
 131
 132/**
 133 * rx6110_data_to_rtc_tm - convert native time encoding to rtc_time
 134 *
 135 * @data: holds the encoding in rx6110 native form
 136 * @tm: holds date and time
 137 */
 138static int rx6110_data_to_rtc_tm(u8 *data, struct rtc_time *tm)
 139{
 140        tm->tm_sec = bcd2bin(data[RTC_SEC] & 0x7f);
 141        tm->tm_min = bcd2bin(data[RTC_MIN] & 0x7f);
 142        /* only 24-hour clock */
 143        tm->tm_hour = bcd2bin(data[RTC_HOUR] & 0x3f);
 144        tm->tm_wday = ffs(data[RTC_WDAY] & 0x7f);
 145        tm->tm_mday = bcd2bin(data[RTC_MDAY] & 0x3f);
 146        tm->tm_mon = bcd2bin(data[RTC_MONTH] & 0x1f) - 1;
 147        tm->tm_year = bcd2bin(data[RTC_YEAR]) + 100;
 148
 149        pr_debug("%s: date %ptRr\n", __func__, tm);
 150
 151        /*
 152         * The year in the RTC is a value between 0 and 99.
 153         * Assume that this represents the current century
 154         * and disregard all other values.
 155         */
 156        if (tm->tm_year < 100 || tm->tm_year >= 200)
 157                return -EINVAL;
 158
 159        return 0;
 160}
 161
 162/**
 163 * rx6110_set_time - set the current time in the rx6110 registers
 164 *
 165 * @dev: the rtc device in use
 166 * @tm: holds date and time
 167 *
 168 * BUG: The HW assumes every year that is a multiple of 4 to be a leap
 169 * year. Next time this is wrong is 2100, which will not be a leap year
 170 *
 171 * Note: If STOP is not set/cleared, the clock will start when the seconds
 172 *       register is written
 173 *
 174 */
 175static int rx6110_set_time(struct device *dev, struct rtc_time *tm)
 176{
 177        struct rx6110_data *rx6110 = dev_get_drvdata(dev);
 178        u8 data[RTC_NR_TIME];
 179        int ret;
 180
 181        ret = rx6110_rtc_tm_to_data(tm, data);
 182        if (ret < 0)
 183                return ret;
 184
 185        /* set STOP bit before changing clock/calendar */
 186        ret = regmap_update_bits(rx6110->regmap, RX6110_REG_CTRL,
 187                                 RX6110_BIT_CTRL_STOP, RX6110_BIT_CTRL_STOP);
 188        if (ret)
 189                return ret;
 190
 191        ret = regmap_bulk_write(rx6110->regmap, RX6110_REG_SEC, data,
 192                                RTC_NR_TIME);
 193        if (ret)
 194                return ret;
 195
 196        /* The time in the RTC is valid. Be sure to have VLF cleared. */
 197        ret = regmap_update_bits(rx6110->regmap, RX6110_REG_FLAG,
 198                                 RX6110_BIT_FLAG_VLF, 0);
 199        if (ret)
 200                return ret;
 201
 202        /* clear STOP bit after changing clock/calendar */
 203        ret = regmap_update_bits(rx6110->regmap, RX6110_REG_CTRL,
 204                                 RX6110_BIT_CTRL_STOP, 0);
 205
 206        return ret;
 207}
 208
 209/**
 210 * rx6110_get_time - get the current time from the rx6110 registers
 211 * @dev: the rtc device in use
 212 * @tm: holds date and time
 213 */
 214static int rx6110_get_time(struct device *dev, struct rtc_time *tm)
 215{
 216        struct rx6110_data *rx6110 = dev_get_drvdata(dev);
 217        u8 data[RTC_NR_TIME];
 218        int flags;
 219        int ret;
 220
 221        ret = regmap_read(rx6110->regmap, RX6110_REG_FLAG, &flags);
 222        if (ret)
 223                return -EINVAL;
 224
 225        /* check for VLF Flag (set at power-on) */
 226        if ((flags & RX6110_BIT_FLAG_VLF)) {
 227                dev_warn(dev, "Voltage low, data is invalid.\n");
 228                return -EINVAL;
 229        }
 230
 231        /* read registers to date */
 232        ret = regmap_bulk_read(rx6110->regmap, RX6110_REG_SEC, data,
 233                               RTC_NR_TIME);
 234        if (ret)
 235                return ret;
 236
 237        ret = rx6110_data_to_rtc_tm(data, tm);
 238        if (ret)
 239                return ret;
 240
 241        dev_dbg(dev, "%s: date %ptRr\n", __func__, tm);
 242
 243        return 0;
 244}
 245
 246static const struct reg_sequence rx6110_default_regs[] = {
 247        { RX6110_REG_RES1,   0xB8 },
 248        { RX6110_REG_RES2,   0x00 },
 249        { RX6110_REG_RES3,   0x10 },
 250        { RX6110_REG_IRQ,    0x00 },
 251        { RX6110_REG_ALMIN,  0x00 },
 252        { RX6110_REG_ALHOUR, 0x00 },
 253        { RX6110_REG_ALWDAY, 0x00 },
 254};
 255
 256/**
 257 * rx6110_init - initialize the rx6110 registers
 258 *
 259 * @rx6110: pointer to the rx6110 struct in use
 260 *
 261 */
 262static int rx6110_init(struct rx6110_data *rx6110)
 263{
 264        struct rtc_device *rtc = rx6110->rtc;
 265        int flags;
 266        int ret;
 267
 268        ret = regmap_update_bits(rx6110->regmap, RX6110_REG_EXT,
 269                                 RX6110_BIT_EXT_TE, 0);
 270        if (ret)
 271                return ret;
 272
 273        ret = regmap_register_patch(rx6110->regmap, rx6110_default_regs,
 274                                    ARRAY_SIZE(rx6110_default_regs));
 275        if (ret)
 276                return ret;
 277
 278        ret = regmap_read(rx6110->regmap, RX6110_REG_FLAG, &flags);
 279        if (ret)
 280                return ret;
 281
 282        /* check for VLF Flag (set at power-on) */
 283        if ((flags & RX6110_BIT_FLAG_VLF))
 284                dev_warn(&rtc->dev, "Voltage low, data loss detected.\n");
 285
 286        /* check for Alarm Flag */
 287        if (flags & RX6110_BIT_FLAG_AF)
 288                dev_warn(&rtc->dev, "An alarm may have been missed.\n");
 289
 290        /* check for Periodic Timer Flag */
 291        if (flags & RX6110_BIT_FLAG_TF)
 292                dev_warn(&rtc->dev, "Periodic timer was detected\n");
 293
 294        /* check for Update Timer Flag */
 295        if (flags & RX6110_BIT_FLAG_UF)
 296                dev_warn(&rtc->dev, "Update timer was detected\n");
 297
 298        /* clear all flags BUT VLF */
 299        ret = regmap_update_bits(rx6110->regmap, RX6110_REG_FLAG,
 300                                 RX6110_BIT_FLAG_AF |
 301                                 RX6110_BIT_FLAG_UF |
 302                                 RX6110_BIT_FLAG_TF,
 303                                 0);
 304
 305        return ret;
 306}
 307
 308static const struct rtc_class_ops rx6110_rtc_ops = {
 309        .read_time = rx6110_get_time,
 310        .set_time = rx6110_set_time,
 311};
 312
 313static struct regmap_config regmap_spi_config = {
 314        .reg_bits = 8,
 315        .val_bits = 8,
 316        .max_register = RX6110_REG_IRQ,
 317        .read_flag_mask = 0x80,
 318};
 319
 320/**
 321 * rx6110_probe - initialize rtc driver
 322 * @spi: pointer to spi device
 323 */
 324static int rx6110_probe(struct spi_device *spi)
 325{
 326        struct rx6110_data *rx6110;
 327        int err;
 328
 329        if ((spi->bits_per_word && spi->bits_per_word != 8) ||
 330            (spi->max_speed_hz > 2000000) ||
 331            (spi->mode != (SPI_CS_HIGH | SPI_CPOL | SPI_CPHA))) {
 332                dev_warn(&spi->dev, "SPI settings: bits_per_word: %d, max_speed_hz: %d, mode: %xh\n",
 333                         spi->bits_per_word, spi->max_speed_hz, spi->mode);
 334                dev_warn(&spi->dev, "driving device in an unsupported mode");
 335        }
 336
 337        rx6110 = devm_kzalloc(&spi->dev, sizeof(*rx6110), GFP_KERNEL);
 338        if (!rx6110)
 339                return -ENOMEM;
 340
 341        rx6110->regmap = devm_regmap_init_spi(spi, &regmap_spi_config);
 342        if (IS_ERR(rx6110->regmap)) {
 343                dev_err(&spi->dev, "regmap init failed for rtc rx6110\n");
 344                return PTR_ERR(rx6110->regmap);
 345        }
 346
 347        spi_set_drvdata(spi, rx6110);
 348
 349        rx6110->rtc = devm_rtc_device_register(&spi->dev,
 350                                               RX6110_DRIVER_NAME,
 351                                               &rx6110_rtc_ops, THIS_MODULE);
 352
 353        if (IS_ERR(rx6110->rtc))
 354                return PTR_ERR(rx6110->rtc);
 355
 356        err = rx6110_init(rx6110);
 357        if (err)
 358                return err;
 359
 360        rx6110->rtc->max_user_freq = 1;
 361
 362        return 0;
 363}
 364
 365static const struct spi_device_id rx6110_id[] = {
 366        { "rx6110", 0 },
 367        { }
 368};
 369MODULE_DEVICE_TABLE(spi, rx6110_id);
 370
 371static const struct of_device_id rx6110_spi_of_match[] = {
 372        { .compatible = "epson,rx6110" },
 373        { },
 374};
 375MODULE_DEVICE_TABLE(of, rx6110_spi_of_match);
 376
 377static struct spi_driver rx6110_driver = {
 378        .driver = {
 379                .name = RX6110_DRIVER_NAME,
 380                .of_match_table = of_match_ptr(rx6110_spi_of_match),
 381        },
 382        .probe          = rx6110_probe,
 383        .id_table       = rx6110_id,
 384};
 385
 386module_spi_driver(rx6110_driver);
 387
 388MODULE_AUTHOR("Val Krutov <val.krutov@erd.epson.com>");
 389MODULE_DESCRIPTION("RX-6110 SA RTC driver");
 390MODULE_LICENSE("GPL");
 391