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
  85 enum {
  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
  98 struct 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  */
 109 static 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  */
 138 static 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  */
 175 static 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  */
 214 static 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
 246 static 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  */
 262 static 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
 308 static const struct rtc_class_ops rx6110_rtc_ops = {
 309         .read_time = rx6110_get_time,
 310         .set_time = rx6110_set_time,
 311 };
 312
 313 static 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  */
 324 static 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
 365 static const struct spi_device_id rx6110_id[] = {
 366         { "rx6110", 0 },
 367         { }
 368 };
 369 MODULE_DEVICE_TABLE(spi, rx6110_id);
 370
 371 static const struct of_device_id rx6110_spi_of_match[] = {
 372         { .compatible = "epson,rx6110" },
 373         { },
 374 };
 375 MODULE_DEVICE_TABLE(of, rx6110_spi_of_match);
 376
 377 static 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
 386 module_spi_driver(rx6110_driver);
 387
 388 MODULE_AUTHOR("Val Krutov <val.krutov@erd.epson.com>");
 389 MODULE_DESCRIPTION("RX-6110 SA RTC driver");
 390 MODULE_LICENSE("GPL");