drivers/rtc/rtc-rx6110.c

   1 /*
   2  * Driver for the Epson RTC module RX-6110 SA
   3  *
   4  * Copyright(C) 2015 Pengutronix, Steffen Trumtrar <kernel@pengutronix.de>
   5  * Copyright(C) SEIKO EPSON CORPORATION 2013. All rights reserved.
   6  *
   7  * This driver software is distributed as is, without any warranty of any kind,
   8  * either express or implied as further specified in the GNU Public License.
   9  * This software may be used and distributed according to the terms of the GNU
  10  * Public License, version 2 as published by the Free Software Foundation.
  11  * See the file COPYING in the main directory of this archive for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program. If not, see <http://www.gnu.org/licenses/>.
  15  */
  16
  17 #include <linux/bcd.h>
  18 #include <linux/init.h>
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/of_gpio.h>
  22 #include <linux/regmap.h>
  23 #include <linux/rtc.h>
  24 #include <linux/spi/spi.h>
  25
  26 /* RX-6110 Register definitions */
  27 #define RX6110_REG_SEC          0x10
  28 #define RX6110_REG_MIN          0x11
  29 #define RX6110_REG_HOUR         0x12
  30 #define RX6110_REG_WDAY         0x13
  31 #define RX6110_REG_MDAY         0x14
  32 #define RX6110_REG_MONTH        0x15
  33 #define RX6110_REG_YEAR         0x16
  34 #define RX6110_REG_RES1         0x17
  35 #define RX6110_REG_ALMIN        0x18
  36 #define RX6110_REG_ALHOUR       0x19
  37 #define RX6110_REG_ALWDAY       0x1A
  38 #define RX6110_REG_TCOUNT0      0x1B
  39 #define RX6110_REG_TCOUNT1      0x1C
  40 #define RX6110_REG_EXT          0x1D
  41 #define RX6110_REG_FLAG         0x1E
  42 #define RX6110_REG_CTRL         0x1F
  43 #define RX6110_REG_USER0        0x20
  44 #define RX6110_REG_USER1        0x21
  45 #define RX6110_REG_USER2        0x22
  46 #define RX6110_REG_USER3        0x23
  47 #define RX6110_REG_USER4        0x24
  48 #define RX6110_REG_USER5        0x25
  49 #define RX6110_REG_USER6        0x26
  50 #define RX6110_REG_USER7        0x27
  51 #define RX6110_REG_USER8        0x28
  52 #define RX6110_REG_USER9        0x29
  53 #define RX6110_REG_USERA        0x2A
  54 #define RX6110_REG_USERB        0x2B
  55 #define RX6110_REG_USERC        0x2C
  56 #define RX6110_REG_USERD        0x2D
  57 #define RX6110_REG_USERE        0x2E
  58 #define RX6110_REG_USERF        0x2F
  59 #define RX6110_REG_RES2         0x30
  60 #define RX6110_REG_RES3         0x31
  61 #define RX6110_REG_IRQ          0x32
  62
  63 #define RX6110_BIT_ALARM_EN             BIT(7)
  64
  65 /* Extension Register (1Dh) bit positions */
  66 #define RX6110_BIT_EXT_TSEL0            BIT(0)
  67 #define RX6110_BIT_EXT_TSEL1            BIT(1)
  68 #define RX6110_BIT_EXT_TSEL2            BIT(2)
  69 #define RX6110_BIT_EXT_WADA             BIT(3)
  70 #define RX6110_BIT_EXT_TE               BIT(4)
  71 #define RX6110_BIT_EXT_USEL             BIT(5)
  72 #define RX6110_BIT_EXT_FSEL0            BIT(6)
  73 #define RX6110_BIT_EXT_FSEL1            BIT(7)
  74
  75 /* Flag Register (1Eh) bit positions */
  76 #define RX6110_BIT_FLAG_VLF             BIT(1)
  77 #define RX6110_BIT_FLAG_AF              BIT(3)
  78 #define RX6110_BIT_FLAG_TF              BIT(4)
  79 #define RX6110_BIT_FLAG_UF              BIT(5)
  80
  81 /* Control Register (1Fh) bit positions */
  82 #define RX6110_BIT_CTRL_TBKE            BIT(0)
  83 #define RX6110_BIT_CTRL_TBKON           BIT(1)
  84 #define RX6110_BIT_CTRL_TSTP            BIT(2)
  85 #define RX6110_BIT_CTRL_AIE             BIT(3)
  86 #define RX6110_BIT_CTRL_TIE             BIT(4)
  87 #define RX6110_BIT_CTRL_UIE             BIT(5)
  88 #define RX6110_BIT_CTRL_STOP            BIT(6)
  89 #define RX6110_BIT_CTRL_TEST            BIT(7)
  90
  91 enum {
  92         RTC_SEC = 0,
  93         RTC_MIN,
  94         RTC_HOUR,
  95         RTC_WDAY,
  96         RTC_MDAY,
  97         RTC_MONTH,
  98         RTC_YEAR,
  99         RTC_NR_TIME
 100 };
 101
 102 #define RX6110_DRIVER_NAME              "rx6110"
 103
 104 struct rx6110_data {
 105         struct rtc_device *rtc;
 106         struct regmap *regmap;
 107 };
 108
 109 /**
 110  * rx6110_rtc_tm_to_data - convert rtc_time to native time encoding
 111  *
 112  * @tm: holds date and time
 113  * @data: holds the encoding in rx6110 native form
 114  */
 115 static int rx6110_rtc_tm_to_data(struct rtc_time *tm, u8 *data)
 116 {
 117         pr_debug("%s: date %ds %dm %dh %dmd %dm %dy\n", __func__,
 118                  tm->tm_sec, tm->tm_min, tm->tm_hour,
 119                  tm->tm_mday, tm->tm_mon, tm->tm_year);
 120
 121         /*
 122          * The year in the RTC is a value between 0 and 99.
 123          * Assume that this represents the current century
 124          * and disregard all other values.
 125          */
 126         if (tm->tm_year < 100 || tm->tm_year >= 200)
 127                 return -EINVAL;
 128
 129         data[RTC_SEC] = bin2bcd(tm->tm_sec);
 130         data[RTC_MIN] = bin2bcd(tm->tm_min);
 131         data[RTC_HOUR] = bin2bcd(tm->tm_hour);
 132         data[RTC_WDAY] = BIT(bin2bcd(tm->tm_wday));
 133         data[RTC_MDAY] = bin2bcd(tm->tm_mday);
 134         data[RTC_MONTH] = bin2bcd(tm->tm_mon + 1);
 135         data[RTC_YEAR] = bin2bcd(tm->tm_year % 100);
 136
 137         return 0;
 138 }
 139
 140 /**
 141  * rx6110_data_to_rtc_tm - convert native time encoding to rtc_time
 142  *
 143  * @data: holds the encoding in rx6110 native form
 144  * @tm: holds date and time
 145  */
 146 static int rx6110_data_to_rtc_tm(u8 *data, struct rtc_time *tm)
 147 {
 148         tm->tm_sec = bcd2bin(data[RTC_SEC] & 0x7f);
 149         tm->tm_min = bcd2bin(data[RTC_MIN] & 0x7f);
 150         /* only 24-hour clock */
 151         tm->tm_hour = bcd2bin(data[RTC_HOUR] & 0x3f);
 152         tm->tm_wday = ffs(data[RTC_WDAY] & 0x7f);
 153         tm->tm_mday = bcd2bin(data[RTC_MDAY] & 0x3f);
 154         tm->tm_mon = bcd2bin(data[RTC_MONTH] & 0x1f) - 1;
 155         tm->tm_year = bcd2bin(data[RTC_YEAR]) + 100;
 156
 157         pr_debug("%s: date %ds %dm %dh %dmd %dm %dy\n", __func__,
 158                  tm->tm_sec, tm->tm_min, tm->tm_hour,
 159                  tm->tm_mday, tm->tm_mon, tm->tm_year);
 160
 161         /*
 162          * The year in the RTC is a value between 0 and 99.
 163          * Assume that this represents the current century
 164          * and disregard all other values.
 165          */
 166         if (tm->tm_year < 100 || tm->tm_year >= 200)
 167                 return -EINVAL;
 168
 169         return 0;
 170 }
 171
 172 /**
 173  * rx6110_set_time - set the current time in the rx6110 registers
 174  *
 175  * @dev: the rtc device in use
 176  * @tm: holds date and time
 177  *
 178  * BUG: The HW assumes every year that is a multiple of 4 to be a leap
 179  * year. Next time this is wrong is 2100, which will not be a leap year
 180  *
 181  * Note: If STOP is not set/cleared, the clock will start when the seconds
 182  *       register is written
 183  *
 184  */
 185 static int rx6110_set_time(struct device *dev, struct rtc_time *tm)
 186 {
 187         struct rx6110_data *rx6110 = dev_get_drvdata(dev);
 188         u8 data[RTC_NR_TIME];
 189         int ret;
 190
 191         ret = rx6110_rtc_tm_to_data(tm, data);
 192         if (ret < 0)
 193                 return ret;
 194
 195         /* set STOP bit before changing clock/calendar */
 196         ret = regmap_update_bits(rx6110->regmap, RX6110_REG_CTRL,
 197                                  RX6110_BIT_CTRL_STOP, RX6110_BIT_CTRL_STOP);
 198         if (ret)
 199                 return ret;
 200
 201         ret = regmap_bulk_write(rx6110->regmap, RX6110_REG_SEC, data,
 202                                 RTC_NR_TIME);
 203         if (ret)
 204                 return ret;
 205
 206         /* The time in the RTC is valid. Be sure to have VLF cleared. */
 207         ret = regmap_update_bits(rx6110->regmap, RX6110_REG_FLAG,
 208                                  RX6110_BIT_FLAG_VLF, 0);
 209         if (ret)
 210                 return ret;
 211
 212         /* clear STOP bit after changing clock/calendar */
 213         ret = regmap_update_bits(rx6110->regmap, RX6110_REG_CTRL,
 214                                  RX6110_BIT_CTRL_STOP, 0);
 215
 216         return ret;
 217 }
 218
 219 /**
 220  * rx6110_get_time - get the current time from the rx6110 registers
 221  * @dev: the rtc device in use
 222  * @tm: holds date and time
 223  */
 224 static int rx6110_get_time(struct device *dev, struct rtc_time *tm)
 225 {
 226         struct rx6110_data *rx6110 = dev_get_drvdata(dev);
 227         u8 data[RTC_NR_TIME];
 228         int flags;
 229         int ret;
 230
 231         ret = regmap_read(rx6110->regmap, RX6110_REG_FLAG, &flags);
 232         if (ret)
 233                 return -EINVAL;
 234
 235         /* check for VLF Flag (set at power-on) */
 236         if ((flags & RX6110_BIT_FLAG_VLF)) {
 237                 dev_warn(dev, "Voltage low, data is invalid.\n");
 238                 return -EINVAL;
 239         }
 240
 241         /* read registers to date */
 242         ret = regmap_bulk_read(rx6110->regmap, RX6110_REG_SEC, data,
 243                                RTC_NR_TIME);
 244         if (ret)
 245                 return ret;
 246
 247         ret = rx6110_data_to_rtc_tm(data, tm);
 248         if (ret)
 249                 return ret;
 250
 251         dev_dbg(dev, "%s: date %ds %dm %dh %dmd %dm %dy\n", __func__,
 252                 tm->tm_sec, tm->tm_min, tm->tm_hour,
 253                 tm->tm_mday, tm->tm_mon, tm->tm_year);
 254
 255         return rtc_valid_tm(tm);
 256 }
 257
 258 static const struct reg_sequence rx6110_default_regs[] = {
 259         { RX6110_REG_RES1,   0xB8 },
 260         { RX6110_REG_RES2,   0x00 },
 261         { RX6110_REG_RES3,   0x10 },
 262         { RX6110_REG_IRQ,    0x00 },
 263         { RX6110_REG_ALMIN,  0x00 },
 264         { RX6110_REG_ALHOUR, 0x00 },
 265         { RX6110_REG_ALWDAY, 0x00 },
 266 };
 267
 268 /**
 269  * rx6110_init - initialize the rx6110 registers
 270  *
 271  * @rx6110: pointer to the rx6110 struct in use
 272  *
 273  */
 274 static int rx6110_init(struct rx6110_data *rx6110)
 275 {
 276         struct rtc_device *rtc = rx6110->rtc;
 277         int flags;
 278         int ret;
 279
 280         ret = regmap_update_bits(rx6110->regmap, RX6110_REG_EXT,
 281                                  RX6110_BIT_EXT_TE, 0);
 282         if (ret)
 283                 return ret;
 284
 285         ret = regmap_register_patch(rx6110->regmap, rx6110_default_regs,
 286                                     ARRAY_SIZE(rx6110_default_regs));
 287         if (ret)
 288                 return ret;
 289
 290         ret = regmap_read(rx6110->regmap, RX6110_REG_FLAG, &flags);
 291         if (ret)
 292                 return ret;
 293
 294         /* check for VLF Flag (set at power-on) */
 295         if ((flags & RX6110_BIT_FLAG_VLF))
 296                 dev_warn(&rtc->dev, "Voltage low, data loss detected.\n");
 297
 298         /* check for Alarm Flag */
 299         if (flags & RX6110_BIT_FLAG_AF)
 300                 dev_warn(&rtc->dev, "An alarm may have been missed.\n");
 301
 302         /* check for Periodic Timer Flag */
 303         if (flags & RX6110_BIT_FLAG_TF)
 304                 dev_warn(&rtc->dev, "Periodic timer was detected\n");
 305
 306         /* check for Update Timer Flag */
 307         if (flags & RX6110_BIT_FLAG_UF)
 308                 dev_warn(&rtc->dev, "Update timer was detected\n");
 309
 310         /* clear all flags BUT VLF */
 311         ret = regmap_update_bits(rx6110->regmap, RX6110_REG_FLAG,
 312                                  RX6110_BIT_FLAG_AF |
 313                                  RX6110_BIT_FLAG_UF |
 314                                  RX6110_BIT_FLAG_TF,
 315                                  0);
 316
 317         return ret;
 318 }
 319
 320 static const struct rtc_class_ops rx6110_rtc_ops = {
 321         .read_time = rx6110_get_time,
 322         .set_time = rx6110_set_time,
 323 };
 324
 325 static struct regmap_config regmap_spi_config = {
 326         .reg_bits = 8,
 327         .val_bits = 8,
 328         .max_register = RX6110_REG_IRQ,
 329         .read_flag_mask = 0x80,
 330 };
 331
 332 /**
 333  * rx6110_probe - initialize rtc driver
 334  * @spi: pointer to spi device
 335  */
 336 static int rx6110_probe(struct spi_device *spi)
 337 {
 338         struct rx6110_data *rx6110;
 339         int err;
 340
 341         if ((spi->bits_per_word && spi->bits_per_word != 8) ||
 342             (spi->max_speed_hz > 2000000) ||
 343             (spi->mode != (SPI_CS_HIGH | SPI_CPOL | SPI_CPHA))) {
 344                 dev_warn(&spi->dev, "SPI settings: bits_per_word: %d, max_speed_hz: %d, mode: %xh\n",
 345                          spi->bits_per_word, spi->max_speed_hz, spi->mode);
 346                 dev_warn(&spi->dev, "driving device in an unsupported mode");
 347         }
 348
 349         rx6110 = devm_kzalloc(&spi->dev, sizeof(*rx6110), GFP_KERNEL);
 350         if (!rx6110)
 351                 return -ENOMEM;
 352
 353         rx6110->regmap = devm_regmap_init_spi(spi, &regmap_spi_config);
 354         if (IS_ERR(rx6110->regmap)) {
 355                 dev_err(&spi->dev, "regmap init failed for rtc rx6110\n");
 356                 return PTR_ERR(rx6110->regmap);
 357         }
 358
 359         spi_set_drvdata(spi, rx6110);
 360
 361         rx6110->rtc = devm_rtc_device_register(&spi->dev,
 362                                                RX6110_DRIVER_NAME,
 363                                                &rx6110_rtc_ops, THIS_MODULE);
 364
 365         if (IS_ERR(rx6110->rtc))
 366                 return PTR_ERR(rx6110->rtc);
 367
 368         err = rx6110_init(rx6110);
 369         if (err)
 370                 return err;
 371
 372         rx6110->rtc->max_user_freq = 1;
 373
 374         return 0;
 375 }
 376
 377 static int rx6110_remove(struct spi_device *spi)
 378 {
 379         return 0;
 380 }
 381
 382 static const struct spi_device_id rx6110_id[] = {
 383         { "rx6110", 0 },
 384         { }
 385 };
 386 MODULE_DEVICE_TABLE(spi, rx6110_id);
 387
 388 static struct spi_driver rx6110_driver = {
 389         .driver = {
 390                 .name = RX6110_DRIVER_NAME,
 391         },
 392         .probe          = rx6110_probe,
 393         .remove         = rx6110_remove,
 394         .id_table       = rx6110_id,
 395 };
 396
 397 module_spi_driver(rx6110_driver);
 398
 399 MODULE_AUTHOR("Val Krutov <val.krutov@erd.epson.com>");
 400 MODULE_DESCRIPTION("RX-6110 SA RTC driver");
 401 MODULE_LICENSE("GPL");