drivers/rtc/rtc-rv8803.c

   1 /*
   2  * RTC driver for the Micro Crystal RV8803
   3  *
   4  * Copyright (C) 2015 Micro Crystal SA
   5  *
   6  * Alexandre Belloni <alexandre.belloni@free-electrons.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  */
  13
  14 #include <linux/bcd.h>
  15 #include <linux/bitops.h>
  16 #include <linux/log2.h>
  17 #include <linux/i2c.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/rtc.h>
  22
  23 #define RV8803_I2C_TRY_COUNT            4
  24
  25 #define RV8803_SEC                      0x00
  26 #define RV8803_MIN                      0x01
  27 #define RV8803_HOUR                     0x02
  28 #define RV8803_WEEK                     0x03
  29 #define RV8803_DAY                      0x04
  30 #define RV8803_MONTH                    0x05
  31 #define RV8803_YEAR                     0x06
  32 #define RV8803_RAM                      0x07
  33 #define RV8803_ALARM_MIN                0x08
  34 #define RV8803_ALARM_HOUR               0x09
  35 #define RV8803_ALARM_WEEK_OR_DAY        0x0A
  36 #define RV8803_EXT                      0x0D
  37 #define RV8803_FLAG                     0x0E
  38 #define RV8803_CTRL                     0x0F
  39
  40 #define RV8803_EXT_WADA                 BIT(6)
  41
  42 #define RV8803_FLAG_V1F                 BIT(0)
  43 #define RV8803_FLAG_V2F                 BIT(1)
  44 #define RV8803_FLAG_AF                  BIT(3)
  45 #define RV8803_FLAG_TF                  BIT(4)
  46 #define RV8803_FLAG_UF                  BIT(5)
  47
  48 #define RV8803_CTRL_RESET               BIT(0)
  49
  50 #define RV8803_CTRL_EIE                 BIT(2)
  51 #define RV8803_CTRL_AIE                 BIT(3)
  52 #define RV8803_CTRL_TIE                 BIT(4)
  53 #define RV8803_CTRL_UIE                 BIT(5)
  54
  55 struct rv8803_data {
  56         struct i2c_client *client;
  57         struct rtc_device *rtc;
  58         struct mutex flags_lock;
  59         u8 ctrl;
  60 };
  61
  62 static int rv8803_read_reg(const struct i2c_client *client, u8 reg)
  63 {
  64         int try = RV8803_I2C_TRY_COUNT;
  65         s32 ret;
  66
  67         /*
  68          * There is a 61µs window during which the RTC does not acknowledge I2C
  69          * transfers. In that case, ensure that there are multiple attempts.
  70          */
  71         do
  72                 ret = i2c_smbus_read_byte_data(client, reg);
  73         while ((ret == -ENXIO || ret == -EIO) && --try);
  74         if (ret < 0)
  75                 dev_err(&client->dev, "Unable to read register 0x%02x\n", reg);
  76
  77         return ret;
  78 }
  79
  80 static int rv8803_read_regs(const struct i2c_client *client,
  81                             u8 reg, u8 count, u8 *values)
  82 {
  83         int try = RV8803_I2C_TRY_COUNT;
  84         s32 ret;
  85
  86         do
  87                 ret = i2c_smbus_read_i2c_block_data(client, reg, count, values);
  88         while ((ret == -ENXIO || ret == -EIO) && --try);
  89         if (ret != count) {
  90                 dev_err(&client->dev,
  91                         "Unable to read registers 0x%02x..0x%02x\n",
  92                         reg, reg + count - 1);
  93                 return ret < 0 ? ret : -EIO;
  94         }
  95
  96         return 0;
  97 }
  98
  99 static int rv8803_write_reg(const struct i2c_client *client, u8 reg, u8 value)
 100 {
 101         int try = RV8803_I2C_TRY_COUNT;
 102         s32 ret;
 103
 104         do
 105                 ret = i2c_smbus_write_byte_data(client, reg, value);
 106         while ((ret == -ENXIO || ret == -EIO) && --try);
 107         if (ret)
 108                 dev_err(&client->dev, "Unable to write register 0x%02x\n", reg);
 109
 110         return ret;
 111 }
 112
 113 static int rv8803_write_regs(const struct i2c_client *client,
 114                              u8 reg, u8 count, const u8 *values)
 115 {
 116         int try = RV8803_I2C_TRY_COUNT;
 117         s32 ret;
 118
 119         do
 120                 ret = i2c_smbus_write_i2c_block_data(client, reg, count,
 121                                                      values);
 122         while ((ret == -ENXIO || ret == -EIO) && --try);
 123         if (ret)
 124                 dev_err(&client->dev,
 125                         "Unable to write registers 0x%02x..0x%02x\n",
 126                         reg, reg + count - 1);
 127
 128         return ret;
 129 }
 130
 131 static irqreturn_t rv8803_handle_irq(int irq, void *dev_id)
 132 {
 133         struct i2c_client *client = dev_id;
 134         struct rv8803_data *rv8803 = i2c_get_clientdata(client);
 135         unsigned long events = 0;
 136         int flags;
 137
 138         mutex_lock(&rv8803->flags_lock);
 139
 140         flags = rv8803_read_reg(client, RV8803_FLAG);
 141         if (flags <= 0) {
 142                 mutex_unlock(&rv8803->flags_lock);
 143                 return IRQ_NONE;
 144         }
 145
 146         if (flags & RV8803_FLAG_V1F)
 147                 dev_warn(&client->dev, "Voltage low, temperature compensation stopped.\n");
 148
 149         if (flags & RV8803_FLAG_V2F)
 150                 dev_warn(&client->dev, "Voltage low, data loss detected.\n");
 151
 152         if (flags & RV8803_FLAG_TF) {
 153                 flags &= ~RV8803_FLAG_TF;
 154                 rv8803->ctrl &= ~RV8803_CTRL_TIE;
 155                 events |= RTC_PF;
 156         }
 157
 158         if (flags & RV8803_FLAG_AF) {
 159                 flags &= ~RV8803_FLAG_AF;
 160                 rv8803->ctrl &= ~RV8803_CTRL_AIE;
 161                 events |= RTC_AF;
 162         }
 163
 164         if (flags & RV8803_FLAG_UF) {
 165                 flags &= ~RV8803_FLAG_UF;
 166                 rv8803->ctrl &= ~RV8803_CTRL_UIE;
 167                 events |= RTC_UF;
 168         }
 169
 170         if (events) {
 171                 rtc_update_irq(rv8803->rtc, 1, events);
 172                 rv8803_write_reg(client, RV8803_FLAG, flags);
 173                 rv8803_write_reg(rv8803->client, RV8803_CTRL, rv8803->ctrl);
 174         }
 175
 176         mutex_unlock(&rv8803->flags_lock);
 177
 178         return IRQ_HANDLED;
 179 }
 180
 181 static int rv8803_get_time(struct device *dev, struct rtc_time *tm)
 182 {
 183         struct rv8803_data *rv8803 = dev_get_drvdata(dev);
 184         u8 date1[7];
 185         u8 date2[7];
 186         u8 *date = date1;
 187         int ret, flags;
 188
 189         flags = rv8803_read_reg(rv8803->client, RV8803_FLAG);
 190         if (flags < 0)
 191                 return flags;
 192
 193         if (flags & RV8803_FLAG_V2F) {
 194                 dev_warn(dev, "Voltage low, data is invalid.\n");
 195                 return -EINVAL;
 196         }
 197
 198         ret = rv8803_read_regs(rv8803->client, RV8803_SEC, 7, date);
 199         if (ret)
 200                 return ret;
 201
 202         if ((date1[RV8803_SEC] & 0x7f) == bin2bcd(59)) {
 203                 ret = rv8803_read_regs(rv8803->client, RV8803_SEC, 7, date2);
 204                 if (ret)
 205                         return ret;
 206
 207                 if ((date2[RV8803_SEC] & 0x7f) != bin2bcd(59))
 208                         date = date2;
 209         }
 210
 211         tm->tm_sec  = bcd2bin(date[RV8803_SEC] & 0x7f);
 212         tm->tm_min  = bcd2bin(date[RV8803_MIN] & 0x7f);
 213         tm->tm_hour = bcd2bin(date[RV8803_HOUR] & 0x3f);
 214         tm->tm_wday = ilog2(date[RV8803_WEEK] & 0x7f);
 215         tm->tm_mday = bcd2bin(date[RV8803_DAY] & 0x3f);
 216         tm->tm_mon  = bcd2bin(date[RV8803_MONTH] & 0x1f) - 1;
 217         tm->tm_year = bcd2bin(date[RV8803_YEAR]) + 100;
 218
 219         return 0;
 220 }
 221
 222 static int rv8803_set_time(struct device *dev, struct rtc_time *tm)
 223 {
 224         struct rv8803_data *rv8803 = dev_get_drvdata(dev);
 225         u8 date[7];
 226         int ctrl, flags, ret;
 227
 228         if ((tm->tm_year < 100) || (tm->tm_year > 199))
 229                 return -EINVAL;
 230
 231         ctrl = rv8803_read_reg(rv8803->client, RV8803_CTRL);
 232         if (ctrl < 0)
 233                 return ctrl;
 234
 235         /* Stop the clock */
 236         ret = rv8803_write_reg(rv8803->client, RV8803_CTRL,
 237                                ctrl | RV8803_CTRL_RESET);
 238         if (ret)
 239                 return ret;
 240
 241         date[RV8803_SEC]   = bin2bcd(tm->tm_sec);
 242         date[RV8803_MIN]   = bin2bcd(tm->tm_min);
 243         date[RV8803_HOUR]  = bin2bcd(tm->tm_hour);
 244         date[RV8803_WEEK]  = 1 << (tm->tm_wday);
 245         date[RV8803_DAY]   = bin2bcd(tm->tm_mday);
 246         date[RV8803_MONTH] = bin2bcd(tm->tm_mon + 1);
 247         date[RV8803_YEAR]  = bin2bcd(tm->tm_year - 100);
 248
 249         ret = rv8803_write_regs(rv8803->client, RV8803_SEC, 7, date);
 250         if (ret)
 251                 return ret;
 252
 253         /* Restart the clock */
 254         ret = rv8803_write_reg(rv8803->client, RV8803_CTRL,
 255                                ctrl & ~RV8803_CTRL_RESET);
 256         if (ret)
 257                 return ret;
 258
 259         mutex_lock(&rv8803->flags_lock);
 260
 261         flags = rv8803_read_reg(rv8803->client, RV8803_FLAG);
 262         if (flags < 0) {
 263                 mutex_unlock(&rv8803->flags_lock);
 264                 return flags;
 265         }
 266
 267         ret = rv8803_write_reg(rv8803->client, RV8803_FLAG,
 268                                flags & ~(RV8803_FLAG_V1F | RV8803_FLAG_V2F));
 269
 270         mutex_unlock(&rv8803->flags_lock);
 271
 272         return ret;
 273 }
 274
 275 static int rv8803_get_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 276 {
 277         struct rv8803_data *rv8803 = dev_get_drvdata(dev);
 278         struct i2c_client *client = rv8803->client;
 279         u8 alarmvals[3];
 280         int flags, ret;
 281
 282         ret = rv8803_read_regs(client, RV8803_ALARM_MIN, 3, alarmvals);
 283         if (ret)
 284                 return ret;
 285
 286         flags = rv8803_read_reg(client, RV8803_FLAG);
 287         if (flags < 0)
 288                 return flags;
 289
 290         alrm->time.tm_sec  = 0;
 291         alrm->time.tm_min  = bcd2bin(alarmvals[0] & 0x7f);
 292         alrm->time.tm_hour = bcd2bin(alarmvals[1] & 0x3f);
 293         alrm->time.tm_mday = bcd2bin(alarmvals[2] & 0x3f);
 294
 295         alrm->enabled = !!(rv8803->ctrl & RV8803_CTRL_AIE);
 296         alrm->pending = (flags & RV8803_FLAG_AF) && alrm->enabled;
 297
 298         return 0;
 299 }
 300
 301 static int rv8803_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 302 {
 303         struct i2c_client *client = to_i2c_client(dev);
 304         struct rv8803_data *rv8803 = dev_get_drvdata(dev);
 305         u8 alarmvals[3];
 306         u8 ctrl[2];
 307         int ret, err;
 308
 309         /* The alarm has no seconds, round up to nearest minute */
 310         if (alrm->time.tm_sec) {
 311                 time64_t alarm_time = rtc_tm_to_time64(&alrm->time);
 312
 313                 alarm_time += 60 - alrm->time.tm_sec;
 314                 rtc_time64_to_tm(alarm_time, &alrm->time);
 315         }
 316
 317         mutex_lock(&rv8803->flags_lock);
 318
 319         ret = rv8803_read_regs(client, RV8803_FLAG, 2, ctrl);
 320         if (ret) {
 321                 mutex_unlock(&rv8803->flags_lock);
 322                 return ret;
 323         }
 324
 325         alarmvals[0] = bin2bcd(alrm->time.tm_min);
 326         alarmvals[1] = bin2bcd(alrm->time.tm_hour);
 327         alarmvals[2] = bin2bcd(alrm->time.tm_mday);
 328
 329         if (rv8803->ctrl & (RV8803_CTRL_AIE | RV8803_CTRL_UIE)) {
 330                 rv8803->ctrl &= ~(RV8803_CTRL_AIE | RV8803_CTRL_UIE);
 331                 err = rv8803_write_reg(rv8803->client, RV8803_CTRL,
 332                                        rv8803->ctrl);
 333                 if (err) {
 334                         mutex_unlock(&rv8803->flags_lock);
 335                         return err;
 336                 }
 337         }
 338
 339         ctrl[1] &= ~RV8803_FLAG_AF;
 340         err = rv8803_write_reg(rv8803->client, RV8803_FLAG, ctrl[1]);
 341         mutex_unlock(&rv8803->flags_lock);
 342         if (err)
 343                 return err;
 344
 345         err = rv8803_write_regs(rv8803->client, RV8803_ALARM_MIN, 3, alarmvals);
 346         if (err)
 347                 return err;
 348
 349         if (alrm->enabled) {
 350                 if (rv8803->rtc->uie_rtctimer.enabled)
 351                         rv8803->ctrl |= RV8803_CTRL_UIE;
 352                 if (rv8803->rtc->aie_timer.enabled)
 353                         rv8803->ctrl |= RV8803_CTRL_AIE;
 354
 355                 err = rv8803_write_reg(rv8803->client, RV8803_CTRL,
 356                                        rv8803->ctrl);
 357                 if (err)
 358                         return err;
 359         }
 360
 361         return 0;
 362 }
 363
 364 static int rv8803_alarm_irq_enable(struct device *dev, unsigned int enabled)
 365 {
 366         struct i2c_client *client = to_i2c_client(dev);
 367         struct rv8803_data *rv8803 = dev_get_drvdata(dev);
 368         int ctrl, flags, err;
 369
 370         ctrl = rv8803->ctrl;
 371
 372         if (enabled) {
 373                 if (rv8803->rtc->uie_rtctimer.enabled)
 374                         ctrl |= RV8803_CTRL_UIE;
 375                 if (rv8803->rtc->aie_timer.enabled)
 376                         ctrl |= RV8803_CTRL_AIE;
 377         } else {
 378                 if (!rv8803->rtc->uie_rtctimer.enabled)
 379                         ctrl &= ~RV8803_CTRL_UIE;
 380                 if (!rv8803->rtc->aie_timer.enabled)
 381                         ctrl &= ~RV8803_CTRL_AIE;
 382         }
 383
 384         mutex_lock(&rv8803->flags_lock);
 385         flags = rv8803_read_reg(client, RV8803_FLAG);
 386         if (flags < 0) {
 387                 mutex_unlock(&rv8803->flags_lock);
 388                 return flags;
 389         }
 390         flags &= ~(RV8803_FLAG_AF | RV8803_FLAG_UF);
 391         err = rv8803_write_reg(client, RV8803_FLAG, flags);
 392         mutex_unlock(&rv8803->flags_lock);
 393         if (err)
 394                 return err;
 395
 396         if (ctrl != rv8803->ctrl) {
 397                 rv8803->ctrl = ctrl;
 398                 err = rv8803_write_reg(client, RV8803_CTRL, rv8803->ctrl);
 399                 if (err)
 400                         return err;
 401         }
 402
 403         return 0;
 404 }
 405
 406 static int rv8803_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 407 {
 408         struct i2c_client *client = to_i2c_client(dev);
 409         struct rv8803_data *rv8803 = dev_get_drvdata(dev);
 410         int flags, ret = 0;
 411
 412         switch (cmd) {
 413         case RTC_VL_READ:
 414                 flags = rv8803_read_reg(client, RV8803_FLAG);
 415                 if (flags < 0)
 416                         return flags;
 417
 418                 if (flags & RV8803_FLAG_V1F)
 419                         dev_warn(&client->dev, "Voltage low, temperature compensation stopped.\n");
 420
 421                 if (flags & RV8803_FLAG_V2F)
 422                         dev_warn(&client->dev, "Voltage low, data loss detected.\n");
 423
 424                 flags &= RV8803_FLAG_V1F | RV8803_FLAG_V2F;
 425
 426                 if (copy_to_user((void __user *)arg, &flags, sizeof(int)))
 427                         return -EFAULT;
 428
 429                 return 0;
 430
 431         case RTC_VL_CLR:
 432                 mutex_lock(&rv8803->flags_lock);
 433                 flags = rv8803_read_reg(client, RV8803_FLAG);
 434                 if (flags < 0) {
 435                         mutex_unlock(&rv8803->flags_lock);
 436                         return flags;
 437                 }
 438
 439                 flags &= ~(RV8803_FLAG_V1F | RV8803_FLAG_V2F);
 440                 ret = rv8803_write_reg(client, RV8803_FLAG, flags);
 441                 mutex_unlock(&rv8803->flags_lock);
 442                 if (ret)
 443                         return ret;
 444
 445                 return 0;
 446
 447         default:
 448                 return -ENOIOCTLCMD;
 449         }
 450 }
 451
 452 static ssize_t rv8803_nvram_write(struct file *filp, struct kobject *kobj,
 453                                   struct bin_attribute *attr,
 454                                   char *buf, loff_t off, size_t count)
 455 {
 456         struct device *dev = kobj_to_dev(kobj);
 457         struct i2c_client *client = to_i2c_client(dev);
 458         int ret;
 459
 460         ret = rv8803_write_reg(client, RV8803_RAM, buf[0]);
 461         if (ret)
 462                 return ret;
 463
 464         return 1;
 465 }
 466
 467 static ssize_t rv8803_nvram_read(struct file *filp, struct kobject *kobj,
 468                                  struct bin_attribute *attr,
 469                                  char *buf, loff_t off, size_t count)
 470 {
 471         struct device *dev = kobj_to_dev(kobj);
 472         struct i2c_client *client = to_i2c_client(dev);
 473         int ret;
 474
 475         ret = rv8803_read_reg(client, RV8803_RAM);
 476         if (ret < 0)
 477                 return ret;
 478
 479         buf[0] = ret;
 480
 481         return 1;
 482 }
 483
 484 static struct bin_attribute rv8803_nvram_attr = {
 485         .attr = {
 486                 .name = "nvram",
 487                 .mode = S_IRUGO | S_IWUSR,
 488         },
 489         .size = 1,
 490         .read = rv8803_nvram_read,
 491         .write = rv8803_nvram_write,
 492 };
 493
 494 static struct rtc_class_ops rv8803_rtc_ops = {
 495         .read_time = rv8803_get_time,
 496         .set_time = rv8803_set_time,
 497         .ioctl = rv8803_ioctl,
 498 };
 499
 500 static int rv8803_probe(struct i2c_client *client,
 501                         const struct i2c_device_id *id)
 502 {
 503         struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
 504         struct rv8803_data *rv8803;
 505         int err, flags;
 506
 507         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
 508                                      I2C_FUNC_SMBUS_I2C_BLOCK)) {
 509                 dev_err(&adapter->dev, "doesn't support I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_I2C_BLOCK\n");
 510                 return -EIO;
 511         }
 512
 513         rv8803 = devm_kzalloc(&client->dev, sizeof(struct rv8803_data),
 514                               GFP_KERNEL);
 515         if (!rv8803)
 516                 return -ENOMEM;
 517
 518         mutex_init(&rv8803->flags_lock);
 519         rv8803->client = client;
 520         i2c_set_clientdata(client, rv8803);
 521
 522         flags = rv8803_read_reg(client, RV8803_FLAG);
 523         if (flags < 0)
 524                 return flags;
 525
 526         if (flags & RV8803_FLAG_V1F)
 527                 dev_warn(&client->dev, "Voltage low, temperature compensation stopped.\n");
 528
 529         if (flags & RV8803_FLAG_V2F)
 530                 dev_warn(&client->dev, "Voltage low, data loss detected.\n");
 531
 532         if (flags & RV8803_FLAG_AF)
 533                 dev_warn(&client->dev, "An alarm maybe have been missed.\n");
 534
 535         if (client->irq > 0) {
 536                 err = devm_request_threaded_irq(&client->dev, client->irq,
 537                                                 NULL, rv8803_handle_irq,
 538                                                 IRQF_TRIGGER_LOW | IRQF_ONESHOT,
 539                                                 "rv8803", client);
 540                 if (err) {
 541                         dev_warn(&client->dev, "unable to request IRQ, alarms disabled\n");
 542                         client->irq = 0;
 543                 } else {
 544                         rv8803_rtc_ops.read_alarm = rv8803_get_alarm;
 545                         rv8803_rtc_ops.set_alarm = rv8803_set_alarm;
 546                         rv8803_rtc_ops.alarm_irq_enable = rv8803_alarm_irq_enable;
 547                 }
 548         }
 549
 550         rv8803->rtc = devm_rtc_device_register(&client->dev, client->name,
 551                                                &rv8803_rtc_ops, THIS_MODULE);
 552         if (IS_ERR(rv8803->rtc)) {
 553                 dev_err(&client->dev, "unable to register the class device\n");
 554                 return PTR_ERR(rv8803->rtc);
 555         }
 556
 557         err = rv8803_write_reg(rv8803->client, RV8803_EXT, RV8803_EXT_WADA);
 558         if (err)
 559                 return err;
 560
 561         err = device_create_bin_file(&client->dev, &rv8803_nvram_attr);
 562         if (err)
 563                 return err;
 564
 565         rv8803->rtc->max_user_freq = 1;
 566
 567         return 0;
 568 }
 569
 570 static int rv8803_remove(struct i2c_client *client)
 571 {
 572         device_remove_bin_file(&client->dev, &rv8803_nvram_attr);
 573
 574         return 0;
 575 }
 576
 577 static const struct i2c_device_id rv8803_id[] = {
 578         { "rv8803", 0 },
 579         { "rx8900", 0 },
 580         { }
 581 };
 582 MODULE_DEVICE_TABLE(i2c, rv8803_id);
 583
 584 static struct i2c_driver rv8803_driver = {
 585         .driver = {
 586                 .name = "rtc-rv8803",
 587         },
 588         .probe          = rv8803_probe,
 589         .remove         = rv8803_remove,
 590         .id_table       = rv8803_id,
 591 };
 592 module_i2c_driver(rv8803_driver);
 593
 594 MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>");
 595 MODULE_DESCRIPTION("Micro Crystal RV8803 RTC driver");
 596 MODULE_LICENSE("GPL v2");