drivers/rtc/rtc-at91rm9200.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      Real Time Clock interface for Linux on Atmel AT91RM9200
   4  *
   5  *      Copyright (C) 2002 Rick Bronson
   6  *
   7  *      Converted to RTC class model by Andrew Victor
   8  *
   9  *      Ported to Linux 2.6 by Steven Scholz
  10  *      Based on s3c2410-rtc.c Simtec Electronics
  11  *
  12  *      Based on sa1100-rtc.c by Nils Faerber
  13  *      Based on rtc.c by Paul Gortmaker
  14  */
  15
  16 #include <linux/bcd.h>
  17 #include <linux/clk.h>
  18 #include <linux/completion.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/ioctl.h>
  21 #include <linux/io.h>
  22 #include <linux/kernel.h>
  23 #include <linux/module.h>
  24 #include <linux/of_device.h>
  25 #include <linux/of.h>
  26 #include <linux/platform_device.h>
  27 #include <linux/rtc.h>
  28 #include <linux/spinlock.h>
  29 #include <linux/suspend.h>
  30 #include <linux/time.h>
  31 #include <linux/uaccess.h>
  32
  33 #include "rtc-at91rm9200.h"
  34
  35 #define at91_rtc_read(field) \
  36         readl_relaxed(at91_rtc_regs + field)
  37 #define at91_rtc_write(field, val) \
  38         writel_relaxed((val), at91_rtc_regs + field)
  39
  40 struct at91_rtc_config {
  41         bool use_shadow_imr;
  42 };
  43
  44 static const struct at91_rtc_config *at91_rtc_config;
  45 static DECLARE_COMPLETION(at91_rtc_updated);
  46 static DECLARE_COMPLETION(at91_rtc_upd_rdy);
  47 static void __iomem *at91_rtc_regs;
  48 static int irq;
  49 static DEFINE_SPINLOCK(at91_rtc_lock);
  50 static u32 at91_rtc_shadow_imr;
  51 static bool suspended;
  52 static DEFINE_SPINLOCK(suspended_lock);
  53 static unsigned long cached_events;
  54 static u32 at91_rtc_imr;
  55 static struct clk *sclk;
  56
  57 static void at91_rtc_write_ier(u32 mask)
  58 {
  59         unsigned long flags;
  60
  61         spin_lock_irqsave(&at91_rtc_lock, flags);
  62         at91_rtc_shadow_imr |= mask;
  63         at91_rtc_write(AT91_RTC_IER, mask);
  64         spin_unlock_irqrestore(&at91_rtc_lock, flags);
  65 }
  66
  67 static void at91_rtc_write_idr(u32 mask)
  68 {
  69         unsigned long flags;
  70
  71         spin_lock_irqsave(&at91_rtc_lock, flags);
  72         at91_rtc_write(AT91_RTC_IDR, mask);
  73         /*
  74          * Register read back (of any RTC-register) needed to make sure
  75          * IDR-register write has reached the peripheral before updating
  76          * shadow mask.
  77          *
  78          * Note that there is still a possibility that the mask is updated
  79          * before interrupts have actually been disabled in hardware. The only
  80          * way to be certain would be to poll the IMR-register, which is is
  81          * the very register we are trying to emulate. The register read back
  82          * is a reasonable heuristic.
  83          */
  84         at91_rtc_read(AT91_RTC_SR);
  85         at91_rtc_shadow_imr &= ~mask;
  86         spin_unlock_irqrestore(&at91_rtc_lock, flags);
  87 }
  88
  89 static u32 at91_rtc_read_imr(void)
  90 {
  91         unsigned long flags;
  92         u32 mask;
  93
  94         if (at91_rtc_config->use_shadow_imr) {
  95                 spin_lock_irqsave(&at91_rtc_lock, flags);
  96                 mask = at91_rtc_shadow_imr;
  97                 spin_unlock_irqrestore(&at91_rtc_lock, flags);
  98         } else {
  99                 mask = at91_rtc_read(AT91_RTC_IMR);
 100         }
 101
 102         return mask;
 103 }
 104
 105 /*
 106  * Decode time/date into rtc_time structure
 107  */
 108 static void at91_rtc_decodetime(unsigned int timereg, unsigned int calreg,
 109                                 struct rtc_time *tm)
 110 {
 111         unsigned int time, date;
 112
 113         /* must read twice in case it changes */
 114         do {
 115                 time = at91_rtc_read(timereg);
 116                 date = at91_rtc_read(calreg);
 117         } while ((time != at91_rtc_read(timereg)) ||
 118                         (date != at91_rtc_read(calreg)));
 119
 120         tm->tm_sec  = bcd2bin((time & AT91_RTC_SEC) >> 0);
 121         tm->tm_min  = bcd2bin((time & AT91_RTC_MIN) >> 8);
 122         tm->tm_hour = bcd2bin((time & AT91_RTC_HOUR) >> 16);
 123
 124         /*
 125          * The Calendar Alarm register does not have a field for
 126          * the year - so these will return an invalid value.
 127          */
 128         tm->tm_year  = bcd2bin(date & AT91_RTC_CENT) * 100;     /* century */
 129         tm->tm_year += bcd2bin((date & AT91_RTC_YEAR) >> 8);    /* year */
 130
 131         tm->tm_wday = bcd2bin((date & AT91_RTC_DAY) >> 21) - 1; /* day of the week [0-6], Sunday=0 */
 132         tm->tm_mon  = bcd2bin((date & AT91_RTC_MONTH) >> 16) - 1;
 133         tm->tm_mday = bcd2bin((date & AT91_RTC_DATE) >> 24);
 134 }
 135
 136 /*
 137  * Read current time and date in RTC
 138  */
 139 static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm)
 140 {
 141         at91_rtc_decodetime(AT91_RTC_TIMR, AT91_RTC_CALR, tm);
 142         tm->tm_yday = rtc_year_days(tm->tm_mday, tm->tm_mon, tm->tm_year);
 143         tm->tm_year = tm->tm_year - 1900;
 144
 145         dev_dbg(dev, "%s(): %ptR\n", __func__, tm);
 146
 147         return 0;
 148 }
 149
 150 /*
 151  * Set current time and date in RTC
 152  */
 153 static int at91_rtc_settime(struct device *dev, struct rtc_time *tm)
 154 {
 155         unsigned long cr;
 156
 157         dev_dbg(dev, "%s(): %ptR\n", __func__, tm);
 158
 159         wait_for_completion(&at91_rtc_upd_rdy);
 160
 161         /* Stop Time/Calendar from counting */
 162         cr = at91_rtc_read(AT91_RTC_CR);
 163         at91_rtc_write(AT91_RTC_CR, cr | AT91_RTC_UPDCAL | AT91_RTC_UPDTIM);
 164
 165         at91_rtc_write_ier(AT91_RTC_ACKUPD);
 166         wait_for_completion(&at91_rtc_updated); /* wait for ACKUPD interrupt */
 167         at91_rtc_write_idr(AT91_RTC_ACKUPD);
 168
 169         at91_rtc_write(AT91_RTC_TIMR,
 170                           bin2bcd(tm->tm_sec) << 0
 171                         | bin2bcd(tm->tm_min) << 8
 172                         | bin2bcd(tm->tm_hour) << 16);
 173
 174         at91_rtc_write(AT91_RTC_CALR,
 175                           bin2bcd((tm->tm_year + 1900) / 100)   /* century */
 176                         | bin2bcd(tm->tm_year % 100) << 8       /* year */
 177                         | bin2bcd(tm->tm_mon + 1) << 16         /* tm_mon starts at zero */
 178                         | bin2bcd(tm->tm_wday + 1) << 21        /* day of the week [0-6], Sunday=0 */
 179                         | bin2bcd(tm->tm_mday) << 24);
 180
 181         /* Restart Time/Calendar */
 182         cr = at91_rtc_read(AT91_RTC_CR);
 183         at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_SECEV);
 184         at91_rtc_write(AT91_RTC_CR, cr & ~(AT91_RTC_UPDCAL | AT91_RTC_UPDTIM));
 185         at91_rtc_write_ier(AT91_RTC_SECEV);
 186
 187         return 0;
 188 }
 189
 190 /*
 191  * Read alarm time and date in RTC
 192  */
 193 static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
 194 {
 195         struct rtc_time *tm = &alrm->time;
 196
 197         at91_rtc_decodetime(AT91_RTC_TIMALR, AT91_RTC_CALALR, tm);
 198         tm->tm_year = -1;
 199
 200         alrm->enabled = (at91_rtc_read_imr() & AT91_RTC_ALARM)
 201                         ? 1 : 0;
 202
 203         dev_dbg(dev, "%s(): %ptR %sabled\n", __func__, tm,
 204                 alrm->enabled ? "en" : "dis");
 205
 206         return 0;
 207 }
 208
 209 /*
 210  * Set alarm time and date in RTC
 211  */
 212 static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
 213 {
 214         struct rtc_time tm;
 215
 216         at91_rtc_decodetime(AT91_RTC_TIMR, AT91_RTC_CALR, &tm);
 217
 218         tm.tm_mon = alrm->time.tm_mon;
 219         tm.tm_mday = alrm->time.tm_mday;
 220         tm.tm_hour = alrm->time.tm_hour;
 221         tm.tm_min = alrm->time.tm_min;
 222         tm.tm_sec = alrm->time.tm_sec;
 223
 224         at91_rtc_write_idr(AT91_RTC_ALARM);
 225         at91_rtc_write(AT91_RTC_TIMALR,
 226                   bin2bcd(tm.tm_sec) << 0
 227                 | bin2bcd(tm.tm_min) << 8
 228                 | bin2bcd(tm.tm_hour) << 16
 229                 | AT91_RTC_HOUREN | AT91_RTC_MINEN | AT91_RTC_SECEN);
 230         at91_rtc_write(AT91_RTC_CALALR,
 231                   bin2bcd(tm.tm_mon + 1) << 16          /* tm_mon starts at zero */
 232                 | bin2bcd(tm.tm_mday) << 24
 233                 | AT91_RTC_DATEEN | AT91_RTC_MTHEN);
 234
 235         if (alrm->enabled) {
 236                 at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
 237                 at91_rtc_write_ier(AT91_RTC_ALARM);
 238         }
 239
 240         dev_dbg(dev, "%s(): %ptR\n", __func__, &tm);
 241
 242         return 0;
 243 }
 244
 245 static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 246 {
 247         dev_dbg(dev, "%s(): cmd=%08x\n", __func__, enabled);
 248
 249         if (enabled) {
 250                 at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
 251                 at91_rtc_write_ier(AT91_RTC_ALARM);
 252         } else
 253                 at91_rtc_write_idr(AT91_RTC_ALARM);
 254
 255         return 0;
 256 }
 257 /*
 258  * Provide additional RTC information in /proc/driver/rtc
 259  */
 260 static int at91_rtc_proc(struct device *dev, struct seq_file *seq)
 261 {
 262         unsigned long imr = at91_rtc_read_imr();
 263
 264         seq_printf(seq, "update_IRQ\t: %s\n",
 265                         (imr & AT91_RTC_ACKUPD) ? "yes" : "no");
 266         seq_printf(seq, "periodic_IRQ\t: %s\n",
 267                         (imr & AT91_RTC_SECEV) ? "yes" : "no");
 268
 269         return 0;
 270 }
 271
 272 /*
 273  * IRQ handler for the RTC
 274  */
 275 static irqreturn_t at91_rtc_interrupt(int irq, void *dev_id)
 276 {
 277         struct platform_device *pdev = dev_id;
 278         struct rtc_device *rtc = platform_get_drvdata(pdev);
 279         unsigned int rtsr;
 280         unsigned long events = 0;
 281         int ret = IRQ_NONE;
 282
 283         spin_lock(&suspended_lock);
 284         rtsr = at91_rtc_read(AT91_RTC_SR) & at91_rtc_read_imr();
 285         if (rtsr) {             /* this interrupt is shared!  Is it ours? */
 286                 if (rtsr & AT91_RTC_ALARM)
 287                         events |= (RTC_AF | RTC_IRQF);
 288                 if (rtsr & AT91_RTC_SECEV) {
 289                         complete(&at91_rtc_upd_rdy);
 290                         at91_rtc_write_idr(AT91_RTC_SECEV);
 291                 }
 292                 if (rtsr & AT91_RTC_ACKUPD)
 293                         complete(&at91_rtc_updated);
 294
 295                 at91_rtc_write(AT91_RTC_SCCR, rtsr);    /* clear status reg */
 296
 297                 if (!suspended) {
 298                         rtc_update_irq(rtc, 1, events);
 299
 300                         dev_dbg(&pdev->dev, "%s(): num=%ld, events=0x%02lx\n",
 301                                 __func__, events >> 8, events & 0x000000FF);
 302                 } else {
 303                         cached_events |= events;
 304                         at91_rtc_write_idr(at91_rtc_imr);
 305                         pm_system_wakeup();
 306                 }
 307
 308                 ret = IRQ_HANDLED;
 309         }
 310         spin_unlock(&suspended_lock);
 311
 312         return ret;
 313 }
 314
 315 static const struct at91_rtc_config at91rm9200_config = {
 316 };
 317
 318 static const struct at91_rtc_config at91sam9x5_config = {
 319         .use_shadow_imr = true,
 320 };
 321
 322 static const struct of_device_id at91_rtc_dt_ids[] = {
 323         {
 324                 .compatible = "atmel,at91rm9200-rtc",
 325                 .data = &at91rm9200_config,
 326         }, {
 327                 .compatible = "atmel,at91sam9x5-rtc",
 328                 .data = &at91sam9x5_config,
 329         }, {
 330                 /* sentinel */
 331         }
 332 };
 333 MODULE_DEVICE_TABLE(of, at91_rtc_dt_ids);
 334
 335 static const struct rtc_class_ops at91_rtc_ops = {
 336         .read_time      = at91_rtc_readtime,
 337         .set_time       = at91_rtc_settime,
 338         .read_alarm     = at91_rtc_readalarm,
 339         .set_alarm      = at91_rtc_setalarm,
 340         .proc           = at91_rtc_proc,
 341         .alarm_irq_enable = at91_rtc_alarm_irq_enable,
 342 };
 343
 344 /*
 345  * Initialize and install RTC driver
 346  */
 347 static int __init at91_rtc_probe(struct platform_device *pdev)
 348 {
 349         struct rtc_device *rtc;
 350         struct resource *regs;
 351         int ret = 0;
 352
 353         at91_rtc_config = of_device_get_match_data(&pdev->dev);
 354         if (!at91_rtc_config)
 355                 return -ENODEV;
 356
 357         regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 358         if (!regs) {
 359                 dev_err(&pdev->dev, "no mmio resource defined\n");
 360                 return -ENXIO;
 361         }
 362
 363         irq = platform_get_irq(pdev, 0);
 364         if (irq < 0)
 365                 return -ENXIO;
 366
 367         at91_rtc_regs = devm_ioremap(&pdev->dev, regs->start,
 368                                      resource_size(regs));
 369         if (!at91_rtc_regs) {
 370                 dev_err(&pdev->dev, "failed to map registers, aborting.\n");
 371                 return -ENOMEM;
 372         }
 373
 374         rtc = devm_rtc_allocate_device(&pdev->dev);
 375         if (IS_ERR(rtc))
 376                 return PTR_ERR(rtc);
 377         platform_set_drvdata(pdev, rtc);
 378
 379         sclk = devm_clk_get(&pdev->dev, NULL);
 380         if (IS_ERR(sclk))
 381                 return PTR_ERR(sclk);
 382
 383         ret = clk_prepare_enable(sclk);
 384         if (ret) {
 385                 dev_err(&pdev->dev, "Could not enable slow clock\n");
 386                 return ret;
 387         }
 388
 389         at91_rtc_write(AT91_RTC_CR, 0);
 390         at91_rtc_write(AT91_RTC_MR, 0);         /* 24 hour mode */
 391
 392         /* Disable all interrupts */
 393         at91_rtc_write_idr(AT91_RTC_ACKUPD | AT91_RTC_ALARM |
 394                                         AT91_RTC_SECEV | AT91_RTC_TIMEV |
 395                                         AT91_RTC_CALEV);
 396
 397         ret = devm_request_irq(&pdev->dev, irq, at91_rtc_interrupt,
 398                                IRQF_SHARED | IRQF_COND_SUSPEND,
 399                                "at91_rtc", pdev);
 400         if (ret) {
 401                 dev_err(&pdev->dev, "IRQ %d already in use.\n", irq);
 402                 goto err_clk;
 403         }
 404
 405         /* cpu init code should really have flagged this device as
 406          * being wake-capable; if it didn't, do that here.
 407          */
 408         if (!device_can_wakeup(&pdev->dev))
 409                 device_init_wakeup(&pdev->dev, 1);
 410
 411         rtc->ops = &at91_rtc_ops;
 412         rtc->range_min = RTC_TIMESTAMP_BEGIN_1900;
 413         rtc->range_max = RTC_TIMESTAMP_END_2099;
 414         ret = rtc_register_device(rtc);
 415         if (ret)
 416                 goto err_clk;
 417
 418         /* enable SECEV interrupt in order to initialize at91_rtc_upd_rdy
 419          * completion.
 420          */
 421         at91_rtc_write_ier(AT91_RTC_SECEV);
 422
 423         dev_info(&pdev->dev, "AT91 Real Time Clock driver.\n");
 424         return 0;
 425
 426 err_clk:
 427         clk_disable_unprepare(sclk);
 428
 429         return ret;
 430 }
 431
 432 /*
 433  * Disable and remove the RTC driver
 434  */
 435 static int __exit at91_rtc_remove(struct platform_device *pdev)
 436 {
 437         /* Disable all interrupts */
 438         at91_rtc_write_idr(AT91_RTC_ACKUPD | AT91_RTC_ALARM |
 439                                         AT91_RTC_SECEV | AT91_RTC_TIMEV |
 440                                         AT91_RTC_CALEV);
 441
 442         clk_disable_unprepare(sclk);
 443
 444         return 0;
 445 }
 446
 447 static void at91_rtc_shutdown(struct platform_device *pdev)
 448 {
 449         /* Disable all interrupts */
 450         at91_rtc_write(AT91_RTC_IDR, AT91_RTC_ACKUPD | AT91_RTC_ALARM |
 451                                         AT91_RTC_SECEV | AT91_RTC_TIMEV |
 452                                         AT91_RTC_CALEV);
 453 }
 454
 455 #ifdef CONFIG_PM_SLEEP
 456
 457 /* AT91RM9200 RTC Power management control */
 458
 459 static int at91_rtc_suspend(struct device *dev)
 460 {
 461         /* this IRQ is shared with DBGU and other hardware which isn't
 462          * necessarily doing PM like we are...
 463          */
 464         at91_rtc_write(AT91_RTC_SCCR, AT91_RTC_ALARM);
 465
 466         at91_rtc_imr = at91_rtc_read_imr()
 467                         & (AT91_RTC_ALARM|AT91_RTC_SECEV);
 468         if (at91_rtc_imr) {
 469                 if (device_may_wakeup(dev)) {
 470                         unsigned long flags;
 471
 472                         enable_irq_wake(irq);
 473
 474                         spin_lock_irqsave(&suspended_lock, flags);
 475                         suspended = true;
 476                         spin_unlock_irqrestore(&suspended_lock, flags);
 477                 } else {
 478                         at91_rtc_write_idr(at91_rtc_imr);
 479                 }
 480         }
 481         return 0;
 482 }
 483
 484 static int at91_rtc_resume(struct device *dev)
 485 {
 486         struct rtc_device *rtc = dev_get_drvdata(dev);
 487
 488         if (at91_rtc_imr) {
 489                 if (device_may_wakeup(dev)) {
 490                         unsigned long flags;
 491
 492                         spin_lock_irqsave(&suspended_lock, flags);
 493
 494                         if (cached_events) {
 495                                 rtc_update_irq(rtc, 1, cached_events);
 496                                 cached_events = 0;
 497                         }
 498
 499                         suspended = false;
 500                         spin_unlock_irqrestore(&suspended_lock, flags);
 501
 502                         disable_irq_wake(irq);
 503                 }
 504                 at91_rtc_write_ier(at91_rtc_imr);
 505         }
 506         return 0;
 507 }
 508 #endif
 509
 510 static SIMPLE_DEV_PM_OPS(at91_rtc_pm_ops, at91_rtc_suspend, at91_rtc_resume);
 511
 512 static struct platform_driver at91_rtc_driver = {
 513         .remove         = __exit_p(at91_rtc_remove),
 514         .shutdown       = at91_rtc_shutdown,
 515         .driver         = {
 516                 .name   = "at91_rtc",
 517                 .pm     = &at91_rtc_pm_ops,
 518                 .of_match_table = of_match_ptr(at91_rtc_dt_ids),
 519         },
 520 };
 521
 522 module_platform_driver_probe(at91_rtc_driver, at91_rtc_probe);
 523
 524 MODULE_AUTHOR("Rick Bronson");
 525 MODULE_DESCRIPTION("RTC driver for Atmel AT91RM9200");
 526 MODULE_LICENSE("GPL");
 527 MODULE_ALIAS("platform:at91_rtc");