drivers/rtc/rtc-at91sam9.c

   1 /*
   2  * "RTT as Real Time Clock" driver for AT91SAM9 SoC family
   3  *
   4  * (C) 2007 Michel Benoit
   5  *
   6  * Based on rtc-at91rm9200.c by Rick Bronson
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License
  10  * as published by the Free Software Foundation; either version
  11  * 2 of the License, or (at your option) any later version.
  12  */
  13
  14 #include <linux/module.h>
  15 #include <linux/kernel.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/time.h>
  18 #include <linux/rtc.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/ioctl.h>
  21 #include <linux/slab.h>
  22
  23 #include <mach/board.h>
  24 #include <mach/at91_rtt.h>
  25 #include <mach/cpu.h>
  26
  27
  28 /*
  29  * This driver uses two configurable hardware resources that live in the
  30  * AT91SAM9 backup power domain (intended to be powered at all times)
  31  * to implement the Real Time Clock interfaces
  32  *
  33  *  - A "Real-time Timer" (RTT) counts up in seconds from a base time.
  34  *    We can't assign the counter value (CRTV) ... but we can reset it.
  35  *
  36  *  - One of the "General Purpose Backup Registers" (GPBRs) holds the
  37  *    base time, normally an offset from the beginning of the POSIX
  38  *    epoch (1970-Jan-1 00:00:00 UTC).  Some systems also include the
  39  *    local timezone's offset.
  40  *
  41  * The RTC's value is the RTT counter plus that offset.  The RTC's alarm
  42  * is likewise a base (ALMV) plus that offset.
  43  *
  44  * Not all RTTs will be used as RTCs; some systems have multiple RTTs to
  45  * choose from, or a "real" RTC module.  All systems have multiple GPBR
  46  * registers available, likewise usable for more than "RTC" support.
  47  */
  48
  49 /*
  50  * We store ALARM_DISABLED in ALMV to record that no alarm is set.
  51  * It's also the reset value for that field.
  52  */
  53 #define ALARM_DISABLED  ((u32)~0)
  54
  55
  56 struct sam9_rtc {
  57         void __iomem            *rtt;
  58         struct rtc_device       *rtcdev;
  59         u32                     imr;
  60 };
  61
  62 #define rtt_readl(rtc, field) \
  63         __raw_readl((rtc)->rtt + AT91_RTT_ ## field)
  64 #define rtt_writel(rtc, field, val) \
  65         __raw_writel((val), (rtc)->rtt + AT91_RTT_ ## field)
  66
  67 #define gpbr_readl(rtc) \
  68         at91_sys_read(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR)
  69 #define gpbr_writel(rtc, val) \
  70         at91_sys_write(AT91_GPBR + 4 * CONFIG_RTC_DRV_AT91SAM9_GPBR, (val))
  71
  72 /*
  73  * Read current time and date in RTC
  74  */
  75 static int at91_rtc_readtime(struct device *dev, struct rtc_time *tm)
  76 {
  77         struct sam9_rtc *rtc = dev_get_drvdata(dev);
  78         u32 secs, secs2;
  79         u32 offset;
  80
  81         /* read current time offset */
  82         offset = gpbr_readl(rtc);
  83         if (offset == 0)
  84                 return -EILSEQ;
  85
  86         /* reread the counter to help sync the two clock domains */
  87         secs = rtt_readl(rtc, VR);
  88         secs2 = rtt_readl(rtc, VR);
  89         if (secs != secs2)
  90                 secs = rtt_readl(rtc, VR);
  91
  92         rtc_time_to_tm(offset + secs, tm);
  93
  94         dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readtime",
  95                 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
  96                 tm->tm_hour, tm->tm_min, tm->tm_sec);
  97
  98         return 0;
  99 }
 100
 101 /*
 102  * Set current time and date in RTC
 103  */
 104 static int at91_rtc_settime(struct device *dev, struct rtc_time *tm)
 105 {
 106         struct sam9_rtc *rtc = dev_get_drvdata(dev);
 107         int err;
 108         u32 offset, alarm, mr;
 109         unsigned long secs;
 110
 111         dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "settime",
 112                 1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
 113                 tm->tm_hour, tm->tm_min, tm->tm_sec);
 114
 115         err = rtc_tm_to_time(tm, &secs);
 116         if (err != 0)
 117                 return err;
 118
 119         mr = rtt_readl(rtc, MR);
 120
 121         /* disable interrupts */
 122         rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));
 123
 124         /* read current time offset */
 125         offset = gpbr_readl(rtc);
 126
 127         /* store the new base time in a battery backup register */
 128         secs += 1;
 129         gpbr_writel(rtc, secs);
 130
 131         /* adjust the alarm time for the new base */
 132         alarm = rtt_readl(rtc, AR);
 133         if (alarm != ALARM_DISABLED) {
 134                 if (offset > secs) {
 135                         /* time jumped backwards, increase time until alarm */
 136                         alarm += (offset - secs);
 137                 } else if ((alarm + offset) > secs) {
 138                         /* time jumped forwards, decrease time until alarm */
 139                         alarm -= (secs - offset);
 140                 } else {
 141                         /* time jumped past the alarm, disable alarm */
 142                         alarm = ALARM_DISABLED;
 143                         mr &= ~AT91_RTT_ALMIEN;
 144                 }
 145                 rtt_writel(rtc, AR, alarm);
 146         }
 147
 148         /* reset the timer, and re-enable interrupts */
 149         rtt_writel(rtc, MR, mr | AT91_RTT_RTTRST);
 150
 151         return 0;
 152 }
 153
 154 static int at91_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm)
 155 {
 156         struct sam9_rtc *rtc = dev_get_drvdata(dev);
 157         struct rtc_time *tm = &alrm->time;
 158         u32 alarm = rtt_readl(rtc, AR);
 159         u32 offset;
 160
 161         offset = gpbr_readl(rtc);
 162         if (offset == 0)
 163                 return -EILSEQ;
 164
 165         memset(alrm, 0, sizeof(*alrm));
 166         if (alarm != ALARM_DISABLED && offset != 0) {
 167                 rtc_time_to_tm(offset + alarm, tm);
 168
 169                 dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "readalarm",
 170                         1900 + tm->tm_year, tm->tm_mon, tm->tm_mday,
 171                         tm->tm_hour, tm->tm_min, tm->tm_sec);
 172
 173                 if (rtt_readl(rtc, MR) & AT91_RTT_ALMIEN)
 174                         alrm->enabled = 1;
 175         }
 176
 177         return 0;
 178 }
 179
 180 static int at91_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm)
 181 {
 182         struct sam9_rtc *rtc = dev_get_drvdata(dev);
 183         struct rtc_time *tm = &alrm->time;
 184         unsigned long secs;
 185         u32 offset;
 186         u32 mr;
 187         int err;
 188
 189         err = rtc_tm_to_time(tm, &secs);
 190         if (err != 0)
 191                 return err;
 192
 193         offset = gpbr_readl(rtc);
 194         if (offset == 0) {
 195                 /* time is not set */
 196                 return -EILSEQ;
 197         }
 198         mr = rtt_readl(rtc, MR);
 199         rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
 200
 201         /* alarm in the past? finish and leave disabled */
 202         if (secs <= offset) {
 203                 rtt_writel(rtc, AR, ALARM_DISABLED);
 204                 return 0;
 205         }
 206
 207         /* else set alarm and maybe enable it */
 208         rtt_writel(rtc, AR, secs - offset);
 209         if (alrm->enabled)
 210                 rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);
 211
 212         dev_dbg(dev, "%s: %4d-%02d-%02d %02d:%02d:%02d\n", "setalarm",
 213                 tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour,
 214                 tm->tm_min, tm->tm_sec);
 215
 216         return 0;
 217 }
 218
 219 /*
 220  * Handle commands from user-space
 221  */
 222 static int at91_rtc_ioctl(struct device *dev, unsigned int cmd,
 223                         unsigned long arg)
 224 {
 225         struct sam9_rtc *rtc = dev_get_drvdata(dev);
 226         int ret = 0;
 227         u32 mr = rtt_readl(rtc, MR);
 228
 229         dev_dbg(dev, "ioctl: cmd=%08x, arg=%08lx, mr %08x\n", cmd, arg, mr);
 230
 231         switch (cmd) {
 232         case RTC_AIE_OFF:               /* alarm off */
 233                 rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
 234                 break;
 235         case RTC_AIE_ON:                /* alarm on */
 236                 rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);
 237                 break;
 238         case RTC_UIE_OFF:               /* update off */
 239                 rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN);
 240                 break;
 241         case RTC_UIE_ON:                /* update on */
 242                 rtt_writel(rtc, MR, mr | AT91_RTT_RTTINCIEN);
 243                 break;
 244         default:
 245                 ret = -ENOIOCTLCMD;
 246                 break;
 247         }
 248
 249         return ret;
 250 }
 251
 252 /*
 253  * Provide additional RTC information in /proc/driver/rtc
 254  */
 255 static int at91_rtc_proc(struct device *dev, struct seq_file *seq)
 256 {
 257         struct sam9_rtc *rtc = dev_get_drvdata(dev);
 258         u32 mr = mr = rtt_readl(rtc, MR);
 259
 260         seq_printf(seq, "update_IRQ\t: %s\n",
 261                         (mr & AT91_RTT_RTTINCIEN) ? "yes" : "no");
 262         return 0;
 263 }
 264
 265 /*
 266  * IRQ handler for the RTC
 267  */
 268 static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc)
 269 {
 270         struct sam9_rtc *rtc = _rtc;
 271         u32 sr, mr;
 272         unsigned long events = 0;
 273
 274         /* Shared interrupt may be for another device.  Note: reading
 275          * SR clears it, so we must only read it in this irq handler!
 276          */
 277         mr = rtt_readl(rtc, MR) & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
 278         sr = rtt_readl(rtc, SR) & (mr >> 16);
 279         if (!sr)
 280                 return IRQ_NONE;
 281
 282         /* alarm status */
 283         if (sr & AT91_RTT_ALMS)
 284                 events |= (RTC_AF | RTC_IRQF);
 285
 286         /* timer update/increment */
 287         if (sr & AT91_RTT_RTTINC)
 288                 events |= (RTC_UF | RTC_IRQF);
 289
 290         rtc_update_irq(rtc->rtcdev, 1, events);
 291
 292         pr_debug("%s: num=%ld, events=0x%02lx\n", __func__,
 293                 events >> 8, events & 0x000000FF);
 294
 295         return IRQ_HANDLED;
 296 }
 297
 298 static const struct rtc_class_ops at91_rtc_ops = {
 299         .ioctl          = at91_rtc_ioctl,
 300         .read_time      = at91_rtc_readtime,
 301         .set_time       = at91_rtc_settime,
 302         .read_alarm     = at91_rtc_readalarm,
 303         .set_alarm      = at91_rtc_setalarm,
 304         .proc           = at91_rtc_proc,
 305 };
 306
 307 /*
 308  * Initialize and install RTC driver
 309  */
 310 static int __init at91_rtc_probe(struct platform_device *pdev)
 311 {
 312         struct resource *r;
 313         struct sam9_rtc *rtc;
 314         int             ret;
 315         u32             mr;
 316
 317         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 318         if (!r)
 319                 return -ENODEV;
 320
 321         rtc = kzalloc(sizeof *rtc, GFP_KERNEL);
 322         if (!rtc)
 323                 return -ENOMEM;
 324
 325         /* platform setup code should have handled this; sigh */
 326         if (!device_can_wakeup(&pdev->dev))
 327                 device_init_wakeup(&pdev->dev, 1);
 328
 329         platform_set_drvdata(pdev, rtc);
 330         rtc->rtt = (void __force __iomem *) (AT91_VA_BASE_SYS - AT91_BASE_SYS);
 331         rtc->rtt += r->start;
 332
 333         mr = rtt_readl(rtc, MR);
 334
 335         /* unless RTT is counting at 1 Hz, re-initialize it */
 336         if ((mr & AT91_RTT_RTPRES) != AT91_SLOW_CLOCK) {
 337                 mr = AT91_RTT_RTTRST | (AT91_SLOW_CLOCK & AT91_RTT_RTPRES);
 338                 gpbr_writel(rtc, 0);
 339         }
 340
 341         /* disable all interrupts (same as on shutdown path) */
 342         mr &= ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
 343         rtt_writel(rtc, MR, mr);
 344
 345         rtc->rtcdev = rtc_device_register(pdev->name, &pdev->dev,
 346                                 &at91_rtc_ops, THIS_MODULE);
 347         if (IS_ERR(rtc->rtcdev)) {
 348                 ret = PTR_ERR(rtc->rtcdev);
 349                 goto fail;
 350         }
 351
 352         /* register irq handler after we know what name we'll use */
 353         ret = request_irq(AT91_ID_SYS, at91_rtc_interrupt,
 354                                 IRQF_DISABLED | IRQF_SHARED,
 355                                 dev_name(&rtc->rtcdev->dev), rtc);
 356         if (ret) {
 357                 dev_dbg(&pdev->dev, "can't share IRQ %d?\n", AT91_ID_SYS);
 358                 rtc_device_unregister(rtc->rtcdev);
 359                 goto fail;
 360         }
 361
 362         /* NOTE:  sam9260 rev A silicon has a ROM bug which resets the
 363          * RTT on at least some reboots.  If you have that chip, you must
 364          * initialize the time from some external source like a GPS, wall
 365          * clock, discrete RTC, etc
 366          */
 367
 368         if (gpbr_readl(rtc) == 0)
 369                 dev_warn(&pdev->dev, "%s: SET TIME!\n",
 370                                 dev_name(&rtc->rtcdev->dev));
 371
 372         return 0;
 373
 374 fail:
 375         platform_set_drvdata(pdev, NULL);
 376         kfree(rtc);
 377         return ret;
 378 }
 379
 380 /*
 381  * Disable and remove the RTC driver
 382  */
 383 static int __exit at91_rtc_remove(struct platform_device *pdev)
 384 {
 385         struct sam9_rtc *rtc = platform_get_drvdata(pdev);
 386         u32             mr = rtt_readl(rtc, MR);
 387
 388         /* disable all interrupts */
 389         rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));
 390         free_irq(AT91_ID_SYS, rtc);
 391
 392         rtc_device_unregister(rtc->rtcdev);
 393
 394         platform_set_drvdata(pdev, NULL);
 395         kfree(rtc);
 396         return 0;
 397 }
 398
 399 static void at91_rtc_shutdown(struct platform_device *pdev)
 400 {
 401         struct sam9_rtc *rtc = platform_get_drvdata(pdev);
 402         u32             mr = rtt_readl(rtc, MR);
 403
 404         rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
 405         rtt_writel(rtc, MR, mr & ~rtc->imr);
 406 }
 407
 408 #ifdef CONFIG_PM
 409
 410 /* AT91SAM9 RTC Power management control */
 411
 412 static int at91_rtc_suspend(struct platform_device *pdev,
 413                                         pm_message_t state)
 414 {
 415         struct sam9_rtc *rtc = platform_get_drvdata(pdev);
 416         u32             mr = rtt_readl(rtc, MR);
 417
 418         /*
 419          * This IRQ is shared with DBGU and other hardware which isn't
 420          * necessarily a wakeup event source.
 421          */
 422         rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
 423         if (rtc->imr) {
 424                 if (device_may_wakeup(&pdev->dev) && (mr & AT91_RTT_ALMIEN)) {
 425                         enable_irq_wake(AT91_ID_SYS);
 426                         /* don't let RTTINC cause wakeups */
 427                         if (mr & AT91_RTT_RTTINCIEN)
 428                                 rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN);
 429                 } else
 430                         rtt_writel(rtc, MR, mr & ~rtc->imr);
 431         }
 432
 433         return 0;
 434 }
 435
 436 static int at91_rtc_resume(struct platform_device *pdev)
 437 {
 438         struct sam9_rtc *rtc = platform_get_drvdata(pdev);
 439         u32             mr;
 440
 441         if (rtc->imr) {
 442                 if (device_may_wakeup(&pdev->dev))
 443                         disable_irq_wake(AT91_ID_SYS);
 444                 mr = rtt_readl(rtc, MR);
 445                 rtt_writel(rtc, MR, mr | rtc->imr);
 446         }
 447
 448         return 0;
 449 }
 450 #else
 451 #define at91_rtc_suspend        NULL
 452 #define at91_rtc_resume         NULL
 453 #endif
 454
 455 static struct platform_driver at91_rtc_driver = {
 456         .driver.name    = "rtc-at91sam9",
 457         .driver.owner   = THIS_MODULE,
 458         .remove         = __exit_p(at91_rtc_remove),
 459         .shutdown       = at91_rtc_shutdown,
 460         .suspend        = at91_rtc_suspend,
 461         .resume         = at91_rtc_resume,
 462 };
 463
 464 /* Chips can have more than one RTT module, and they can be used for more
 465  * than just RTCs.  So we can't just register as "the" RTT driver.
 466  *
 467  * A normal approach in such cases is to create a library to allocate and
 468  * free the modules.  Here we just use bus_find_device() as like such a
 469  * library, binding directly ... no runtime "library" footprint is needed.
 470  */
 471 static int __init at91_rtc_match(struct device *dev, void *v)
 472 {
 473         struct platform_device *pdev = to_platform_device(dev);
 474         int ret;
 475
 476         /* continue searching if this isn't the RTT we need */
 477         if (strcmp("at91_rtt", pdev->name) != 0
 478                         || pdev->id != CONFIG_RTC_DRV_AT91SAM9_RTT)
 479                 goto fail;
 480
 481         /* else we found it ... but fail unless we can bind to the RTC driver */
 482         if (dev->driver) {
 483                 dev_dbg(dev, "busy, can't use as RTC!\n");
 484                 goto fail;
 485         }
 486         dev->driver = &at91_rtc_driver.driver;
 487         if (device_attach(dev) == 0) {
 488                 dev_dbg(dev, "can't attach RTC!\n");
 489                 goto fail;
 490         }
 491         ret = at91_rtc_probe(pdev);
 492         if (ret == 0)
 493                 return true;
 494
 495         dev_dbg(dev, "RTC probe err %d!\n", ret);
 496 fail:
 497         return false;
 498 }
 499
 500 static int __init at91_rtc_init(void)
 501 {
 502         int status;
 503         struct device *rtc;
 504
 505         status = platform_driver_register(&at91_rtc_driver);
 506         if (status)
 507                 return status;
 508         rtc = bus_find_device(&platform_bus_type, NULL,
 509                         NULL, at91_rtc_match);
 510         if (!rtc)
 511                 platform_driver_unregister(&at91_rtc_driver);
 512         return rtc ? 0 : -ENODEV;
 513 }
 514 module_init(at91_rtc_init);
 515
 516 static void __exit at91_rtc_exit(void)
 517 {
 518         platform_driver_unregister(&at91_rtc_driver);
 519 }
 520 module_exit(at91_rtc_exit);
 521
 522
 523 MODULE_AUTHOR("Michel Benoit");
 524 MODULE_DESCRIPTION("RTC driver for Atmel AT91SAM9x");
 525 MODULE_LICENSE("GPL");