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 static int at91_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 220 {
 221         struct sam9_rtc *rtc = dev_get_drvdata(dev);
 222         u32 mr = rtt_readl(rtc, MR);
 223
 224         dev_dbg(dev, "alarm_irq_enable: enabled=%08x, mr %08x\n", enabled, mr);
 225         if (enabled)
 226                 rtt_writel(rtc, MR, mr | AT91_RTT_ALMIEN);
 227         else
 228                 rtt_writel(rtc, MR, mr & ~AT91_RTT_ALMIEN);
 229         return 0;
 230 }
 231
 232 /*
 233  * Provide additional RTC information in /proc/driver/rtc
 234  */
 235 static int at91_rtc_proc(struct device *dev, struct seq_file *seq)
 236 {
 237         struct sam9_rtc *rtc = dev_get_drvdata(dev);
 238         u32 mr = mr = rtt_readl(rtc, MR);
 239
 240         seq_printf(seq, "update_IRQ\t: %s\n",
 241                         (mr & AT91_RTT_RTTINCIEN) ? "yes" : "no");
 242         return 0;
 243 }
 244
 245 /*
 246  * IRQ handler for the RTC
 247  */
 248 static irqreturn_t at91_rtc_interrupt(int irq, void *_rtc)
 249 {
 250         struct sam9_rtc *rtc = _rtc;
 251         u32 sr, mr;
 252         unsigned long events = 0;
 253
 254         /* Shared interrupt may be for another device.  Note: reading
 255          * SR clears it, so we must only read it in this irq handler!
 256          */
 257         mr = rtt_readl(rtc, MR) & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
 258         sr = rtt_readl(rtc, SR) & (mr >> 16);
 259         if (!sr)
 260                 return IRQ_NONE;
 261
 262         /* alarm status */
 263         if (sr & AT91_RTT_ALMS)
 264                 events |= (RTC_AF | RTC_IRQF);
 265
 266         /* timer update/increment */
 267         if (sr & AT91_RTT_RTTINC)
 268                 events |= (RTC_UF | RTC_IRQF);
 269
 270         rtc_update_irq(rtc->rtcdev, 1, events);
 271
 272         pr_debug("%s: num=%ld, events=0x%02lx\n", __func__,
 273                 events >> 8, events & 0x000000FF);
 274
 275         return IRQ_HANDLED;
 276 }
 277
 278 static const struct rtc_class_ops at91_rtc_ops = {
 279         .read_time      = at91_rtc_readtime,
 280         .set_time       = at91_rtc_settime,
 281         .read_alarm     = at91_rtc_readalarm,
 282         .set_alarm      = at91_rtc_setalarm,
 283         .proc           = at91_rtc_proc,
 284         .alarm_irq_enable = at91_rtc_alarm_irq_enable,
 285 };
 286
 287 /*
 288  * Initialize and install RTC driver
 289  */
 290 static int __init at91_rtc_probe(struct platform_device *pdev)
 291 {
 292         struct resource *r;
 293         struct sam9_rtc *rtc;
 294         int             ret;
 295         u32             mr;
 296
 297         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 298         if (!r)
 299                 return -ENODEV;
 300
 301         rtc = kzalloc(sizeof *rtc, GFP_KERNEL);
 302         if (!rtc)
 303                 return -ENOMEM;
 304
 305         /* platform setup code should have handled this; sigh */
 306         if (!device_can_wakeup(&pdev->dev))
 307                 device_init_wakeup(&pdev->dev, 1);
 308
 309         platform_set_drvdata(pdev, rtc);
 310         rtc->rtt = (void __force __iomem *) (AT91_VA_BASE_SYS - AT91_BASE_SYS);
 311         rtc->rtt += r->start;
 312
 313         mr = rtt_readl(rtc, MR);
 314
 315         /* unless RTT is counting at 1 Hz, re-initialize it */
 316         if ((mr & AT91_RTT_RTPRES) != AT91_SLOW_CLOCK) {
 317                 mr = AT91_RTT_RTTRST | (AT91_SLOW_CLOCK & AT91_RTT_RTPRES);
 318                 gpbr_writel(rtc, 0);
 319         }
 320
 321         /* disable all interrupts (same as on shutdown path) */
 322         mr &= ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
 323         rtt_writel(rtc, MR, mr);
 324
 325         rtc->rtcdev = rtc_device_register(pdev->name, &pdev->dev,
 326                                 &at91_rtc_ops, THIS_MODULE);
 327         if (IS_ERR(rtc->rtcdev)) {
 328                 ret = PTR_ERR(rtc->rtcdev);
 329                 goto fail;
 330         }
 331
 332         /* register irq handler after we know what name we'll use */
 333         ret = request_irq(AT91_ID_SYS, at91_rtc_interrupt,
 334                                 IRQF_DISABLED | IRQF_SHARED,
 335                                 dev_name(&rtc->rtcdev->dev), rtc);
 336         if (ret) {
 337                 dev_dbg(&pdev->dev, "can't share IRQ %d?\n", AT91_ID_SYS);
 338                 rtc_device_unregister(rtc->rtcdev);
 339                 goto fail;
 340         }
 341
 342         /* NOTE:  sam9260 rev A silicon has a ROM bug which resets the
 343          * RTT on at least some reboots.  If you have that chip, you must
 344          * initialize the time from some external source like a GPS, wall
 345          * clock, discrete RTC, etc
 346          */
 347
 348         if (gpbr_readl(rtc) == 0)
 349                 dev_warn(&pdev->dev, "%s: SET TIME!\n",
 350                                 dev_name(&rtc->rtcdev->dev));
 351
 352         return 0;
 353
 354 fail:
 355         platform_set_drvdata(pdev, NULL);
 356         kfree(rtc);
 357         return ret;
 358 }
 359
 360 /*
 361  * Disable and remove the RTC driver
 362  */
 363 static int __exit at91_rtc_remove(struct platform_device *pdev)
 364 {
 365         struct sam9_rtc *rtc = platform_get_drvdata(pdev);
 366         u32             mr = rtt_readl(rtc, MR);
 367
 368         /* disable all interrupts */
 369         rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN));
 370         free_irq(AT91_ID_SYS, rtc);
 371
 372         rtc_device_unregister(rtc->rtcdev);
 373
 374         platform_set_drvdata(pdev, NULL);
 375         kfree(rtc);
 376         return 0;
 377 }
 378
 379 static void at91_rtc_shutdown(struct platform_device *pdev)
 380 {
 381         struct sam9_rtc *rtc = platform_get_drvdata(pdev);
 382         u32             mr = rtt_readl(rtc, MR);
 383
 384         rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
 385         rtt_writel(rtc, MR, mr & ~rtc->imr);
 386 }
 387
 388 #ifdef CONFIG_PM
 389
 390 /* AT91SAM9 RTC Power management control */
 391
 392 static int at91_rtc_suspend(struct platform_device *pdev,
 393                                         pm_message_t state)
 394 {
 395         struct sam9_rtc *rtc = platform_get_drvdata(pdev);
 396         u32             mr = rtt_readl(rtc, MR);
 397
 398         /*
 399          * This IRQ is shared with DBGU and other hardware which isn't
 400          * necessarily a wakeup event source.
 401          */
 402         rtc->imr = mr & (AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN);
 403         if (rtc->imr) {
 404                 if (device_may_wakeup(&pdev->dev) && (mr & AT91_RTT_ALMIEN)) {
 405                         enable_irq_wake(AT91_ID_SYS);
 406                         /* don't let RTTINC cause wakeups */
 407                         if (mr & AT91_RTT_RTTINCIEN)
 408                                 rtt_writel(rtc, MR, mr & ~AT91_RTT_RTTINCIEN);
 409                 } else
 410                         rtt_writel(rtc, MR, mr & ~rtc->imr);
 411         }
 412
 413         return 0;
 414 }
 415
 416 static int at91_rtc_resume(struct platform_device *pdev)
 417 {
 418         struct sam9_rtc *rtc = platform_get_drvdata(pdev);
 419         u32             mr;
 420
 421         if (rtc->imr) {
 422                 if (device_may_wakeup(&pdev->dev))
 423                         disable_irq_wake(AT91_ID_SYS);
 424                 mr = rtt_readl(rtc, MR);
 425                 rtt_writel(rtc, MR, mr | rtc->imr);
 426         }
 427
 428         return 0;
 429 }
 430 #else
 431 #define at91_rtc_suspend        NULL
 432 #define at91_rtc_resume         NULL
 433 #endif
 434
 435 static struct platform_driver at91_rtc_driver = {
 436         .driver.name    = "rtc-at91sam9",
 437         .driver.owner   = THIS_MODULE,
 438         .remove         = __exit_p(at91_rtc_remove),
 439         .shutdown       = at91_rtc_shutdown,
 440         .suspend        = at91_rtc_suspend,
 441         .resume         = at91_rtc_resume,
 442 };
 443
 444 /* Chips can have more than one RTT module, and they can be used for more
 445  * than just RTCs.  So we can't just register as "the" RTT driver.
 446  *
 447  * A normal approach in such cases is to create a library to allocate and
 448  * free the modules.  Here we just use bus_find_device() as like such a
 449  * library, binding directly ... no runtime "library" footprint is needed.
 450  */
 451 static int __init at91_rtc_match(struct device *dev, void *v)
 452 {
 453         struct platform_device *pdev = to_platform_device(dev);
 454         int ret;
 455
 456         /* continue searching if this isn't the RTT we need */
 457         if (strcmp("at91_rtt", pdev->name) != 0
 458                         || pdev->id != CONFIG_RTC_DRV_AT91SAM9_RTT)
 459                 goto fail;
 460
 461         /* else we found it ... but fail unless we can bind to the RTC driver */
 462         if (dev->driver) {
 463                 dev_dbg(dev, "busy, can't use as RTC!\n");
 464                 goto fail;
 465         }
 466         dev->driver = &at91_rtc_driver.driver;
 467         if (device_attach(dev) == 0) {
 468                 dev_dbg(dev, "can't attach RTC!\n");
 469                 goto fail;
 470         }
 471         ret = at91_rtc_probe(pdev);
 472         if (ret == 0)
 473                 return true;
 474
 475         dev_dbg(dev, "RTC probe err %d!\n", ret);
 476 fail:
 477         return false;
 478 }
 479
 480 static int __init at91_rtc_init(void)
 481 {
 482         int status;
 483         struct device *rtc;
 484
 485         status = platform_driver_register(&at91_rtc_driver);
 486         if (status)
 487                 return status;
 488         rtc = bus_find_device(&platform_bus_type, NULL,
 489                         NULL, at91_rtc_match);
 490         if (!rtc)
 491                 platform_driver_unregister(&at91_rtc_driver);
 492         return rtc ? 0 : -ENODEV;
 493 }
 494 module_init(at91_rtc_init);
 495
 496 static void __exit at91_rtc_exit(void)
 497 {
 498         platform_driver_unregister(&at91_rtc_driver);
 499 }
 500 module_exit(at91_rtc_exit);
 501
 502
 503 MODULE_AUTHOR("Michel Benoit");
 504 MODULE_DESCRIPTION("RTC driver for Atmel AT91SAM9x");
 505 MODULE_LICENSE("GPL");