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