drivers/rtc/rtc-sa1100.c

   1 /*
   2  * Real Time Clock interface for StrongARM SA1x00 and XScale PXA2xx
   3  *
   4  * Copyright (c) 2000 Nils Faerber
   5  *
   6  * Based on rtc.c by Paul Gortmaker
   7  *
   8  * Original Driver by Nils Faerber <nils@kernelconcepts.de>
   9  *
  10  * Modifications from:
  11  *   CIH <cih@coventive.com>
  12  *   Nicolas Pitre <nico@fluxnic.net>
  13  *   Andrew Christian <andrew.christian@hp.com>
  14  *
  15  * Converted to the RTC subsystem and Driver Model
  16  *   by Richard Purdie <rpurdie@rpsys.net>
  17  *
  18  * This program is free software; you can redistribute it and/or
  19  * modify it under the terms of the GNU General Public License
  20  * as published by the Free Software Foundation; either version
  21  * 2 of the License, or (at your option) any later version.
  22  */
  23
  24 #include <linux/platform_device.h>
  25 #include <linux/module.h>
  26 #include <linux/rtc.h>
  27 #include <linux/init.h>
  28 #include <linux/fs.h>
  29 #include <linux/interrupt.h>
  30 #include <linux/string.h>
  31 #include <linux/pm.h>
  32 #include <linux/bitops.h>
  33
  34 #include <mach/hardware.h>
  35 #include <asm/irq.h>
  36
  37 #ifdef CONFIG_ARCH_PXA
  38 #include <mach/regs-rtc.h>
  39 #include <mach/regs-ost.h>
  40 #endif
  41
  42 #define RTC_DEF_DIVIDER         (32768 - 1)
  43 #define RTC_DEF_TRIM            0
  44
  45 static const unsigned long RTC_FREQ = 1024;
  46 static struct rtc_time rtc_alarm;
  47 static DEFINE_SPINLOCK(sa1100_rtc_lock);
  48
  49 static inline int rtc_periodic_alarm(struct rtc_time *tm)
  50 {
  51         return  (tm->tm_year == -1) ||
  52                 ((unsigned)tm->tm_mon >= 12) ||
  53                 ((unsigned)(tm->tm_mday - 1) >= 31) ||
  54                 ((unsigned)tm->tm_hour > 23) ||
  55                 ((unsigned)tm->tm_min > 59) ||
  56                 ((unsigned)tm->tm_sec > 59);
  57 }
  58
  59 /*
  60  * Calculate the next alarm time given the requested alarm time mask
  61  * and the current time.
  62  */
  63 static void rtc_next_alarm_time(struct rtc_time *next, struct rtc_time *now,
  64         struct rtc_time *alrm)
  65 {
  66         unsigned long next_time;
  67         unsigned long now_time;
  68
  69         next->tm_year = now->tm_year;
  70         next->tm_mon = now->tm_mon;
  71         next->tm_mday = now->tm_mday;
  72         next->tm_hour = alrm->tm_hour;
  73         next->tm_min = alrm->tm_min;
  74         next->tm_sec = alrm->tm_sec;
  75
  76         rtc_tm_to_time(now, &now_time);
  77         rtc_tm_to_time(next, &next_time);
  78
  79         if (next_time < now_time) {
  80                 /* Advance one day */
  81                 next_time += 60 * 60 * 24;
  82                 rtc_time_to_tm(next_time, next);
  83         }
  84 }
  85
  86 static int rtc_update_alarm(struct rtc_time *alrm)
  87 {
  88         struct rtc_time alarm_tm, now_tm;
  89         unsigned long now, time;
  90         int ret;
  91
  92         do {
  93                 now = RCNR;
  94                 rtc_time_to_tm(now, &now_tm);
  95                 rtc_next_alarm_time(&alarm_tm, &now_tm, alrm);
  96                 ret = rtc_tm_to_time(&alarm_tm, &time);
  97                 if (ret != 0)
  98                         break;
  99
 100                 RTSR = RTSR & (RTSR_HZE|RTSR_ALE|RTSR_AL);
 101                 RTAR = time;
 102         } while (now != RCNR);
 103
 104         return ret;
 105 }
 106
 107 static irqreturn_t sa1100_rtc_interrupt(int irq, void *dev_id)
 108 {
 109         struct platform_device *pdev = to_platform_device(dev_id);
 110         struct rtc_device *rtc = platform_get_drvdata(pdev);
 111         unsigned int rtsr;
 112         unsigned long events = 0;
 113
 114         spin_lock(&sa1100_rtc_lock);
 115
 116         rtsr = RTSR;
 117         /* clear interrupt sources */
 118         RTSR = 0;
 119         /* Fix for a nasty initialization problem the in SA11xx RTSR register.
 120          * See also the comments in sa1100_rtc_probe(). */
 121         if (rtsr & (RTSR_ALE | RTSR_HZE)) {
 122                 /* This is the original code, before there was the if test
 123                  * above. This code does not clear interrupts that were not
 124                  * enabled. */
 125                 RTSR = (RTSR_AL | RTSR_HZ) & (rtsr >> 2);
 126         } else {
 127                 /* For some reason, it is possible to enter this routine
 128                  * without interruptions enabled, it has been tested with
 129                  * several units (Bug in SA11xx chip?).
 130                  *
 131                  * This situation leads to an infinite "loop" of interrupt
 132                  * routine calling and as a result the processor seems to
 133                  * lock on its first call to open(). */
 134                 RTSR = RTSR_AL | RTSR_HZ;
 135         }
 136
 137         /* clear alarm interrupt if it has occurred */
 138         if (rtsr & RTSR_AL)
 139                 rtsr &= ~RTSR_ALE;
 140         RTSR = rtsr & (RTSR_ALE | RTSR_HZE);
 141
 142         /* update irq data & counter */
 143         if (rtsr & RTSR_AL)
 144                 events |= RTC_AF | RTC_IRQF;
 145         if (rtsr & RTSR_HZ)
 146                 events |= RTC_UF | RTC_IRQF;
 147
 148         rtc_update_irq(rtc, 1, events);
 149
 150         if (rtsr & RTSR_AL && rtc_periodic_alarm(&rtc_alarm))
 151                 rtc_update_alarm(&rtc_alarm);
 152
 153         spin_unlock(&sa1100_rtc_lock);
 154
 155         return IRQ_HANDLED;
 156 }
 157
 158 static int sa1100_rtc_open(struct device *dev)
 159 {
 160         int ret;
 161         struct platform_device *plat_dev = to_platform_device(dev);
 162         struct rtc_device *rtc = platform_get_drvdata(plat_dev);
 163
 164         ret = request_irq(IRQ_RTC1Hz, sa1100_rtc_interrupt, IRQF_DISABLED,
 165                 "rtc 1Hz", dev);
 166         if (ret) {
 167                 dev_err(dev, "IRQ %d already in use.\n", IRQ_RTC1Hz);
 168                 goto fail_ui;
 169         }
 170         ret = request_irq(IRQ_RTCAlrm, sa1100_rtc_interrupt, IRQF_DISABLED,
 171                 "rtc Alrm", dev);
 172         if (ret) {
 173                 dev_err(dev, "IRQ %d already in use.\n", IRQ_RTCAlrm);
 174                 goto fail_ai;
 175         }
 176         rtc->max_user_freq = RTC_FREQ;
 177         rtc_irq_set_freq(rtc, NULL, RTC_FREQ);
 178
 179         return 0;
 180
 181  fail_ai:
 182         free_irq(IRQ_RTC1Hz, dev);
 183  fail_ui:
 184         return ret;
 185 }
 186
 187 static void sa1100_rtc_release(struct device *dev)
 188 {
 189         spin_lock_irq(&sa1100_rtc_lock);
 190         RTSR = 0;
 191         OIER &= ~OIER_E1;
 192         OSSR = OSSR_M1;
 193         spin_unlock_irq(&sa1100_rtc_lock);
 194
 195         free_irq(IRQ_RTCAlrm, dev);
 196         free_irq(IRQ_RTC1Hz, dev);
 197 }
 198
 199 static int sa1100_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 200 {
 201         spin_lock_irq(&sa1100_rtc_lock);
 202         if (enabled)
 203                 RTSR |= RTSR_ALE;
 204         else
 205                 RTSR &= ~RTSR_ALE;
 206         spin_unlock_irq(&sa1100_rtc_lock);
 207         return 0;
 208 }
 209
 210 static int sa1100_rtc_read_time(struct device *dev, struct rtc_time *tm)
 211 {
 212         rtc_time_to_tm(RCNR, tm);
 213         return 0;
 214 }
 215
 216 static int sa1100_rtc_set_time(struct device *dev, struct rtc_time *tm)
 217 {
 218         unsigned long time;
 219         int ret;
 220
 221         ret = rtc_tm_to_time(tm, &time);
 222         if (ret == 0)
 223                 RCNR = time;
 224         return ret;
 225 }
 226
 227 static int sa1100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 228 {
 229         u32     rtsr;
 230
 231         memcpy(&alrm->time, &rtc_alarm, sizeof(struct rtc_time));
 232         rtsr = RTSR;
 233         alrm->enabled = (rtsr & RTSR_ALE) ? 1 : 0;
 234         alrm->pending = (rtsr & RTSR_AL) ? 1 : 0;
 235         return 0;
 236 }
 237
 238 static int sa1100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 239 {
 240         int ret;
 241
 242         spin_lock_irq(&sa1100_rtc_lock);
 243         ret = rtc_update_alarm(&alrm->time);
 244         if (ret == 0) {
 245                 if (alrm->enabled)
 246                         RTSR |= RTSR_ALE;
 247                 else
 248                         RTSR &= ~RTSR_ALE;
 249         }
 250         spin_unlock_irq(&sa1100_rtc_lock);
 251
 252         return ret;
 253 }
 254
 255 static int sa1100_rtc_proc(struct device *dev, struct seq_file *seq)
 256 {
 257         seq_printf(seq, "trim/divider\t\t: 0x%08x\n", (u32) RTTR);
 258         seq_printf(seq, "RTSR\t\t\t: 0x%08x\n", (u32)RTSR);
 259
 260         return 0;
 261 }
 262
 263 static const struct rtc_class_ops sa1100_rtc_ops = {
 264         .open = sa1100_rtc_open,
 265         .release = sa1100_rtc_release,
 266         .read_time = sa1100_rtc_read_time,
 267         .set_time = sa1100_rtc_set_time,
 268         .read_alarm = sa1100_rtc_read_alarm,
 269         .set_alarm = sa1100_rtc_set_alarm,
 270         .proc = sa1100_rtc_proc,
 271         .alarm_irq_enable = sa1100_rtc_alarm_irq_enable,
 272 };
 273
 274 static int sa1100_rtc_probe(struct platform_device *pdev)
 275 {
 276         struct rtc_device *rtc;
 277
 278         /*
 279          * According to the manual we should be able to let RTTR be zero
 280          * and then a default diviser for a 32.768KHz clock is used.
 281          * Apparently this doesn't work, at least for my SA1110 rev 5.
 282          * If the clock divider is uninitialized then reset it to the
 283          * default value to get the 1Hz clock.
 284          */
 285         if (RTTR == 0) {
 286                 RTTR = RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16);
 287                 dev_warn(&pdev->dev, "warning: "
 288                         "initializing default clock divider/trim value\n");
 289                 /* The current RTC value probably doesn't make sense either */
 290                 RCNR = 0;
 291         }
 292
 293         device_init_wakeup(&pdev->dev, 1);
 294
 295         rtc = rtc_device_register(pdev->name, &pdev->dev, &sa1100_rtc_ops,
 296                 THIS_MODULE);
 297
 298         if (IS_ERR(rtc))
 299                 return PTR_ERR(rtc);
 300
 301         platform_set_drvdata(pdev, rtc);
 302
 303         /* Fix for a nasty initialization problem the in SA11xx RTSR register.
 304          * See also the comments in sa1100_rtc_interrupt().
 305          *
 306          * Sometimes bit 1 of the RTSR (RTSR_HZ) will wake up 1, which means an
 307          * interrupt pending, even though interrupts were never enabled.
 308          * In this case, this bit it must be reset before enabling
 309          * interruptions to avoid a nonexistent interrupt to occur.
 310          *
 311          * In principle, the same problem would apply to bit 0, although it has
 312          * never been observed to happen.
 313          *
 314          * This issue is addressed both here and in sa1100_rtc_interrupt().
 315          * If the issue is not addressed here, in the times when the processor
 316          * wakes up with the bit set there will be one spurious interrupt.
 317          *
 318          * The issue is also dealt with in sa1100_rtc_interrupt() to be on the
 319          * safe side, once the condition that lead to this strange
 320          * initialization is unknown and could in principle happen during
 321          * normal processing.
 322          *
 323          * Notice that clearing bit 1 and 0 is accomplished by writting ONES to
 324          * the corresponding bits in RTSR. */
 325         RTSR = RTSR_AL | RTSR_HZ;
 326
 327         return 0;
 328 }
 329
 330 static int sa1100_rtc_remove(struct platform_device *pdev)
 331 {
 332         struct rtc_device *rtc = platform_get_drvdata(pdev);
 333
 334         if (rtc)
 335                 rtc_device_unregister(rtc);
 336
 337         return 0;
 338 }
 339
 340 #ifdef CONFIG_PM
 341 static int sa1100_rtc_suspend(struct device *dev)
 342 {
 343         if (device_may_wakeup(dev))
 344                 enable_irq_wake(IRQ_RTCAlrm);
 345         return 0;
 346 }
 347
 348 static int sa1100_rtc_resume(struct device *dev)
 349 {
 350         if (device_may_wakeup(dev))
 351                 disable_irq_wake(IRQ_RTCAlrm);
 352         return 0;
 353 }
 354
 355 static const struct dev_pm_ops sa1100_rtc_pm_ops = {
 356         .suspend        = sa1100_rtc_suspend,
 357         .resume         = sa1100_rtc_resume,
 358 };
 359 #endif
 360
 361 static struct platform_driver sa1100_rtc_driver = {
 362         .probe          = sa1100_rtc_probe,
 363         .remove         = sa1100_rtc_remove,
 364         .driver         = {
 365                 .name   = "sa1100-rtc",
 366 #ifdef CONFIG_PM
 367                 .pm     = &sa1100_rtc_pm_ops,
 368 #endif
 369         },
 370 };
 371
 372 static int __init sa1100_rtc_init(void)
 373 {
 374         return platform_driver_register(&sa1100_rtc_driver);
 375 }
 376
 377 static void __exit sa1100_rtc_exit(void)
 378 {
 379         platform_driver_unregister(&sa1100_rtc_driver);
 380 }
 381
 382 module_init(sa1100_rtc_init);
 383 module_exit(sa1100_rtc_exit);
 384
 385 MODULE_AUTHOR("Richard Purdie <rpurdie@rpsys.net>");
 386 MODULE_DESCRIPTION("SA11x0/PXA2xx Realtime Clock Driver (RTC)");
 387 MODULE_LICENSE("GPL");
 388 MODULE_ALIAS("platform:sa1100-rtc");