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