linux/drivers/rtc/rtc-sa1100.c
<<
>>
Prefs
   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
  44static const unsigned long RTC_FREQ = 1024;
  45static struct rtc_time rtc_alarm;
  46static DEFINE_SPINLOCK(sa1100_rtc_lock);
  47
  48static 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 */
  62static 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
  85static 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
 106static 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
 157static 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, IRQF_DISABLED,
 164                "rtc 1Hz", dev);
 165        if (ret) {
 166                dev_err(dev, "IRQ %d already in use.\n", IRQ_RTC1Hz);
 167                goto fail_ui;
 168        }
 169        ret = request_irq(IRQ_RTCAlrm, sa1100_rtc_interrupt, IRQF_DISABLED,
 170                "rtc Alrm", dev);
 171        if (ret) {
 172                dev_err(dev, "IRQ %d already in use.\n", IRQ_RTCAlrm);
 173                goto fail_ai;
 174        }
 175        rtc->max_user_freq = RTC_FREQ;
 176        rtc_irq_set_freq(rtc, NULL, RTC_FREQ);
 177
 178        return 0;
 179
 180 fail_ai:
 181        free_irq(IRQ_RTC1Hz, dev);
 182 fail_ui:
 183        return ret;
 184}
 185
 186static void sa1100_rtc_release(struct device *dev)
 187{
 188        spin_lock_irq(&sa1100_rtc_lock);
 189        RTSR = 0;
 190        spin_unlock_irq(&sa1100_rtc_lock);
 191
 192        free_irq(IRQ_RTCAlrm, dev);
 193        free_irq(IRQ_RTC1Hz, dev);
 194}
 195
 196static int sa1100_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 197{
 198        spin_lock_irq(&sa1100_rtc_lock);
 199        if (enabled)
 200                RTSR |= RTSR_ALE;
 201        else
 202                RTSR &= ~RTSR_ALE;
 203        spin_unlock_irq(&sa1100_rtc_lock);
 204        return 0;
 205}
 206
 207static int sa1100_rtc_read_time(struct device *dev, struct rtc_time *tm)
 208{
 209        rtc_time_to_tm(RCNR, tm);
 210        return 0;
 211}
 212
 213static int sa1100_rtc_set_time(struct device *dev, struct rtc_time *tm)
 214{
 215        unsigned long time;
 216        int ret;
 217
 218        ret = rtc_tm_to_time(tm, &time);
 219        if (ret == 0)
 220                RCNR = time;
 221        return ret;
 222}
 223
 224static int sa1100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 225{
 226        u32     rtsr;
 227
 228        memcpy(&alrm->time, &rtc_alarm, sizeof(struct rtc_time));
 229        rtsr = RTSR;
 230        alrm->enabled = (rtsr & RTSR_ALE) ? 1 : 0;
 231        alrm->pending = (rtsr & RTSR_AL) ? 1 : 0;
 232        return 0;
 233}
 234
 235static int sa1100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 236{
 237        int ret;
 238
 239        spin_lock_irq(&sa1100_rtc_lock);
 240        ret = rtc_update_alarm(&alrm->time);
 241        if (ret == 0) {
 242                if (alrm->enabled)
 243                        RTSR |= RTSR_ALE;
 244                else
 245                        RTSR &= ~RTSR_ALE;
 246        }
 247        spin_unlock_irq(&sa1100_rtc_lock);
 248
 249        return ret;
 250}
 251
 252static int sa1100_rtc_proc(struct device *dev, struct seq_file *seq)
 253{
 254        seq_printf(seq, "trim/divider\t\t: 0x%08x\n", (u32) RTTR);
 255        seq_printf(seq, "RTSR\t\t\t: 0x%08x\n", (u32)RTSR);
 256
 257        return 0;
 258}
 259
 260static const struct rtc_class_ops sa1100_rtc_ops = {
 261        .open = sa1100_rtc_open,
 262        .release = sa1100_rtc_release,
 263        .read_time = sa1100_rtc_read_time,
 264        .set_time = sa1100_rtc_set_time,
 265        .read_alarm = sa1100_rtc_read_alarm,
 266        .set_alarm = sa1100_rtc_set_alarm,
 267        .proc = sa1100_rtc_proc,
 268        .alarm_irq_enable = sa1100_rtc_alarm_irq_enable,
 269};
 270
 271static int sa1100_rtc_probe(struct platform_device *pdev)
 272{
 273        struct rtc_device *rtc;
 274
 275        /*
 276         * According to the manual we should be able to let RTTR be zero
 277         * and then a default diviser for a 32.768KHz clock is used.
 278         * Apparently this doesn't work, at least for my SA1110 rev 5.
 279         * If the clock divider is uninitialized then reset it to the
 280         * default value to get the 1Hz clock.
 281         */
 282        if (RTTR == 0) {
 283                RTTR = RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16);
 284                dev_warn(&pdev->dev, "warning: "
 285                        "initializing default clock divider/trim value\n");
 286                /* The current RTC value probably doesn't make sense either */
 287                RCNR = 0;
 288        }
 289
 290        device_init_wakeup(&pdev->dev, 1);
 291
 292        rtc = rtc_device_register(pdev->name, &pdev->dev, &sa1100_rtc_ops,
 293                THIS_MODULE);
 294
 295        if (IS_ERR(rtc))
 296                return PTR_ERR(rtc);
 297
 298        platform_set_drvdata(pdev, rtc);
 299
 300        /* Fix for a nasty initialization problem the in SA11xx RTSR register.
 301         * See also the comments in sa1100_rtc_interrupt().
 302         *
 303         * Sometimes bit 1 of the RTSR (RTSR_HZ) will wake up 1, which means an
 304         * interrupt pending, even though interrupts were never enabled.
 305         * In this case, this bit it must be reset before enabling
 306         * interruptions to avoid a nonexistent interrupt to occur.
 307         *
 308         * In principle, the same problem would apply to bit 0, although it has
 309         * never been observed to happen.
 310         *
 311         * This issue is addressed both here and in sa1100_rtc_interrupt().
 312         * If the issue is not addressed here, in the times when the processor
 313         * wakes up with the bit set there will be one spurious interrupt.
 314         *
 315         * The issue is also dealt with in sa1100_rtc_interrupt() to be on the
 316         * safe side, once the condition that lead to this strange
 317         * initialization is unknown and could in principle happen during
 318         * normal processing.
 319         *
 320         * Notice that clearing bit 1 and 0 is accomplished by writting ONES to
 321         * the corresponding bits in RTSR. */
 322        RTSR = RTSR_AL | RTSR_HZ;
 323
 324        return 0;
 325}
 326
 327static int sa1100_rtc_remove(struct platform_device *pdev)
 328{
 329        struct rtc_device *rtc = platform_get_drvdata(pdev);
 330
 331        if (rtc)
 332                rtc_device_unregister(rtc);
 333
 334        return 0;
 335}
 336
 337#ifdef CONFIG_PM
 338static int sa1100_rtc_suspend(struct device *dev)
 339{
 340        if (device_may_wakeup(dev))
 341                enable_irq_wake(IRQ_RTCAlrm);
 342        return 0;
 343}
 344
 345static int sa1100_rtc_resume(struct device *dev)
 346{
 347        if (device_may_wakeup(dev))
 348                disable_irq_wake(IRQ_RTCAlrm);
 349        return 0;
 350}
 351
 352static const struct dev_pm_ops sa1100_rtc_pm_ops = {
 353        .suspend        = sa1100_rtc_suspend,
 354        .resume         = sa1100_rtc_resume,
 355};
 356#endif
 357
 358static struct platform_driver sa1100_rtc_driver = {
 359        .probe          = sa1100_rtc_probe,
 360        .remove         = sa1100_rtc_remove,
 361        .driver         = {
 362                .name   = "sa1100-rtc",
 363#ifdef CONFIG_PM
 364                .pm     = &sa1100_rtc_pm_ops,
 365#endif
 366        },
 367};
 368
 369module_platform_driver(sa1100_rtc_driver);
 370
 371MODULE_AUTHOR("Richard Purdie <rpurdie@rpsys.net>");
 372MODULE_DESCRIPTION("SA11x0/PXA2xx Realtime Clock Driver (RTC)");
 373MODULE_LICENSE("GPL");
 374MODULE_ALIAS("platform:sa1100-rtc");
 375