linux/drivers/rtc/rtc-sa1100.c
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   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/clk.h>
  27#include <linux/rtc.h>
  28#include <linux/init.h>
  29#include <linux/fs.h>
  30#include <linux/interrupt.h>
  31#include <linux/slab.h>
  32#include <linux/string.h>
  33#include <linux/of.h>
  34#include <linux/pm.h>
  35#include <linux/bitops.h>
  36#include <linux/io.h>
  37
  38#include <mach/hardware.h>
  39#include <mach/irqs.h>
  40
  41#if defined(CONFIG_ARCH_PXA) || defined(CONFIG_ARCH_MMP)
  42#include <mach/regs-rtc.h>
  43#endif
  44
  45#define RTC_DEF_DIVIDER         (32768 - 1)
  46#define RTC_DEF_TRIM            0
  47#define RTC_FREQ                1024
  48
  49struct sa1100_rtc {
  50        spinlock_t              lock;
  51        int                     irq_1hz;
  52        int                     irq_alarm;
  53        struct rtc_device       *rtc;
  54        struct clk              *clk;
  55};
  56
  57static irqreturn_t sa1100_rtc_interrupt(int irq, void *dev_id)
  58{
  59        struct sa1100_rtc *info = dev_get_drvdata(dev_id);
  60        struct rtc_device *rtc = info->rtc;
  61        unsigned int rtsr;
  62        unsigned long events = 0;
  63
  64        spin_lock(&info->lock);
  65
  66        rtsr = RTSR;
  67        /* clear interrupt sources */
  68        RTSR = 0;
  69        /* Fix for a nasty initialization problem the in SA11xx RTSR register.
  70         * See also the comments in sa1100_rtc_probe(). */
  71        if (rtsr & (RTSR_ALE | RTSR_HZE)) {
  72                /* This is the original code, before there was the if test
  73                 * above. This code does not clear interrupts that were not
  74                 * enabled. */
  75                RTSR = (RTSR_AL | RTSR_HZ) & (rtsr >> 2);
  76        } else {
  77                /* For some reason, it is possible to enter this routine
  78                 * without interruptions enabled, it has been tested with
  79                 * several units (Bug in SA11xx chip?).
  80                 *
  81                 * This situation leads to an infinite "loop" of interrupt
  82                 * routine calling and as a result the processor seems to
  83                 * lock on its first call to open(). */
  84                RTSR = RTSR_AL | RTSR_HZ;
  85        }
  86
  87        /* clear alarm interrupt if it has occurred */
  88        if (rtsr & RTSR_AL)
  89                rtsr &= ~RTSR_ALE;
  90        RTSR = rtsr & (RTSR_ALE | RTSR_HZE);
  91
  92        /* update irq data & counter */
  93        if (rtsr & RTSR_AL)
  94                events |= RTC_AF | RTC_IRQF;
  95        if (rtsr & RTSR_HZ)
  96                events |= RTC_UF | RTC_IRQF;
  97
  98        rtc_update_irq(rtc, 1, events);
  99
 100        spin_unlock(&info->lock);
 101
 102        return IRQ_HANDLED;
 103}
 104
 105static int sa1100_rtc_open(struct device *dev)
 106{
 107        struct sa1100_rtc *info = dev_get_drvdata(dev);
 108        struct rtc_device *rtc = info->rtc;
 109        int ret;
 110
 111        ret = clk_prepare_enable(info->clk);
 112        if (ret)
 113                goto fail_clk;
 114        ret = request_irq(info->irq_1hz, sa1100_rtc_interrupt, 0, "rtc 1Hz", dev);
 115        if (ret) {
 116                dev_err(dev, "IRQ %d already in use.\n", info->irq_1hz);
 117                goto fail_ui;
 118        }
 119        ret = request_irq(info->irq_alarm, sa1100_rtc_interrupt, 0, "rtc Alrm", dev);
 120        if (ret) {
 121                dev_err(dev, "IRQ %d already in use.\n", info->irq_alarm);
 122                goto fail_ai;
 123        }
 124        rtc->max_user_freq = RTC_FREQ;
 125        rtc_irq_set_freq(rtc, NULL, RTC_FREQ);
 126
 127        return 0;
 128
 129 fail_ai:
 130        free_irq(info->irq_1hz, dev);
 131 fail_ui:
 132        clk_disable_unprepare(info->clk);
 133 fail_clk:
 134        return ret;
 135}
 136
 137static void sa1100_rtc_release(struct device *dev)
 138{
 139        struct sa1100_rtc *info = dev_get_drvdata(dev);
 140
 141        spin_lock_irq(&info->lock);
 142        RTSR = 0;
 143        spin_unlock_irq(&info->lock);
 144
 145        free_irq(info->irq_alarm, dev);
 146        free_irq(info->irq_1hz, dev);
 147        clk_disable_unprepare(info->clk);
 148}
 149
 150static int sa1100_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 151{
 152        struct sa1100_rtc *info = dev_get_drvdata(dev);
 153
 154        spin_lock_irq(&info->lock);
 155        if (enabled)
 156                RTSR |= RTSR_ALE;
 157        else
 158                RTSR &= ~RTSR_ALE;
 159        spin_unlock_irq(&info->lock);
 160        return 0;
 161}
 162
 163static int sa1100_rtc_read_time(struct device *dev, struct rtc_time *tm)
 164{
 165        rtc_time_to_tm(RCNR, tm);
 166        return 0;
 167}
 168
 169static int sa1100_rtc_set_time(struct device *dev, struct rtc_time *tm)
 170{
 171        unsigned long time;
 172        int ret;
 173
 174        ret = rtc_tm_to_time(tm, &time);
 175        if (ret == 0)
 176                RCNR = time;
 177        return ret;
 178}
 179
 180static int sa1100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 181{
 182        u32     rtsr;
 183
 184        rtsr = RTSR;
 185        alrm->enabled = (rtsr & RTSR_ALE) ? 1 : 0;
 186        alrm->pending = (rtsr & RTSR_AL) ? 1 : 0;
 187        return 0;
 188}
 189
 190static int sa1100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 191{
 192        struct sa1100_rtc *info = dev_get_drvdata(dev);
 193        unsigned long time;
 194        int ret;
 195
 196        spin_lock_irq(&info->lock);
 197        ret = rtc_tm_to_time(&alrm->time, &time);
 198        if (ret != 0)
 199                goto out;
 200        RTSR = RTSR & (RTSR_HZE|RTSR_ALE|RTSR_AL);
 201        RTAR = time;
 202        if (alrm->enabled)
 203                RTSR |= RTSR_ALE;
 204        else
 205                RTSR &= ~RTSR_ALE;
 206out:
 207        spin_unlock_irq(&info->lock);
 208
 209        return ret;
 210}
 211
 212static int sa1100_rtc_proc(struct device *dev, struct seq_file *seq)
 213{
 214        seq_printf(seq, "trim/divider\t\t: 0x%08x\n", (u32) RTTR);
 215        seq_printf(seq, "RTSR\t\t\t: 0x%08x\n", (u32)RTSR);
 216
 217        return 0;
 218}
 219
 220static const struct rtc_class_ops sa1100_rtc_ops = {
 221        .open = sa1100_rtc_open,
 222        .release = sa1100_rtc_release,
 223        .read_time = sa1100_rtc_read_time,
 224        .set_time = sa1100_rtc_set_time,
 225        .read_alarm = sa1100_rtc_read_alarm,
 226        .set_alarm = sa1100_rtc_set_alarm,
 227        .proc = sa1100_rtc_proc,
 228        .alarm_irq_enable = sa1100_rtc_alarm_irq_enable,
 229};
 230
 231static int sa1100_rtc_probe(struct platform_device *pdev)
 232{
 233        struct rtc_device *rtc;
 234        struct sa1100_rtc *info;
 235        int irq_1hz, irq_alarm, ret = 0;
 236
 237        irq_1hz = platform_get_irq_byname(pdev, "rtc 1Hz");
 238        irq_alarm = platform_get_irq_byname(pdev, "rtc alarm");
 239        if (irq_1hz < 0 || irq_alarm < 0)
 240                return -ENODEV;
 241
 242        info = kzalloc(sizeof(struct sa1100_rtc), GFP_KERNEL);
 243        if (!info)
 244                return -ENOMEM;
 245        info->clk = clk_get(&pdev->dev, NULL);
 246        if (IS_ERR(info->clk)) {
 247                dev_err(&pdev->dev, "failed to find rtc clock source\n");
 248                ret = PTR_ERR(info->clk);
 249                goto err_clk;
 250        }
 251        info->irq_1hz = irq_1hz;
 252        info->irq_alarm = irq_alarm;
 253        spin_lock_init(&info->lock);
 254        platform_set_drvdata(pdev, info);
 255
 256        /*
 257         * According to the manual we should be able to let RTTR be zero
 258         * and then a default diviser for a 32.768KHz clock is used.
 259         * Apparently this doesn't work, at least for my SA1110 rev 5.
 260         * If the clock divider is uninitialized then reset it to the
 261         * default value to get the 1Hz clock.
 262         */
 263        if (RTTR == 0) {
 264                RTTR = RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16);
 265                dev_warn(&pdev->dev, "warning: "
 266                        "initializing default clock divider/trim value\n");
 267                /* The current RTC value probably doesn't make sense either */
 268                RCNR = 0;
 269        }
 270
 271        device_init_wakeup(&pdev->dev, 1);
 272
 273        rtc = rtc_device_register(pdev->name, &pdev->dev, &sa1100_rtc_ops,
 274                THIS_MODULE);
 275
 276        if (IS_ERR(rtc)) {
 277                ret = PTR_ERR(rtc);
 278                goto err_dev;
 279        }
 280        info->rtc = rtc;
 281
 282        /* Fix for a nasty initialization problem the in SA11xx RTSR register.
 283         * See also the comments in sa1100_rtc_interrupt().
 284         *
 285         * Sometimes bit 1 of the RTSR (RTSR_HZ) will wake up 1, which means an
 286         * interrupt pending, even though interrupts were never enabled.
 287         * In this case, this bit it must be reset before enabling
 288         * interruptions to avoid a nonexistent interrupt to occur.
 289         *
 290         * In principle, the same problem would apply to bit 0, although it has
 291         * never been observed to happen.
 292         *
 293         * This issue is addressed both here and in sa1100_rtc_interrupt().
 294         * If the issue is not addressed here, in the times when the processor
 295         * wakes up with the bit set there will be one spurious interrupt.
 296         *
 297         * The issue is also dealt with in sa1100_rtc_interrupt() to be on the
 298         * safe side, once the condition that lead to this strange
 299         * initialization is unknown and could in principle happen during
 300         * normal processing.
 301         *
 302         * Notice that clearing bit 1 and 0 is accomplished by writting ONES to
 303         * the corresponding bits in RTSR. */
 304        RTSR = RTSR_AL | RTSR_HZ;
 305
 306        return 0;
 307err_dev:
 308        platform_set_drvdata(pdev, NULL);
 309        clk_put(info->clk);
 310err_clk:
 311        kfree(info);
 312        return ret;
 313}
 314
 315static int sa1100_rtc_remove(struct platform_device *pdev)
 316{
 317        struct sa1100_rtc *info = platform_get_drvdata(pdev);
 318
 319        if (info) {
 320                rtc_device_unregister(info->rtc);
 321                clk_put(info->clk);
 322                platform_set_drvdata(pdev, NULL);
 323                kfree(info);
 324        }
 325
 326        return 0;
 327}
 328
 329#ifdef CONFIG_PM
 330static int sa1100_rtc_suspend(struct device *dev)
 331{
 332        struct sa1100_rtc *info = dev_get_drvdata(dev);
 333        if (device_may_wakeup(dev))
 334                enable_irq_wake(info->irq_alarm);
 335        return 0;
 336}
 337
 338static int sa1100_rtc_resume(struct device *dev)
 339{
 340        struct sa1100_rtc *info = dev_get_drvdata(dev);
 341        if (device_may_wakeup(dev))
 342                disable_irq_wake(info->irq_alarm);
 343        return 0;
 344}
 345
 346static const struct dev_pm_ops sa1100_rtc_pm_ops = {
 347        .suspend        = sa1100_rtc_suspend,
 348        .resume         = sa1100_rtc_resume,
 349};
 350#endif
 351
 352static struct of_device_id sa1100_rtc_dt_ids[] = {
 353        { .compatible = "mrvl,sa1100-rtc", },
 354        { .compatible = "mrvl,mmp-rtc", },
 355        {}
 356};
 357MODULE_DEVICE_TABLE(of, sa1100_rtc_dt_ids);
 358
 359static struct platform_driver sa1100_rtc_driver = {
 360        .probe          = sa1100_rtc_probe,
 361        .remove         = sa1100_rtc_remove,
 362        .driver         = {
 363                .name   = "sa1100-rtc",
 364#ifdef CONFIG_PM
 365                .pm     = &sa1100_rtc_pm_ops,
 366#endif
 367                .of_match_table = sa1100_rtc_dt_ids,
 368        },
 369};
 370
 371module_platform_driver(sa1100_rtc_driver);
 372
 373MODULE_AUTHOR("Richard Purdie <rpurdie@rpsys.net>");
 374MODULE_DESCRIPTION("SA11x0/PXA2xx Realtime Clock Driver (RTC)");
 375MODULE_LICENSE("GPL");
 376MODULE_ALIAS("platform:sa1100-rtc");
 377
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