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 = request_irq(info->irq_1hz, sa1100_rtc_interrupt, 0, "rtc 1Hz", dev);
 112        if (ret) {
 113                dev_err(dev, "IRQ %d already in use.\n", info->irq_1hz);
 114                goto fail_ui;
 115        }
 116        ret = request_irq(info->irq_alarm, sa1100_rtc_interrupt, 0, "rtc Alrm", dev);
 117        if (ret) {
 118                dev_err(dev, "IRQ %d already in use.\n", info->irq_alarm);
 119                goto fail_ai;
 120        }
 121        rtc->max_user_freq = RTC_FREQ;
 122        rtc_irq_set_freq(rtc, NULL, RTC_FREQ);
 123
 124        return 0;
 125
 126 fail_ai:
 127        free_irq(info->irq_1hz, dev);
 128 fail_ui:
 129        clk_disable_unprepare(info->clk);
 130        return ret;
 131}
 132
 133static void sa1100_rtc_release(struct device *dev)
 134{
 135        struct sa1100_rtc *info = dev_get_drvdata(dev);
 136
 137        spin_lock_irq(&info->lock);
 138        RTSR = 0;
 139        spin_unlock_irq(&info->lock);
 140
 141        free_irq(info->irq_alarm, dev);
 142        free_irq(info->irq_1hz, dev);
 143}
 144
 145static int sa1100_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
 146{
 147        struct sa1100_rtc *info = dev_get_drvdata(dev);
 148
 149        spin_lock_irq(&info->lock);
 150        if (enabled)
 151                RTSR |= RTSR_ALE;
 152        else
 153                RTSR &= ~RTSR_ALE;
 154        spin_unlock_irq(&info->lock);
 155        return 0;
 156}
 157
 158static int sa1100_rtc_read_time(struct device *dev, struct rtc_time *tm)
 159{
 160        rtc_time_to_tm(RCNR, tm);
 161        return 0;
 162}
 163
 164static int sa1100_rtc_set_time(struct device *dev, struct rtc_time *tm)
 165{
 166        unsigned long time;
 167        int ret;
 168
 169        ret = rtc_tm_to_time(tm, &time);
 170        if (ret == 0)
 171                RCNR = time;
 172        return ret;
 173}
 174
 175static int sa1100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 176{
 177        u32     rtsr;
 178
 179        rtsr = RTSR;
 180        alrm->enabled = (rtsr & RTSR_ALE) ? 1 : 0;
 181        alrm->pending = (rtsr & RTSR_AL) ? 1 : 0;
 182        return 0;
 183}
 184
 185static int sa1100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 186{
 187        struct sa1100_rtc *info = dev_get_drvdata(dev);
 188        unsigned long time;
 189        int ret;
 190
 191        spin_lock_irq(&info->lock);
 192        ret = rtc_tm_to_time(&alrm->time, &time);
 193        if (ret != 0)
 194                goto out;
 195        RTSR = RTSR & (RTSR_HZE|RTSR_ALE|RTSR_AL);
 196        RTAR = time;
 197        if (alrm->enabled)
 198                RTSR |= RTSR_ALE;
 199        else
 200                RTSR &= ~RTSR_ALE;
 201out:
 202        spin_unlock_irq(&info->lock);
 203
 204        return ret;
 205}
 206
 207static int sa1100_rtc_proc(struct device *dev, struct seq_file *seq)
 208{
 209        seq_printf(seq, "trim/divider\t\t: 0x%08x\n", (u32) RTTR);
 210        seq_printf(seq, "RTSR\t\t\t: 0x%08x\n", (u32)RTSR);
 211
 212        return 0;
 213}
 214
 215static const struct rtc_class_ops sa1100_rtc_ops = {
 216        .open = sa1100_rtc_open,
 217        .release = sa1100_rtc_release,
 218        .read_time = sa1100_rtc_read_time,
 219        .set_time = sa1100_rtc_set_time,
 220        .read_alarm = sa1100_rtc_read_alarm,
 221        .set_alarm = sa1100_rtc_set_alarm,
 222        .proc = sa1100_rtc_proc,
 223        .alarm_irq_enable = sa1100_rtc_alarm_irq_enable,
 224};
 225
 226static int sa1100_rtc_probe(struct platform_device *pdev)
 227{
 228        struct rtc_device *rtc;
 229        struct sa1100_rtc *info;
 230        int irq_1hz, irq_alarm, ret = 0;
 231
 232        irq_1hz = platform_get_irq_byname(pdev, "rtc 1Hz");
 233        irq_alarm = platform_get_irq_byname(pdev, "rtc alarm");
 234        if (irq_1hz < 0 || irq_alarm < 0)
 235                return -ENODEV;
 236
 237        info = devm_kzalloc(&pdev->dev, sizeof(struct sa1100_rtc), GFP_KERNEL);
 238        if (!info)
 239                return -ENOMEM;
 240        info->clk = devm_clk_get(&pdev->dev, NULL);
 241        if (IS_ERR(info->clk)) {
 242                dev_err(&pdev->dev, "failed to find rtc clock source\n");
 243                return PTR_ERR(info->clk);
 244        }
 245        info->irq_1hz = irq_1hz;
 246        info->irq_alarm = irq_alarm;
 247        spin_lock_init(&info->lock);
 248        platform_set_drvdata(pdev, info);
 249
 250        ret = clk_prepare_enable(info->clk);
 251        if (ret)
 252                return ret;
 253        /*
 254         * According to the manual we should be able to let RTTR be zero
 255         * and then a default diviser for a 32.768KHz clock is used.
 256         * Apparently this doesn't work, at least for my SA1110 rev 5.
 257         * If the clock divider is uninitialized then reset it to the
 258         * default value to get the 1Hz clock.
 259         */
 260        if (RTTR == 0) {
 261                RTTR = RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16);
 262                dev_warn(&pdev->dev, "warning: "
 263                        "initializing default clock divider/trim value\n");
 264                /* The current RTC value probably doesn't make sense either */
 265                RCNR = 0;
 266        }
 267
 268        device_init_wakeup(&pdev->dev, 1);
 269
 270        rtc = devm_rtc_device_register(&pdev->dev, pdev->name, &sa1100_rtc_ops,
 271                                        THIS_MODULE);
 272
 273        if (IS_ERR(rtc)) {
 274                ret = PTR_ERR(rtc);
 275                goto err_dev;
 276        }
 277        info->rtc = rtc;
 278
 279        /* Fix for a nasty initialization problem the in SA11xx RTSR register.
 280         * See also the comments in sa1100_rtc_interrupt().
 281         *
 282         * Sometimes bit 1 of the RTSR (RTSR_HZ) will wake up 1, which means an
 283         * interrupt pending, even though interrupts were never enabled.
 284         * In this case, this bit it must be reset before enabling
 285         * interruptions to avoid a nonexistent interrupt to occur.
 286         *
 287         * In principle, the same problem would apply to bit 0, although it has
 288         * never been observed to happen.
 289         *
 290         * This issue is addressed both here and in sa1100_rtc_interrupt().
 291         * If the issue is not addressed here, in the times when the processor
 292         * wakes up with the bit set there will be one spurious interrupt.
 293         *
 294         * The issue is also dealt with in sa1100_rtc_interrupt() to be on the
 295         * safe side, once the condition that lead to this strange
 296         * initialization is unknown and could in principle happen during
 297         * normal processing.
 298         *
 299         * Notice that clearing bit 1 and 0 is accomplished by writting ONES to
 300         * the corresponding bits in RTSR. */
 301        RTSR = RTSR_AL | RTSR_HZ;
 302
 303        return 0;
 304err_dev:
 305        clk_disable_unprepare(info->clk);
 306        return ret;
 307}
 308
 309static int sa1100_rtc_remove(struct platform_device *pdev)
 310{
 311        struct sa1100_rtc *info = platform_get_drvdata(pdev);
 312
 313        if (info)
 314                clk_disable_unprepare(info->clk);
 315
 316        return 0;
 317}
 318
 319#ifdef CONFIG_PM_SLEEP
 320static int sa1100_rtc_suspend(struct device *dev)
 321{
 322        struct sa1100_rtc *info = dev_get_drvdata(dev);
 323        if (device_may_wakeup(dev))
 324                enable_irq_wake(info->irq_alarm);
 325        return 0;
 326}
 327
 328static int sa1100_rtc_resume(struct device *dev)
 329{
 330        struct sa1100_rtc *info = dev_get_drvdata(dev);
 331        if (device_may_wakeup(dev))
 332                disable_irq_wake(info->irq_alarm);
 333        return 0;
 334}
 335#endif
 336
 337static SIMPLE_DEV_PM_OPS(sa1100_rtc_pm_ops, sa1100_rtc_suspend,
 338                        sa1100_rtc_resume);
 339
 340#ifdef CONFIG_OF
 341static struct of_device_id sa1100_rtc_dt_ids[] = {
 342        { .compatible = "mrvl,sa1100-rtc", },
 343        { .compatible = "mrvl,mmp-rtc", },
 344        {}
 345};
 346MODULE_DEVICE_TABLE(of, sa1100_rtc_dt_ids);
 347#endif
 348
 349static struct platform_driver sa1100_rtc_driver = {
 350        .probe          = sa1100_rtc_probe,
 351        .remove         = sa1100_rtc_remove,
 352        .driver         = {
 353                .name   = "sa1100-rtc",
 354                .pm     = &sa1100_rtc_pm_ops,
 355                .of_match_table = of_match_ptr(sa1100_rtc_dt_ids),
 356        },
 357};
 358
 359module_platform_driver(sa1100_rtc_driver);
 360
 361MODULE_AUTHOR("Richard Purdie <rpurdie@rpsys.net>");
 362MODULE_DESCRIPTION("SA11x0/PXA2xx Realtime Clock Driver (RTC)");
 363MODULE_LICENSE("GPL");
 364MODULE_ALIAS("platform:sa1100-rtc");
 365
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