rtc-sa1100.c

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/*
 * Real Time Clock interface for StrongARM SA1x00 and XScale PXA2xx
 *
 * Copyright (c) 2000 Nils Faerber
 *
 * Based on rtc.c by Paul Gortmaker
 *
 * Original Driver by Nils Faerber <[email protected]>
 *
 * Modifications from:
 *   CIH <[email protected]>
 *   Nicolas Pitre <[email protected]>
 *   Andrew Christian <[email protected]>
 *
 * Converted to the RTC subsystem and Driver Model
 *   by Richard Purdie <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/clk.h>
#include <linux/rtc.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/of.h>
#include <linux/pm.h>
#include <linux/bitops.h>
#include <linux/io.h>

#include <mach/hardware.h>
#include <mach/irqs.h>

#if defined(CONFIG_ARCH_PXA) || defined(CONFIG_ARCH_MMP)
#include <mach/regs-rtc.h>
#endif

#define RTC_DEF_DIVIDER     (32768 - 1)
#define RTC_DEF_TRIM        0
#define RTC_FREQ        1024

struct sa1100_rtc {
    spinlock_t      lock;
    int         irq_1hz;
    int         irq_alarm;
    struct rtc_device   *rtc;
    struct clk      *clk;
};

static irqreturn_t sa1100_rtc_interrupt(int irq, void *dev_id)
{
    struct sa1100_rtc *info = dev_get_drvdata(dev_id);
    struct rtc_device *rtc = info->rtc;
    unsigned int rtsr;
    unsigned long events = 0;

    spin_lock(&info->lock);

    rtsr = RTSR;
    /* clear interrupt sources */
    RTSR = 0;
    /* Fix for a nasty initialization problem the in SA11xx RTSR register.
     * See also the comments in sa1100_rtc_probe(). */
    if (rtsr & (RTSR_ALE | RTSR_HZE)) {
        /* This is the original code, before there was the if test
         * above. This code does not clear interrupts that were not
         * enabled. */
        RTSR = (RTSR_AL | RTSR_HZ) & (rtsr >> 2);
    } else {
        /* For some reason, it is possible to enter this routine
         * without interruptions enabled, it has been tested with
         * several units (Bug in SA11xx chip?).
         *
         * This situation leads to an infinite "loop" of interrupt
         * routine calling and as a result the processor seems to
         * lock on its first call to open(). */
        RTSR = RTSR_AL | RTSR_HZ;
    }

    /* clear alarm interrupt if it has occurred */
    if (rtsr & RTSR_AL)
        rtsr &= ~RTSR_ALE;
    RTSR = rtsr & (RTSR_ALE | RTSR_HZE);

    /* update irq data & counter */
    if (rtsr & RTSR_AL)
        events |= RTC_AF | RTC_IRQF;
    if (rtsr & RTSR_HZ)
        events |= RTC_UF | RTC_IRQF;

    rtc_update_irq(rtc, 1, events);

    spin_unlock(&info->lock);

    return IRQ_HANDLED;
}

static int sa1100_rtc_open(struct device *dev)
{
    struct sa1100_rtc *info = dev_get_drvdata(dev);
    struct rtc_device *rtc = info->rtc;
    int ret;

    ret = clk_prepare_enable(info->clk);
    if (ret)
        goto fail_clk;
    ret = request_irq(info->irq_1hz, sa1100_rtc_interrupt, 0, "rtc 1Hz", dev);
    if (ret) {
        dev_err(dev, "IRQ %d already in use.\n", info->irq_1hz);
        goto fail_ui;
    }
    ret = request_irq(info->irq_alarm, sa1100_rtc_interrupt, 0, "rtc Alrm", dev);
    if (ret) {
        dev_err(dev, "IRQ %d already in use.\n", info->irq_alarm);
        goto fail_ai;
    }
    rtc->max_user_freq = RTC_FREQ;
    rtc_irq_set_freq(rtc, NULL, RTC_FREQ);

    return 0;

 fail_ai:
    free_irq(info->irq_1hz, dev);
 fail_ui:
    clk_disable_unprepare(info->clk);
 fail_clk:
    return ret;
}

static void sa1100_rtc_release(struct device *dev)
{
    struct sa1100_rtc *info = dev_get_drvdata(dev);

    spin_lock_irq(&info->lock);
    RTSR = 0;
    spin_unlock_irq(&info->lock);

    free_irq(info->irq_alarm, dev);
    free_irq(info->irq_1hz, dev);
    clk_disable_unprepare(info->clk);
}

static int sa1100_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
    struct sa1100_rtc *info = dev_get_drvdata(dev);

    spin_lock_irq(&info->lock);
    if (enabled)
        RTSR |= RTSR_ALE;
    else
        RTSR &= ~RTSR_ALE;
    spin_unlock_irq(&info->lock);
    return 0;
}

static int sa1100_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
    rtc_time_to_tm(RCNR, tm);
    return 0;
}

static int sa1100_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
    unsigned long time;
    int ret;

    ret = rtc_tm_to_time(tm, &time);
    if (ret == 0)
        RCNR = time;
    return ret;
}

static int sa1100_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
    u32 rtsr;

    rtsr = RTSR;
    alrm->enabled = (rtsr & RTSR_ALE) ? 1 : 0;
    alrm->pending = (rtsr & RTSR_AL) ? 1 : 0;
    return 0;
}

static int sa1100_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
{
    struct sa1100_rtc *info = dev_get_drvdata(dev);
    unsigned long time;
    int ret;

    spin_lock_irq(&info->lock);
    ret = rtc_tm_to_time(&alrm->time, &time);
    if (ret != 0)
        goto out;
    RTSR = RTSR & (RTSR_HZE|RTSR_ALE|RTSR_AL);
    RTAR = time;
    if (alrm->enabled)
        RTSR |= RTSR_ALE;
    else
        RTSR &= ~RTSR_ALE;
out:
    spin_unlock_irq(&info->lock);

    return ret;
}

static int sa1100_rtc_proc(struct device *dev, struct seq_file *seq)
{
    seq_printf(seq, "trim/divider\t\t: 0x%08x\n", (u32) RTTR);
    seq_printf(seq, "RTSR\t\t\t: 0x%08x\n", (u32)RTSR);

    return 0;
}

static const struct rtc_class_ops sa1100_rtc_ops = {
    .open = sa1100_rtc_open,
    .release = sa1100_rtc_release,
    .read_time = sa1100_rtc_read_time,
    .set_time = sa1100_rtc_set_time,
    .read_alarm = sa1100_rtc_read_alarm,
    .set_alarm = sa1100_rtc_set_alarm,
    .proc = sa1100_rtc_proc,
    .alarm_irq_enable = sa1100_rtc_alarm_irq_enable,
};

static int sa1100_rtc_probe(struct platform_device *pdev)
{
    struct rtc_device *rtc;
    struct sa1100_rtc *info;
    int irq_1hz, irq_alarm, ret = 0;

    irq_1hz = platform_get_irq_byname(pdev, "rtc 1Hz");
    irq_alarm = platform_get_irq_byname(pdev, "rtc alarm");
    if (irq_1hz < 0 || irq_alarm < 0)
        return -ENODEV;

    info = kzalloc(sizeof(struct sa1100_rtc), GFP_KERNEL);
    if (!info)
        return -ENOMEM;
    info->clk = clk_get(&pdev->dev, NULL);
    if (IS_ERR(info->clk)) {
        dev_err(&pdev->dev, "failed to find rtc clock source\n");
        ret = PTR_ERR(info->clk);
        goto err_clk;
    }
    info->irq_1hz = irq_1hz;
    info->irq_alarm = irq_alarm;
    spin_lock_init(&info->lock);
    platform_set_drvdata(pdev, info);

    /*
     * According to the manual we should be able to let RTTR be zero
     * and then a default diviser for a 32.768KHz clock is used.
     * Apparently this doesn't work, at least for my SA1110 rev 5.
     * If the clock divider is uninitialized then reset it to the
     * default value to get the 1Hz clock.
     */
    if (RTTR == 0) {
        RTTR = RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16);
        dev_warn(&pdev->dev, "warning: "
            "initializing default clock divider/trim value\n");
        /* The current RTC value probably doesn't make sense either */
        RCNR = 0;
    }

    device_init_wakeup(&pdev->dev, 1);

    rtc = rtc_device_register(pdev->name, &pdev->dev, &sa1100_rtc_ops,
        THIS_MODULE);

    if (IS_ERR(rtc)) {
        ret = PTR_ERR(rtc);
        goto err_dev;
    }
    info->rtc = rtc;

    /* Fix for a nasty initialization problem the in SA11xx RTSR register.
     * See also the comments in sa1100_rtc_interrupt().
     *
     * Sometimes bit 1 of the RTSR (RTSR_HZ) will wake up 1, which means an
     * interrupt pending, even though interrupts were never enabled.
     * In this case, this bit it must be reset before enabling
     * interruptions to avoid a nonexistent interrupt to occur.
     *
     * In principle, the same problem would apply to bit 0, although it has
     * never been observed to happen.
     *
     * This issue is addressed both here and in sa1100_rtc_interrupt().
     * If the issue is not addressed here, in the times when the processor
     * wakes up with the bit set there will be one spurious interrupt.
     *
     * The issue is also dealt with in sa1100_rtc_interrupt() to be on the
     * safe side, once the condition that lead to this strange
     * initialization is unknown and could in principle happen during
     * normal processing.
     *
     * Notice that clearing bit 1 and 0 is accomplished by writting ONES to
     * the corresponding bits in RTSR. */
    RTSR = RTSR_AL | RTSR_HZ;

    return 0;
err_dev:
    platform_set_drvdata(pdev, NULL);
    clk_put(info->clk);
err_clk:
    kfree(info);
    return ret;
}

static int sa1100_rtc_remove(struct platform_device *pdev)
{
    struct sa1100_rtc *info = platform_get_drvdata(pdev);

    if (info) {
        rtc_device_unregister(info->rtc);
        clk_put(info->clk);
        platform_set_drvdata(pdev, NULL);
        kfree(info);
    }

    return 0;
}

#ifdef CONFIG_PM
static int sa1100_rtc_suspend(struct device *dev)
{
    struct sa1100_rtc *info = dev_get_drvdata(dev);
    if (device_may_wakeup(dev))
        enable_irq_wake(info->irq_alarm);
    return 0;
}

static int sa1100_rtc_resume(struct device *dev)
{
    struct sa1100_rtc *info = dev_get_drvdata(dev);
    if (device_may_wakeup(dev))
        disable_irq_wake(info->irq_alarm);
    return 0;
}

static const struct dev_pm_ops sa1100_rtc_pm_ops = {
    .suspend    = sa1100_rtc_suspend,
    .resume     = sa1100_rtc_resume,
};
#endif

static struct of_device_id sa1100_rtc_dt_ids[] = {
    { .compatible = "mrvl,sa1100-rtc", },
    { .compatible = "mrvl,mmp-rtc", },
    {}
};
MODULE_DEVICE_TABLE(of, sa1100_rtc_dt_ids);

static struct platform_driver sa1100_rtc_driver = {
    .probe      = sa1100_rtc_probe,
    .remove     = sa1100_rtc_remove,
    .driver     = {
        .name   = "sa1100-rtc",
#ifdef CONFIG_PM
        .pm = &sa1100_rtc_pm_ops,
#endif
        .of_match_table = sa1100_rtc_dt_ids,
    },
};

module_platform_driver(sa1100_rtc_driver);

MODULE_AUTHOR("Richard Purdie <[email protected]>");
MODULE_DESCRIPTION("SA11x0/PXA2xx Realtime Clock Driver (RTC)");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:sa1100-rtc");