rtc-cmos.c

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/*
 * RTC class driver for "CMOS RTC":  PCs, ACPI, etc
 *
 * Copyright (C) 1996 Paul Gortmaker (drivers/char/rtc.c)
 * Copyright (C) 2006 David Brownell (convert to new framework)
 *
 * 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.
 */

/*
 * The original "cmos clock" chip was an MC146818 chip, now obsolete.
 * That defined the register interface now provided by all PCs, some
 * non-PC systems, and incorporated into ACPI.  Modern PC chipsets
 * integrate an MC146818 clone in their southbridge, and boards use
 * that instead of discrete clones like the DS12887 or M48T86.  There
 * are also clones that connect using the LPC bus.
 *
 * That register API is also used directly by various other drivers
 * (notably for integrated NVRAM), infrastructure (x86 has code to
 * bypass the RTC framework, directly reading the RTC during boot
 * and updating minutes/seconds for systems using NTP synch) and
 * utilities (like userspace 'hwclock', if no /dev node exists).
 *
 * So **ALL** calls to CMOS_READ and CMOS_WRITE must be done with
 * interrupts disabled, holding the global rtc_lock, to exclude those
 * other drivers and utilities on correctly configured systems.
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/platform_device.h>
#include <linux/mod_devicetable.h>
#include <linux/log2.h>
#include <linux/pm.h>
#include <linux/of.h>
#include <linux/of_platform.h>

/* this is for "generic access to PC-style RTC" using CMOS_READ/CMOS_WRITE */
#include <asm-generic/rtc.h>

struct cmos_rtc {
    struct rtc_device   *rtc;
    struct device       *dev;
    int         irq;
    struct resource     *iomem;

    void            (*wake_on)(struct device *);
    void            (*wake_off)(struct device *);

    u8          enabled_wake;
    u8          suspend_ctrl;

    /* newer hardware extends the original register set */
    u8          day_alrm;
    u8          mon_alrm;
    u8          century;
};

/* both platform and pnp busses use negative numbers for invalid irqs */
#define is_valid_irq(n)     ((n) > 0)

static const char driver_name[] = "rtc_cmos";

/* The RTC_INTR register may have e.g. RTC_PF set even if RTC_PIE is clear;
 * always mask it against the irq enable bits in RTC_CONTROL.  Bit values
 * are the same: PF==PIE, AF=AIE, UF=UIE; so RTC_IRQMASK works with both.
 */
#define RTC_IRQMASK (RTC_PF | RTC_AF | RTC_UF)

static inline int is_intr(u8 rtc_intr)
{
    if (!(rtc_intr & RTC_IRQF))
        return 0;
    return rtc_intr & RTC_IRQMASK;
}

/*----------------------------------------------------------------*/

/* Much modern x86 hardware has HPETs (10+ MHz timers) which, because
 * many BIOS programmers don't set up "sane mode" IRQ routing, are mostly
 * used in a broken "legacy replacement" mode.  The breakage includes
 * HPET #1 hijacking the IRQ for this RTC, and being unavailable for
 * other (better) use.
 *
 * When that broken mode is in use, platform glue provides a partial
 * emulation of hardware RTC IRQ facilities using HPET #1.  We don't
 * want to use HPET for anything except those IRQs though...
 */
#ifdef CONFIG_HPET_EMULATE_RTC
#include <asm/hpet.h>
#else

static inline int is_hpet_enabled(void)
{
    return 0;
}

static inline int hpet_mask_rtc_irq_bit(unsigned long mask)
{
    return 0;
}

static inline int hpet_set_rtc_irq_bit(unsigned long mask)
{
    return 0;
}

static inline int
hpet_set_alarm_time(unsigned char hrs, unsigned char min, unsigned char sec)
{
    return 0;
}

static inline int hpet_set_periodic_freq(unsigned long freq)
{
    return 0;
}

static inline int hpet_rtc_dropped_irq(void)
{
    return 0;
}

static inline int hpet_rtc_timer_init(void)
{
    return 0;
}

extern irq_handler_t hpet_rtc_interrupt;

static inline int hpet_register_irq_handler(irq_handler_t handler)
{
    return 0;
}

static inline int hpet_unregister_irq_handler(irq_handler_t handler)
{
    return 0;
}

#endif

/*----------------------------------------------------------------*/

#ifdef RTC_PORT

/* Most newer x86 systems have two register banks, the first used
 * for RTC and NVRAM and the second only for NVRAM.  Caller must
 * own rtc_lock ... and we won't worry about access during NMI.
 */
#define can_bank2   true

static inline unsigned char cmos_read_bank2(unsigned char addr)
{
    outb(addr, RTC_PORT(2));
    return inb(RTC_PORT(3));
}

static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
{
    outb(addr, RTC_PORT(2));
    outb(val, RTC_PORT(3));
}

#else

#define can_bank2   false

static inline unsigned char cmos_read_bank2(unsigned char addr)
{
    return 0;
}

static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
{
}

#endif

/*----------------------------------------------------------------*/

static int cmos_read_time(struct device *dev, struct rtc_time *t)
{
    /* REVISIT:  if the clock has a "century" register, use
     * that instead of the heuristic in get_rtc_time().
     * That'll make Y3K compatility (year > 2070) easy!
     */
    get_rtc_time(t);
    return 0;
}

static int cmos_set_time(struct device *dev, struct rtc_time *t)
{
    /* REVISIT:  set the "century" register if available
     *
     * NOTE: this ignores the issue whereby updating the seconds
     * takes effect exactly 500ms after we write the register.
     * (Also queueing and other delays before we get this far.)
     */
    return set_rtc_time(t);
}

static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t)
{
    struct cmos_rtc *cmos = dev_get_drvdata(dev);
    unsigned char   rtc_control;

    if (!is_valid_irq(cmos->irq))
        return -EIO;

    /* Basic alarms only support hour, minute, and seconds fields.
     * Some also support day and month, for alarms up to a year in
     * the future.
     */
    t->time.tm_mday = -1;
    t->time.tm_mon = -1;

    spin_lock_irq(&rtc_lock);
    t->time.tm_sec = CMOS_READ(RTC_SECONDS_ALARM);
    t->time.tm_min = CMOS_READ(RTC_MINUTES_ALARM);
    t->time.tm_hour = CMOS_READ(RTC_HOURS_ALARM);

    if (cmos->day_alrm) {
        /* ignore upper bits on readback per ACPI spec */
        t->time.tm_mday = CMOS_READ(cmos->day_alrm) & 0x3f;
        if (!t->time.tm_mday)
            t->time.tm_mday = -1;

        if (cmos->mon_alrm) {
            t->time.tm_mon = CMOS_READ(cmos->mon_alrm);
            if (!t->time.tm_mon)
                t->time.tm_mon = -1;
        }
    }

    rtc_control = CMOS_READ(RTC_CONTROL);
    spin_unlock_irq(&rtc_lock);

    if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
        if (((unsigned)t->time.tm_sec) < 0x60)
            t->time.tm_sec = bcd2bin(t->time.tm_sec);
        else
            t->time.tm_sec = -1;
        if (((unsigned)t->time.tm_min) < 0x60)
            t->time.tm_min = bcd2bin(t->time.tm_min);
        else
            t->time.tm_min = -1;
        if (((unsigned)t->time.tm_hour) < 0x24)
            t->time.tm_hour = bcd2bin(t->time.tm_hour);
        else
            t->time.tm_hour = -1;

        if (cmos->day_alrm) {
            if (((unsigned)t->time.tm_mday) <= 0x31)
                t->time.tm_mday = bcd2bin(t->time.tm_mday);
            else
                t->time.tm_mday = -1;

            if (cmos->mon_alrm) {
                if (((unsigned)t->time.tm_mon) <= 0x12)
                    t->time.tm_mon = bcd2bin(t->time.tm_mon)-1;
                else
                    t->time.tm_mon = -1;
            }
        }
    }
    t->time.tm_year = -1;

    t->enabled = !!(rtc_control & RTC_AIE);
    t->pending = 0;

    return 0;
}

static void cmos_checkintr(struct cmos_rtc *cmos, unsigned char rtc_control)
{
    unsigned char   rtc_intr;

    /* NOTE after changing RTC_xIE bits we always read INTR_FLAGS;
     * allegedly some older rtcs need that to handle irqs properly
     */
    rtc_intr = CMOS_READ(RTC_INTR_FLAGS);

    if (is_hpet_enabled())
        return;

    rtc_intr &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;
    if (is_intr(rtc_intr))
        rtc_update_irq(cmos->rtc, 1, rtc_intr);
}

static void cmos_irq_enable(struct cmos_rtc *cmos, unsigned char mask)
{
    unsigned char   rtc_control;

    /* flush any pending IRQ status, notably for update irqs,
     * before we enable new IRQs
     */
    rtc_control = CMOS_READ(RTC_CONTROL);
    cmos_checkintr(cmos, rtc_control);

    rtc_control |= mask;
    CMOS_WRITE(rtc_control, RTC_CONTROL);
    hpet_set_rtc_irq_bit(mask);

    cmos_checkintr(cmos, rtc_control);
}

static void cmos_irq_disable(struct cmos_rtc *cmos, unsigned char mask)
{
    unsigned char   rtc_control;

    rtc_control = CMOS_READ(RTC_CONTROL);
    rtc_control &= ~mask;
    CMOS_WRITE(rtc_control, RTC_CONTROL);
    hpet_mask_rtc_irq_bit(mask);

    cmos_checkintr(cmos, rtc_control);
}

static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
{
    struct cmos_rtc *cmos = dev_get_drvdata(dev);
       unsigned char   mon, mday, hrs, min, sec, rtc_control;

    if (!is_valid_irq(cmos->irq))
        return -EIO;

    mon = t->time.tm_mon + 1;
    mday = t->time.tm_mday;
    hrs = t->time.tm_hour;
    min = t->time.tm_min;
    sec = t->time.tm_sec;

    rtc_control = CMOS_READ(RTC_CONTROL);
    if (!(rtc_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
        /* Writing 0xff means "don't care" or "match all".  */
        mon = (mon <= 12) ? bin2bcd(mon) : 0xff;
        mday = (mday >= 1 && mday <= 31) ? bin2bcd(mday) : 0xff;
        hrs = (hrs < 24) ? bin2bcd(hrs) : 0xff;
        min = (min < 60) ? bin2bcd(min) : 0xff;
        sec = (sec < 60) ? bin2bcd(sec) : 0xff;
    }

    spin_lock_irq(&rtc_lock);

    /* next rtc irq must not be from previous alarm setting */
    cmos_irq_disable(cmos, RTC_AIE);

    /* update alarm */
    CMOS_WRITE(hrs, RTC_HOURS_ALARM);
    CMOS_WRITE(min, RTC_MINUTES_ALARM);
    CMOS_WRITE(sec, RTC_SECONDS_ALARM);

    /* the system may support an "enhanced" alarm */
    if (cmos->day_alrm) {
        CMOS_WRITE(mday, cmos->day_alrm);
        if (cmos->mon_alrm)
            CMOS_WRITE(mon, cmos->mon_alrm);
    }

    /* FIXME the HPET alarm glue currently ignores day_alrm
     * and mon_alrm ...
     */
    hpet_set_alarm_time(t->time.tm_hour, t->time.tm_min, t->time.tm_sec);

    if (t->enabled)
        cmos_irq_enable(cmos, RTC_AIE);

    spin_unlock_irq(&rtc_lock);

    return 0;
}

static int cmos_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
    struct cmos_rtc *cmos = dev_get_drvdata(dev);
    unsigned long   flags;

    if (!is_valid_irq(cmos->irq))
        return -EINVAL;

    spin_lock_irqsave(&rtc_lock, flags);

    if (enabled)
        cmos_irq_enable(cmos, RTC_AIE);
    else
        cmos_irq_disable(cmos, RTC_AIE);

    spin_unlock_irqrestore(&rtc_lock, flags);
    return 0;
}

#if defined(CONFIG_RTC_INTF_PROC) || defined(CONFIG_RTC_INTF_PROC_MODULE)

static int cmos_procfs(struct device *dev, struct seq_file *seq)
{
    struct cmos_rtc *cmos = dev_get_drvdata(dev);
    unsigned char   rtc_control, valid;

    spin_lock_irq(&rtc_lock);
    rtc_control = CMOS_READ(RTC_CONTROL);
    valid = CMOS_READ(RTC_VALID);
    spin_unlock_irq(&rtc_lock);

    /* NOTE:  at least ICH6 reports battery status using a different
     * (non-RTC) bit; and SQWE is ignored on many current systems.
     */
    return seq_printf(seq,
            "periodic_IRQ\t: %s\n"
            "update_IRQ\t: %s\n"
            "HPET_emulated\t: %s\n"
            // "square_wave\t: %s\n"
            "BCD\t\t: %s\n"
            "DST_enable\t: %s\n"
            "periodic_freq\t: %d\n"
            "batt_status\t: %s\n",
            (rtc_control & RTC_PIE) ? "yes" : "no",
            (rtc_control & RTC_UIE) ? "yes" : "no",
            is_hpet_enabled() ? "yes" : "no",
            // (rtc_control & RTC_SQWE) ? "yes" : "no",
            (rtc_control & RTC_DM_BINARY) ? "no" : "yes",
            (rtc_control & RTC_DST_EN) ? "yes" : "no",
            cmos->rtc->irq_freq,
            (valid & RTC_VRT) ? "okay" : "dead");
}

#else
#define cmos_procfs NULL
#endif

static const struct rtc_class_ops cmos_rtc_ops = {
    .read_time      = cmos_read_time,
    .set_time       = cmos_set_time,
    .read_alarm     = cmos_read_alarm,
    .set_alarm      = cmos_set_alarm,
    .proc           = cmos_procfs,
    .alarm_irq_enable   = cmos_alarm_irq_enable,
};

/*----------------------------------------------------------------*/

/*
 * All these chips have at least 64 bytes of address space, shared by
 * RTC registers and NVRAM.  Most of those bytes of NVRAM are used
 * by boot firmware.  Modern chips have 128 or 256 bytes.
 */

#define NVRAM_OFFSET    (RTC_REG_D + 1)

static ssize_t
cmos_nvram_read(struct file *filp, struct kobject *kobj,
        struct bin_attribute *attr,
        char *buf, loff_t off, size_t count)
{
    int retval;

    if (unlikely(off >= attr->size))
        return 0;
    if (unlikely(off < 0))
        return -EINVAL;
    if ((off + count) > attr->size)
        count = attr->size - off;

    off += NVRAM_OFFSET;
    spin_lock_irq(&rtc_lock);
    for (retval = 0; count; count--, off++, retval++) {
        if (off < 128)
            *buf++ = CMOS_READ(off);
        else if (can_bank2)
            *buf++ = cmos_read_bank2(off);
        else
            break;
    }
    spin_unlock_irq(&rtc_lock);

    return retval;
}

static ssize_t
cmos_nvram_write(struct file *filp, struct kobject *kobj,
        struct bin_attribute *attr,
        char *buf, loff_t off, size_t count)
{
    struct cmos_rtc *cmos;
    int     retval;

    cmos = dev_get_drvdata(container_of(kobj, struct device, kobj));
    if (unlikely(off >= attr->size))
        return -EFBIG;
    if (unlikely(off < 0))
        return -EINVAL;
    if ((off + count) > attr->size)
        count = attr->size - off;

    /* NOTE:  on at least PCs and Ataris, the boot firmware uses a
     * checksum on part of the NVRAM data.  That's currently ignored
     * here.  If userspace is smart enough to know what fields of
     * NVRAM to update, updating checksums is also part of its job.
     */
    off += NVRAM_OFFSET;
    spin_lock_irq(&rtc_lock);
    for (retval = 0; count; count--, off++, retval++) {
        /* don't trash RTC registers */
        if (off == cmos->day_alrm
                || off == cmos->mon_alrm
                || off == cmos->century)
            buf++;
        else if (off < 128)
            CMOS_WRITE(*buf++, off);
        else if (can_bank2)
            cmos_write_bank2(*buf++, off);
        else
            break;
    }
    spin_unlock_irq(&rtc_lock);

    return retval;
}

static struct bin_attribute nvram = {
    .attr = {
        .name   = "nvram",
        .mode   = S_IRUGO | S_IWUSR,
    },

    .read   = cmos_nvram_read,
    .write  = cmos_nvram_write,
    /* size gets set up later */
};

/*----------------------------------------------------------------*/

static struct cmos_rtc  cmos_rtc;

static irqreturn_t cmos_interrupt(int irq, void *p)
{
    u8      irqstat;
    u8      rtc_control;

    spin_lock(&rtc_lock);

    /* When the HPET interrupt handler calls us, the interrupt
     * status is passed as arg1 instead of the irq number.  But
     * always clear irq status, even when HPET is in the way.
     *
     * Note that HPET and RTC are almost certainly out of phase,
     * giving different IRQ status ...
     */
    irqstat = CMOS_READ(RTC_INTR_FLAGS);
    rtc_control = CMOS_READ(RTC_CONTROL);
    if (is_hpet_enabled())
        irqstat = (unsigned long)irq & 0xF0;
    irqstat &= (rtc_control & RTC_IRQMASK) | RTC_IRQF;

    /* All Linux RTC alarms should be treated as if they were oneshot.
     * Similar code may be needed in system wakeup paths, in case the
     * alarm woke the system.
     */
    if (irqstat & RTC_AIE) {
        rtc_control &= ~RTC_AIE;
        CMOS_WRITE(rtc_control, RTC_CONTROL);
        hpet_mask_rtc_irq_bit(RTC_AIE);

        CMOS_READ(RTC_INTR_FLAGS);
    }
    spin_unlock(&rtc_lock);

    if (is_intr(irqstat)) {
        rtc_update_irq(p, 1, irqstat);
        return IRQ_HANDLED;
    } else
        return IRQ_NONE;
}

#ifdef  CONFIG_PNP
#define INITSECTION

#else
#define INITSECTION __init
#endif

static int INITSECTION
cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
{
    struct cmos_rtc_board_info  *info = dev->platform_data;
    int             retval = 0;
    unsigned char           rtc_control;
    unsigned            address_space;

    /* there can be only one ... */
    if (cmos_rtc.dev)
        return -EBUSY;

    if (!ports)
        return -ENODEV;

    /* Claim I/O ports ASAP, minimizing conflict with legacy driver.
     *
     * REVISIT non-x86 systems may instead use memory space resources
     * (needing ioremap etc), not i/o space resources like this ...
     */
    ports = request_region(ports->start,
            resource_size(ports),
            driver_name);
    if (!ports) {
        dev_dbg(dev, "i/o registers already in use\n");
        return -EBUSY;
    }

    cmos_rtc.irq = rtc_irq;
    cmos_rtc.iomem = ports;

    /* Heuristic to deduce NVRAM size ... do what the legacy NVRAM
     * driver did, but don't reject unknown configs.   Old hardware
     * won't address 128 bytes.  Newer chips have multiple banks,
     * though they may not be listed in one I/O resource.
     */
#if defined(CONFIG_ATARI)
    address_space = 64;
#elif defined(__i386__) || defined(__x86_64__) || defined(__arm__) \
            || defined(__sparc__) || defined(__mips__) \
            || defined(__powerpc__)
    address_space = 128;
#else
#warning Assuming 128 bytes of RTC+NVRAM address space, not 64 bytes.
    address_space = 128;
#endif
    if (can_bank2 && ports->end > (ports->start + 1))
        address_space = 256;

    /* For ACPI systems extension info comes from the FADT.  On others,
     * board specific setup provides it as appropriate.  Systems where
     * the alarm IRQ isn't automatically a wakeup IRQ (like ACPI, and
     * some almost-clones) can provide hooks to make that behave.
     *
     * Note that ACPI doesn't preclude putting these registers into
     * "extended" areas of the chip, including some that we won't yet
     * expect CMOS_READ and friends to handle.
     */
    if (info) {
        if (info->rtc_day_alarm && info->rtc_day_alarm < 128)
            cmos_rtc.day_alrm = info->rtc_day_alarm;
        if (info->rtc_mon_alarm && info->rtc_mon_alarm < 128)
            cmos_rtc.mon_alrm = info->rtc_mon_alarm;
        if (info->rtc_century && info->rtc_century < 128)
            cmos_rtc.century = info->rtc_century;

        if (info->wake_on && info->wake_off) {
            cmos_rtc.wake_on = info->wake_on;
            cmos_rtc.wake_off = info->wake_off;
        }
    }

    cmos_rtc.dev = dev;
    dev_set_drvdata(dev, &cmos_rtc);

    cmos_rtc.rtc = rtc_device_register(driver_name, dev,
                &cmos_rtc_ops, THIS_MODULE);
    if (IS_ERR(cmos_rtc.rtc)) {
        retval = PTR_ERR(cmos_rtc.rtc);
        goto cleanup0;
    }

    rename_region(ports, dev_name(&cmos_rtc.rtc->dev));

    spin_lock_irq(&rtc_lock);

    /* force periodic irq to CMOS reset default of 1024Hz;
     *
     * REVISIT it's been reported that at least one x86_64 ALI mobo
     * doesn't use 32KHz here ... for portability we might need to
     * do something about other clock frequencies.
     */
    cmos_rtc.rtc->irq_freq = 1024;
    hpet_set_periodic_freq(cmos_rtc.rtc->irq_freq);
    CMOS_WRITE(RTC_REF_CLCK_32KHZ | 0x06, RTC_FREQ_SELECT);

    /* disable irqs */
    cmos_irq_disable(&cmos_rtc, RTC_PIE | RTC_AIE | RTC_UIE);

    rtc_control = CMOS_READ(RTC_CONTROL);

    spin_unlock_irq(&rtc_lock);

    /* FIXME:
     * <asm-generic/rtc.h> doesn't know 12-hour mode either.
     */
       if (is_valid_irq(rtc_irq) && !(rtc_control & RTC_24H)) {
        dev_warn(dev, "only 24-hr supported\n");
        retval = -ENXIO;
        goto cleanup1;
    }

    if (is_valid_irq(rtc_irq)) {
        irq_handler_t rtc_cmos_int_handler;

        if (is_hpet_enabled()) {
            int err;

            rtc_cmos_int_handler = hpet_rtc_interrupt;
            err = hpet_register_irq_handler(cmos_interrupt);
            if (err != 0) {
                printk(KERN_WARNING "hpet_register_irq_handler "
                        " failed in rtc_init().");
                goto cleanup1;
            }
        } else
            rtc_cmos_int_handler = cmos_interrupt;

        retval = request_irq(rtc_irq, rtc_cmos_int_handler,
                0, dev_name(&cmos_rtc.rtc->dev),
                cmos_rtc.rtc);
        if (retval < 0) {
            dev_dbg(dev, "IRQ %d is already in use\n", rtc_irq);
            goto cleanup1;
        }
    }
    hpet_rtc_timer_init();

    /* export at least the first block of NVRAM */
    nvram.size = address_space - NVRAM_OFFSET;
    retval = sysfs_create_bin_file(&dev->kobj, &nvram);
    if (retval < 0) {
        dev_dbg(dev, "can't create nvram file? %d\n", retval);
        goto cleanup2;
    }

    pr_info("%s: %s%s, %zd bytes nvram%s\n",
        dev_name(&cmos_rtc.rtc->dev),
        !is_valid_irq(rtc_irq) ? "no alarms" :
            cmos_rtc.mon_alrm ? "alarms up to one year" :
            cmos_rtc.day_alrm ? "alarms up to one month" :
            "alarms up to one day",
        cmos_rtc.century ? ", y3k" : "",
        nvram.size,
        is_hpet_enabled() ? ", hpet irqs" : "");

    return 0;

cleanup2:
    if (is_valid_irq(rtc_irq))
        free_irq(rtc_irq, cmos_rtc.rtc);
cleanup1:
    cmos_rtc.dev = NULL;
    rtc_device_unregister(cmos_rtc.rtc);
cleanup0:
    release_region(ports->start, resource_size(ports));
    return retval;
}

static void cmos_do_shutdown(void)
{
    spin_lock_irq(&rtc_lock);
    cmos_irq_disable(&cmos_rtc, RTC_IRQMASK);
    spin_unlock_irq(&rtc_lock);
}

static void __exit cmos_do_remove(struct device *dev)
{
    struct cmos_rtc *cmos = dev_get_drvdata(dev);
    struct resource *ports;

    cmos_do_shutdown();

    sysfs_remove_bin_file(&dev->kobj, &nvram);

    if (is_valid_irq(cmos->irq)) {
        free_irq(cmos->irq, cmos->rtc);
        hpet_unregister_irq_handler(cmos_interrupt);
    }

    rtc_device_unregister(cmos->rtc);
    cmos->rtc = NULL;

    ports = cmos->iomem;
    release_region(ports->start, resource_size(ports));
    cmos->iomem = NULL;

    cmos->dev = NULL;
    dev_set_drvdata(dev, NULL);
}

#ifdef  CONFIG_PM

static int cmos_suspend(struct device *dev)
{
    struct cmos_rtc *cmos = dev_get_drvdata(dev);
    unsigned char   tmp;

    /* only the alarm might be a wakeup event source */
    spin_lock_irq(&rtc_lock);
    cmos->suspend_ctrl = tmp = CMOS_READ(RTC_CONTROL);
    if (tmp & (RTC_PIE|RTC_AIE|RTC_UIE)) {
        unsigned char   mask;

        if (device_may_wakeup(dev))
            mask = RTC_IRQMASK & ~RTC_AIE;
        else
            mask = RTC_IRQMASK;
        tmp &= ~mask;
        CMOS_WRITE(tmp, RTC_CONTROL);

        /* shut down hpet emulation - we don't need it for alarm */
        hpet_mask_rtc_irq_bit(RTC_PIE|RTC_AIE|RTC_UIE);
        cmos_checkintr(cmos, tmp);
    }
    spin_unlock_irq(&rtc_lock);

    if (tmp & RTC_AIE) {
        cmos->enabled_wake = 1;
        if (cmos->wake_on)
            cmos->wake_on(dev);
        else
            enable_irq_wake(cmos->irq);
    }

    pr_debug("%s: suspend%s, ctrl %02x\n",
            dev_name(&cmos_rtc.rtc->dev),
            (tmp & RTC_AIE) ? ", alarm may wake" : "",
            tmp);

    return 0;
}

/* We want RTC alarms to wake us from e.g. ACPI G2/S5 "soft off", even
 * after a detour through G3 "mechanical off", although the ACPI spec
 * says wakeup should only work from G1/S4 "hibernate".  To most users,
 * distinctions between S4 and S5 are pointless.  So when the hardware
 * allows, don't draw that distinction.
 */
static inline int cmos_poweroff(struct device *dev)
{
    return cmos_suspend(dev);
}

static int cmos_resume(struct device *dev)
{
    struct cmos_rtc *cmos = dev_get_drvdata(dev);
    unsigned char   tmp = cmos->suspend_ctrl;

    /* re-enable any irqs previously active */
    if (tmp & RTC_IRQMASK) {
        unsigned char   mask;

        if (cmos->enabled_wake) {
            if (cmos->wake_off)
                cmos->wake_off(dev);
            else
                disable_irq_wake(cmos->irq);
            cmos->enabled_wake = 0;
        }

        spin_lock_irq(&rtc_lock);
        do {
            CMOS_WRITE(tmp, RTC_CONTROL);
            hpet_set_rtc_irq_bit(tmp & RTC_IRQMASK);

            mask = CMOS_READ(RTC_INTR_FLAGS);
            mask &= (tmp & RTC_IRQMASK) | RTC_IRQF;
            if (!is_hpet_enabled() || !is_intr(mask))
                break;

            /* force one-shot behavior if HPET blocked
             * the wake alarm's irq
             */
            rtc_update_irq(cmos->rtc, 1, mask);
            tmp &= ~RTC_AIE;
            hpet_mask_rtc_irq_bit(RTC_AIE);
        } while (mask & RTC_AIE);
        spin_unlock_irq(&rtc_lock);
    }

    pr_debug("%s: resume, ctrl %02x\n",
            dev_name(&cmos_rtc.rtc->dev),
            tmp);

    return 0;
}

static SIMPLE_DEV_PM_OPS(cmos_pm_ops, cmos_suspend, cmos_resume);

#else

static inline int cmos_poweroff(struct device *dev)
{
    return -ENOSYS;
}

#endif

/*----------------------------------------------------------------*/

/* On non-x86 systems, a "CMOS" RTC lives most naturally on platform_bus.
 * ACPI systems always list these as PNPACPI devices, and pre-ACPI PCs
 * probably list them in similar PNPBIOS tables; so PNP is more common.
 *
 * We don't use legacy "poke at the hardware" probing.  Ancient PCs that
 * predate even PNPBIOS should set up platform_bus devices.
 */

#ifdef  CONFIG_ACPI

#include <linux/acpi.h>

static u32 rtc_handler(void *context)
{
    struct device *dev = context;

    pm_wakeup_event(dev, 0);
    acpi_clear_event(ACPI_EVENT_RTC);
    acpi_disable_event(ACPI_EVENT_RTC, 0);
    return ACPI_INTERRUPT_HANDLED;
}

static inline void rtc_wake_setup(struct device *dev)
{
    acpi_install_fixed_event_handler(ACPI_EVENT_RTC, rtc_handler, dev);
    /*
     * After the RTC handler is installed, the Fixed_RTC event should
     * be disabled. Only when the RTC alarm is set will it be enabled.
     */
    acpi_clear_event(ACPI_EVENT_RTC);
    acpi_disable_event(ACPI_EVENT_RTC, 0);
}

static void rtc_wake_on(struct device *dev)
{
    acpi_clear_event(ACPI_EVENT_RTC);
    acpi_enable_event(ACPI_EVENT_RTC, 0);
}

static void rtc_wake_off(struct device *dev)
{
    acpi_disable_event(ACPI_EVENT_RTC, 0);
}

/* Every ACPI platform has a mc146818 compatible "cmos rtc".  Here we find
 * its device node and pass extra config data.  This helps its driver use
 * capabilities that the now-obsolete mc146818 didn't have, and informs it
 * that this board's RTC is wakeup-capable (per ACPI spec).
 */
static struct cmos_rtc_board_info acpi_rtc_info;

static void __devinit
cmos_wake_setup(struct device *dev)
{
    if (acpi_disabled)
        return;

    rtc_wake_setup(dev);
    acpi_rtc_info.wake_on = rtc_wake_on;
    acpi_rtc_info.wake_off = rtc_wake_off;

    /* workaround bug in some ACPI tables */
    if (acpi_gbl_FADT.month_alarm && !acpi_gbl_FADT.day_alarm) {
        dev_dbg(dev, "bogus FADT month_alarm (%d)\n",
            acpi_gbl_FADT.month_alarm);
        acpi_gbl_FADT.month_alarm = 0;
    }

    acpi_rtc_info.rtc_day_alarm = acpi_gbl_FADT.day_alarm;
    acpi_rtc_info.rtc_mon_alarm = acpi_gbl_FADT.month_alarm;
    acpi_rtc_info.rtc_century = acpi_gbl_FADT.century;

    /* NOTE:  S4_RTC_WAKE is NOT currently useful to Linux */
    if (acpi_gbl_FADT.flags & ACPI_FADT_S4_RTC_WAKE)
        dev_info(dev, "RTC can wake from S4\n");

    dev->platform_data = &acpi_rtc_info;

    /* RTC always wakes from S1/S2/S3, and often S4/STD */
    device_init_wakeup(dev, 1);
}

#else

static void __devinit
cmos_wake_setup(struct device *dev)
{
}

#endif

#ifdef  CONFIG_PNP

#include <linux/pnp.h>

static int __devinit
cmos_pnp_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
{
    cmos_wake_setup(&pnp->dev);

    if (pnp_port_start(pnp,0) == 0x70 && !pnp_irq_valid(pnp,0))
        /* Some machines contain a PNP entry for the RTC, but
         * don't define the IRQ. It should always be safe to
         * hardcode it in these cases
         */
        return cmos_do_probe(&pnp->dev,
                pnp_get_resource(pnp, IORESOURCE_IO, 0), 8);
    else
        return cmos_do_probe(&pnp->dev,
                pnp_get_resource(pnp, IORESOURCE_IO, 0),
                pnp_irq(pnp, 0));
}

static void __exit cmos_pnp_remove(struct pnp_dev *pnp)
{
    cmos_do_remove(&pnp->dev);
}

#ifdef  CONFIG_PM

static int cmos_pnp_suspend(struct pnp_dev *pnp, pm_message_t mesg)
{
    return cmos_suspend(&pnp->dev);
}

static int cmos_pnp_resume(struct pnp_dev *pnp)
{
    return cmos_resume(&pnp->dev);
}

#else
#define cmos_pnp_suspend    NULL
#define cmos_pnp_resume     NULL
#endif

static void cmos_pnp_shutdown(struct pnp_dev *pnp)
{
    if (system_state == SYSTEM_POWER_OFF && !cmos_poweroff(&pnp->dev))
        return;

    cmos_do_shutdown();
}

static const struct pnp_device_id rtc_ids[] = {
    { .id = "PNP0b00", },
    { .id = "PNP0b01", },
    { .id = "PNP0b02", },
    { },
};
MODULE_DEVICE_TABLE(pnp, rtc_ids);

static struct pnp_driver cmos_pnp_driver = {
    .name       = (char *) driver_name,
    .id_table   = rtc_ids,
    .probe      = cmos_pnp_probe,
    .remove     = __exit_p(cmos_pnp_remove),
    .shutdown   = cmos_pnp_shutdown,

    /* flag ensures resume() gets called, and stops syslog spam */
    .flags      = PNP_DRIVER_RES_DO_NOT_CHANGE,
    .suspend    = cmos_pnp_suspend,
    .resume     = cmos_pnp_resume,
};

#endif  /* CONFIG_PNP */

#ifdef CONFIG_OF
static const struct of_device_id of_cmos_match[] = {
    {
        .compatible = "motorola,mc146818",
    },
    { },
};
MODULE_DEVICE_TABLE(of, of_cmos_match);

static __init void cmos_of_init(struct platform_device *pdev)
{
    struct device_node *node = pdev->dev.of_node;
    struct rtc_time time;
    int ret;
    const __be32 *val;

    if (!node)
        return;

    val = of_get_property(node, "ctrl-reg", NULL);
    if (val)
        CMOS_WRITE(be32_to_cpup(val), RTC_CONTROL);

    val = of_get_property(node, "freq-reg", NULL);
    if (val)
        CMOS_WRITE(be32_to_cpup(val), RTC_FREQ_SELECT);

    get_rtc_time(&time);
    ret = rtc_valid_tm(&time);
    if (ret) {
        struct rtc_time def_time = {
            .tm_year = 1,
            .tm_mday = 1,
        };
        set_rtc_time(&def_time);
    }
}
#else
static inline void cmos_of_init(struct platform_device *pdev) {}
#define of_cmos_match NULL
#endif
/*----------------------------------------------------------------*/

/* Platform setup should have set up an RTC device, when PNP is
 * unavailable ... this could happen even on (older) PCs.
 */

static int __init cmos_platform_probe(struct platform_device *pdev)
{
    cmos_of_init(pdev);
    cmos_wake_setup(&pdev->dev);
    return cmos_do_probe(&pdev->dev,
            platform_get_resource(pdev, IORESOURCE_IO, 0),
            platform_get_irq(pdev, 0));
}

static int __exit cmos_platform_remove(struct platform_device *pdev)
{
    cmos_do_remove(&pdev->dev);
    return 0;
}

static void cmos_platform_shutdown(struct platform_device *pdev)
{
    if (system_state == SYSTEM_POWER_OFF && !cmos_poweroff(&pdev->dev))
        return;

    cmos_do_shutdown();
}

/* work with hotplug and coldplug */
MODULE_ALIAS("platform:rtc_cmos");

static struct platform_driver cmos_platform_driver = {
    .remove     = __exit_p(cmos_platform_remove),
    .shutdown   = cmos_platform_shutdown,
    .driver = {
        .name       = (char *) driver_name,
#ifdef CONFIG_PM
        .pm     = &cmos_pm_ops,
#endif
        .of_match_table = of_cmos_match,
    }
};

#ifdef CONFIG_PNP
static bool pnp_driver_registered;
#endif
static bool platform_driver_registered;

static int __init cmos_init(void)
{
    int retval = 0;

#ifdef  CONFIG_PNP
    retval = pnp_register_driver(&cmos_pnp_driver);
    if (retval == 0)
        pnp_driver_registered = true;
#endif

    if (!cmos_rtc.dev) {
        retval = platform_driver_probe(&cmos_platform_driver,
                           cmos_platform_probe);
        if (retval == 0)
            platform_driver_registered = true;
    }

    if (retval == 0)
        return 0;

#ifdef  CONFIG_PNP
    if (pnp_driver_registered)
        pnp_unregister_driver(&cmos_pnp_driver);
#endif
    return retval;
}
module_init(cmos_init);

static void __exit cmos_exit(void)
{
#ifdef  CONFIG_PNP
    if (pnp_driver_registered)
        pnp_unregister_driver(&cmos_pnp_driver);
#endif
    if (platform_driver_registered)
        platform_driver_unregister(&cmos_platform_driver);
}
module_exit(cmos_exit);


MODULE_AUTHOR("David Brownell");
MODULE_DESCRIPTION("Driver for PC-style 'CMOS' RTCs");
MODULE_LICENSE("GPL");