/*
 * RTC related functions
 */
#include <linux/platform_device.h>
#include <linux/mc146818rtc.h>
#include <linux/acpi.h>
#include <linux/bcd.h>
#include <linux/pnp.h>
#include <linux/of.h>

#include <asm/vsyscall.h>
#include <asm/x86_init.h>
#include <asm/time.h>

#ifdef CONFIG_X86_32
/*
 * This is a special lock that is owned by the CPU and holds the index
 * register we are working with.  It is required for NMI access to the
 * CMOS/RTC registers.  See include/asm-i386/mc146818rtc.h for details.
 */
volatile unsigned long cmos_lock;
EXPORT_SYMBOL(cmos_lock);
#endif /* CONFIG_X86_32 */

/* For two digit years assume time is always after that */
#define CMOS_YEARS_OFFS 2000

DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL(rtc_lock);

/*
 * In order to set the CMOS clock precisely, set_rtc_mmss has to be
 * called 500 ms after the second nowtime has started, because when
 * nowtime is written into the registers of the CMOS clock, it will
 * jump to the next second precisely 500 ms later. Check the Motorola
 * MC146818A or Dallas DS12887 data sheet for details.
 *
 * BUG: This routine does not handle hour overflow properly; it just
 *      sets the minutes. Usually you'll only notice that after reboot!
 */
int mach_set_rtc_mmss(unsigned long nowtime)
{
        int real_seconds, real_minutes, cmos_minutes;
        unsigned char save_control, save_freq_select;
        int retval = 0;

         /* tell the clock it's being set */
        save_control = CMOS_READ(RTC_CONTROL);
        CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);

        /* stop and reset prescaler */
        save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
        CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);

        cmos_minutes = CMOS_READ(RTC_MINUTES);
        if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
                cmos_minutes = bcd2bin(cmos_minutes);

        /*
         * since we're only adjusting minutes and seconds,
         * don't interfere with hour overflow. This avoids
         * messing with unknown time zones but requires your
         * RTC not to be off by more than 15 minutes
         */
        real_seconds = nowtime % 60;
        real_minutes = nowtime / 60;
        /* correct for half hour time zone */
        if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
                real_minutes += 30;
        real_minutes %= 60;

        if (abs(real_minutes - cmos_minutes) < 30) {
                if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
                        real_seconds = bin2bcd(real_seconds);
                        real_minutes = bin2bcd(real_minutes);
                }
                CMOS_WRITE(real_seconds, RTC_SECONDS);
                CMOS_WRITE(real_minutes, RTC_MINUTES);
        } else {
                printk_once(KERN_NOTICE
                       "set_rtc_mmss: can't update from %d to %d\n",
                       cmos_minutes, real_minutes);
                retval = -1;
        }

        /* The following flags have to be released exactly in this order,
         * otherwise the DS12887 (popular MC146818A clone with integrated
         * battery and quartz) will not reset the oscillator and will not
         * update precisely 500 ms later. You won't find this mentioned in
         * the Dallas Semiconductor data sheets, but who believes data
         * sheets anyway ...                           -- Markus Kuhn
         */
        CMOS_WRITE(save_control, RTC_CONTROL);
        CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);

        return retval;
}

unsigned long mach_get_cmos_time(void)
{
        unsigned int status, year, mon, day, hour, min, sec, century = 0;

        /*
         * If UIP is clear, then we have >= 244 microseconds before
         * RTC registers will be updated.  Spec sheet says that this
         * is the reliable way to read RTC - registers. If UIP is set
         * then the register access might be invalid.
         */
        while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
                cpu_relax();

        sec = CMOS_READ(RTC_SECONDS);
        min = CMOS_READ(RTC_MINUTES);
        hour = CMOS_READ(RTC_HOURS);
        day = CMOS_READ(RTC_DAY_OF_MONTH);
        mon = CMOS_READ(RTC_MONTH);
        year = CMOS_READ(RTC_YEAR);

#ifdef CONFIG_ACPI
        if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
            acpi_gbl_FADT.century)
                century = CMOS_READ(acpi_gbl_FADT.century);
#endif

        status = CMOS_READ(RTC_CONTROL);
        WARN_ON_ONCE(RTC_ALWAYS_BCD && (status & RTC_DM_BINARY));

        if (RTC_ALWAYS_BCD || !(status & RTC_DM_BINARY)) {
                sec = bcd2bin(sec);
                min = bcd2bin(min);
                hour = bcd2bin(hour);
                day = bcd2bin(day);
                mon = bcd2bin(mon);
                year = bcd2bin(year);
        }

        if (century) {
                century = bcd2bin(century);
                year += century * 100;
                printk(KERN_INFO "Extended CMOS year: %d\n", century * 100);
        } else
                year += CMOS_YEARS_OFFS;

        return mktime(year, mon, day, hour, min, sec);
}

/* Routines for accessing the CMOS RAM/RTC. */
unsigned char rtc_cmos_read(unsigned char addr)
{
        unsigned char val;

        lock_cmos_prefix(addr);
        outb(addr, RTC_PORT(0));
        val = inb(RTC_PORT(1));
        lock_cmos_suffix(addr);

        return val;
}
EXPORT_SYMBOL(rtc_cmos_read);

void rtc_cmos_write(unsigned char val, unsigned char addr)
{
        lock_cmos_prefix(addr);
        outb(addr, RTC_PORT(0));
        outb(val, RTC_PORT(1));
        lock_cmos_suffix(addr);
}
EXPORT_SYMBOL(rtc_cmos_write);

int update_persistent_clock(struct timespec now)
{
        unsigned long flags;
        int retval;

        spin_lock_irqsave(&rtc_lock, flags);
        retval = x86_platform.set_wallclock(now.tv_sec);
        spin_unlock_irqrestore(&rtc_lock, flags);

        return retval;
}

/* not static: needed by APM */
void read_persistent_clock(struct timespec *ts)
{
        unsigned long retval, flags;

        spin_lock_irqsave(&rtc_lock, flags);
        retval = x86_platform.get_wallclock();
        spin_unlock_irqrestore(&rtc_lock, flags);

        ts->tv_sec = retval;
        ts->tv_nsec = 0;
}

unsigned long long native_read_tsc(void)
{
        return __native_read_tsc();
}
EXPORT_SYMBOL(native_read_tsc);


static struct resource rtc_resources[] = {
        [0] = {
                .start  = RTC_PORT(0),
                .end    = RTC_PORT(1),
                .flags  = IORESOURCE_IO,
        },
        [1] = {
                .start  = RTC_IRQ,
                .end    = RTC_IRQ,
                .flags  = IORESOURCE_IRQ,
        }
};

static struct platform_device rtc_device = {
        .name           = "rtc_cmos",
        .id             = -1,
        .resource       = rtc_resources,
        .num_resources  = ARRAY_SIZE(rtc_resources),
};

static __init int add_rtc_cmos(void)
{
#ifdef CONFIG_PNP
        static const char *ids[] __initconst =
            { "PNP0b00", "PNP0b01", "PNP0b02", };
        struct pnp_dev *dev;
        struct pnp_id *id;
        int i;

        pnp_for_each_dev(dev) {
                for (id = dev->id; id; id = id->next) {
                        for (i = 0; i < ARRAY_SIZE(ids); i++) {
                                if (compare_pnp_id(id, ids[i]) != 0)
                                        return 0;
                        }
                }
        }
#endif
        if (of_have_populated_dt())
                return 0;

        platform_device_register(&rtc_device);
        dev_info(&rtc_device.dev,
                 "registered platform RTC device (no PNP device found)\n");

        return 0;
}
device_initcall(add_rtc_cmos);