// SPDX-License-Identifier: GPL-2.0
/*
 * linux/arch/sh/boards/sh03/rtc.c -- CTP/PCI-SH03 on-chip RTC support
 *
 *  Copyright (C) 2004  Saito.K & Jeanne(ksaito@interface.co.jp)
 *
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/time.h>
#include <linux/bcd.h>
#include <linux/spinlock.h>
#include <linux/io.h>
#include <linux/rtc.h>
#include <linux/platform_device.h>

#define RTC_BASE        0xb0000000
#define RTC_SEC1        (RTC_BASE + 0)
#define RTC_SEC10       (RTC_BASE + 1)
#define RTC_MIN1        (RTC_BASE + 2)
#define RTC_MIN10       (RTC_BASE + 3)
#define RTC_HOU1        (RTC_BASE + 4)
#define RTC_HOU10       (RTC_BASE + 5)
#define RTC_WEE1        (RTC_BASE + 6)
#define RTC_DAY1        (RTC_BASE + 7)
#define RTC_DAY10       (RTC_BASE + 8)
#define RTC_MON1        (RTC_BASE + 9)
#define RTC_MON10       (RTC_BASE + 10)
#define RTC_YEA1        (RTC_BASE + 11)
#define RTC_YEA10       (RTC_BASE + 12)
#define RTC_YEA100      (RTC_BASE + 13)
#define RTC_YEA1000     (RTC_BASE + 14)
#define RTC_CTL         (RTC_BASE + 15)
#define RTC_BUSY        1
#define RTC_STOP        2

static DEFINE_SPINLOCK(sh03_rtc_lock);

static int sh03_rtc_gettimeofday(struct device *dev, struct rtc_time *tm)
{
        unsigned int year, mon, day, hour, min, sec;

        spin_lock(&sh03_rtc_lock);
 again:
        do {
                sec  = (__raw_readb(RTC_SEC1) & 0xf) + (__raw_readb(RTC_SEC10) & 0x7) * 10;
                min  = (__raw_readb(RTC_MIN1) & 0xf) + (__raw_readb(RTC_MIN10) & 0xf) * 10;
                hour = (__raw_readb(RTC_HOU1) & 0xf) + (__raw_readb(RTC_HOU10) & 0xf) * 10;
                day  = (__raw_readb(RTC_DAY1) & 0xf) + (__raw_readb(RTC_DAY10) & 0xf) * 10;
                mon  = (__raw_readb(RTC_MON1) & 0xf) + (__raw_readb(RTC_MON10) & 0xf) * 10;
                year = (__raw_readb(RTC_YEA1) & 0xf) + (__raw_readb(RTC_YEA10) & 0xf) * 10
                     + (__raw_readb(RTC_YEA100 ) & 0xf) * 100
                     + (__raw_readb(RTC_YEA1000) & 0xf) * 1000;
        } while (sec != (__raw_readb(RTC_SEC1) & 0xf) + (__raw_readb(RTC_SEC10) & 0x7) * 10);
        if (year == 0 || mon < 1 || mon > 12 || day > 31 || day < 1 ||
            hour > 23 || min > 59 || sec > 59) {
                printk(KERN_ERR
                       "SH-03 RTC: invalid value, resetting to 1 Jan 2000\n");
                printk("year=%d, mon=%d, day=%d, hour=%d, min=%d, sec=%d\n",
                       year, mon, day, hour, min, sec);

                __raw_writeb(0, RTC_SEC1); __raw_writeb(0, RTC_SEC10);
                __raw_writeb(0, RTC_MIN1); __raw_writeb(0, RTC_MIN10);
                __raw_writeb(0, RTC_HOU1); __raw_writeb(0, RTC_HOU10);
                __raw_writeb(6, RTC_WEE1);
                __raw_writeb(1, RTC_DAY1); __raw_writeb(0, RTC_DAY10);
                __raw_writeb(1, RTC_MON1); __raw_writeb(0, RTC_MON10);
                __raw_writeb(0, RTC_YEA1); __raw_writeb(0, RTC_YEA10);
                __raw_writeb(0, RTC_YEA100);
                __raw_writeb(2, RTC_YEA1000);
                __raw_writeb(0, RTC_CTL);
                goto again;
        }

        spin_unlock(&sh03_rtc_lock);

        tm->tm_sec  = sec;
        tm->tm_min  = min;
        tm->tm_hour = hour;
        tm->tm_mday = day;
        tm->tm_mon  = mon;
        tm->tm_year = year - 1900;

        return 0;
}

static int set_rtc_mmss(struct rtc_time *tm)
{
        int retval = 0;
        int real_seconds, real_minutes, cmos_minutes;
        int i;

        /* gets recalled with irq locally disabled */
        spin_lock(&sh03_rtc_lock);
        for (i = 0 ; i < 1000000 ; i++) /* may take up to 1 second... */
                if (!(__raw_readb(RTC_CTL) & RTC_BUSY))
                        break;
        cmos_minutes = (__raw_readb(RTC_MIN1) & 0xf) + (__raw_readb(RTC_MIN10) & 0xf) * 10;
        real_seconds = tm->tm_sec;
        real_minutes = tm->tm_min;
        if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
                real_minutes += 30;             /* correct for half hour time zone */
        real_minutes %= 60;

        if (abs(real_minutes - cmos_minutes) < 30) {
                __raw_writeb(real_seconds % 10, RTC_SEC1);
                __raw_writeb(real_seconds / 10, RTC_SEC10);
                __raw_writeb(real_minutes % 10, RTC_MIN1);
                __raw_writeb(real_minutes / 10, RTC_MIN10);
        } else {
                printk_once(KERN_NOTICE
                       "set_rtc_mmss: can't update from %d to %d\n",
                       cmos_minutes, real_minutes);
                retval = -EINVAL;
        }
        spin_unlock(&sh03_rtc_lock);

        return retval;
}

static int sh03_rtc_settimeofday(struct device *dev, struct rtc_time *tm)
{
        return set_rtc_mmss(tm);
}

static const struct rtc_class_ops rtc_generic_ops = {
        .read_time = sh03_rtc_gettimeofday,
        .set_time = sh03_rtc_settimeofday,
};

static int __init sh03_time_init(void)
{
        struct platform_device *pdev;

        pdev = platform_device_register_data(NULL, "rtc-generic", -1,
                                             &rtc_generic_ops,
                                             sizeof(rtc_generic_ops));

        return PTR_ERR_OR_ZERO(pdev);
}
arch_initcall(sh03_time_init);