// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * PowerNV Real Time Clock.
 *
 * Copyright 2011 IBM Corp.
 */


#include <linux/kernel.h>
#include <linux/time.h>
#include <linux/bcd.h>
#include <linux/rtc.h>
#include <linux/delay.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>

#include <asm/opal.h>
#include <asm/firmware.h>
#include <asm/machdep.h>

static void __init opal_to_tm(u32 y_m_d, u64 h_m_s_ms, struct rtc_time *tm)
{
        tm->tm_year     = ((bcd2bin(y_m_d >> 24) * 100) +
                           bcd2bin((y_m_d >> 16) & 0xff)) - 1900;
        tm->tm_mon      = bcd2bin((y_m_d >> 8) & 0xff) - 1;
        tm->tm_mday     = bcd2bin(y_m_d & 0xff);
        tm->tm_hour     = bcd2bin((h_m_s_ms >> 56) & 0xff);
        tm->tm_min      = bcd2bin((h_m_s_ms >> 48) & 0xff);
        tm->tm_sec      = bcd2bin((h_m_s_ms >> 40) & 0xff);
        tm->tm_wday     = -1;
}

time64_t __init opal_get_boot_time(void)
{
        struct rtc_time tm;
        u32 y_m_d;
        u64 h_m_s_ms;
        __be32 __y_m_d;
        __be64 __h_m_s_ms;
        long rc = OPAL_BUSY;

        if (!opal_check_token(OPAL_RTC_READ))
                return 0;

        while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
                rc = opal_rtc_read(&__y_m_d, &__h_m_s_ms);
                if (rc == OPAL_BUSY_EVENT) {
                        mdelay(OPAL_BUSY_DELAY_MS);
                        opal_poll_events(NULL);
                } else if (rc == OPAL_BUSY) {
                        mdelay(OPAL_BUSY_DELAY_MS);
                }
        }
        if (rc != OPAL_SUCCESS)
                return 0;

        y_m_d = be32_to_cpu(__y_m_d);
        h_m_s_ms = be64_to_cpu(__h_m_s_ms);
        opal_to_tm(y_m_d, h_m_s_ms, &tm);
        return rtc_tm_to_time64(&tm);
}

static __init int opal_time_init(void)
{
        struct platform_device *pdev;
        struct device_node *rtc;

        rtc = of_find_node_by_path("/ibm,opal/rtc");
        if (rtc) {
                pdev = of_platform_device_create(rtc, "opal-rtc", NULL);
                of_node_put(rtc);
        } else {
                if (opal_check_token(OPAL_RTC_READ) ||
                    opal_check_token(OPAL_READ_TPO))
                        pdev = platform_device_register_simple("opal-rtc", -1,
                                                               NULL, 0);
                else
                        return -ENODEV;
        }

        return PTR_ERR_OR_ZERO(pdev);
}
machine_subsys_initcall(powernv, opal_time_init);