// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/time.h>
#include <linux/timer.h>
#include <linux/init.h>
#include <linux/rtc.h>
#include <linux/delay.h>
#include <linux/ratelimit.h>
#include <asm/rtas.h>
#include <asm/time.h>


#define MAX_RTC_WAIT 5000       /* 5 sec */

time64_t __init rtas_get_boot_time(void)
{
        int ret[8];
        int error;
        unsigned int wait_time;
        u64 max_wait_tb;

        max_wait_tb = get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
        do {
                error = rtas_call(rtas_function_token(RTAS_FN_GET_TIME_OF_DAY), 0, 8, ret);

                wait_time = rtas_busy_delay_time(error);
                if (wait_time) {
                        /* This is boot time so we spin. */
                        udelay(wait_time*1000);
                }
        } while (wait_time && (get_tb() < max_wait_tb));

        if (error != 0) {
                printk_ratelimited(KERN_WARNING
                                   "error: reading the clock failed (%d)\n",
                                   error);
                return 0;
        }

        return mktime64(ret[0], ret[1], ret[2], ret[3], ret[4], ret[5]);
}

/* NOTE: get_rtc_time will get an error if executed in interrupt context
 * and if a delay is needed to read the clock.  In this case we just
 * silently return without updating rtc_tm.
 */
void rtas_get_rtc_time(struct rtc_time *rtc_tm)
{
        int ret[8];
        int error;
        unsigned int wait_time;
        u64 max_wait_tb;

        max_wait_tb = get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
        do {
                error = rtas_call(rtas_function_token(RTAS_FN_GET_TIME_OF_DAY), 0, 8, ret);

                wait_time = rtas_busy_delay_time(error);
                if (wait_time) {
                        if (in_interrupt()) {
                                memset(rtc_tm, 0, sizeof(struct rtc_time));
                                printk_ratelimited(KERN_WARNING
                                                   "error: reading clock "
                                                   "would delay interrupt\n");
                                return; /* delay not allowed */
                        }
                        msleep(wait_time);
                }
        } while (wait_time && (get_tb() < max_wait_tb));

        if (error != 0) {
                printk_ratelimited(KERN_WARNING
                                   "error: reading the clock failed (%d)\n",
                                   error);
                return;
        }

        rtc_tm->tm_sec = ret[5];
        rtc_tm->tm_min = ret[4];
        rtc_tm->tm_hour = ret[3];
        rtc_tm->tm_mday = ret[2];
        rtc_tm->tm_mon = ret[1] - 1;
        rtc_tm->tm_year = ret[0] - 1900;
}

int rtas_set_rtc_time(struct rtc_time *tm)
{
        int error, wait_time;
        u64 max_wait_tb;

        max_wait_tb = get_tb() + tb_ticks_per_usec * 1000 * MAX_RTC_WAIT;
        do {
                error = rtas_call(rtas_function_token(RTAS_FN_SET_TIME_OF_DAY), 7, 1, NULL,
                                  tm->tm_year + 1900, tm->tm_mon + 1,
                                  tm->tm_mday, tm->tm_hour, tm->tm_min,
                                  tm->tm_sec, 0);

                wait_time = rtas_busy_delay_time(error);
                if (wait_time) {
                        if (in_interrupt())
                                return 1;       /* probably decrementer */
                        msleep(wait_time);
                }
        } while (wait_time && (get_tb() < max_wait_tb));

        if (error != 0)
                printk_ratelimited(KERN_WARNING
                                   "error: setting the clock failed (%d)\n",
                                   error);

        return 0;
}