/**
 * @file udelay.c
 * @brief udelay common source
 *
 * @copyright Copyright (c) 2022  Semidrive Semiconductor.
 *            All rights reserved.
 */

#include <udelay/udelay.h>
#include <armv7-r/pmu.h>
#include <sdrv_ckgen.h>
#include <clock_ip.h>
#include <debug.h>

static uint32_t core_frequency;
static uint32_t cnt_per_us;

static inline uint32_t udelay_us_to_counter(uint32_t us)
{
    if (us > MAX_UDELAY) {
        us = MAX_UDELAY;
    }

    if (cnt_per_us == 0x0) {
        core_frequency = sdrv_ckgen_bus_get_rate(CLK_NODE(g_ckgen_bus_cr5_sf),
                                                CKGEN_BUS_CLK_OUT_M);

        cnt_per_us = (uint32_t)(core_frequency / 1000000);
    }

    return cnt_per_us * us;
}

/**
 * @brief Initialize ARM Performance Monitor cycle counter
 *
 *  sdrv udelay is implement by arm pmu cycle counter, you must
 *  call this function before use udelay().
 *
 *  note: this function must called after cpu clock has configurated.
 */
void sdrv_pmu_counter_init(void)
{
    core_frequency = sdrv_ckgen_bus_get_rate(CLK_NODE(g_ckgen_bus_cr5_sf),
                                             CKGEN_BUS_CLK_OUT_M);

    cnt_per_us = (uint32_t)(core_frequency / 1000000);

    if (!pmu_cycle_cntr_status()) {
        pmu_enable();
        pmu_start_cycle_cntr(false);
    }
    else {
        pmu_stop_clear_cycle_cntr();
        pmu_start_cycle_cntr(false);
    }
}


/**
 * @brief delay for microseconds
 *
 * @param us microseconds
 */
void udelay(uint32_t us)
{
#if CONFIG_ARM_WITH_PMU
    if (!pmu_cycle_cntr_status()) {
        sdrv_pmu_counter_init();
    }

    if (pmu_cycle_cntr_status() && (us > 0)) {
        uint32_t tick_to, start_tick, current_tick;
        uint32_t tmt = 0u;

        start_tick = pmu_get_cycle_cntr();

        /* make sure cycled information: 100 loops takes ~5us */
        while ((start_tick == pmu_get_cycle_cntr()) && (tmt++ < 100u));

        /* timeout check is not a must here, just in case the pmccntr abnormal */
        if (tmt < 100u) {
            tick_to = start_tick + udelay_us_to_counter(us);

            if (tick_to > start_tick) {
                /* tick_to not overflowed */
                do {
                    current_tick = pmu_get_cycle_cntr();
                } while ((current_tick < tick_to)
                        && (current_tick > start_tick));
            } else {
                /* current_tick overflowed */
                do {
                    current_tick = pmu_get_cycle_cntr();
                } while ((current_tick > start_tick) || (current_tick < tick_to));
            }
        }
    }
#endif
}