/*
 * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Apache-2.0
 */

// #define LOG_LOCAL_LEVEL ESP_LOG_DEBUG // uncomment this line to enable debug logs

#include <stdlib.h>
#include <sys/lock.h>
#include "freertos/FreeRTOS.h"
#include "esp_attr.h"
#include "esp_err.h"
#include "esp_heap_caps.h"
#include "esp_intr_alloc.h"
#include "esp_log.h"
#include "esp_check.h"
#include "esp_pm.h"
#include "driver/gptimer.h"
#include "hal/timer_types.h"
#include "hal/timer_hal.h"
#include "hal/timer_ll.h"
#include "soc/timer_periph.h"
#include "soc/soc_memory_types.h"
#include "esp_private/periph_ctrl.h"
#include "esp_private/esp_clk.h"

// If ISR handler is allowed to run whilst cache is disabled,
// Make sure all the code and related variables used by the handler are in the SRAM
#if CONFIG_GPTIMER_ISR_IRAM_SAFE
#define GPTIMER_INTR_ALLOC_FLAGS    (ESP_INTR_FLAG_IRAM | ESP_INTR_FLAG_INTRDISABLED)
#define GPTIMER_MEM_ALLOC_CAPS      (MALLOC_CAP_INTERNAL | MALLOC_CAP_8BIT)
#else
#define GPTIMER_INTR_ALLOC_FLAGS    ESP_INTR_FLAG_INTRDISABLED
#define GPTIMER_MEM_ALLOC_CAPS      MALLOC_CAP_DEFAULT
#endif //CONFIG_GPTIMER_ISR_IRAM_SAFE

#define GPTIMER_PM_LOCK_NAME_LEN_MAX 16

static const char *TAG = "gptimer";

typedef struct gptimer_platform_t gptimer_platform_t;
typedef struct gptimer_group_t gptimer_group_t;
typedef struct gptimer_t gptimer_t;

struct gptimer_platform_t {
    _lock_t mutex;                             // platform level mutex lock
    gptimer_group_t *groups[SOC_TIMER_GROUPS]; // timer group pool
    int group_ref_counts[SOC_TIMER_GROUPS];    // reference count used to protect group install/uninstall
};

struct gptimer_group_t {
    int group_id;
    portMUX_TYPE spinlock; // to protect per-group register level concurrent access
    gptimer_t *timers[SOC_TIMER_GROUP_TIMERS_PER_GROUP];
};

typedef enum {
    GPTIMER_FSM_STOP,
    GPTIMER_FSM_START,
} gptimer_lifecycle_fsm_t;

struct gptimer_t {
    gptimer_group_t *group;
    int timer_id;
    unsigned int resolution_hz;
    unsigned long long reload_count;
    unsigned long long alarm_count;
    gptimer_count_direction_t direction;
    timer_hal_context_t hal;
    gptimer_lifecycle_fsm_t fsm; // access to fsm should be protect by spinlock, as fsm is also accessed from ISR handler
    intr_handle_t intr;
    portMUX_TYPE spinlock; // to protect per-timer resources concurent accessed by task and ISR handler
    gptimer_alarm_cb_t on_alarm;
    void *user_ctx;
    esp_pm_lock_handle_t pm_lock; // power management lock
#if CONFIG_PM_ENABLE
    char pm_lock_name[GPTIMER_PM_LOCK_NAME_LEN_MAX]; // pm lock name
#endif
    struct {
        uint32_t intr_shared: 1;
        uint32_t auto_reload_on_alarm: 1;
        uint32_t alarm_en: 1;
    } flags;
};

// gptimer driver platform, it's always a singleton
static gptimer_platform_t s_platform;

static gptimer_group_t *gptimer_acquire_group_handle(int group_id);
static void gptimer_release_group_handle(gptimer_group_t *group);
static esp_err_t gptimer_select_periph_clock(gptimer_t *timer, gptimer_clock_source_t src_clk, uint32_t resolution_hz);
IRAM_ATTR static void gptimer_default_isr(void *args);

esp_err_t gptimer_new_timer(const gptimer_config_t *config, gptimer_handle_t *ret_timer)
{
    esp_err_t ret = ESP_OK;
    gptimer_group_t *group = NULL;
    gptimer_t *timer = NULL;
    int group_id = -1;
    int timer_id = -1;
    ESP_GOTO_ON_FALSE(config && ret_timer, ESP_ERR_INVALID_ARG, err, TAG, "invalid argument");
    ESP_GOTO_ON_FALSE(config->resolution_hz, ESP_ERR_INVALID_ARG, err, TAG, "invalid timer resolution:%d", config->resolution_hz);

    timer = heap_caps_calloc(1, sizeof(gptimer_t), GPTIMER_MEM_ALLOC_CAPS);
    ESP_GOTO_ON_FALSE(timer, ESP_ERR_NO_MEM, err, TAG, "no mem for gptimer");

    for (int i = 0; (i < SOC_TIMER_GROUPS) && (timer_id < 0); i++) {
        group = gptimer_acquire_group_handle(i);
        ESP_GOTO_ON_FALSE(group, ESP_ERR_NO_MEM, err, TAG, "no mem for group (%d)", i);
        // loop to search free timer in the group
        portENTER_CRITICAL(&group->spinlock);
        for (int j = 0; j < SOC_TIMER_GROUP_TIMERS_PER_GROUP; j++) {
            if (!group->timers[j]) {
                group_id = i;
                timer_id = j;
                group->timers[j] = timer;
                break;
            }
        }
        portEXIT_CRITICAL(&group->spinlock);
        if (timer_id < 0) {
            gptimer_release_group_handle(group);
            group = NULL;
        }
    }

    ESP_GOTO_ON_FALSE(timer_id != -1, ESP_ERR_NOT_FOUND, err, TAG, "no free timer");
    timer->timer_id = timer_id;
    timer->group = group;
    // initialize HAL layer
    timer_hal_init(&timer->hal, group_id, timer_id);
    // stop counter, alarm, auto-reload
    timer_ll_enable_counter(timer->hal.dev, timer_id, false);
    timer_ll_enable_auto_reload(timer->hal.dev, timer_id, false);
    timer_ll_enable_alarm(timer->hal.dev, timer_id, false);
    // select clock source, set clock resolution
    ESP_GOTO_ON_ERROR(gptimer_select_periph_clock(timer, config->clk_src, config->resolution_hz), err, TAG, "set periph clock failed");
    // initialize counter value to zero
    timer_hal_set_counter_value(&timer->hal, 0);
    // set counting direction
    timer_ll_set_count_direction(timer->hal.dev, timer_id, config->direction);

    // interrupt register is shared by all timers in the same group
    portENTER_CRITICAL(&group->spinlock);
    timer_ll_enable_intr(timer->hal.dev, TIMER_LL_EVENT_ALARM(timer_id), false); // disable interrupt
    timer_ll_clear_intr_status(timer->hal.dev, TIMER_LL_EVENT_ALARM(timer_id)); // clear pending interrupt event
    portEXIT_CRITICAL(&group->spinlock);
    // initialize other members of timer
    timer->spinlock = (portMUX_TYPE)portMUX_INITIALIZER_UNLOCKED;
    timer->fsm = GPTIMER_FSM_STOP;
    timer->direction = config->direction;
    timer->flags.intr_shared = config->flags.intr_shared;
    ESP_LOGD(TAG, "new gptimer (%d,%d) at %p, resolution=%uHz", group_id, timer_id, timer, timer->resolution_hz);
    *ret_timer = timer;
    return ESP_OK;

err:
    if (timer) {
        if (timer->pm_lock) {
            esp_pm_lock_delete(timer->pm_lock);
        }
        free(timer);
    }
    if (group) {
        gptimer_release_group_handle(group);
    }
    return ret;
}

esp_err_t gptimer_del_timer(gptimer_handle_t timer)
{
    gptimer_group_t *group = NULL;
    bool valid_state = true;
    ESP_RETURN_ON_FALSE(timer, ESP_ERR_INVALID_ARG, TAG, "invalid argument");
    portENTER_CRITICAL(&timer->spinlock);
    if (timer->fsm != GPTIMER_FSM_STOP) {
        valid_state = false;
    }
    portEXIT_CRITICAL(&timer->spinlock);
    ESP_RETURN_ON_FALSE(valid_state, ESP_ERR_INVALID_STATE, TAG, "can't delete timer as it's not in stop state");
    group = timer->group;
    int group_id = group->group_id;
    int timer_id = timer->timer_id;

    if (timer->intr) {
        esp_intr_free(timer->intr);
        ESP_LOGD(TAG, "uninstall interrupt service for timer (%d,%d)", group_id, timer_id);
    }
    if (timer->pm_lock) {
        esp_pm_lock_delete(timer->pm_lock);
        ESP_LOGD(TAG, "uninstall APB_FREQ_MAX lock for timer (%d,%d)", group_id, timer_id);
    }
    free(timer);
    ESP_LOGD(TAG, "del timer (%d,%d)", group_id, timer_id);

    portENTER_CRITICAL(&group->spinlock);
    group->timers[timer_id] = NULL;
    portEXIT_CRITICAL(&group->spinlock);
    // timer has a reference on group, release it now
    gptimer_release_group_handle(group);

    return ESP_OK;
}

esp_err_t gptimer_set_raw_count(gptimer_handle_t timer, unsigned long long value)
{
    ESP_RETURN_ON_FALSE(timer, ESP_ERR_INVALID_ARG, TAG, "invalid argument");

    portENTER_CRITICAL_SAFE(&timer->spinlock);
    timer_hal_set_counter_value(&timer->hal, value);
    portEXIT_CRITICAL_SAFE(&timer->spinlock);
    return ESP_OK;
}

esp_err_t gptimer_get_raw_count(gptimer_handle_t timer, unsigned long long *value)
{
    ESP_RETURN_ON_FALSE(timer && value, ESP_ERR_INVALID_ARG, TAG, "invalid argument");

    portENTER_CRITICAL_SAFE(&timer->spinlock);
    *value = timer_ll_get_counter_value(timer->hal.dev, timer->timer_id);
    portEXIT_CRITICAL_SAFE(&timer->spinlock);
    return ESP_OK;
}

esp_err_t gptimer_register_event_callbacks(gptimer_handle_t timer, const gptimer_event_callbacks_t *cbs, void *user_data)
{
    gptimer_group_t *group = NULL;
    ESP_RETURN_ON_FALSE(timer && cbs, ESP_ERR_INVALID_ARG, TAG, "invalid argument");
    group = timer->group;
    int group_id = group->group_id;
    int timer_id = timer->timer_id;

#if CONFIG_GPTIMER_ISR_IRAM_SAFE
    if (cbs->on_alarm) {
        ESP_RETURN_ON_FALSE(esp_ptr_in_iram(cbs->on_alarm), ESP_ERR_INVALID_ARG, TAG, "on_alarm callback not in IRAM");
    }
    if (user_data) {
        ESP_RETURN_ON_FALSE(esp_ptr_in_dram(user_data) ||
                            esp_ptr_in_diram_dram(user_data) ||
                            esp_ptr_in_rtc_dram_fast(user_data), ESP_ERR_INVALID_ARG, TAG, "user context not in DRAM");
    }
#endif

    // lazy install interrupt service
    if (!timer->intr) {
        // if user wants to control the interrupt allocation more precisely, we can expose more flags in `gptimer_config_t`
        int isr_flags = timer->flags.intr_shared ? ESP_INTR_FLAG_SHARED | GPTIMER_INTR_ALLOC_FLAGS : GPTIMER_INTR_ALLOC_FLAGS;
        ESP_RETURN_ON_ERROR(esp_intr_alloc_intrstatus(timer_group_periph_signals.groups[group_id].timer_irq_id[timer_id], isr_flags,
                            (uint32_t)timer_ll_get_intr_status_reg(timer->hal.dev), TIMER_LL_EVENT_ALARM(timer_id),
                            gptimer_default_isr, timer, &timer->intr), TAG, "install interrupt service failed");
    }

    // enable/disable GPTimer interrupt events
    portENTER_CRITICAL_SAFE(&group->spinlock);
    timer_ll_enable_intr(timer->hal.dev, TIMER_LL_EVENT_ALARM(timer->timer_id), cbs->on_alarm != NULL); // enable timer interrupt
    portEXIT_CRITICAL_SAFE(&group->spinlock);

    timer->on_alarm = cbs->on_alarm;
    timer->user_ctx = user_data;
    return ESP_OK;
}

esp_err_t gptimer_set_alarm_action(gptimer_handle_t timer, const gptimer_alarm_config_t *config)
{
    ESP_RETURN_ON_FALSE(timer, ESP_ERR_INVALID_ARG, TAG, "invalid argument");
    if (config) {
        // When auto_reload is enabled, alarm_count should not be equal to reload_count
        bool valid_auto_reload = !config->flags.auto_reload_on_alarm || config->alarm_count != config->reload_count;
        ESP_RETURN_ON_FALSE(valid_auto_reload, ESP_ERR_INVALID_ARG, TAG, "reload count can't equal to alarm count");

        timer->reload_count = config->reload_count;
        timer->alarm_count = config->alarm_count;
        timer->flags.auto_reload_on_alarm = config->flags.auto_reload_on_alarm;
        timer->flags.alarm_en = true;

        portENTER_CRITICAL_SAFE(&timer->spinlock);
        timer_ll_set_reload_value(timer->hal.dev, timer->timer_id, config->reload_count);
        timer_ll_set_alarm_value(timer->hal.dev, timer->timer_id, config->alarm_count);
        portEXIT_CRITICAL_SAFE(&timer->spinlock);
    } else {
        timer->flags.auto_reload_on_alarm = false;
        timer->flags.alarm_en = false;
    }

    portENTER_CRITICAL_SAFE(&timer->spinlock);
    timer_ll_enable_auto_reload(timer->hal.dev, timer->timer_id, timer->flags.auto_reload_on_alarm);
    timer_ll_enable_alarm(timer->hal.dev, timer->timer_id, timer->flags.alarm_en);
    portEXIT_CRITICAL_SAFE(&timer->spinlock);
    return ESP_OK;
}

esp_err_t gptimer_start(gptimer_handle_t timer)
{
    ESP_RETURN_ON_FALSE(timer, ESP_ERR_INVALID_ARG, TAG, "invalid argument");

    // acquire power manager lock
    if (timer->pm_lock) {
        ESP_RETURN_ON_ERROR(esp_pm_lock_acquire(timer->pm_lock), TAG, "acquire APB_FREQ_MAX lock failed");
    }
    // interrupt interupt service
    if (timer->intr) {
        ESP_RETURN_ON_ERROR(esp_intr_enable(timer->intr), TAG, "enable interrupt service failed");
    }

    portENTER_CRITICAL_SAFE(&timer->spinlock);
    timer_ll_enable_counter(timer->hal.dev, timer->timer_id, true);
    timer_ll_enable_alarm(timer->hal.dev, timer->timer_id, timer->flags.alarm_en);
    timer->fsm = GPTIMER_FSM_START;
    portEXIT_CRITICAL_SAFE(&timer->spinlock);

    return ESP_OK;
}

esp_err_t gptimer_stop(gptimer_handle_t timer)
{
    ESP_RETURN_ON_FALSE(timer, ESP_ERR_INVALID_ARG, TAG, "invalid argument");

    // disable counter, alarm, autoreload
    portENTER_CRITICAL_SAFE(&timer->spinlock);
    timer_ll_enable_counter(timer->hal.dev, timer->timer_id, false);
    timer_ll_enable_alarm(timer->hal.dev, timer->timer_id, false);
    timer->fsm = GPTIMER_FSM_STOP;
    portEXIT_CRITICAL_SAFE(&timer->spinlock);

    // disable interrupt service
    if (timer->intr) {
        ESP_RETURN_ON_ERROR(esp_intr_disable(timer->intr), TAG, "disable interrupt service failed");
    }
    // release power manager lock
    if (timer->pm_lock) {
        ESP_RETURN_ON_ERROR(esp_pm_lock_release(timer->pm_lock), TAG, "release APB_FREQ_MAX lock failed");
    }

    return ESP_OK;
}

static gptimer_group_t *gptimer_acquire_group_handle(int group_id)
{
    // esp_log_level_set(TAG, ESP_LOG_DEBUG);
    bool new_group = false;
    gptimer_group_t *group = NULL;

    // prevent install timer group concurrently
    _lock_acquire(&s_platform.mutex);
    if (!s_platform.groups[group_id]) {
        group = heap_caps_calloc(1, sizeof(gptimer_group_t), GPTIMER_MEM_ALLOC_CAPS);
        if (group) {
            new_group = true;
            s_platform.groups[group_id] = group;
            // initialize timer group members
            group->group_id = group_id;
            group->spinlock = (portMUX_TYPE)portMUX_INITIALIZER_UNLOCKED;
            // enable APB access timer registers
            periph_module_enable(timer_group_periph_signals.groups[group_id].module);
        }
    } else {
        group = s_platform.groups[group_id];
    }
    if (group) {
        // someone acquired the group handle means we have a new object that refer to this group
        s_platform.group_ref_counts[group_id]++;
    }
    _lock_release(&s_platform.mutex);

    if (new_group) {
        ESP_LOGD(TAG, "new group (%d) @%p", group_id, group);
    }

    return group;
}

static void gptimer_release_group_handle(gptimer_group_t *group)
{
    int group_id = group->group_id;
    bool do_deinitialize = false;

    _lock_acquire(&s_platform.mutex);
    s_platform.group_ref_counts[group_id]--;
    if (s_platform.group_ref_counts[group_id] == 0) {
        assert(s_platform.groups[group_id]);
        do_deinitialize = true;
        s_platform.groups[group_id] = NULL;
        // Theoretically we need to disable the peripheral clock for the timer group
        // However, next time when we enable the peripheral again, the registers will be reset to default value, including the watchdog registers inside the group
        // Then the watchdog will go into reset state, e.g. the flash boot watchdog is enabled again and reset the system very soon
        // periph_module_disable(timer_group_periph_signals.groups[group_id].module);
    }
    _lock_release(&s_platform.mutex);

    if (do_deinitialize) {
        free(group);
        ESP_LOGD(TAG, "del group (%d)", group_id);
    }
}

static esp_err_t gptimer_select_periph_clock(gptimer_t *timer, gptimer_clock_source_t src_clk, uint32_t resolution_hz)
{
    unsigned int counter_src_hz = 0;
    esp_err_t ret = ESP_OK;
    int timer_id = timer->timer_id;
    switch (src_clk) {
    case GPTIMER_CLK_SRC_APB:
        counter_src_hz = esp_clk_apb_freq();
#if CONFIG_PM_ENABLE
        sprintf(timer->pm_lock_name, "gptimer_%d_%d", timer->group->group_id, timer_id); // e.g. gptimer_0_0
        ret  = esp_pm_lock_create(ESP_PM_APB_FREQ_MAX, 0, timer->pm_lock_name, &timer->pm_lock);
        ESP_RETURN_ON_ERROR(ret, TAG, "create APB_FREQ_MAX lock failed");
        ESP_LOGD(TAG, "install APB_FREQ_MAX lock for timer (%d,%d)", timer->group->group_id, timer_id);
#endif
        break;
#if SOC_TIMER_GROUP_SUPPORT_XTAL
    case GPTIMER_CLK_SRC_XTAL:
        counter_src_hz = esp_clk_xtal_freq();
        break;
#endif
    default:
        ESP_RETURN_ON_FALSE(false, ESP_ERR_NOT_SUPPORTED, TAG, "clock source %d is not support", src_clk);
        break;
    }
    timer_ll_set_clock_source(timer->hal.dev, timer_id, src_clk);
    unsigned int prescale = counter_src_hz / resolution_hz; // potential resolution loss here
    timer_ll_set_clock_prescale(timer->hal.dev, timer_id, prescale);
    timer->resolution_hz = counter_src_hz / prescale; // this is the real resolution
    if (timer->resolution_hz != resolution_hz) {
        ESP_LOGW(TAG, "resolution lost, expect %ul, real %ul", resolution_hz, timer->resolution_hz);
    }
    return ret;
}

// Put the default ISR handler in the IRAM for better performance
IRAM_ATTR static void gptimer_default_isr(void *args)
{
    bool need_yield = false;
    gptimer_t *timer = (gptimer_t *)args;
    gptimer_group_t *group = timer->group;
    gptimer_alarm_cb_t on_alarm_cb = timer->on_alarm;
    uint32_t intr_status = timer_ll_get_intr_status(timer->hal.dev);

    if (intr_status & TIMER_LL_EVENT_ALARM(timer->timer_id)) {
        // Note: when alarm event happends, the alarm will be disabled automatically by hardware
        gptimer_alarm_event_data_t edata = {
            .count_value = timer_ll_get_counter_value(timer->hal.dev, timer->timer_id),
            .alarm_value = timer->alarm_count,
        };

        portENTER_CRITICAL_ISR(&group->spinlock);
        timer_ll_clear_intr_status(timer->hal.dev, TIMER_LL_EVENT_ALARM(timer->timer_id));
        // for auto-reload, we need to re-enable the alarm manually
        if (timer->flags.auto_reload_on_alarm) {
            timer_ll_enable_alarm(timer->hal.dev, timer->timer_id, true);
        }
        portEXIT_CRITICAL_ISR(&group->spinlock);

        if (on_alarm_cb) {
            if (on_alarm_cb(timer, &edata, timer->user_ctx)) {
                need_yield = true;
            }
        }
    }

    if (need_yield) {
        portYIELD_FROM_ISR();
    }
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
///// The Following APIs are for internal use only (e.g. unit test)    /////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

esp_err_t gptimer_get_intr_handle(gptimer_handle_t timer, intr_handle_t *ret_intr_handle)
{
    ESP_RETURN_ON_FALSE(timer && ret_intr_handle, ESP_ERR_INVALID_ARG, TAG, "invalid argument");
    *ret_intr_handle = timer->intr;
    return ESP_OK;
}

esp_err_t gptimer_get_pm_lock(gptimer_handle_t timer, esp_pm_lock_handle_t *ret_pm_lock)
{
    ESP_RETURN_ON_FALSE(timer && ret_pm_lock, ESP_ERR_INVALID_ARG, TAG, "invalid argument");
    *ret_pm_lock = timer->pm_lock;
    return ESP_OK;
}

/**
 * @brief This function will be called during start up, to check that gptimer driver is not running along with the legacy timer group driver
 */
__attribute__((constructor))
static void check_gptimer_driver_conflict(void)
{
    extern int timer_group_driver_init_count;
    timer_group_driver_init_count++;
    if (timer_group_driver_init_count > 1) {
        ESP_EARLY_LOGE(TAG, "CONFLICT! The gptimer driver can't work along with the legacy timer group driver");
        abort();
    }
}