/* PWM 的 ESP-IDF 实现（LEDC 低速组）。本项目只有风扇一路。 */
#include "driver/ledc.h"
#include "hal_pwm.h"

#define PWM_SPEED_MODE  LEDC_LOW_SPEED_MODE
#define PWM_RES_BITS    LEDC_TIMER_10_BIT
#define PWM_DUTY_FULL   1023u /* 2^10 - 1 */

static bool s_ready[HAL_PWM_CH_MAX];
static uint16_t s_permille[HAL_PWM_CH_MAX];

hal_err_t hal_pwm_config(int ch, int pin, uint32_t freq_hz)
{
    if (ch < 0 || ch >= HAL_PWM_CH_MAX || pin < 0 || freq_hz == 0) {
        return HAL_ERR_ARG;
    }
    /* 一个通道一个定时器：风扇 25 kHz 与将来别的用途未必同频。 */
    ledc_timer_config_t tc = {
        .speed_mode = PWM_SPEED_MODE,
        .duty_resolution = PWM_RES_BITS,
        .timer_num = (ledc_timer_t)ch,
        .freq_hz = freq_hz,
        .clk_cfg = LEDC_AUTO_CLK,
    };
    if (ledc_timer_config(&tc) != ESP_OK) {
        return HAL_ERR_ARG;
    }
    ledc_channel_config_t cc = {
        .gpio_num = pin,
        .speed_mode = PWM_SPEED_MODE,
        .channel = (ledc_channel_t)ch,
        .timer_sel = (ledc_timer_t)ch,
        .duty = 0,
        .hpoint = 0,
    };
    if (ledc_channel_config(&cc) != ESP_OK) {
        return HAL_ERR_ARG;
    }
    s_ready[ch] = true;
    s_permille[ch] = 0;
    return HAL_OK;
}

hal_err_t hal_pwm_set_permille(int ch, uint16_t permille)
{
    if (ch < 0 || ch >= HAL_PWM_CH_MAX || !s_ready[ch] || permille > 1000) {
        return HAL_ERR_ARG;
    }
    /* +500 是四舍五入：1000 permille 必须正好是满占空比，别差一个码值。 */
    uint32_t duty = ((uint32_t)permille * PWM_DUTY_FULL + 500u) / 1000u;
    if (ledc_set_duty(PWM_SPEED_MODE, (ledc_channel_t)ch, duty) != ESP_OK ||
        ledc_update_duty(PWM_SPEED_MODE, (ledc_channel_t)ch) != ESP_OK) {
        return HAL_ERR_BUS;
    }
    s_permille[ch] = permille;
    return HAL_OK;
}

hal_err_t hal_pwm_get_permille(int ch, uint16_t *permille)
{
    if (ch < 0 || ch >= HAL_PWM_CH_MAX || !s_ready[ch] || permille == NULL) {
        return HAL_ERR_ARG;
    }
    *permille = s_permille[ch];
    return HAL_OK;
}