/*
   This example code is in the Public Domain (or CC0 licensed, at your option.)

   Unless required by applicable law or agreed to in writing, this
   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
   CONDITIONS OF ANY KIND, either express or implied.
*/

#include <string.h>
#include "driver/periph_ctrl.h"
#include "driver/gpio.h"
#include "driver/uart.h"
#include "soc/lldesc.h"
#include "esp_private/gdma.h"
#include "hal/uhci_ll.h"
#include "esp_bt.h"
#include "esp_log.h"

static const char *tag = "UHCI";

#define UART_HCI_NUM       (1)

#define UART_RX_THRS       (120)

#define GPIO_UART_TXD_OUT  (4)
#define GPIO_UART_RXD_IN   (5)
#define GPIO_UART_RTS_OUT  (6)
#define GPIO_UART_CTS_IN   (7)

#define GPIO_OUTPUT_PIN_SEL  ((1ULL<<GPIO_UART_TXD_OUT) | (1ULL<<GPIO_UART_RTS_OUT))
#define GPIO_INPUT_PIN_SEL   ((1ULL<<GPIO_UART_RXD_IN) | (1ULL<<GPIO_UART_CTS_IN))

// Operation functions for HCI UART Transport Layer
static bool hci_uart_tl_init(void);
static void hci_uart_tl_deinit(void);
static void hci_uart_tl_recv_async(uint8_t *buf, uint32_t size, esp_bt_hci_tl_callback_t callback, void *arg);
static void hci_uart_tl_send_async(uint8_t *buf, uint32_t size, esp_bt_hci_tl_callback_t callback, void *arg);
static void hci_uart_tl_flow_on(void);
static bool hci_uart_tl_flow_off(void);
static void hci_uart_tl_finish_transfers(void);

struct uart_txrxchannel {
    esp_bt_hci_tl_callback_t callback;
    void *arg;
    lldesc_t link;
};

struct uart_env_tag {
    struct uart_txrxchannel tx;
    struct uart_txrxchannel rx;
};

struct uart_env_tag uart_env;

static volatile uhci_dev_t *s_uhci_hw = &UHCI0;
static gdma_channel_handle_t s_rx_channel;
static gdma_channel_handle_t s_tx_channel;

static esp_bt_hci_tl_t s_hci_uart_tl_funcs = {
    ._magic = ESP_BT_HCI_TL_MAGIC_VALUE,
    ._version = ESP_BT_HCI_TL_VERSION,
    ._reserved = 0,
    ._open = (void *)hci_uart_tl_init,
    ._close = (void *)hci_uart_tl_deinit,
    ._finish_transfers = (void *)hci_uart_tl_finish_transfers,
    ._recv = (void *)hci_uart_tl_recv_async,
    ._send = (void *)hci_uart_tl_send_async,
    ._flow_on = (void *)hci_uart_tl_flow_on,
    ._flow_off = (void *)hci_uart_tl_flow_off,
};

static bool hci_uart_tl_init(void)
{
    return true;
}

static void hci_uart_tl_deinit(void)
{
}

static IRAM_ATTR void hci_uart_tl_recv_async(uint8_t *buf, uint32_t size, esp_bt_hci_tl_callback_t callback, void *arg)
{
    assert(buf != NULL);
    assert(size != 0);
    assert(callback != NULL);
    uart_env.rx.callback = callback;
    uart_env.rx.arg = arg;

    memset(&uart_env.rx.link, 0, sizeof(lldesc_t));
    uart_env.rx.link.buf = buf;
    uart_env.rx.link.size = size;

    s_uhci_hw->pkt_thres.thrs = size;

    gdma_start(s_rx_channel, (intptr_t)(&uart_env.rx.link));
}

static IRAM_ATTR void hci_uart_tl_send_async(uint8_t *buf, uint32_t size, esp_bt_hci_tl_callback_t callback, void *arg)
{
    assert(buf != NULL);
    assert(size != 0);
    assert(callback != NULL);

    uart_env.tx.callback = callback;
    uart_env.tx.arg = arg;

    memset(&uart_env.tx.link, 0, sizeof(lldesc_t));
    uart_env.tx.link.length = size;
    uart_env.tx.link.buf = buf;
    uart_env.tx.link.eof = 1;

    gdma_start(s_tx_channel, (intptr_t)(&uart_env.tx.link));
}

static void hci_uart_tl_flow_on(void)
{
}

static bool hci_uart_tl_flow_off(void)
{
    return true;
}

static void hci_uart_tl_finish_transfers(void)
{
}

static IRAM_ATTR bool hci_uart_tl_rx_eof_callback(gdma_channel_handle_t dma_chan, gdma_event_data_t *event_data, void *user_data)
{
    assert(dma_chan == s_rx_channel);
    assert(uart_env.rx.callback != NULL);
    esp_bt_hci_tl_callback_t callback = uart_env.rx.callback;
    void *arg = uart_env.rx.arg;

    // clear callback pointer
    uart_env.rx.callback = NULL;
    uart_env.rx.arg = NULL;

    // call handler
    callback(arg, ESP_BT_HCI_TL_STATUS_OK);

    // send notification to Bluetooth Controller task
    esp_bt_h4tl_eif_io_event_notify(1);

    return true;
}

static IRAM_ATTR bool hci_uart_tl_tx_eof_callback(gdma_channel_handle_t dma_chan, gdma_event_data_t *event_data, void *user_data)
{
    assert(dma_chan == s_tx_channel);
    assert(uart_env.tx.callback != NULL);
    esp_bt_hci_tl_callback_t callback = uart_env.tx.callback;
    void *arg = uart_env.tx.arg;

    // clear callback pointer
    uart_env.tx.callback = NULL;
    uart_env.tx.arg = NULL;

    // call handler
    callback(arg, ESP_BT_HCI_TL_STATUS_OK);

    // send notification to Bluetooth Controller task
    esp_bt_h4tl_eif_io_event_notify(1);

    return true;
}

static void uart_gpio_set(void)
{
    gpio_config_t io_output_conf = {
        .intr_type = GPIO_PIN_INTR_DISABLE,    //disable interrupt
        .mode = GPIO_MODE_OUTPUT,    // output mode
        .pin_bit_mask = GPIO_OUTPUT_PIN_SEL,    // bit mask of the output pins
        .pull_down_en = 0,    // disable pull-down mode
        .pull_up_en = 0,    // disable pull-up mode
    };
    gpio_config(&io_output_conf);

    gpio_config_t io_input_conf = {
        .intr_type = GPIO_PIN_INTR_DISABLE,    //disable interrupt
        .mode = GPIO_MODE_INPUT,    // input mode
        .pin_bit_mask = GPIO_OUTPUT_PIN_SEL,  // bit mask of the input pins
        .pull_down_en = 0,    // disable pull-down mode
        .pull_up_en = 0,    // disable pull-down mode
    };
    gpio_config(&io_input_conf);

    uart_set_pin(UART_HCI_NUM, GPIO_UART_TXD_OUT, GPIO_UART_RXD_IN, GPIO_UART_RTS_OUT, GPIO_UART_CTS_IN);
}

void uhci_uart_install(void)
{
    periph_module_enable(PERIPH_UHCI0_MODULE);
    periph_module_reset(PERIPH_UHCI0_MODULE);

    periph_module_enable(PERIPH_UART1_MODULE);
    periph_module_reset(PERIPH_UART1_MODULE);

    uart_gpio_set();

    // configure UART1
    uart_config_t uart_config = {
        .baud_rate = CONFIG_EXAMPLE_HCI_UART_BAUDRATE,
        .data_bits = UART_DATA_8_BITS,
        .parity = UART_PARITY_DISABLE,
        .stop_bits = UART_STOP_BITS_1,
        .flow_ctrl = UART_HW_FLOWCTRL_CTS_RTS,
        .rx_flow_ctrl_thresh = UART_RX_THRS,
        .source_clk = UART_SCLK_APB,
    };
    ESP_ERROR_CHECK(uart_param_config(UART_HCI_NUM, &uart_config));

    // install DMA driver
    gdma_channel_alloc_config_t tx_channel_config = {
        .flags.reserve_sibling = 1,
        .direction = GDMA_CHANNEL_DIRECTION_TX,
    };
    ESP_ERROR_CHECK(gdma_new_channel(&tx_channel_config, &s_tx_channel));
    gdma_channel_alloc_config_t rx_channel_config = {
        .direction = GDMA_CHANNEL_DIRECTION_RX,
        .sibling_chan = s_tx_channel,
    };
    ESP_ERROR_CHECK(gdma_new_channel(&rx_channel_config, &s_rx_channel));

    gdma_connect(s_tx_channel, GDMA_MAKE_TRIGGER(GDMA_TRIG_PERIPH_UART, 0));
    gdma_connect(s_rx_channel, GDMA_MAKE_TRIGGER(GDMA_TRIG_PERIPH_UART, 0));

    gdma_strategy_config_t strategy_config = {
        .auto_update_desc = false,
        .owner_check = false
    };
    gdma_apply_strategy(s_tx_channel, &strategy_config);
    gdma_apply_strategy(s_rx_channel, &strategy_config);

    gdma_rx_event_callbacks_t rx_cbs = {
        .on_recv_eof = hci_uart_tl_rx_eof_callback
    };
    gdma_register_rx_event_callbacks(s_rx_channel, &rx_cbs, NULL);

    gdma_tx_event_callbacks_t tx_cbs = {
        .on_trans_eof = hci_uart_tl_tx_eof_callback
    };
    gdma_register_tx_event_callbacks(s_tx_channel, &tx_cbs, NULL);

    // configure UHCI
    uhci_ll_init(s_uhci_hw);
    uhci_ll_set_eof_mode(s_uhci_hw, UHCI_RX_LEN_EOF);
    // disable software flow control
    s_uhci_hw->escape_conf.val = 0;
    uhci_ll_attach_uart_port(s_uhci_hw, 1);
}


void app_main(void)
{
    esp_err_t ret;

    uhci_uart_install();

    esp_bt_controller_config_t bt_cfg = BT_CONTROLLER_INIT_CONFIG_DEFAULT();
    bt_cfg.hci_tl_funcs = &s_hci_uart_tl_funcs;

    ret = esp_bt_controller_init(&bt_cfg);
    if (ret != ESP_OK) {
        ESP_LOGE(tag, "Bluetooth Controller initialize failed: %s", esp_err_to_name(ret));
        return;
    }

    ret = esp_bt_controller_enable(ESP_BT_MODE_BLE);
    if (ret != ESP_OK) {
        ESP_LOGE(tag, "Bluetooth Controller initialize failed: %s", esp_err_to_name(ret));
        return;
    }

    ESP_LOGI(tag, "HCI messages can be communicated over UART%d: \n"
             "--PINs: TxD %d, RxD %d, RTS %d, CTS %d\n"
             "--Baudrate: %d", UART_HCI_NUM,
             GPIO_UART_TXD_OUT, GPIO_UART_RXD_IN, GPIO_UART_RTS_OUT, GPIO_UART_CTS_IN,
             CONFIG_EXAMPLE_HCI_UART_BAUDRATE);
}