usb.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2021 Damien P. George
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "py/runtime.h"
#include "py/mphal.h"
#include "usb.h"

#if CONFIG_USB_ENABLED

#include "tinyusb.h"
#include "tusb_cdc_acm.h"

#define CDC_ITF TINYUSB_CDC_ACM_0

static uint8_t usb_rx_buf[CONFIG_USB_CDC_RX_BUFSIZE];
static uint8_t usb_cdc_connected;

static void usb_callback_rx(int itf, cdcacm_event_t *event) {
    // TODO: what happens if more chars come in during this function, are they lost?
    for (;;) {
        size_t len = 0;
        esp_err_t ret = tinyusb_cdcacm_read(itf, usb_rx_buf, sizeof(usb_rx_buf), &len);
        if (ret != ESP_OK) {
            break;
        }
        if (len == 0) {
            break;
        }
        for (size_t i = 0; i < len; ++i) {
            if (usb_rx_buf[i] == mp_interrupt_char) {
                mp_sched_keyboard_interrupt();
            } else {
                ringbuf_put(&stdin_ringbuf, usb_rx_buf[i]);
            }
        }
    }
}

void usb_callback_line_state_changed(int itf, cdcacm_event_t *event) {
    int dtr = event->line_state_changed_data.dtr;
    int rts = event->line_state_changed_data.rts;
    // If dtr && rts are both true, the CDC is connected to a HOST.
    usb_cdc_connected = dtr && rts;
}

void usb_init(void) {
    // Initialise the USB with defaults.
    tinyusb_config_t tusb_cfg = {0};
    ESP_ERROR_CHECK(tinyusb_driver_install(&tusb_cfg));

    // Initialise the USB serial interface.
    tinyusb_config_cdcacm_t amc_cfg = {
        .usb_dev = TINYUSB_USBDEV_0,
        .cdc_port = CDC_ITF,
        .rx_unread_buf_sz = 256,
        .callback_rx = &usb_callback_rx,
        .callback_rx_wanted_char = NULL,
        .callback_line_state_changed = &usb_callback_line_state_changed,
        .callback_line_coding_changed = NULL
    };
    usb_cdc_connected = 0;
    ESP_ERROR_CHECK(tusb_cdc_acm_init(&amc_cfg));

}

void usb_tx_strn(const char *str, size_t len) {
    // Write out the data to the CDC interface, but only while the USB host is connected.
    while (usb_cdc_connected && len) {
        size_t l = tinyusb_cdcacm_write_queue(CDC_ITF, (uint8_t *)str, len);
        str += l;
        len -= l;
        tud_cdc_n_write_flush(CDC_ITF);
    }
}

#endif // CONFIG_USB_ENABLED