circuitpython/ports/espressif/peripherals/rmt.c

/*
 * This file is part of the Micro Python project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2020 Lucian Copeland for Adafruit Industries
 *
 * 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 "peripherals/rmt.h"
#include "py/runtime.h"

bool rmt_reserved_channels[RMT_CHANNEL_MAX];

void peripherals_rmt_reset(void) {
    for (size_t i = 0; i < RMT_CHANNEL_MAX; i++) {
        if (rmt_reserved_channels[i]) {
            peripherals_free_rmt(i);
        }
    }
}

rmt_channel_t peripherals_find_and_reserve_rmt(bool mode) {
    size_t start_channel = 0;
    size_t end_channel = RMT_CHANNEL_MAX;
    // ESP32C3 can only send on channels 0-1 and receive on channels 2-3
    #if defined(CONFIG_IDF_TARGET_ESP32C3)
    if (mode == RECEIVE_MODE) {
        start_channel = 2;
    } else {
        end_channel = 2;
    }
    #endif // ESP32C3
    #if SOC_RMT_CHANNELS_PER_GROUP > 4
    if (mode == RECEIVE_MODE) {
        start_channel = 4;
    } else {
        end_channel = 4;
    }
    #endif
    for (size_t i = start_channel; i < end_channel; i++) {
        if (!rmt_reserved_channels[i]) {
            rmt_reserved_channels[i] = true;
            return i;
        }
    }
    // Returning the max indicates a reservation failure.
    return RMT_CHANNEL_MAX;
}

void peripherals_free_rmt(rmt_channel_t chan) {
    rmt_reserved_channels[chan] = false;
    rmt_driver_uninstall(chan);
}