circuitpython/ports/nrf/common-hal/_bleio/Adapter.c

/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2018 Dan Halbert for Adafruit Industries
 * Copyright (c) 2016 Glenn Ruben Bakke
 * Copyright (c) 2018 Artur Pacholec
 *
 * 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 <stdint.h>
#include <stdio.h>
#include <string.h>

#include "ble.h"
#include "ble_drv.h"
#include "nrfx_power.h"
#include "nrf_nvic.h"
#include "nrf_sdm.h"
#include "tick.h"
#include "py/gc.h"
#include "py/objstr.h"
#include "py/runtime.h"
#include "supervisor/shared/safe_mode.h"
#include "supervisor/shared/tick.h"
#include "supervisor/usb.h"
#include "shared-bindings/_bleio/__init__.h"
#include "shared-bindings/_bleio/Adapter.h"
#include "shared-bindings/_bleio/Address.h"
#include "shared-bindings/_bleio/Connection.h"
#include "shared-bindings/_bleio/ScanEntry.h"
#include "shared-bindings/time/__init__.h"

#define BLE_MIN_CONN_INTERVAL        MSEC_TO_UNITS(15, UNIT_0_625_MS)
#define BLE_MAX_CONN_INTERVAL        MSEC_TO_UNITS(15, UNIT_0_625_MS)
#define BLE_SLAVE_LATENCY            0
#define BLE_CONN_SUP_TIMEOUT         MSEC_TO_UNITS(4000, UNIT_10_MS)

STATIC void softdevice_assert_handler(uint32_t id, uint32_t pc, uint32_t info) {
    reset_into_safe_mode(NORDIC_SOFT_DEVICE_ASSERT);
}

bleio_connection_internal_t connections[BLEIO_TOTAL_CONNECTION_COUNT];

// Linker script provided ram start.
extern uint32_t _ram_start;
STATIC uint32_t ble_stack_enable(void) {
    nrf_clock_lf_cfg_t clock_config = {
#if BOARD_HAS_32KHZ_XTAL
        .source       = NRF_CLOCK_LF_SRC_XTAL,
        .rc_ctiv      = 0,
        .rc_temp_ctiv = 0,
        .accuracy     = NRF_CLOCK_LF_ACCURACY_20_PPM,
#else
        .source       = NRF_CLOCK_LF_SRC_RC,
        .rc_ctiv      = 16,
        .rc_temp_ctiv = 2,
        .accuracy     = NRF_CLOCK_LF_ACCURACY_250_PPM,
#endif
    };

    uint32_t err_code = sd_softdevice_enable(&clock_config, softdevice_assert_handler);
    if (err_code != NRF_SUCCESS) {
        return err_code;
    }

    err_code = sd_nvic_EnableIRQ(SD_EVT_IRQn);
    if (err_code != NRF_SUCCESS) {
        return err_code;
    }

    // Start with no event handlers, etc.
    ble_drv_reset();

    // Set everything up to have one persistent code editing connection and one user managed
    // connection. In the future we could move .data and .bss to the other side of the stack and
    // dynamically adjust for different memory requirements of the SD based on boot.py
    // configuration.
    uint32_t app_ram_start = (uint32_t) &_ram_start;

    ble_cfg_t ble_conf;
    ble_conf.conn_cfg.conn_cfg_tag = BLE_CONN_CFG_TAG_CUSTOM;
    ble_conf.conn_cfg.params.gap_conn_cfg.conn_count = BLEIO_TOTAL_CONNECTION_COUNT;
    // Event length here can influence throughput so perhaps make multiple connection profiles
    // available.
    ble_conf.conn_cfg.params.gap_conn_cfg.event_length = BLE_GAP_EVENT_LENGTH_DEFAULT;
    err_code = sd_ble_cfg_set(BLE_CONN_CFG_GAP, &ble_conf, app_ram_start);
    if (err_code != NRF_SUCCESS) {
        return err_code;
    }

    memset(&ble_conf, 0, sizeof(ble_conf));
    ble_conf.gap_cfg.role_count_cfg.adv_set_count = 1;
    ble_conf.gap_cfg.role_count_cfg.periph_role_count = 2;
    ble_conf.gap_cfg.role_count_cfg.central_role_count = 1;
    err_code = sd_ble_cfg_set(BLE_GAP_CFG_ROLE_COUNT, &ble_conf, app_ram_start);
    if (err_code != NRF_SUCCESS) {
        return err_code;
    }

    memset(&ble_conf, 0, sizeof(ble_conf));
    ble_conf.conn_cfg.conn_cfg_tag = BLE_CONN_CFG_TAG_CUSTOM;
    ble_conf.conn_cfg.params.gatts_conn_cfg.hvn_tx_queue_size = MAX_TX_IN_PROGRESS;
    err_code = sd_ble_cfg_set(BLE_CONN_CFG_GATTS, &ble_conf, app_ram_start);
    if (err_code != NRF_SUCCESS) {
        return err_code;
    }

    // Triple the GATT Server attribute size to accomodate both the CircuitPython built-in service
    // and anything the user does.
    memset(&ble_conf, 0, sizeof(ble_conf));
    ble_conf.gatts_cfg.attr_tab_size.attr_tab_size = BLE_GATTS_ATTR_TAB_SIZE_DEFAULT * 3;
    err_code = sd_ble_cfg_set(BLE_GATTS_CFG_ATTR_TAB_SIZE, &ble_conf, app_ram_start);
    if (err_code != NRF_SUCCESS) {
        return err_code;
    }

    // TODO set ATT_MTU so that the maximum MTU we can negotiate is higher than the default.

    // This sets app_ram_start to the minimum value needed for the settings set above.
    err_code = sd_ble_enable(&app_ram_start);
    if (err_code != NRF_SUCCESS) {
        return err_code;
    }

    ble_gap_conn_params_t gap_conn_params = {
        .min_conn_interval = BLE_MIN_CONN_INTERVAL,
        .max_conn_interval = BLE_MAX_CONN_INTERVAL,
        .slave_latency     = BLE_SLAVE_LATENCY,
        .conn_sup_timeout  = BLE_CONN_SUP_TIMEOUT,
    };
   err_code = sd_ble_gap_ppcp_set(&gap_conn_params);
   if (err_code != NRF_SUCCESS) {
       return err_code;
   }

   err_code = sd_ble_gap_appearance_set(BLE_APPEARANCE_UNKNOWN);
   return err_code;
}

STATIC bool adapter_on_ble_evt(ble_evt_t *ble_evt, void *self_in) {
    bleio_adapter_obj_t *self = (bleio_adapter_obj_t*)self_in;

    // For debugging.
    // mp_printf(&mp_plat_print, "Adapter event: 0x%04x\n", ble_evt->header.evt_id);

    switch (ble_evt->header.evt_id) {
        case BLE_GAP_EVT_CONNECTED: {
            // Find an empty connection. One must always be available because the SD has the same
            // total connection limit.
            bleio_connection_internal_t *connection;
            for (size_t i = 0; i < BLEIO_TOTAL_CONNECTION_COUNT; i++) {
                connection = &connections[i];
                if (connection->conn_handle == BLE_CONN_HANDLE_INVALID) {
                    break;
                }
            }

            // Central has connected.
            ble_gap_evt_connected_t* connected = &ble_evt->evt.gap_evt.params.connected;

            connection->conn_handle = ble_evt->evt.gap_evt.conn_handle;
            connection->connection_obj = mp_const_none;
            connection->pair_status = PAIR_NOT_PAIRED;

            ble_drv_add_event_handler_entry(&connection->handler_entry, connection_on_ble_evt, connection);
            self->connection_objs = NULL;

            // Save the current connection parameters.
            memcpy(&connection->conn_params, &connected->conn_params, sizeof(ble_gap_conn_params_t));

            #if CIRCUITPY_VERBOSE_BLE
            ble_gap_conn_params_t *cp = &connected->conn_params;
            mp_printf(&mp_plat_print, "conn params: min_ci %d max_ci %d s_l %d sup_timeout %d\n", cp->min_conn_interval, cp->max_conn_interval, cp->slave_latency, cp->conn_sup_timeout);
            #endif

            // See if connection interval set by Central is out of range.
            // If so, negotiate our preferred range.
            ble_gap_conn_params_t conn_params;
            sd_ble_gap_ppcp_get(&conn_params);
            if (conn_params.min_conn_interval < connected->conn_params.min_conn_interval ||
                conn_params.min_conn_interval > connected->conn_params.max_conn_interval) {
                sd_ble_gap_conn_param_update(ble_evt->evt.gap_evt.conn_handle, &conn_params);
            }
            self->current_advertising_data = NULL;
            break;
        }
        case BLE_GAP_EVT_DISCONNECTED: {
            // Find the connection that was disconnected.
            bleio_connection_internal_t *connection;
            for (size_t i = 0; i < BLEIO_TOTAL_CONNECTION_COUNT; i++) {
                connection = &connections[i];
                if (connection->conn_handle == ble_evt->evt.gap_evt.conn_handle) {
                    break;
                }
            }
            ble_drv_remove_event_handler(connection_on_ble_evt, connection);
            connection->conn_handle = BLE_CONN_HANDLE_INVALID;
            if (connection->connection_obj != mp_const_none) {
                bleio_connection_obj_t* obj = connection->connection_obj;
                obj->connection = NULL;
                obj->disconnect_reason = ble_evt->evt.gap_evt.params.disconnected.reason;
            }
            self->connection_objs = NULL;

            break;
        }

        case BLE_GAP_EVT_ADV_SET_TERMINATED:
            self->current_advertising_data = NULL;
            break;

        default:
            // For debugging.
            // mp_printf(&mp_plat_print, "Unhandled adapter event: 0x%04x\n", ble_evt->header.evt_id);
            return false;
            break;
    }
    return true;
}

STATIC void get_address(bleio_adapter_obj_t *self, ble_gap_addr_t *address) {
    check_nrf_error(sd_ble_gap_addr_get(address));
}

char default_ble_name[] = { 'C', 'I', 'R', 'C', 'U', 'I', 'T', 'P', 'Y', 0, 0, 0, 0 , 0};

STATIC void bleio_adapter_reset_name(bleio_adapter_obj_t *self) {
    uint8_t len = sizeof(default_ble_name) - 1;

    ble_gap_addr_t local_address;
    get_address(self, &local_address);

    default_ble_name[len - 4] = nibble_to_hex_lower[local_address.addr[1] >> 4 & 0xf];
    default_ble_name[len - 3] = nibble_to_hex_lower[local_address.addr[1] & 0xf];
    default_ble_name[len - 2] = nibble_to_hex_lower[local_address.addr[0] >> 4 & 0xf];
    default_ble_name[len - 1] = nibble_to_hex_lower[local_address.addr[0] & 0xf];
    default_ble_name[len] = '\0'; // for now we add null for compatibility with C ASCIIZ strings

    common_hal_bleio_adapter_set_name(self, (char*) default_ble_name);
}

void common_hal_bleio_adapter_set_enabled(bleio_adapter_obj_t *self, bool enabled) {
    const bool is_enabled = common_hal_bleio_adapter_get_enabled(self);

    // Don't enable or disable twice
    if (is_enabled == enabled) {
        return;
    }

    uint32_t err_code;
    if (enabled) {
        // The SD takes over the POWER module and will fail if the module is already in use.
        // Occurs when USB is initialized previously
        nrfx_power_uninit();

        err_code = ble_stack_enable();
    } else {
        err_code = sd_softdevice_disable();
    }
    // Re-init USB hardware
    init_usb_hardware();

    check_nrf_error(err_code);

    // Add a handler for incoming peripheral connections.
    if (enabled) {
        for (size_t i = 0; i < BLEIO_TOTAL_CONNECTION_COUNT; i++) {
            bleio_connection_internal_t *connection = &connections[i];
            connection->conn_handle = BLE_CONN_HANDLE_INVALID;
        }
        bleio_adapter_reset_name(self);
        ble_drv_add_event_handler_entry(&self->handler_entry, adapter_on_ble_evt, self);
    } else {
        ble_drv_reset();
        self->scan_results = NULL;
        self->current_advertising_data = NULL;
        self->advertising_data = NULL;
        self->scan_response_data = NULL;
    }
}

bool common_hal_bleio_adapter_get_enabled(bleio_adapter_obj_t *self) {
    uint8_t is_enabled;

    check_nrf_error(sd_softdevice_is_enabled(&is_enabled));

    return is_enabled;
}

bleio_address_obj_t *common_hal_bleio_adapter_get_address(bleio_adapter_obj_t *self) {
    common_hal_bleio_adapter_set_enabled(self, true);

    ble_gap_addr_t local_address;
    get_address(self, &local_address);

    bleio_address_obj_t *address = m_new_obj(bleio_address_obj_t);
    address->base.type = &bleio_address_type;

    common_hal_bleio_address_construct(address, local_address.addr, local_address.addr_type);
    return address;
}

mp_obj_str_t* common_hal_bleio_adapter_get_name(bleio_adapter_obj_t *self) {
    uint16_t len = 0;
    sd_ble_gap_device_name_get(NULL, &len);
    uint8_t buf[len];
    uint32_t err_code = sd_ble_gap_device_name_get(buf, &len);
    if (err_code != NRF_SUCCESS) {
        return NULL;
    }
    return mp_obj_new_str((char*) buf, len);
}

void common_hal_bleio_adapter_set_name(bleio_adapter_obj_t *self, const char* name) {
    ble_gap_conn_sec_mode_t sec;
    sec.lv = 0;
    sec.sm = 0;
    sd_ble_gap_device_name_set(&sec, (const uint8_t*) name, strlen(name));
}

STATIC bool scan_on_ble_evt(ble_evt_t *ble_evt, void *scan_results_in) {
    bleio_scanresults_obj_t *scan_results = (bleio_scanresults_obj_t*)scan_results_in;

    if (ble_evt->header.evt_id == BLE_GAP_EVT_TIMEOUT &&
        ble_evt->evt.gap_evt.params.timeout.src == BLE_GAP_TIMEOUT_SRC_SCAN) {
        shared_module_bleio_scanresults_set_done(scan_results, true);
        ble_drv_remove_event_handler(scan_on_ble_evt, scan_results);
        return true;
    }

    if (ble_evt->header.evt_id != BLE_GAP_EVT_ADV_REPORT) {
        return false;
    }
    ble_gap_evt_adv_report_t *report = &ble_evt->evt.gap_evt.params.adv_report;

    shared_module_bleio_scanresults_append(scan_results,
                                           supervisor_ticks_ms64(),
                                           report->type.connectable,
                                           report->type.scan_response,
                                           report->rssi,
                                           report->peer_addr.addr,
                                           report->peer_addr.addr_type,
                                           report->data.p_data,
                                           report->data.len);

    const uint32_t err_code = sd_ble_gap_scan_start(NULL, scan_results->common_hal_data);
    if (err_code != NRF_SUCCESS) {
        // TODO: Pass the error into the scan results so it can throw an exception.
        scan_results->done = true;
    }
    return true;
}

mp_obj_t common_hal_bleio_adapter_start_scan(bleio_adapter_obj_t *self, uint8_t* prefixes, size_t prefix_length, bool extended, mp_int_t buffer_size, mp_float_t timeout, mp_float_t interval, mp_float_t window, mp_int_t minimum_rssi, bool active) {
    if (self->scan_results != NULL) {
        if (!shared_module_bleio_scanresults_get_done(self->scan_results)) {
            mp_raise_bleio_BluetoothError(translate("Scan already in progess. Stop with stop_scan."));
        }
        self->scan_results = NULL;
    }
    self->scan_results = shared_module_bleio_new_scanresults(buffer_size, prefixes, prefix_length, minimum_rssi);
    size_t max_packet_size = extended ? BLE_GAP_SCAN_BUFFER_EXTENDED_MAX_SUPPORTED : BLE_GAP_SCAN_BUFFER_MAX;
    uint8_t *raw_data = m_malloc(sizeof(ble_data_t) + max_packet_size, false);
    ble_data_t * sd_data = (ble_data_t *) raw_data;
    self->scan_results->common_hal_data = sd_data;
    sd_data->len = max_packet_size;
    sd_data->p_data = raw_data + sizeof(ble_data_t);

    ble_drv_add_event_handler(scan_on_ble_evt, self->scan_results);

    uint32_t nrf_timeout = SEC_TO_UNITS(timeout, UNIT_10_MS);
    if (timeout <= 0.0001) {
        nrf_timeout = BLE_GAP_SCAN_TIMEOUT_UNLIMITED;
    }

    ble_gap_scan_params_t scan_params = {
        .extended = extended,
        .interval = SEC_TO_UNITS(interval, UNIT_0_625_MS),
        .timeout = nrf_timeout,
        .window = SEC_TO_UNITS(window, UNIT_0_625_MS),
        .scan_phys = BLE_GAP_PHY_1MBPS,
        .active = active
    };
    uint32_t err_code;
    err_code = sd_ble_gap_scan_start(&scan_params, sd_data);

    if (err_code != NRF_SUCCESS) {
        self->scan_results = NULL;
        ble_drv_remove_event_handler(scan_on_ble_evt, self->scan_results);
        check_nrf_error(err_code);
    }

    return MP_OBJ_FROM_PTR(self->scan_results);
}

void common_hal_bleio_adapter_stop_scan(bleio_adapter_obj_t *self) {
    sd_ble_gap_scan_stop();
    shared_module_bleio_scanresults_set_done(self->scan_results, true);
    ble_drv_remove_event_handler(scan_on_ble_evt, self->scan_results);
    self->scan_results = NULL;
}

typedef struct {
    uint16_t conn_handle;
    volatile bool done;
} connect_info_t;

STATIC bool connect_on_ble_evt(ble_evt_t *ble_evt, void *info_in) {
    connect_info_t *info = (connect_info_t*)info_in;

    switch (ble_evt->header.evt_id) {
        case BLE_GAP_EVT_CONNECTED:
            info->conn_handle = ble_evt->evt.gap_evt.conn_handle;
            info->done = true;

            break;

        case BLE_GAP_EVT_TIMEOUT:
            // Handle will be invalid.
            info->done = true;
            break;
        default:
            // For debugging.
            // mp_printf(&mp_plat_print, "Unhandled central event: 0x%04x\n", ble_evt->header.evt_id);
            return false;
            break;
    }
    return true;
}

mp_obj_t common_hal_bleio_adapter_connect(bleio_adapter_obj_t *self, bleio_address_obj_t *address, mp_float_t timeout) {

    ble_gap_addr_t addr;

    addr.addr_type = address->type;
    mp_buffer_info_t address_buf_info;
    mp_get_buffer_raise(address->bytes, &address_buf_info, MP_BUFFER_READ);
    memcpy(addr.addr, (uint8_t *) address_buf_info.buf, NUM_BLEIO_ADDRESS_BYTES);

    ble_gap_scan_params_t scan_params = {
        .interval = MSEC_TO_UNITS(100, UNIT_0_625_MS),
        .window = MSEC_TO_UNITS(100, UNIT_0_625_MS),
        .scan_phys = BLE_GAP_PHY_1MBPS,
        // timeout of 0 means no timeout
        .timeout = SEC_TO_UNITS(timeout, UNIT_10_MS),
    };

    ble_gap_conn_params_t conn_params = {
        .conn_sup_timeout = MSEC_TO_UNITS(4000, UNIT_10_MS),
        .min_conn_interval = MSEC_TO_UNITS(15, UNIT_1_25_MS),
        .max_conn_interval = MSEC_TO_UNITS(300, UNIT_1_25_MS),
        .slave_latency = 0,          // number of conn events
    };

    connect_info_t event_info;
    ble_drv_add_event_handler(connect_on_ble_evt, &event_info);
    event_info.done = false;

    uint32_t err_code = sd_ble_gap_connect(&addr, &scan_params, &conn_params, BLE_CONN_CFG_TAG_CUSTOM);

    if (err_code != NRF_SUCCESS) {
        ble_drv_remove_event_handler(connect_on_ble_evt, &event_info);
        check_nrf_error(err_code);
    }

    while (!event_info.done) {
        RUN_BACKGROUND_TASKS;
    }

    ble_drv_remove_event_handler(connect_on_ble_evt, &event_info);

    if (event_info.conn_handle == BLE_CONN_HANDLE_INVALID) {
        mp_raise_bleio_BluetoothError(translate("Failed to connect: timeout"));
    }

    // Make the connection object and return it.
    for (size_t i = 0; i < BLEIO_TOTAL_CONNECTION_COUNT; i++) {
        bleio_connection_internal_t *connection = &connections[i];
        if (connection->conn_handle == event_info.conn_handle) {
            return bleio_connection_new_from_internal(connection);
        }
    }

    mp_raise_bleio_BluetoothError(translate("Failed to connect: internal error"));

    return mp_const_none;
}

// The nRF SD 6.1.0 can only do one concurrent advertisement so share the advertising handle.
uint8_t adv_handle = BLE_GAP_ADV_SET_HANDLE_NOT_SET;

STATIC void check_data_fit(size_t data_len) {
    if (data_len > BLE_GAP_ADV_SET_DATA_SIZE_MAX) {
        mp_raise_ValueError(translate("Data too large for advertisement packet"));
    }
}

uint32_t _common_hal_bleio_adapter_start_advertising(bleio_adapter_obj_t *self, bool connectable, float interval, uint8_t *advertising_data, uint16_t advertising_data_len, uint8_t *scan_response_data, uint16_t scan_response_data_len) {
    if (self->current_advertising_data != NULL && self->current_advertising_data == self->advertising_data) {
        return NRF_ERROR_BUSY;
    }

    // If the current advertising data isn't owned by the adapter then it must be an internal
    // advertisement that we should stop.
    if (self->current_advertising_data != NULL) {
        common_hal_bleio_adapter_stop_advertising(self);
    }

    uint32_t err_code;
    ble_gap_adv_params_t adv_params = {
        .interval = SEC_TO_UNITS(interval, UNIT_0_625_MS),
        .properties.type = connectable ? BLE_GAP_ADV_TYPE_CONNECTABLE_SCANNABLE_UNDIRECTED
        : BLE_GAP_ADV_TYPE_NONCONNECTABLE_NONSCANNABLE_UNDIRECTED,
        .duration = BLE_GAP_ADV_TIMEOUT_GENERAL_UNLIMITED,
        .filter_policy = BLE_GAP_ADV_FP_ANY,
        .primary_phy = BLE_GAP_PHY_1MBPS,
    };

    const ble_gap_adv_data_t ble_gap_adv_data = {
        .adv_data.p_data = advertising_data,
        .adv_data.len = advertising_data_len,
        .scan_rsp_data.p_data = scan_response_data_len > 0 ? scan_response_data : NULL,
        .scan_rsp_data.len = scan_response_data_len,
    };

    err_code = sd_ble_gap_adv_set_configure(&adv_handle, &ble_gap_adv_data, &adv_params);
    if (err_code != NRF_SUCCESS) {
        return err_code;
    }

    err_code = sd_ble_gap_adv_start(adv_handle, BLE_CONN_CFG_TAG_CUSTOM);
    if (err_code != NRF_SUCCESS) {
        return err_code;
    }
    self->current_advertising_data = advertising_data;
    return NRF_SUCCESS;
}


void common_hal_bleio_adapter_start_advertising(bleio_adapter_obj_t *self, bool connectable, mp_float_t interval, mp_buffer_info_t *advertising_data_bufinfo, mp_buffer_info_t *scan_response_data_bufinfo) {
    if (self->current_advertising_data != NULL && self->current_advertising_data == self->advertising_data) {
        mp_raise_bleio_BluetoothError(translate("Already advertising."));
    }
    // interval value has already been validated.

    check_data_fit(advertising_data_bufinfo->len);
    check_data_fit(scan_response_data_bufinfo->len);
    // The advertising data buffers must not move, because the SoftDevice depends on them.
    // So make them long-lived and reuse them onwards.
    if (self->advertising_data == NULL) {
        self->advertising_data = (uint8_t *) gc_alloc(BLE_GAP_ADV_SET_DATA_SIZE_MAX * sizeof(uint8_t), false, true);
    }
    if (self->scan_response_data == NULL) {
        self->scan_response_data = (uint8_t *) gc_alloc(BLE_GAP_ADV_SET_DATA_SIZE_MAX * sizeof(uint8_t), false, true);
    }

    memcpy(self->advertising_data, advertising_data_bufinfo->buf, advertising_data_bufinfo->len);
    memcpy(self->scan_response_data, scan_response_data_bufinfo->buf, scan_response_data_bufinfo->len);

    check_nrf_error(_common_hal_bleio_adapter_start_advertising(self, connectable, interval,
                                                                self->advertising_data,
                                                                advertising_data_bufinfo->len,
                                                                self->scan_response_data,
                                                                scan_response_data_bufinfo->len));
}

void common_hal_bleio_adapter_stop_advertising(bleio_adapter_obj_t *self) {
    if (adv_handle == BLE_GAP_ADV_SET_HANDLE_NOT_SET)
        return;

    // TODO: Don't actually stop. Switch to advertising CircuitPython if we don't already have a connection.
    const uint32_t err_code = sd_ble_gap_adv_stop(adv_handle);
    self->current_advertising_data = NULL;

    if ((err_code != NRF_SUCCESS) && (err_code != NRF_ERROR_INVALID_STATE)) {
        check_nrf_error(err_code);
    }
}

bool common_hal_bleio_adapter_get_connected(bleio_adapter_obj_t *self) {
    for (size_t i = 0; i < BLEIO_TOTAL_CONNECTION_COUNT; i++) {
        bleio_connection_internal_t *connection = &connections[i];
        if (connection->conn_handle != BLE_CONN_HANDLE_INVALID) {
            return true;
        }
    }
    return false;
}

mp_obj_t common_hal_bleio_adapter_get_connections(bleio_adapter_obj_t *self) {
    if (self->connection_objs != NULL) {
        return self->connection_objs;
    }
    size_t total_connected = 0;
    mp_obj_t items[BLEIO_TOTAL_CONNECTION_COUNT];
    for (size_t i = 0; i < BLEIO_TOTAL_CONNECTION_COUNT; i++) {
        bleio_connection_internal_t *connection = &connections[i];
        if (connection->conn_handle != BLE_CONN_HANDLE_INVALID) {
            if (connection->connection_obj == mp_const_none) {
                connection->connection_obj = bleio_connection_new_from_internal(connection);
            }
            items[total_connected] = connection->connection_obj;
            total_connected++;
        }
    }
    self->connection_objs = mp_obj_new_tuple(total_connected, items);
    return self->connection_objs;
}

void bleio_adapter_gc_collect(bleio_adapter_obj_t* adapter) {
    gc_collect_root((void**)adapter, sizeof(bleio_adapter_obj_t) / sizeof(size_t));
    gc_collect_root((void**)connections, sizeof(connections) / sizeof(size_t));
}

void bleio_adapter_reset(bleio_adapter_obj_t* adapter) {
    common_hal_bleio_adapter_stop_scan(adapter);
    common_hal_bleio_adapter_stop_advertising(adapter);
    adapter->connection_objs = NULL;
    for (size_t i = 0; i < BLEIO_TOTAL_CONNECTION_COUNT; i++) {
        bleio_connection_internal_t *connection = &connections[i];
        connection->connection_obj = mp_const_none;
    }
}