samples/bluetooth/central_gatt_write/src/gatt_write_common.c

/*
 * Copyright (c) 2022 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr/kernel.h>
#include <zephyr/sys/printk.h>

#include <zephyr/bluetooth/bluetooth.h>
#include <zephyr/bluetooth/conn.h>
#include <zephyr/bluetooth/gatt.h>

static struct bt_gatt_exchange_params mtu_exchange_params;
static uint32_t write_count;
static uint32_t write_len;
static uint32_t write_rate;
struct bt_conn *conn_connected;
uint32_t last_write_rate;
void (*start_scan_func)(void);

static void write_cmd_cb(struct bt_conn *conn, void *user_data)
{
	static uint32_t cycle_stamp;
	uint64_t delta;

	delta = k_cycle_get_32() - cycle_stamp;
	delta = k_cyc_to_ns_floor64(delta);

	/* if last data rx-ed was greater than 1 second in the past,
	 * reset the metrics.
	 */
	if (delta > (1U * NSEC_PER_SEC)) {
		printk("%s: count= %u, len= %u, rate= %u bps.\n", __func__,
		       write_count, write_len, write_rate);

		last_write_rate = write_rate;

		write_count = 0U;
		write_len = 0U;
		write_rate = 0U;
		cycle_stamp = k_cycle_get_32();
	} else {
		uint16_t len;

		write_count++;

		/* Extract the 16-bit data length stored in user_data */
		len = (uint32_t)user_data & 0xFFFF;

		write_len += len;
		write_rate = ((uint64_t)write_len << 3) * (1U * NSEC_PER_SEC) /
			     delta;
	}
}

static void mtu_exchange_cb(struct bt_conn *conn, uint8_t err,
			    struct bt_gatt_exchange_params *params)
{
	printk("%s: MTU exchange %s (%u)\n", __func__,
	       err == 0U ? "successful" : "failed",
	       bt_gatt_get_mtu(conn));
}

static int mtu_exchange(struct bt_conn *conn)
{
	int err;

	printk("%s: Current MTU = %u\n", __func__, bt_gatt_get_mtu(conn));

	mtu_exchange_params.func = mtu_exchange_cb;

	printk("%s: Exchange MTU...\n", __func__);
	err = bt_gatt_exchange_mtu(conn, &mtu_exchange_params);
	if (err) {
		printk("%s: MTU exchange failed (err %d)", __func__, err);
	}

	return err;
}

static void connected(struct bt_conn *conn, uint8_t conn_err)
{
	struct bt_conn_info conn_info;
	char addr[BT_ADDR_LE_STR_LEN];
	int err;

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	if (conn_err) {
		printk("%s: Failed to connect to %s (%u)\n", __func__, addr,
		       conn_err);
		return;
	}

	err = bt_conn_get_info(conn, &conn_info);
	if (err) {
		printk("Failed to get connection info (%d).\n", err);
		return;
	}

	printk("%s: %s role %u\n", __func__, addr, conn_info.role);

	conn_connected = bt_conn_ref(conn);

	(void)mtu_exchange(conn);

#if defined(CONFIG_BT_SMP)
	if (conn_info.role == BT_CONN_ROLE_CENTRAL) {
		err = bt_conn_set_security(conn, BT_SECURITY_L2);
		if (err) {
			printk("Failed to set security (%d).\n", err);
		}
	}
#endif
}

static void disconnected(struct bt_conn *conn, uint8_t reason)
{
	struct bt_conn_info conn_info;
	char addr[BT_ADDR_LE_STR_LEN];
	int err;

	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

	err = bt_conn_get_info(conn, &conn_info);
	if (err) {
		printk("Failed to get connection info (%d).\n", err);
		return;
	}

	printk("%s: %s role %u (reason %u)\n", __func__, addr, conn_info.role,
	       reason);

	conn_connected = NULL;

	bt_conn_unref(conn);

	if (conn_info.role == BT_CONN_ROLE_CENTRAL) {
		start_scan_func();
	}
}

static bool le_param_req(struct bt_conn *conn, struct bt_le_conn_param *param)
{
	printk("%s: int (0x%04x, 0x%04x) lat %u to %u\n", __func__,
	       param->interval_min, param->interval_max, param->latency,
	       param->timeout);

	return true;
}

static void le_param_updated(struct bt_conn *conn, uint16_t interval,
			     uint16_t latency, uint16_t timeout)
{
	printk("%s: int 0x%04x lat %u to %u\n", __func__, interval,
	       latency, timeout);
}

#if defined(CONFIG_BT_SMP)
static void security_changed(struct bt_conn *conn, bt_security_t level,
			     enum bt_security_err err)
{
	printk("%s: to level %u (err %u)\n", __func__, level, err);
}
#endif

BT_CONN_CB_DEFINE(conn_callbacks) = {
	.connected = connected,
	.disconnected = disconnected,
	.le_param_req = le_param_req,
	.le_param_updated = le_param_updated,
#if defined(CONFIG_BT_SMP)
	.security_changed = security_changed,
#endif
};

int write_cmd(struct bt_conn *conn)
{
	static uint8_t data[BT_ATT_MAX_ATTRIBUTE_LEN] = {0, };
	static uint16_t data_len;
	uint16_t data_len_max;
	int err;

	data_len_max = bt_gatt_get_mtu(conn) - 3;
	if (data_len_max > BT_ATT_MAX_ATTRIBUTE_LEN) {
		data_len_max = BT_ATT_MAX_ATTRIBUTE_LEN;
	}

#if TEST_FRAGMENTATION_WITH_VARIABLE_LENGTH_DATA
	/* Use incremental length data for every write command */
	/* TODO: Include test case in BabbleSim tests */
	static bool decrement;

	if (decrement) {
		data_len--;
		if (data_len <= 1) {
			data_len = 1;
			decrement = false;
		}
	} else {
		data_len++;
		if (data_len >= data_len_max) {
			data_len = data_len_max;
			decrement = true;
		}
	}
#else
	/* Use fixed length data for every write command */
	data_len = data_len_max;
#endif

	/* Pass the 16-bit data length value (instead of reference) in
	 * user_data so that unique value is pass for each write callback.
	 * Using handle 0x0001, we do not care if it is writable, we just want
	 * to transmit the data across.
	 */
	err = bt_gatt_write_without_response_cb(conn, 0x0001, data, data_len,
						false, write_cmd_cb,
						(void *)((uint32_t)data_len));
	if (err) {
		printk("%s: Write cmd failed (%d).\n", __func__, err);
	}

	return err;
}