[BT] Move BT tracing to UART1 (IO12) & output in BlueZ btmon tty format

Transient on the ESP32 IOs after reset will make the PC running btmon
receive a spurious bytes which completely throw off irremediably btmon
tty parser.

So the trick is to release the ESP32 reset and then right after issue
the following command on the PC in hope of missing that spurious byte.

Usage: btmon --tty /dev/ttyUSB0 --tty-speed 921600 -w trace.log

main/CMakeLists.txt

@@ -42,6 +42,7 @@ idf_component_register(SRCS "main.c"
                             "bluetooth/att_cfg.c"
                             "bluetooth/att_hid.c"
                             "bluetooth/smp.c"
+                            "bluetooth/mon.c"
                             "bluetooth/hidp/hidp.c"
                             "bluetooth/hidp/generic.c"
                             "bluetooth/hidp/ps3.c"

main/bluetooth/host.c

@@ -24,6 +24,7 @@
 #include "smp.h"
 #include "tools/util.h"
 #include "debug.h"
+#include "mon.h"
 #include "system/fs.h"
 #include "adapter/config.h"
 #include "adapter/gameid.h"
@@ -68,9 +69,6 @@ static uint32_t frag_size = 0;
 static uint32_t frag_offset = 0;
 static uint8_t frag_buf[1024];
 
-#ifdef CONFIG_BLUERETRO_BT_H4_TRACE
-static void bt_h4_trace(uint8_t *data, uint16_t len, uint8_t dir);
-#endif /* CONFIG_BLUERETRO_BT_H4_TRACE */
 static int32_t bt_host_load_bdaddr_from_nvs(void);
 static int32_t bt_host_load_keys_from_file(struct bt_host_link_keys *data);
 static int32_t bt_host_store_keys_on_file(struct bt_host_link_keys *data);
@@ -86,21 +84,6 @@ static esp_vhci_host_callback_t vhci_host_cb = {
     bt_host_rx_pkt
 };
 
-#ifdef CONFIG_BLUERETRO_BT_H4_TRACE
-static void bt_h4_trace(uint8_t *data, uint16_t len, uint8_t dir) {
-    if (dir)
-        printf("I ");
-    else
-        printf("O ");
-
-    printf("%06X", 0);
-    for (uint32_t i = 0; i < len; i++) {
-        printf(" %02X", data[i]);
-    }
-    printf("\n");
-}
-#endif /* CONFIG_BLUERETRO_BT_H4_TRACE */
-
 static int32_t bt_host_load_bdaddr_from_nvs(void) {
     esp_err_t err;
     nvs_handle_t nvs;
@@ -215,7 +198,8 @@ static void bt_tx_task(void *param) {
                 }
                 else {
 #ifdef CONFIG_BLUERETRO_BT_H4_TRACE
-                    bt_h4_trace(packet, packet_len, BT_TX);
+                    bt_mon_tx((packet[0] == BT_HCI_H4_TYPE_CMD) ? BT_MON_CMD : BT_MON_ACL_TX,
+                        packet + 1, packet_len - 1);
 #endif /* CONFIG_BLUERETRO_BT_H4_TRACE */
                     atomic_clear_bit(&bt_flags, BT_CTRL_READY);
                     esp_vhci_host_send_packet(packet, packet_len);
@@ -405,7 +389,8 @@ static void bt_host_tx_pkt_ready(void) {
 static int bt_host_rx_pkt(uint8_t *data, uint16_t len) {
     struct bt_hci_pkt *bt_hci_pkt = (struct bt_hci_pkt *)data;
 #ifdef CONFIG_BLUERETRO_BT_H4_TRACE
-    bt_h4_trace(data, len, BT_RX);
+    bt_mon_tx((bt_hci_pkt->h4_hdr.type == BT_HCI_H4_TYPE_EVT) ? BT_MON_EVT : BT_MON_ACL_RX,
+        data + 1, len - 1);
 #endif /* CONFIG_BLUERETRO_BT_H4_TRACE */
 
 #ifdef CONFIG_BLUERETRO_BT_TIMING_TESTS
@@ -633,6 +618,11 @@ int32_t bt_host_init(void) {
 
     bt_host_load_bdaddr_from_nvs();
 
+#ifdef CONFIG_BLUERETRO_BT_H4_TRACE
+    bt_mon_init(UART_NUM_1, 921600, UART_DATA_8_BITS, UART_STOP_BITS_1,
+        UART_PARITY_DISABLE, UART_HW_FLOWCTRL_DISABLE);
+#endif
+
     esp_bt_controller_config_t bt_cfg = BT_CONTROLLER_INIT_CONFIG_DEFAULT();
 
     if ((ret = esp_bt_controller_init(&bt_cfg)) != ESP_OK) {

main/bluetooth/mon.c

@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2024, Jacques Gagnon
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include <esp_timer.h>
+#include "mon.h"
+#include "host.h"
+#include "zephyr/hci.h"
+
+#define BT_MON_TX_PIN 12
+#define BT_MON_RX_PIN 13
+#define BT_MON_RTS_PIN 15
+#define BT_MON_CTS_PIN 14
+
+struct bt_mon_hdr {
+	uint16_t data_len;
+	uint16_t opcode;
+	uint8_t flags;
+	uint8_t hdr_len;
+	uint8_t ts_type;
+	uint32_t ts_data;
+} __packed;
+
+static int uart_port;
+static struct bt_mon_hdr mon_hdr = {0};
+
+int bt_mon_init(int port_num, int32_t baud_rate, uint8_t data_bits, uint8_t stop_bits,
+    uart_parity_t parity, uart_hw_flowcontrol_t flow_ctl) {
+    uart_config_t uart_cfg = {
+        .baud_rate = baud_rate,
+        .data_bits = data_bits,
+        .parity = parity,
+        .stop_bits = stop_bits,
+        .flow_ctrl = flow_ctl,
+        .source_clk = UART_SCLK_DEFAULT,
+        .rx_flow_ctrl_thresh = UART_HW_FIFO_LEN(port_num) - 1,
+    };
+    uart_port = port_num;
+
+    printf("# %s: set uart pin tx:%d\n", __FUNCTION__, BT_MON_TX_PIN);
+    printf("# %s: set baud_rate:%ld.\n", __FUNCTION__, baud_rate);
+
+    ESP_ERROR_CHECK(uart_driver_delete(port_num));
+    ESP_ERROR_CHECK(uart_driver_install(port_num, UART_HW_FIFO_LEN(port_num) * 2, 0, 0, NULL, 0));
+    ESP_ERROR_CHECK(uart_param_config(port_num, &uart_cfg));
+    ESP_ERROR_CHECK(uart_set_pin(port_num, BT_MON_TX_PIN, BT_MON_RX_PIN, BT_MON_RTS_PIN, BT_MON_CTS_PIN));
+
+    return 0;
+}
+
+void IRAM_ATTR bt_mon_tx(uint16_t opcode, uint8_t *data, uint16_t len) {
+    mon_hdr.data_len = len + 4 + 5;
+    mon_hdr.opcode = opcode;
+    mon_hdr.hdr_len = 5;
+    mon_hdr.ts_type = 8;
+    mon_hdr.ts_data = esp_timer_get_time() / 100;
+
+    uart_write_bytes(uart_port, &mon_hdr, sizeof(mon_hdr));
+    uart_write_bytes(uart_port, data, len);
+}

main/bluetooth/mon.h

@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2024, Jacques Gagnon
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef _BT_MON_H_
+#define _BT_MON_H_
+
+#include "driver/uart.h"
+
+#define BT_MON_CMD 2
+#define BT_MON_EVT 3
+#define BT_MON_ACL_TX 4
+#define BT_MON_ACL_RX 5
+
+int bt_mon_init(int port_num, int32_t baud_rate, uint8_t data_bits,
+    uint8_t stop_bits, uart_parity_t parity, uart_hw_flowcontrol_t flow_ctl);
+void bt_mon_tx(uint16_t opcode, uint8_t *data, uint16_t len);
+
+#endif /* _BT_MON_H_ */