xref: /btstack/src/classic/hsp_ag.c (revision d58a1b5f11ada8ddf896c41fff5a35e7f140c37e)
1 /*
2  * Copyright (C) 2014 BlueKitchen GmbH
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  *
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the copyright holders nor the names of
14  *    contributors may be used to endorse or promote products derived
15  *    from this software without specific prior written permission.
16  * 4. Any redistribution, use, or modification is done solely for
17  *    personal benefit and not for any commercial purpose or for
18  *    monetary gain.
19  *
20  * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
23  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS
24  * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
26  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
27  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
30  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  * Please inquire about commercial licensing options at
34  * [email protected]
35  *
36  */
37 
38 #define BTSTACK_FILE__ "hsp_ag.c"
39 
40 // *****************************************************************************
41 //
42 // HSP Audio Gateway
43 //
44 // *****************************************************************************
45 
46 #include "btstack_config.h"
47 
48 #include <stdint.h>
49 #include <stdio.h>
50 #include <stdlib.h>
51 #include <string.h>
52 
53 #include "bluetooth_sdp.h"
54 #include "btstack_debug.h"
55 #include "btstack_event.h"
56 #include "btstack_memory.h"
57 #include "btstack_run_loop.h"
58 #include "classic/core.h"
59 #include "classic/sdp_server.h"
60 #include "classic/sdp_client_rfcomm.h"
61 #include "classic/sdp_util.h"
62 #include "hci.h"
63 #include "hci_cmd.h"
64 #include "hci_dump.h"
65 #include "hsp_ag.h"
66 #include "l2cap.h"
67 
68 #define HSP_HS_BUTTON_PRESS "AT+CKPD=200"
69 #define HSP_HS_AT_CKPD "AT+CKPD\r\n"
70 #define HSP_AG_OK "\r\nOK\r\n"
71 #define HSP_AG_ERROR "\r\nERROR\r\n"
72 #define HSP_AG_RING "\r\nRING\r\n"
73 #define HSP_MICROPHONE_GAIN "+VGM"
74 #define HSP_SPEAKER_GAIN "+VGS"
75 
76 #define HSP_HS_MICROPHONE_GAIN "AT+VGM="
77 #define HSP_HS_SPEAKER_GAIN "AT+VGS="
78 
79 static const char default_hsp_ag_service_name[] = "Audio Gateway";
80 
81 static bd_addr_t remote;
82 static bd_addr_t sco_event_addr;
83 static uint8_t channel_nr = 0;
84 
85 static uint16_t mtu;
86 static uint16_t rfcomm_cid = 0;
87 static uint16_t sco_handle = 0;
88 static uint16_t rfcomm_handle = 0;
89 static btstack_timer_source_t hs_timeout;
90 
91 static int ag_microphone_gain = -1;
92 static int ag_speaker_gain = -1;
93 static uint8_t ag_ring = 0;
94 static uint8_t ag_send_ok = 0;
95 static uint8_t ag_send_error = 0;
96 static uint8_t ag_num_button_press_received = 0;
97 static uint8_t ag_support_custom_commands = 0;
98 static uint8_t ag_establish_sco = 0;
99 static uint8_t hsp_disconnect_rfcomm = 0;
100 static uint8_t hsp_establish_audio_connection = 0;
101 static uint8_t hsp_release_audio_connection = 0;
102 
103 static btstack_packet_callback_registration_t hci_event_callback_registration;
104 
105 typedef enum {
106     HSP_IDLE,
107     HSP_SDP_QUERY_RFCOMM_CHANNEL,
108     HSP_W4_SDP_EVENT_QUERY_COMPLETE,
109     HSP_W4_RFCOMM_CONNECTED,
110 
111     HSP_RFCOMM_CONNECTION_ESTABLISHED,
112 
113     HSP_W4_RING_ANSWER,
114     HSP_W4_USER_ACTION,
115     HSP_W2_CONNECT_SCO,
116     HSP_W4_SCO_CONNECTED,
117 
118     HSP_AUDIO_CONNECTION_ESTABLISHED,
119 
120     HSP_W2_DISCONNECT_SCO,
121     HSP_W4_SCO_DISCONNECTED,
122 
123     HSP_W2_DISCONNECT_RFCOMM,
124     HSP_W4_RFCOMM_DISCONNECTED,
125     HSP_W4_CONNECTION_ESTABLISHED_TO_SHUTDOWN
126 } hsp_state_t;
127 
128 static hsp_state_t hsp_state = HSP_IDLE;
129 
130 
131 static btstack_packet_handler_t hsp_ag_callback;
132 
133 static void hsp_run(void);
134 static void packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
135 static void handle_query_rfcomm_event(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
136 
137 static void dummy_notify(uint8_t packet_type, uint16_t channel, uint8_t * event, uint16_t size){
138     UNUSED(packet_type);    // ok: no code
139     UNUSED(channel);        // ok: no code
140     UNUSED(event);          // ok: no code
141     UNUSED(size);           // ok: no code
142 }
143 
144 void hsp_ag_register_packet_handler(btstack_packet_handler_t callback){
145     if (callback == NULL){
146         callback = &dummy_notify;
147     }
148     hsp_ag_callback = callback;
149 }
150 
151 static void emit_event(uint8_t event_subtype, uint8_t value){
152     if (!hsp_ag_callback) return;
153     uint8_t event[4];
154     event[0] = HCI_EVENT_HSP_META;
155     event[1] = sizeof(event) - 2;
156     event[2] = event_subtype;
157     event[3] = value; // status 0 == OK
158     (*hsp_ag_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
159 }
160 
161 static void emit_event_audio_connected(uint8_t status, uint16_t handle){
162     if (!hsp_ag_callback) return;
163     uint8_t event[6];
164     event[0] = HCI_EVENT_HSP_META;
165     event[1] = sizeof(event) - 2;
166     event[2] = HSP_SUBEVENT_AUDIO_CONNECTION_COMPLETE;
167     event[3] = status;
168     little_endian_store_16(event, 4, handle);
169     (*hsp_ag_callback)(HCI_EVENT_PACKET, 0, event, sizeof(event));
170 }
171 
172 void hsp_ag_create_sdp_record(uint8_t * service, uint32_t service_record_handle, int rfcomm_channel_nr, const char * name){
173     uint8_t* attribute;
174     de_create_sequence(service);
175 
176     // 0x0000 "Service Record Handle"
177     de_add_number(service, DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_SERVICE_RECORD_HANDLE);
178     de_add_number(service, DE_UINT, DE_SIZE_32, service_record_handle);
179 
180     // 0x0001 "Service Class ID List"
181     de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_SERVICE_CLASS_ID_LIST);
182     attribute = de_push_sequence(service);
183     {
184         //  "UUID for PAN Service"
185         de_add_number(attribute, DE_UUID, DE_SIZE_16, BLUETOOTH_SERVICE_CLASS_HEADSET_AUDIO_GATEWAY_AG);
186         de_add_number(attribute, DE_UUID, DE_SIZE_16, BLUETOOTH_SERVICE_CLASS_GENERIC_AUDIO);
187     }
188     de_pop_sequence(service, attribute);
189 
190     // 0x0004 "Protocol Descriptor List"
191     de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_PROTOCOL_DESCRIPTOR_LIST);
192     attribute = de_push_sequence(service);
193     {
194         uint8_t* l2cpProtocol = de_push_sequence(attribute);
195         {
196             de_add_number(l2cpProtocol,  DE_UUID, DE_SIZE_16, BLUETOOTH_PROTOCOL_L2CAP);
197         }
198         de_pop_sequence(attribute, l2cpProtocol);
199 
200         uint8_t* rfcomm = de_push_sequence(attribute);
201         {
202             de_add_number(rfcomm,  DE_UUID, DE_SIZE_16, BLUETOOTH_PROTOCOL_RFCOMM);  // rfcomm_service
203             de_add_number(rfcomm,  DE_UINT, DE_SIZE_8,  rfcomm_channel_nr);  // rfcomm channel
204         }
205         de_pop_sequence(attribute, rfcomm);
206     }
207     de_pop_sequence(service, attribute);
208 
209     // 0x0005 "Public Browse Group"
210     de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_BROWSE_GROUP_LIST); // public browse group
211     attribute = de_push_sequence(service);
212     {
213         de_add_number(attribute,  DE_UUID, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_PUBLIC_BROWSE_ROOT);
214     }
215     de_pop_sequence(service, attribute);
216 
217     // 0x0009 "Bluetooth Profile Descriptor List"
218     de_add_number(service,  DE_UINT, DE_SIZE_16, BLUETOOTH_ATTRIBUTE_BLUETOOTH_PROFILE_DESCRIPTOR_LIST);
219     attribute = de_push_sequence(service);
220     {
221         uint8_t *sppProfile = de_push_sequence(attribute);
222         {
223             de_add_number(sppProfile,  DE_UUID, DE_SIZE_16, BLUETOOTH_SERVICE_CLASS_HEADSET);
224             de_add_number(sppProfile,  DE_UINT, DE_SIZE_16, 0x0102); // Verision 1.2
225         }
226         de_pop_sequence(attribute, sppProfile);
227     }
228     de_pop_sequence(service, attribute);
229 
230     // 0x0100 "Service Name"
231     de_add_number(service,  DE_UINT, DE_SIZE_16, 0x0100);
232     if (name){
233         de_add_data(service,  DE_STRING, strlen(name), (uint8_t *) name);
234     } else {
235         de_add_data(service,  DE_STRING, strlen(default_hsp_ag_service_name), (uint8_t *) default_hsp_ag_service_name);
236     }
237 }
238 
239 static int hsp_ag_send_str_over_rfcomm(const uint16_t cid, const char * command){
240     int err = rfcomm_send(cid, (uint8_t*) command, strlen(command));
241     if (err){
242         log_error("rfcomm_send_internal -> error 0X%02x", err);
243         return err;
244     }
245     return err;
246 }
247 
248 void hsp_ag_enable_custom_commands(int enable){
249     ag_support_custom_commands = enable;
250 }
251 
252 int hsp_ag_send_result(char * result){
253     if (!ag_support_custom_commands) return 1;
254     return hsp_ag_send_str_over_rfcomm(rfcomm_cid, result);
255 }
256 
257 static void hsp_ag_reset_state(void){
258     hsp_state = HSP_IDLE;
259 
260     rfcomm_cid = 0;
261     rfcomm_handle = 0;
262     sco_handle = 0;
263 
264     ag_send_ok = 0;
265     ag_send_error = 0;
266     ag_ring = 0;
267 
268     ag_num_button_press_received = 0;
269     ag_support_custom_commands = 0;
270 
271     ag_microphone_gain = -1;
272     ag_speaker_gain = -1;
273 
274     hsp_disconnect_rfcomm = 0;
275     hsp_establish_audio_connection = 0;
276     hsp_release_audio_connection = 0;
277 }
278 
279 void hsp_ag_init(uint8_t rfcomm_channel_nr){
280     // register for HCI events
281     hci_event_callback_registration.callback = &packet_handler;
282     hci_add_event_handler(&hci_event_callback_registration);
283 
284     rfcomm_register_service(packet_handler, rfcomm_channel_nr, 0xffff);  // reserved channel, mtu limited by l2cap
285 
286     hsp_ag_reset_state();
287 }
288 
289 void hsp_ag_connect(bd_addr_t bd_addr){
290     if (hsp_state != HSP_IDLE) return;
291     hsp_state = HSP_SDP_QUERY_RFCOMM_CHANNEL;
292     memcpy(remote, bd_addr, 6);
293     hsp_run();
294 }
295 
296 void hsp_ag_disconnect(void){
297     hsp_ag_release_audio_connection();
298     if (hsp_state < HSP_W4_RFCOMM_CONNECTED){
299         hsp_state = HSP_IDLE;
300         return;
301     }
302 
303     if (hsp_state == HSP_W4_RFCOMM_CONNECTED){
304         hsp_state = HSP_W4_CONNECTION_ESTABLISHED_TO_SHUTDOWN;
305         return;
306     }
307     hsp_disconnect_rfcomm = 1;
308     hsp_run();
309 }
310 
311 void hsp_ag_establish_audio_connection(void){
312     switch (hsp_state){
313         case HSP_RFCOMM_CONNECTION_ESTABLISHED:
314             hsp_establish_audio_connection = 1;
315             hsp_state = HSP_W4_SCO_CONNECTED;
316             break;
317         case HSP_W4_RFCOMM_CONNECTED:
318             hsp_state = HSP_W4_CONNECTION_ESTABLISHED_TO_SHUTDOWN;
319             break;
320         default:
321             break;
322     }
323     hsp_run();
324 }
325 
326 void hsp_ag_release_audio_connection(void){
327     if (hsp_state >= HSP_W2_DISCONNECT_SCO) return;
328     if (hsp_state < HSP_AUDIO_CONNECTION_ESTABLISHED) return;
329 
330     hsp_release_audio_connection = 1;
331     hsp_run();
332 }
333 
334 
335 void hsp_ag_set_microphone_gain(uint8_t gain){
336     if (gain >15) {
337         log_error("Gain must be in interval [0..15], it is given %d", gain);
338         return;
339     }
340     ag_microphone_gain = gain;
341     hsp_run();
342 }
343 
344 // AG +VGS=5  [0..15] ; HS AT+VGM=6 | AG OK
345 void hsp_ag_set_speaker_gain(uint8_t gain){
346     if (gain >15) {
347         log_error("Gain must be in interval [0..15], it is given %d", gain);
348         return;
349     }
350     ag_speaker_gain = gain;
351     hsp_run();
352 }
353 
354 static void hsp_ringing_timeout_handler(btstack_timer_source_t * timer){
355     ag_ring = 1;
356     btstack_run_loop_set_timer(timer, 2000); // 2 seconds timeout
357     btstack_run_loop_add_timer(timer);
358     hsp_run();
359 }
360 
361 static void hsp_ringing_timer_start(void){
362     btstack_run_loop_remove_timer(&hs_timeout);
363     btstack_run_loop_set_timer_handler(&hs_timeout, hsp_ringing_timeout_handler);
364     btstack_run_loop_set_timer(&hs_timeout, 2000); // 2 seconds timeout
365     btstack_run_loop_add_timer(&hs_timeout);
366 }
367 
368 static void hsp_ringing_timer_stop(void){
369     btstack_run_loop_remove_timer(&hs_timeout);
370 }
371 
372 void hsp_ag_start_ringing(void){
373     ag_ring = 1;
374     if (hsp_state == HSP_W2_CONNECT_SCO) {
375         hsp_state = HSP_W4_RING_ANSWER;
376     }
377     hsp_ringing_timer_start();
378 }
379 
380 void hsp_ag_stop_ringing(void){
381     ag_ring = 0;
382     if (hsp_state == HSP_W4_RING_ANSWER){
383         hsp_state = HSP_W2_CONNECT_SCO;
384     }
385     hsp_ringing_timer_stop();
386 }
387 
388 static void hsp_run(void){
389     if (ag_establish_sco && hci_can_send_command_packet_now()){
390         ag_establish_sco = 0;
391 
392         log_info("HSP: sending hci_accept_connection_request.");
393         // remote supported feature eSCO is set if link type is eSCO
394         // eSCO: S4 - max latency == transmission interval = 0x000c == 12 ms,
395         uint16_t max_latency;
396         uint8_t  retransmission_effort;
397         uint16_t packet_types;
398 
399         if (hci_remote_esco_supported(rfcomm_handle)){
400             max_latency = 0x000c;
401             retransmission_effort = 0x02;
402             packet_types = 0x388;
403         } else {
404             max_latency = 0xffff;
405             retransmission_effort = 0xff;
406             packet_types = 0x003f;
407         }
408 
409         uint16_t sco_voice_setting = hci_get_sco_voice_setting();
410 
411         log_info("HFP: sending hci_accept_connection_request, sco_voice_setting %02x", sco_voice_setting);
412         hci_send_cmd(&hci_accept_synchronous_connection, remote, 8000, 8000, max_latency,
413                         sco_voice_setting, retransmission_effort, packet_types);
414         return;
415     }
416 
417     if (ag_send_ok){
418         if (!rfcomm_can_send_packet_now(rfcomm_cid)) {
419             rfcomm_request_can_send_now_event(rfcomm_cid);
420             return;
421         }
422         ag_send_ok = 0;
423         hsp_ag_send_str_over_rfcomm(rfcomm_cid, HSP_AG_OK);
424         return;
425     }
426 
427     if (ag_send_error){
428         if (!rfcomm_can_send_packet_now(rfcomm_cid)) {
429             rfcomm_request_can_send_now_event(rfcomm_cid);
430             return;
431         }
432         ag_send_error = 0;
433         hsp_ag_send_str_over_rfcomm(rfcomm_cid, HSP_AG_ERROR);
434         return;
435     }
436 
437     if (ag_ring){
438         if (!rfcomm_can_send_packet_now(rfcomm_cid)) {
439             rfcomm_request_can_send_now_event(rfcomm_cid);
440             return;
441         }
442         ag_ring = 0;
443         hsp_ag_send_str_over_rfcomm(rfcomm_cid, HSP_AG_RING);
444         return;
445     }
446 
447     if (hsp_establish_audio_connection){
448         if (!hci_can_send_command_packet_now()) return;
449         hsp_establish_audio_connection = 0;
450         hci_send_cmd(&hci_setup_synchronous_connection, rfcomm_handle, 8000, 8000, 0xFFFF, hci_get_sco_voice_setting(), 0xFF, 0x003F);
451         return;
452     }
453 
454     if (hsp_release_audio_connection){
455         hsp_release_audio_connection = 0;
456         gap_disconnect(sco_handle);
457         return;
458     }
459 
460     if (hsp_disconnect_rfcomm){
461         hsp_disconnect_rfcomm = 0;
462         hsp_establish_audio_connection = 0;
463         rfcomm_disconnect(rfcomm_cid);
464         return;
465     }
466 
467     switch (hsp_state){
468         case HSP_SDP_QUERY_RFCOMM_CHANNEL:
469             hsp_state = HSP_W4_SDP_EVENT_QUERY_COMPLETE;
470             log_info("Start SDP query %s, 0x%02x", bd_addr_to_str(remote), BLUETOOTH_SERVICE_CLASS_HEADSET);
471             sdp_client_query_rfcomm_channel_and_name_for_uuid(&handle_query_rfcomm_event, remote, BLUETOOTH_SERVICE_CLASS_HEADSET);
472             break;
473 
474         case HSP_W4_RING_ANSWER:
475             if (!ag_num_button_press_received) break;
476 
477             if (!rfcomm_can_send_packet_now(rfcomm_cid)) {
478                 rfcomm_request_can_send_now_event(rfcomm_cid);
479                 return;
480             }
481 
482             ag_send_ok = 0;
483             ag_num_button_press_received = 0;
484             hsp_state = HSP_W2_CONNECT_SCO;
485 
486             hsp_ag_send_str_over_rfcomm(rfcomm_cid, HSP_AG_OK);
487             break;
488 
489         case HSP_W2_CONNECT_SCO:
490             if (!hci_can_send_command_packet_now()) return;
491             hsp_state = HSP_W4_SCO_CONNECTED;
492             hci_send_cmd(&hci_setup_synchronous_connection, rfcomm_handle, 8000, 8000, 0xFFFF, hci_get_sco_voice_setting(), 0xFF, 0x003F);
493             break;
494 
495         case HSP_W2_DISCONNECT_SCO:
496             ag_num_button_press_received = 0;
497 
498             hsp_state = HSP_W4_SCO_DISCONNECTED;
499             gap_disconnect(sco_handle);
500             break;
501 
502         case HSP_W2_DISCONNECT_RFCOMM:
503             rfcomm_disconnect(rfcomm_cid);
504             break;
505 
506         case HSP_AUDIO_CONNECTION_ESTABLISHED:
507         case HSP_RFCOMM_CONNECTION_ESTABLISHED:
508 
509             if (ag_microphone_gain >= 0){
510                 if (!rfcomm_can_send_packet_now(rfcomm_cid)) {
511                     rfcomm_request_can_send_now_event(rfcomm_cid);
512                     return;
513                 }
514                 int gain = ag_microphone_gain;
515                 ag_microphone_gain = -1;
516                 char buffer[10];
517                 sprintf(buffer, "%s=%d\r\n", HSP_MICROPHONE_GAIN, gain);
518                 hsp_ag_send_str_over_rfcomm(rfcomm_cid, buffer);
519                 break;
520             }
521 
522             if (ag_speaker_gain >= 0){
523                 if (!rfcomm_can_send_packet_now(rfcomm_cid)) {
524                     rfcomm_request_can_send_now_event(rfcomm_cid);
525                     return;
526                 }
527                 int gain = ag_speaker_gain;
528                 ag_speaker_gain = -1;
529                 char buffer[10];
530                 sprintf(buffer, "%s=%d\r\n", HSP_SPEAKER_GAIN, gain);
531                 hsp_ag_send_str_over_rfcomm(rfcomm_cid, buffer);
532                 break;
533             }
534             break;
535         default:
536             break;
537     }
538 }
539 
540 
541 static void packet_handler (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
542     UNUSED(channel);    // ok: no channel for HCI_EVENT_PACKET and only single active RFCOMM channel
543 
544     if (packet_type == RFCOMM_DATA_PACKET){
545         while ((size > 0) && ((packet[0] == '\n') || (packet[0] == '\r'))){
546             size--;
547             packet++;
548         }
549 
550         if (strncmp((char *)packet, HSP_HS_BUTTON_PRESS, strlen(HSP_HS_BUTTON_PRESS)) == 0){
551             log_info("Received button press %s", HSP_HS_BUTTON_PRESS);
552             ag_send_ok = 1;
553             switch (hsp_state){
554                 case HSP_AUDIO_CONNECTION_ESTABLISHED:
555                     hsp_release_audio_connection = 1;
556                     break;
557                 case HSP_RFCOMM_CONNECTION_ESTABLISHED:
558                     hsp_establish_audio_connection = 1;
559                     break;
560                 default:
561                     break;
562             }
563         } else if (strncmp((char *)packet, HSP_HS_MICROPHONE_GAIN, strlen(HSP_HS_MICROPHONE_GAIN)) == 0){
564             uint8_t gain = (uint8_t)btstack_atoi((char*)&packet[strlen(HSP_HS_MICROPHONE_GAIN)]);
565             ag_send_ok = 1;
566             emit_event(HSP_SUBEVENT_MICROPHONE_GAIN_CHANGED, gain);
567 
568         } else if (strncmp((char *)packet, HSP_HS_SPEAKER_GAIN, strlen(HSP_HS_SPEAKER_GAIN)) == 0){
569             uint8_t gain = (uint8_t)btstack_atoi((char*)&packet[strlen(HSP_HS_SPEAKER_GAIN)]);
570             ag_send_ok = 1;
571             emit_event(HSP_SUBEVENT_SPEAKER_GAIN_CHANGED, gain);
572 
573         } else if (strncmp((char *)packet, "AT+", 3) == 0){
574             ag_send_error = 1;
575             if (!hsp_ag_callback) return;
576             // re-use incoming buffer to avoid reserving large buffers - ugly but efficient
577             uint8_t * event = packet - 4;
578             event[0] = HCI_EVENT_HSP_META;
579             event[1] = size + 2;
580             event[2] = HSP_SUBEVENT_HS_COMMAND;
581             event[3] = size;
582             (*hsp_ag_callback)(HCI_EVENT_PACKET, 0, event, size+4);
583         }
584 
585         hsp_run();
586         return;
587     }
588 
589     if (packet_type != HCI_EVENT_PACKET) return;
590     uint8_t event = hci_event_packet_get_type(packet);
591     bd_addr_t event_addr;
592     uint16_t handle;
593 
594     switch (event) {
595         case HCI_EVENT_CONNECTION_REQUEST:
596             hci_event_connection_request_get_bd_addr(packet, sco_event_addr);
597             ag_establish_sco = 1;
598             break;
599         case HCI_EVENT_SYNCHRONOUS_CONNECTION_COMPLETE:{
600             uint8_t status = hci_event_synchronous_connection_complete_get_status(packet);
601             if (status != 0){
602                 log_error("(e)SCO Connection failed, status %u", status);
603                 emit_event_audio_connected(status, sco_handle);
604                 break;
605             }
606 
607             hci_event_synchronous_connection_complete_get_bd_addr(packet, event_addr);
608             sco_handle = hci_event_synchronous_connection_complete_get_handle(packet);
609             uint8_t  link_type = hci_event_synchronous_connection_complete_get_link_type(packet);
610             uint8_t  transmission_interval = hci_event_synchronous_connection_complete_get_transmission_interval(packet);  // measured in slots
611             uint8_t  retransmission_interval = hci_event_synchronous_connection_complete_get_retransmission_interval(packet);// measured in slots
612             uint16_t rx_packet_length = hci_event_synchronous_connection_complete_get_rx_packet_length(packet); // measured in bytes
613             uint16_t tx_packet_length = hci_event_synchronous_connection_complete_get_tx_packet_length(packet); // measured in bytes
614             uint8_t  air_mode = hci_event_synchronous_connection_complete_get_air_mode(packet);
615 
616             switch (link_type){
617                 case 0x00:
618                     log_info("SCO Connection established.");
619                     if (transmission_interval != 0) log_error("SCO Connection: transmission_interval not zero: %d.", transmission_interval);
620                     if (retransmission_interval != 0) log_error("SCO Connection: retransmission_interval not zero: %d.", retransmission_interval);
621                     if (rx_packet_length != 0) log_error("SCO Connection: rx_packet_length not zero: %d.", rx_packet_length);
622                     if (tx_packet_length != 0) log_error("SCO Connection: tx_packet_length not zero: %d.", tx_packet_length);
623                     break;
624                 case 0x02:
625                     log_info("eSCO Connection established.");
626                     break;
627                 default:
628                     log_error("(e)SCO reserved link_type 0x%2x", link_type);
629                     break;
630             }
631             log_info("sco_handle 0x%2x, address %s, transmission_interval %u slots, retransmission_interval %u slots, "
632                  " rx_packet_length %u bytes, tx_packet_length %u bytes, air_mode 0x%2x (0x02 == CVSD)", sco_handle,
633                  bd_addr_to_str(event_addr), transmission_interval, retransmission_interval, rx_packet_length, tx_packet_length, air_mode);
634 
635             if (hsp_state == HSP_W4_CONNECTION_ESTABLISHED_TO_SHUTDOWN){
636                 hsp_state = HSP_W2_DISCONNECT_SCO;
637                 break;
638             }
639 
640             hsp_state = HSP_AUDIO_CONNECTION_ESTABLISHED;
641             emit_event_audio_connected(status, sco_handle);
642             break;
643         }
644 
645         case RFCOMM_EVENT_INCOMING_CONNECTION:
646             // data: event (8), len(8), address(48), channel (8), rfcomm_cid (16)
647             if (hsp_state != HSP_IDLE) return;
648 
649             rfcomm_event_incoming_connection_get_bd_addr(packet, event_addr);
650             rfcomm_cid = rfcomm_event_incoming_connection_get_server_channel(packet);
651             log_info("RFCOMM channel %u requested for %s", packet[8], bd_addr_to_str(event_addr));
652             hsp_state = HSP_W4_RFCOMM_CONNECTED;
653             rfcomm_accept_connection(rfcomm_cid);
654             break;
655 
656         case RFCOMM_EVENT_CHANNEL_OPENED:
657             log_info("RFCOMM_EVENT_CHANNEL_OPENED packet_handler type %u, packet[0] %x", packet_type, packet[0]);
658             // data: event(8), len(8), status (8), address (48), handle(16), server channel(8), rfcomm_cid(16), max frame size(16)
659             if (rfcomm_event_channel_opened_get_status(packet)) {
660                 log_info("RFCOMM channel open failed, status %u§", rfcomm_event_channel_opened_get_status(packet));
661                 hsp_ag_reset_state();
662                 hsp_state = HSP_IDLE;
663             } else {
664                 // data: event(8) , len(8), status (8), address (48), handle (16), server channel(8), rfcomm_cid(16), max frame size(16)
665                 rfcomm_handle = rfcomm_event_channel_opened_get_con_handle(packet);
666                 rfcomm_cid = rfcomm_event_channel_opened_get_rfcomm_cid(packet);
667                 mtu = rfcomm_event_channel_opened_get_max_frame_size(packet);
668                 log_info("RFCOMM channel open succeeded. New RFCOMM Channel ID %u, max frame size %u, state %d", rfcomm_cid, mtu, hsp_state);
669                 hsp_state = HSP_RFCOMM_CONNECTION_ESTABLISHED;
670             }
671             emit_event(HSP_SUBEVENT_RFCOMM_CONNECTION_COMPLETE, packet[2]);
672             break;
673 
674         case RFCOMM_EVENT_CHANNEL_CLOSED:
675             rfcomm_handle = 0;
676             hsp_state = HSP_IDLE;
677             hsp_ag_reset_state();
678             emit_event(HSP_SUBEVENT_RFCOMM_DISCONNECTION_COMPLETE,0);
679             break;
680 
681         case RFCOMM_EVENT_CAN_SEND_NOW:
682             hsp_run();
683             break;
684 
685         case HCI_EVENT_DISCONNECTION_COMPLETE:
686             handle = little_endian_read_16(packet,3);
687             if (handle == sco_handle){
688                 sco_handle = 0;
689                 hsp_state = HSP_RFCOMM_CONNECTION_ESTABLISHED;
690                 emit_event(HSP_SUBEVENT_AUDIO_DISCONNECTION_COMPLETE,0);
691                 break;
692             }
693             if (handle == rfcomm_handle) {
694                 rfcomm_handle = 0;
695                 hsp_state = HSP_IDLE;
696                 hsp_ag_reset_state();
697                 emit_event(HSP_SUBEVENT_RFCOMM_DISCONNECTION_COMPLETE,0);
698             }
699             break;
700 
701         default:
702             break;
703     }
704 
705     hsp_run();
706 }
707 
708 static void handle_query_rfcomm_event(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
709     UNUSED(packet_type);    // ok: handling own sdp events
710     UNUSED(channel);        // ok: no channel
711     UNUSED(size);           // ok: handling own sdp events
712 
713     switch (packet[0]){
714         case SDP_EVENT_QUERY_RFCOMM_SERVICE:
715             channel_nr = sdp_event_query_rfcomm_service_get_rfcomm_channel(packet);
716             log_info("** Service name: '%s', RFCOMM port %u", sdp_event_query_rfcomm_service_get_name(packet), channel_nr);
717             break;
718         case SDP_EVENT_QUERY_COMPLETE:
719             if (channel_nr > 0){
720                 hsp_state = HSP_W4_RFCOMM_CONNECTED;
721                 log_info("RFCOMM create channel. state %d", HSP_W4_RFCOMM_CONNECTED);
722                 rfcomm_create_channel(packet_handler, remote, channel_nr, NULL);
723                 break;
724             }
725             hsp_ag_reset_state();
726             log_info("Service not found, status %u.\n", sdp_event_query_complete_get_status(packet));
727             if (sdp_event_query_complete_get_status(packet)){
728                 emit_event(HSP_SUBEVENT_AUDIO_CONNECTION_COMPLETE, sdp_event_query_complete_get_status(packet));
729             } else {
730                 emit_event(HSP_SUBEVENT_AUDIO_CONNECTION_COMPLETE, SDP_SERVICE_NOT_FOUND);
731             }
732             break;
733         default:
734             break;
735     }
736 }
737 
738 
739