xref: /btstack/src/hci_transport_h5.c (revision f9f2075ceac5e9dc08e9abea437e43d733a3a0ea)
1 /*
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37 
38 /*
39  *  hci_transport_h5.c
40  *
41  *  HCI Transport API implementation for basic H5 protocol
42  *
43  *  Created by Matthias Ringwald on 4/29/09.
44  */
45 
46 #include "hci.h"
47 #include "btstack_slip.h"
48 #include "btstack_debug.h"
49 #include "hci_transport.h"
50 #include "btstack_uart_block.h"
51 
52 typedef enum {
53     LINK_UNINITIALIZED,
54     LINK_INITIALIZED,
55     LINK_ACTIVE
56 } hci_transport_link_state_t;
57 
58 typedef enum {
59     HCI_TRANSPORT_LINK_SEND_SYNC            = 1 << 0,
60     HCI_TRANSPORT_LINK_SEND_SYNC_RESPONSE   = 1 << 1,
61     HCI_TRANSPORT_LINK_SEND_CONFIG          = 1 << 2,
62     HCI_TRANSPORT_LINK_SEND_CONFIG_RESPONSE = 1 << 3,
63     HCI_TRANSPORT_LINK_SEND_SLEEP           = 1 << 4,
64     HCI_TRANSPORT_LINK_SEND_WOKEN           = 1 << 5,
65     HCI_TRANSPORT_LINK_SEND_WAKEUP          = 1 << 6,
66     HCI_TRANSPORT_LINK_SEND_QUEUED_PACKET   = 1 << 7,
67     HCI_TRANSPORT_LINK_SEND_ACK_PACKET      = 1 << 8,
68     HCI_TRANSPORT_LINK_ENTER_SLEEP          = 1 << 9,
69 
70 } hci_transport_link_actions_t;
71 
72 // Configuration Field. No packet buffers -> sliding window = 1, no OOF flow control, support data integrity check
73 #define LINK_CONFIG_SLIDING_WINDOW_SIZE 1
74 #define LINK_CONFIG_OOF_FLOW_CONTROL 0
75 #define LINK_CONFIG_DATA_INTEGRITY_CHECK 1
76 #define LINK_CONFIG_VERSION_NR 0
77 #define LINK_CONFIG_FIELD (LINK_CONFIG_SLIDING_WINDOW_SIZE | (LINK_CONFIG_OOF_FLOW_CONTROL << 3) | (LINK_CONFIG_DATA_INTEGRITY_CHECK << 4) | (LINK_CONFIG_VERSION_NR << 5))
78 
79 // periodic sending during link establishment
80 #define LINK_PERIOD_MS 250
81 
82 // resend wakeup
83 #define LINK_WAKEUP_MS 50
84 
85 // additional packet types
86 #define LINK_ACKNOWLEDGEMENT_TYPE 0x00
87 #define LINK_CONTROL_PACKET_TYPE 0x0f
88 
89 // max size of write requests
90 #define LINK_SLIP_TX_CHUNK_LEN 64
91 
92 // ---
93 static const uint8_t link_control_sync[] =   { 0x01, 0x7e};
94 static const uint8_t link_control_sync_response[] = { 0x02, 0x7d};
95 static const uint8_t link_control_config[] = { 0x03, 0xfc, LINK_CONFIG_FIELD};
96 static const uint8_t link_control_config_prefix_len  = 2;
97 static const uint8_t link_control_config_response[] = { 0x04, 0x7b, LINK_CONFIG_FIELD};
98 static const uint8_t link_control_config_response_prefix_len  = 2;
99 static const uint8_t link_control_wakeup[] = { 0x05, 0xfa};
100 static const uint8_t link_control_woken[] =  { 0x06, 0xf9};
101 static const uint8_t link_control_sleep[] =  { 0x07, 0x78};
102 
103 // max size of link control messages
104 #define LINK_CONTROL_MAX_LEN 3
105 
106 // incoming pre-bufffer + 4 bytes H5 header + max(acl header + acl payload, event header + event data) + 2 bytes opt CRC
107 static uint8_t   hci_packet_with_pre_buffer[HCI_INCOMING_PRE_BUFFER_SIZE + 6 + HCI_PACKET_BUFFER_SIZE];
108 
109 // outgoing slip encoded buffer. +4 to assert that DIC fits in buffer. +1 to assert that last SOF fits in buffer.
110 static uint8_t   slip_outgoing_buffer[LINK_SLIP_TX_CHUNK_LEN+4+1];
111 static uint16_t  slip_outgoing_dic;
112 static uint16_t  slip_outgoing_dic_present;
113 static int       slip_write_active;
114 
115 // H5 Link State
116 static hci_transport_link_state_t link_state;
117 static btstack_timer_source_t link_timer;
118 static uint8_t  link_seq_nr;
119 static uint8_t  link_ack_nr;
120 static uint16_t link_resend_timeout_ms;
121 static uint8_t  link_peer_asleep;
122 static uint8_t  link_peer_supports_data_integrity_check;
123 
124 // auto sleep-mode
125 static btstack_timer_source_t inactivity_timer;
126 static uint16_t link_inactivity_timeout_ms; // auto-sleep if set
127 
128 // Outgoing packet
129 static uint8_t   hci_packet_type;
130 static uint16_t  hci_packet_size;
131 static uint8_t * hci_packet;
132 
133 // hci packet handler
134 static  void (*packet_handler)(uint8_t packet_type, uint8_t *packet, uint16_t size);
135 
136 static int hci_transport_link_actions;
137 
138 // UART Driver + Config
139 static const btstack_uart_block_t * btstack_uart;
140 static btstack_uart_config_t uart_config;
141 static btstack_uart_sleep_mode_t btstack_uart_sleep_mode;
142 
143 // Prototypes
144 static void hci_transport_h5_process_frame(uint16_t frame_size);
145 static int  hci_transport_link_have_outgoing_packet(void);
146 static void hci_transport_link_send_queued_packet(void);
147 static void hci_transport_link_set_timer(uint16_t timeout_ms);
148 static void hci_transport_link_timeout_handler(btstack_timer_source_t * timer);
149 static void hci_transport_link_run(void);
150 static void hci_transport_slip_init(void);
151 
152 // -----------------------------
153 // CRC16-CCITT Calculation - compromise: use 32 byte table - 512 byte table would be faster, but that's too large
154 
155 static const uint16_t crc16_ccitt_table[] ={
156     0x0000, 0x1081, 0x2102, 0x3183,
157     0x4204, 0x5285, 0x6306, 0x7387,
158     0x8408, 0x9489, 0xa50a, 0xb58b,
159     0xc60c, 0xd68d, 0xe70e, 0xf78f
160 };
161 
162 static uint16_t crc16_ccitt_update (uint16_t crc, uint8_t ch){
163     crc = (crc >> 4) ^ crc16_ccitt_table[(crc ^ ch) & 0x000f];
164     crc = (crc >> 4) ^ crc16_ccitt_table[(crc ^ (ch >> 4)) & 0x000f];
165     return crc;
166 }
167 
168 static uint16_t btstack_reverse_bits_16(uint16_t value){
169     int reverse = 0;
170     int i;
171     for (i = 0; i < 16; i++) {
172         reverse = reverse << 1;
173         reverse |= value & 1;
174         value = value >> 1;
175     }
176     return reverse;
177 }
178 
179 static uint16_t crc16_calc_for_slip_frame(const uint8_t * header, const uint8_t * payload, uint16_t len){
180     int i;
181     uint16_t crc = 0xffff;
182     for (i=0 ; i < 4 ; i++){
183         crc = crc16_ccitt_update(crc, header[i]);
184     }
185     for (i=0 ; i < len ; i++){
186         crc = crc16_ccitt_update(crc, payload[i]);
187     }
188     return btstack_reverse_bits_16(crc);
189 }
190 
191 // -----------------------------
192 static void hci_transport_inactivity_timeout_handler(btstack_timer_source_t * ts){
193     log_info("h5: inactivity timeout. link state %d, peer asleep %u, actions 0x%02x, outgoing packet %u",
194         link_state, link_peer_asleep, hci_transport_link_actions, hci_transport_link_have_outgoing_packet());
195     if (hci_transport_link_have_outgoing_packet()) return;
196     if (link_state != LINK_ACTIVE) return;
197     if (hci_transport_link_actions) return;
198     if (link_peer_asleep) return;
199     hci_transport_link_actions |= HCI_TRANSPORT_LINK_SEND_SLEEP;
200     hci_transport_link_run();
201 }
202 
203 static void hci_transport_inactivity_timer_set(void){
204     if (!link_inactivity_timeout_ms) return;
205     btstack_run_loop_set_timer_handler(&inactivity_timer, &hci_transport_inactivity_timeout_handler);
206     btstack_run_loop_set_timer(&inactivity_timer, link_inactivity_timeout_ms);
207     btstack_run_loop_remove_timer(&inactivity_timer);
208     btstack_run_loop_add_timer(&inactivity_timer);
209 }
210 
211 // -----------------------------
212 // SLIP Outgoing
213 
214 // Fill chunk and write
215 static void hci_transport_slip_encode_chunk_and_send(int pos){
216     while (btstack_slip_encoder_has_data() & (pos < LINK_SLIP_TX_CHUNK_LEN)) {
217         slip_outgoing_buffer[pos++] = btstack_slip_encoder_get_byte();
218     }
219 
220     if (!btstack_slip_encoder_has_data()){
221         // Payload encoded, append DIC if present.
222         // note: slip_outgoing_buffer is guaranteed to be big enough to add DIC + SOF after LINK_SLIP_TX_CHUNK_LEN
223         if (slip_outgoing_dic_present){
224             uint8_t dic_buffer[2];
225             big_endian_store_16(dic_buffer, 0, slip_outgoing_dic);
226             btstack_slip_encoder_start(dic_buffer, 2);
227             while (btstack_slip_encoder_has_data()){
228                 slip_outgoing_buffer[pos++] = btstack_slip_encoder_get_byte();
229             }
230         }
231         // Start of Frame
232         slip_outgoing_buffer[pos++] = BTSTACK_SLIP_SOF;
233     }
234     slip_write_active = 1;
235     log_info("hci_transport_slip: send %d bytes", pos);
236     btstack_uart->send_block(slip_outgoing_buffer, pos);
237 }
238 
239 static inline void hci_transport_slip_send_next_chunk(void){
240     hci_transport_slip_encode_chunk_and_send(0);
241 }
242 
243 // format: 0xc0 HEADER PACKET [DIC] 0xc0
244 // @param uint8_t header[4]
245 static void hci_transport_slip_send_frame(const uint8_t * header, const uint8_t * packet, uint16_t packet_size, uint16_t data_integrity_check){
246 
247     int pos = 0;
248 
249     // store data integrity check info
250     slip_outgoing_dic         = data_integrity_check;
251     slip_outgoing_dic_present = header[0] & 0x40;
252 
253     // Start of Frame
254     slip_outgoing_buffer[pos++] = BTSTACK_SLIP_SOF;
255 
256     // Header
257     btstack_slip_encoder_start(header, 4);
258     while (btstack_slip_encoder_has_data()){
259         slip_outgoing_buffer[pos++] = btstack_slip_encoder_get_byte();
260     }
261 
262     // Packet
263     btstack_slip_encoder_start(packet, packet_size);
264 
265     // Fill rest of chunk from packet and send
266     hci_transport_slip_encode_chunk_and_send(pos);
267 }
268 
269 // SLIP Incoming
270 
271 static void hci_transport_slip_init(void){
272     btstack_slip_decoder_init(&hci_packet_with_pre_buffer[HCI_INCOMING_PRE_BUFFER_SIZE], 6 + HCI_PACKET_BUFFER_SIZE);
273 }
274 
275 // H5 Three-Wire Implementation
276 
277 static void hci_transport_link_calc_header(uint8_t * header,
278     uint8_t  sequence_nr,
279     uint8_t  acknowledgement_nr,
280     uint8_t  data_integrity_check_present,
281     uint8_t  reliable_packet,
282     uint8_t  packet_type,
283     uint16_t payload_length){
284 
285     header[0] = sequence_nr | (acknowledgement_nr << 3) | (data_integrity_check_present << 6) | (reliable_packet << 7);
286     header[1] = packet_type | ((payload_length & 0x0f) << 4);
287     header[2] = payload_length >> 4;
288     header[3] = 0xff - (header[0] + header[1] + header[2]);
289 }
290 
291 static void hci_transport_link_send_control(const uint8_t * message, int message_len){
292     uint8_t header[4];
293     hci_transport_link_calc_header(header, 0, 0, link_peer_supports_data_integrity_check, 0, LINK_CONTROL_PACKET_TYPE, message_len);
294     uint16_t data_integrity_check = 0;
295     if (link_peer_supports_data_integrity_check){
296         data_integrity_check = crc16_calc_for_slip_frame(header, message, message_len);
297     }
298     log_info("hci_transport_link_send_control: size %u, append dic %u", message_len, link_peer_supports_data_integrity_check);
299     log_info_hexdump(message, message_len);
300     hci_transport_slip_send_frame(header, message, message_len, data_integrity_check);
301 }
302 
303 static void hci_transport_link_send_sync(void){
304     log_info("link: send sync");
305     hci_transport_link_send_control(link_control_sync, sizeof(link_control_sync));
306 }
307 
308 static void hci_transport_link_send_sync_response(void){
309     log_info("link: send sync response");
310     hci_transport_link_send_control(link_control_sync_response, sizeof(link_control_sync_response));
311 }
312 
313 static void hci_transport_link_send_config(void){
314     log_info("link: send config");
315     hci_transport_link_send_control(link_control_config, sizeof(link_control_config));
316 }
317 
318 static void hci_transport_link_send_config_response(void){
319     log_info("link: send config response");
320     hci_transport_link_send_control(link_control_config_response, sizeof(link_control_config_response));
321 }
322 
323 static void hci_transport_link_send_woken(void){
324     log_info("link: send woken");
325     hci_transport_link_send_control(link_control_woken, sizeof(link_control_woken));
326 }
327 
328 static void hci_transport_link_send_wakeup(void){
329     log_info("link: send wakeup");
330     hci_transport_link_send_control(link_control_wakeup, sizeof(link_control_wakeup));
331 }
332 
333 static void hci_transport_link_send_sleep(void){
334     log_info("link: send sleep");
335     hci_transport_link_send_control(link_control_sleep, sizeof(link_control_sleep));
336 }
337 
338 static void hci_transport_link_send_queued_packet(void){
339 
340     uint8_t header[4];
341     hci_transport_link_calc_header(header, link_seq_nr, link_ack_nr, link_peer_supports_data_integrity_check, 1, hci_packet_type, hci_packet_size);
342 
343     uint16_t data_integrity_check = 0;
344     if (link_peer_supports_data_integrity_check){
345         data_integrity_check = crc16_calc_for_slip_frame(header, hci_packet, hci_packet_size);
346     }
347     log_info("hci_transport_link_send_queued_packet: seq %u, ack %u, size %u. Append dic %u, dic = 0x%04x", link_seq_nr, link_ack_nr, hci_packet_size, link_peer_supports_data_integrity_check, data_integrity_check);
348     log_info_hexdump(hci_packet, hci_packet_size);
349 
350     hci_transport_slip_send_frame(header, hci_packet, hci_packet_size, data_integrity_check);
351 
352     // reset inactvitiy timer
353     hci_transport_inactivity_timer_set();
354 }
355 
356 static void hci_transport_link_send_ack_packet(void){
357     // Pure ACK package is without DIC as there is no payload either
358     log_info("link: send ack %u", link_ack_nr);
359     uint8_t header[4];
360     hci_transport_link_calc_header(header, 0, link_ack_nr, 0, 0, LINK_ACKNOWLEDGEMENT_TYPE, 0);
361     hci_transport_slip_send_frame(header, NULL, 0, 0);
362 }
363 
364 static void hci_transport_link_run(void){
365     // exit if outgoing active
366     if (slip_write_active) return;
367 
368     // process queued requests
369     if (hci_transport_link_actions & HCI_TRANSPORT_LINK_SEND_SYNC){
370         hci_transport_link_actions &= ~HCI_TRANSPORT_LINK_SEND_SYNC;
371         hci_transport_link_send_sync();
372         return;
373     }
374     if (hci_transport_link_actions & HCI_TRANSPORT_LINK_SEND_SYNC_RESPONSE){
375         hci_transport_link_actions &= ~HCI_TRANSPORT_LINK_SEND_SYNC_RESPONSE;
376         hci_transport_link_send_sync_response();
377         return;
378     }
379     if (hci_transport_link_actions & HCI_TRANSPORT_LINK_SEND_CONFIG){
380         hci_transport_link_actions &= ~HCI_TRANSPORT_LINK_SEND_CONFIG;
381         hci_transport_link_send_config();
382         return;
383     }
384     if (hci_transport_link_actions & HCI_TRANSPORT_LINK_SEND_CONFIG_RESPONSE){
385         hci_transport_link_actions &= ~HCI_TRANSPORT_LINK_SEND_CONFIG_RESPONSE;
386         hci_transport_link_send_config_response();
387         return;
388     }
389     if (hci_transport_link_actions & HCI_TRANSPORT_LINK_SEND_WOKEN){
390         hci_transport_link_actions &= ~HCI_TRANSPORT_LINK_SEND_WOKEN;
391         hci_transport_link_send_woken();
392         return;
393     }
394     if (hci_transport_link_actions & HCI_TRANSPORT_LINK_SEND_WAKEUP){
395         hci_transport_link_actions &= ~HCI_TRANSPORT_LINK_SEND_WAKEUP;
396         hci_transport_link_send_wakeup();
397         return;
398     }
399     if (hci_transport_link_actions & HCI_TRANSPORT_LINK_SEND_QUEUED_PACKET){
400         hci_transport_link_actions &= ~HCI_TRANSPORT_LINK_SEND_QUEUED_PACKET;
401         // packet already contains ack, no need to send addtitional one
402         hci_transport_link_actions &= ~HCI_TRANSPORT_LINK_SEND_ACK_PACKET;
403         hci_transport_link_send_queued_packet();
404         return;
405     }
406     if (hci_transport_link_actions & HCI_TRANSPORT_LINK_SEND_ACK_PACKET){
407         hci_transport_link_actions &= ~HCI_TRANSPORT_LINK_SEND_ACK_PACKET;
408         hci_transport_link_send_ack_packet();
409         return;
410     }
411     if (hci_transport_link_actions & HCI_TRANSPORT_LINK_SEND_SLEEP){
412         hci_transport_link_actions &= ~HCI_TRANSPORT_LINK_SEND_SLEEP;
413         hci_transport_link_actions |=  HCI_TRANSPORT_LINK_ENTER_SLEEP;
414         link_peer_asleep = 1;
415         hci_transport_link_send_sleep();
416         return;
417     }
418 }
419 
420 static void hci_transport_link_set_timer(uint16_t timeout_ms){
421     btstack_run_loop_set_timer_handler(&link_timer, &hci_transport_link_timeout_handler);
422     btstack_run_loop_set_timer(&link_timer, timeout_ms);
423     btstack_run_loop_add_timer(&link_timer);
424 }
425 
426 static void hci_transport_link_timeout_handler(btstack_timer_source_t * timer){
427     switch (link_state){
428         case LINK_UNINITIALIZED:
429             hci_transport_link_actions |= HCI_TRANSPORT_LINK_SEND_SYNC;
430             hci_transport_link_set_timer(LINK_PERIOD_MS);
431             break;
432         case LINK_INITIALIZED:
433             hci_transport_link_actions |= HCI_TRANSPORT_LINK_SEND_CONFIG;
434             hci_transport_link_set_timer(LINK_PERIOD_MS);
435             break;
436         case LINK_ACTIVE:
437             if (!hci_transport_link_have_outgoing_packet()){
438                 log_info("h5 timeout while active, but no outgoing packet");
439                 return;
440             }
441             if (link_peer_asleep){
442                 hci_transport_link_actions |= HCI_TRANSPORT_LINK_SEND_WAKEUP;
443                 hci_transport_link_set_timer(LINK_WAKEUP_MS);
444                 return;
445             }
446             // resend packet
447             hci_transport_link_actions |= HCI_TRANSPORT_LINK_SEND_QUEUED_PACKET;
448             hci_transport_link_set_timer(link_resend_timeout_ms);
449             break;
450         default:
451             break;
452     }
453 
454     hci_transport_link_run();
455 }
456 
457 static void hci_transport_link_init(void){
458     link_state = LINK_UNINITIALIZED;
459     link_peer_asleep = 0;
460     link_peer_supports_data_integrity_check = 0;
461 
462     // get started
463     hci_transport_link_actions |= HCI_TRANSPORT_LINK_SEND_SYNC;
464     hci_transport_link_set_timer(LINK_PERIOD_MS);
465     hci_transport_link_run();
466 }
467 
468 static int hci_transport_link_inc_seq_nr(int seq_nr){
469     return (seq_nr + 1) & 0x07;
470 }
471 
472 static int hci_transport_link_have_outgoing_packet(void){
473     return hci_packet != 0;
474 }
475 
476 static void hci_transport_link_clear_queue(void){
477     btstack_run_loop_remove_timer(&link_timer);
478     hci_packet = NULL;
479 }
480 
481 static void hci_transport_h5_queue_packet(uint8_t packet_type, uint8_t *packet, int size){
482     hci_packet = packet;
483     hci_packet_type = packet_type;
484     hci_packet_size = size;
485 }
486 
487 static void hci_transport_h5_emit_sleep_state(int sleep_active){
488     static int last_state = 0;
489     if (sleep_active == last_state) return;
490     last_state = sleep_active;
491 
492     log_info("hci_transport_h5_emit_sleep_state: %u", sleep_active);
493     uint8_t event[3];
494     event[0] = HCI_EVENT_TRANSPORT_SLEEP_MODE;
495     event[1] = sizeof(event) - 2;
496     event[2] = sleep_active;
497     packet_handler(HCI_EVENT_PACKET, &event[0], sizeof(event));
498 }
499 
500 static void hci_transport_h5_process_frame(uint16_t frame_size){
501 
502     if (frame_size < 4) return;
503 
504     uint8_t * slip_header  = &hci_packet_with_pre_buffer[HCI_INCOMING_PRE_BUFFER_SIZE];
505     uint8_t * slip_payload = &hci_packet_with_pre_buffer[HCI_INCOMING_PRE_BUFFER_SIZE + 4];
506     int       frame_size_without_header = frame_size - 4;
507 
508     uint8_t  seq_nr =  slip_header[0] & 0x07;
509     uint8_t  ack_nr = (slip_header[0] >> 3)    & 0x07;
510     uint8_t  data_integrity_check_present = (slip_header[0] & 0x40) != 0;
511     uint8_t  reliable_packet  = (slip_header[0] & 0x80) != 0;
512     uint8_t  link_packet_type = slip_header[1] & 0x0f;
513     uint16_t link_payload_len = (slip_header[1] >> 4) | (slip_header[2] << 4);
514 
515     log_info("hci_transport_h5_process_frame, reliable %u, packet type %u, seq_nr %u, ack_nr %u , dic %u", reliable_packet, link_packet_type, seq_nr, ack_nr, data_integrity_check_present);
516     log_info_hexdump(slip_header, 4);
517     log_info_hexdump(slip_payload, frame_size_without_header);
518 
519     // CSR 8811 does not seem to auto-detect H5 mode and sends data with even parity.
520     // if this byte sequence is detected, just enable even parity
521     const uint8_t sync_response_bcsp[] = {0x01, 0x7a, 0x06, 0x10};
522     if (memcmp(sync_response_bcsp, slip_header, 4) == 0){
523         log_info("h5: detected BSCP SYNC sent with Even Parity -> discard frame and enable Even Parity");
524         btstack_uart->set_parity(1);
525         return;
526     }
527 
528     // validate header checksum
529     uint8_t header_checksum = slip_header[0] + slip_header[1] + slip_header[2] + slip_header[3];
530     if (header_checksum != 0xff){
531         log_info("h5: header checksum 0x%02x (instead of 0xff)", header_checksum);
532         return;
533     }
534 
535     // validate payload length
536     int data_integrity_len = data_integrity_check_present ? 2 : 0;
537     uint16_t received_payload_len = frame_size_without_header - data_integrity_len;
538     if (link_payload_len != received_payload_len){
539         log_info("h5: expected payload len %u but got %u", link_payload_len, received_payload_len);
540         return;
541     }
542 
543     // validate data integrity check
544     if (data_integrity_check_present){
545         uint16_t dic_packet = big_endian_read_16(slip_payload, received_payload_len);
546         uint16_t dic_calculate = crc16_calc_for_slip_frame(slip_header, slip_payload, received_payload_len);
547         if (dic_packet != dic_calculate){
548             log_info("h5: expected dic value 0x%04x but got 0x%04x", dic_calculate, dic_packet);
549             return;
550         }
551     }
552 
553     switch (link_state){
554         case LINK_UNINITIALIZED:
555             if (link_packet_type != LINK_CONTROL_PACKET_TYPE) break;
556             if (memcmp(slip_payload, link_control_sync, sizeof(link_control_sync)) == 0){
557                 log_info("link: received sync");
558                 hci_transport_link_actions |= HCI_TRANSPORT_LINK_SEND_SYNC_RESPONSE;
559             }
560             if (memcmp(slip_payload, link_control_sync_response, sizeof(link_control_sync_response)) == 0){
561                 log_info("link: received sync response");
562                 link_state = LINK_INITIALIZED;
563                 btstack_run_loop_remove_timer(&link_timer);
564                 log_info("link initialized");
565                 //
566                 hci_transport_link_actions |= HCI_TRANSPORT_LINK_SEND_CONFIG;
567                 hci_transport_link_set_timer(LINK_PERIOD_MS);
568             }
569             break;
570         case LINK_INITIALIZED:
571             if (link_packet_type != LINK_CONTROL_PACKET_TYPE) break;
572             if (memcmp(slip_payload, link_control_sync, sizeof(link_control_sync)) == 0){
573                 log_info("link: received sync");
574                 hci_transport_link_actions |= HCI_TRANSPORT_LINK_SEND_SYNC_RESPONSE;
575             }
576             if (memcmp(slip_payload, link_control_config, link_control_config_prefix_len) == 0){
577                 log_info("link: received config, 0x%02x", slip_payload[2]);
578                 hci_transport_link_actions |= HCI_TRANSPORT_LINK_SEND_CONFIG_RESPONSE;
579             }
580             if (memcmp(slip_payload, link_control_config_response, link_control_config_response_prefix_len) == 0){
581                 uint8_t config = slip_payload[2];
582                 link_peer_supports_data_integrity_check = (config & 0x10) != 0;
583                 log_info("link: received config response 0x%02x, data integrity check supported %u", config, link_peer_supports_data_integrity_check);
584                 link_state = LINK_ACTIVE;
585                 btstack_run_loop_remove_timer(&link_timer);
586                 log_info("link activated");
587                 //
588                 link_seq_nr = 0;
589                 link_ack_nr = 0;
590                 // notify upper stack that it can start
591                 uint8_t event[] = { HCI_EVENT_TRANSPORT_PACKET_SENT, 0};
592                 packet_handler(HCI_EVENT_PACKET, &event[0], sizeof(event));
593             }
594             break;
595         case LINK_ACTIVE:
596 
597             // validate packet sequence nr in reliable packets (check for out of sequence error)
598             if (reliable_packet){
599                 if (seq_nr != link_ack_nr){
600                     log_info("expected seq nr %u, but received %u", link_ack_nr, seq_nr);
601                     hci_transport_link_actions |= HCI_TRANSPORT_LINK_SEND_ACK_PACKET;
602                     break;
603                 }
604                 // ack packet right away
605                 link_ack_nr = hci_transport_link_inc_seq_nr(link_ack_nr);
606                 hci_transport_link_actions |= HCI_TRANSPORT_LINK_SEND_ACK_PACKET;
607             }
608 
609             // Process ACKs in reliable packet and explicit ack packets
610             if (reliable_packet || link_packet_type == LINK_ACKNOWLEDGEMENT_TYPE){
611                 // our packet is good if the remote expects our seq nr + 1
612                 int next_seq_nr = hci_transport_link_inc_seq_nr(link_seq_nr);
613                 if (hci_transport_link_have_outgoing_packet() && next_seq_nr == ack_nr){
614                     log_info("h5: outoing packet with seq %u ack'ed", link_seq_nr);
615                     link_seq_nr = next_seq_nr;
616                     hci_transport_link_clear_queue();
617 
618                     // notify upper stack that it can send again
619                     uint8_t event[] = { HCI_EVENT_TRANSPORT_PACKET_SENT, 0};
620                     packet_handler(HCI_EVENT_PACKET, &event[0], sizeof(event));
621                 }
622             }
623 
624             switch (link_packet_type){
625                 case LINK_CONTROL_PACKET_TYPE:
626                     if (memcmp(slip_payload, link_control_config, sizeof(link_control_config)) == 0){
627                         log_info("link: received config");
628                         hci_transport_link_actions |= HCI_TRANSPORT_LINK_SEND_CONFIG_RESPONSE;
629                         break;
630                     }
631                     if (memcmp(slip_payload, link_control_sync, sizeof(link_control_sync)) == 0){
632                         log_info("link: received sync in ACTIVE STATE!");
633                         // TODO sync during active indicates peer reset -> full upper layer reset necessary
634                         break;
635                     }
636                     if (memcmp(slip_payload, link_control_sleep, sizeof(link_control_sleep)) == 0){
637                         if (btstack_uart_sleep_mode){
638                             log_info("link: received sleep message. Enabling UART Sleep.");
639                             btstack_uart->set_sleep(btstack_uart_sleep_mode);
640                             hci_transport_h5_emit_sleep_state(1);
641                         } else {
642                             log_info("link: received sleep message. UART Sleep not supported");
643                         }
644                         link_peer_asleep = 1;
645                         break;
646                     }
647                     if (memcmp(slip_payload, link_control_wakeup, sizeof(link_control_wakeup)) == 0){
648                         log_info("link: received wakupe message -> send woken");
649                         link_peer_asleep = 0;
650                         hci_transport_link_actions |= HCI_TRANSPORT_LINK_SEND_WOKEN;
651                         break;
652                     }
653                     if (memcmp(slip_payload, link_control_woken, sizeof(link_control_woken)) == 0){
654                         log_info("link: received woken message");
655                         link_peer_asleep = 0;
656                         // queued packet will be sent in hci_transport_link_run if needed
657                         break;
658                     }
659                     break;
660                 case HCI_EVENT_PACKET:
661                 case HCI_ACL_DATA_PACKET:
662                 case HCI_SCO_DATA_PACKET:
663                     // seems like peer is awake
664                     link_peer_asleep = 0;
665                     // forward packet to stack
666                     packet_handler(link_packet_type, slip_payload, link_payload_len);
667                     // reset inactvitiy timer
668                     hci_transport_inactivity_timer_set();
669                     break;
670             }
671 
672             break;
673         default:
674             break;
675     }
676 
677     hci_transport_link_run();
678 }
679 
680 // recommendet time until resend: 3 * time of largest packet
681 static uint16_t hci_transport_link_calc_resend_timeout(uint32_t baudrate){
682     uint32_t max_packet_size_in_bit = (HCI_PACKET_BUFFER_SIZE + 6) << 3;
683     uint32_t t_max_x3_ms = max_packet_size_in_bit * 3000 / baudrate;
684     log_info("resend timeout for %u baud: %u ms", baudrate, t_max_x3_ms);
685     return t_max_x3_ms;
686 }
687 
688 static void hci_transport_link_update_resend_timeout(uint32_t baudrate){
689     link_resend_timeout_ms = hci_transport_link_calc_resend_timeout(baudrate);
690 }
691 
692 /// H5 Interface
693 
694 static uint8_t hci_transport_link_read_byte;
695 
696 static void hci_transport_h5_read_next_byte(void){
697     log_debug("h5: rx nxt");
698     btstack_uart->receive_block(&hci_transport_link_read_byte, 1);
699 }
700 
701 static void hci_transport_h5_block_received(){
702     log_debug("slip: process 0x%02x", hci_transport_link_read_byte);
703     btstack_slip_decoder_process(hci_transport_link_read_byte);
704     uint16_t frame_size = btstack_slip_decoder_frame_size();
705     if (frame_size) {
706         hci_transport_h5_process_frame(frame_size);
707         hci_transport_slip_init();
708     }
709     hci_transport_h5_read_next_byte();
710 }
711 
712 static void hci_transport_h5_block_sent(void){
713 
714     // check if more data to send
715     if (btstack_slip_encoder_has_data()){
716         hci_transport_slip_send_next_chunk();
717         return;
718     }
719 
720     // done
721     slip_write_active = 0;
722 
723     // enter sleep mode after sending sleep message
724     if (hci_transport_link_actions & HCI_TRANSPORT_LINK_ENTER_SLEEP){
725         hci_transport_link_actions &= ~HCI_TRANSPORT_LINK_ENTER_SLEEP;
726         if (btstack_uart_sleep_mode){
727             log_info("link: sent sleep message. Enabling UART Sleep.");
728             btstack_uart->set_sleep(btstack_uart_sleep_mode);
729         } else {
730             log_info("link: sent sleep message. UART Sleep not supported");
731         }
732         hci_transport_h5_emit_sleep_state(1);
733     }
734 
735     hci_transport_link_run();
736 }
737 
738 static void hci_transport_h5_init(const void * transport_config){
739     // check for hci_transport_config_uart_t
740     if (!transport_config) {
741         log_error("hci_transport_h5: no config!");
742         return;
743     }
744     if (((hci_transport_config_t*)transport_config)->type != HCI_TRANSPORT_CONFIG_UART) {
745         log_error("hci_transport_h5: config not of type != HCI_TRANSPORT_CONFIG_UART!");
746         return;
747     }
748 
749     // extract UART config from transport config
750     hci_transport_config_uart_t * hci_transport_config_uart = (hci_transport_config_uart_t*) transport_config;
751     uart_config.baudrate    = hci_transport_config_uart->baudrate_init;
752     uart_config.flowcontrol = hci_transport_config_uart->flowcontrol;
753     uart_config.device_name = hci_transport_config_uart->device_name;
754 
755     // setup UART driver
756     btstack_uart->init(&uart_config);
757     btstack_uart->set_block_received(&hci_transport_h5_block_received);
758     btstack_uart->set_block_sent(&hci_transport_h5_block_sent);
759 }
760 
761 static int hci_transport_h5_open(void){
762     int res = btstack_uart->open();
763     if (res){
764         return res;
765     }
766 
767     // check if wake on RX can be used
768     btstack_uart_sleep_mode = BTSTACK_UART_SLEEP_OFF;
769     int supported_sleep_modes = 0;
770     if (btstack_uart->get_supported_sleep_modes){
771         supported_sleep_modes = btstack_uart->get_supported_sleep_modes();
772     }
773     if (supported_sleep_modes & BTSTACK_UART_SLEEP_MASK_RTS_LOW_WAKE_ON_RX_EDGE){
774         log_info("H5: using wake on RX");
775         btstack_uart_sleep_mode = BTSTACK_UART_SLEEP_RTS_LOW_WAKE_ON_RX_EDGE;
776     } else {
777         log_info("H5: UART driver does not provide compatible sleep mode");
778     }
779 
780     // setup resend timeout
781     hci_transport_link_update_resend_timeout(uart_config.baudrate);
782 
783     // init slip parser state machine
784     hci_transport_slip_init();
785 
786     // init link management - already starts syncing
787     hci_transport_link_init();
788 
789     // start receiving
790     hci_transport_h5_read_next_byte();
791 
792     return 0;
793 }
794 
795 static int hci_transport_h5_close(void){
796     return btstack_uart->close();
797     return 0;
798 }
799 
800 static void hci_transport_h5_register_packet_handler(void (*handler)(uint8_t packet_type, uint8_t *packet, uint16_t size)){
801     packet_handler = handler;
802 }
803 
804 static int hci_transport_h5_can_send_packet_now(uint8_t packet_type){
805     int res = !hci_transport_link_have_outgoing_packet() && link_state == LINK_ACTIVE;
806     // log_info("hci_transport_h5_can_send_packet_now: %u", res);
807     return res;
808 }
809 
810 static int hci_transport_h5_send_packet(uint8_t packet_type, uint8_t *packet, int size){
811     if (!hci_transport_h5_can_send_packet_now(packet_type)){
812         log_error("hci_transport_h5_send_packet called but in state %d", link_state);
813         return -1;
814     }
815 
816     // store request
817     hci_transport_h5_queue_packet(packet_type, packet, size);
818 
819     // send wakeup first
820     if (link_peer_asleep){
821         hci_transport_h5_emit_sleep_state(0);
822         if (btstack_uart_sleep_mode){
823             log_info("h5: disable UART sleep");
824             btstack_uart->set_sleep(BTSTACK_UART_SLEEP_OFF);
825         }
826         hci_transport_link_actions |= HCI_TRANSPORT_LINK_SEND_WAKEUP;
827         hci_transport_link_set_timer(LINK_WAKEUP_MS);
828     } else {
829         hci_transport_link_actions |= HCI_TRANSPORT_LINK_SEND_QUEUED_PACKET;
830         hci_transport_link_set_timer(link_resend_timeout_ms);
831     }
832     hci_transport_link_run();
833     return 0;
834 }
835 
836 static int hci_transport_h5_set_baudrate(uint32_t baudrate){
837 
838     log_info("hci_transport_h5_set_baudrate %u", baudrate);
839     int res = btstack_uart->set_baudrate(baudrate);
840 
841     if (res) return res;
842     hci_transport_link_update_resend_timeout(baudrate);
843     return 0;
844 }
845 
846 static void hci_transport_h5_reset_link(void){
847 
848     log_info("hci_transport_h5_reset_link");
849 
850     // clear outgoing queue
851     hci_transport_link_clear_queue();
852 
853     // init slip parser state machine
854     hci_transport_slip_init();
855 
856     // init link management - already starts syncing
857     hci_transport_link_init();
858 }
859 
860 static const hci_transport_t hci_transport_h5 = {
861     /* const char * name; */                                        "H5",
862     /* void   (*init) (const void *transport_config); */            &hci_transport_h5_init,
863     /* int    (*open)(void); */                                     &hci_transport_h5_open,
864     /* int    (*close)(void); */                                    &hci_transport_h5_close,
865     /* void   (*register_packet_handler)(void (*handler)(...); */   &hci_transport_h5_register_packet_handler,
866     /* int    (*can_send_packet_now)(uint8_t packet_type); */       &hci_transport_h5_can_send_packet_now,
867     /* int    (*send_packet)(...); */                               &hci_transport_h5_send_packet,
868     /* int    (*set_baudrate)(uint32_t baudrate); */                &hci_transport_h5_set_baudrate,
869     /* void   (*reset_link)(void); */                               &hci_transport_h5_reset_link,
870     /* void   (*set_sco_config)(uint16_t voice_setting, int num_connections); */ NULL,
871 };
872 
873 // configure and return h5 singleton
874 const hci_transport_t * hci_transport_h5_instance(const btstack_uart_block_t * uart_driver) {
875     btstack_uart = uart_driver;
876     return &hci_transport_h5;
877 }
878 
879 void hci_transport_h5_set_auto_sleep(uint16_t inactivity_timeout_ms){
880     link_inactivity_timeout_ms = inactivity_timeout_ms;
881 }
882