xref: /btstack/src/hci_transport_h4.c (revision b28dc8004dd8d4fb9020a6dcd2bc81f05d36a008)
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 BLUEKITCHEN
24  * GMBH 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__ "hci_transport_h4.c"
39 
40 /*
41  *  hci_h4_transport.c
42  *
43  *  HCI Transport API implementation for H4 protocol over POSIX with optional support for eHCILL
44  *
45  *  Created by Matthias Ringwald on 4/29/09.
46  */
47 
48 
49 #include "btstack_config.h"
50 #include "hci_transport_h4.h"
51 
52 #include "btstack_debug.h"
53 #include "hci.h"
54 #include "hci_transport.h"
55 #include "bluetooth_company_id.h"
56 #include "btstack_uart_block.h"
57 
58 #include <inttypes.h>
59 
60 #define ENABLE_LOG_EHCILL
61 
62 #ifdef ENABLE_EHCILL
63 
64 // eHCILL commands
65 enum EHCILL_MESSAGES {
66 	EHCILL_GO_TO_SLEEP_IND = 0x030,
67 	EHCILL_GO_TO_SLEEP_ACK = 0x031,
68 	EHCILL_WAKE_UP_IND     = 0x032,
69 	EHCILL_WAKE_UP_ACK     = 0x033,
70 	EHCILL_WAKEUP_SIGNAL   = 0x034,
71 };
72 
73 static int  hci_transport_h4_ehcill_outgoing_packet_ready(void);
74 static void hci_transport_h4_echill_send_wakeup_ind(void);
75 static void hci_transport_h4_ehcill_handle_command(uint8_t action);
76 static void hci_transport_h4_ehcill_handle_ehcill_command_sent(void);
77 static void hci_transport_h4_ehcill_handle_packet_sent(void);
78 static void hci_transport_h4_ehcill_open(void);
79 static void hci_transport_h4_ehcill_reset_statemachine(void);
80 static void hci_transport_h4_ehcill_send_ehcill_command(void);
81 static void hci_transport_h4_ehcill_sleep_ack_timer_setup(void);
82 static void hci_transport_h4_ehcill_trigger_wakeup(void);
83 
84 typedef enum {
85     EHCILL_STATE_W2_SEND_SLEEP_ACK,
86     EHCILL_STATE_SLEEP,
87     EHCILL_STATE_W4_WAKEUP_IND_OR_ACK,
88     EHCILL_STATE_AWAKE
89 } EHCILL_STATE;
90 
91 // eHCILL state machine
92 static EHCILL_STATE ehcill_state;
93 static uint8_t      ehcill_command_to_send;
94 
95 static btstack_uart_sleep_mode_t btstack_uart_sleep_mode;
96 
97 // work around for eHCILL problem
98 static btstack_timer_source_t ehcill_sleep_ack_timer;
99 
100 #endif
101 
102 
103 // assert pre-buffer for packet type is available
104 #if !defined(HCI_OUTGOING_PRE_BUFFER_SIZE) || (HCI_OUTGOING_PRE_BUFFER_SIZE == 0)
105 #error HCI_OUTGOING_PRE_BUFFER_SIZE not defined. Please update hci.h
106 #endif
107 
108 static void dummy_handler(uint8_t packet_type, uint8_t *packet, uint16_t size);
109 
110 typedef enum {
111     H4_OFF,
112     H4_W4_PACKET_TYPE,
113     H4_W4_EVENT_HEADER,
114     H4_W4_ACL_HEADER,
115     H4_W4_SCO_HEADER,
116     H4_W4_PAYLOAD,
117 } H4_STATE;
118 
119 typedef enum {
120     TX_OFF,
121     TX_IDLE,
122     TX_W4_PACKET_SENT,
123 #ifdef ENABLE_EHCILL
124     TX_W4_WAKEUP,
125     TX_W2_EHCILL_SEND,
126     TX_W4_EHCILL_SENT,
127 #endif
128 } TX_STATE;
129 
130 // UART Driver + Config
131 static const btstack_uart_t * btstack_uart;
132 static btstack_uart_config_t hci_transport_h4_uart_config;
133 
134 // write state
135 static TX_STATE tx_state;
136 #ifdef ENABLE_EHCILL
137 static uint8_t * ehcill_tx_data;
138 static uint16_t  ehcill_tx_len;   // 0 == no outgoing packet
139 #endif
140 
141 static void (*hci_transport_h4_packet_handler)(uint8_t packet_type, uint8_t *packet, uint16_t size) = dummy_handler;
142 
143 // packet reader state machine
144 static  H4_STATE h4_state;
145 static uint16_t bytes_to_read;
146 static uint16_t read_pos;
147 
148 // incoming packet buffer
149 static uint8_t hci_packet_with_pre_buffer[HCI_INCOMING_PRE_BUFFER_SIZE + HCI_INCOMING_PACKET_BUFFER_SIZE + 1]; // packet type + max(acl header + acl payload, event header + event data)
150 static uint8_t * hci_packet = &hci_packet_with_pre_buffer[HCI_INCOMING_PRE_BUFFER_SIZE];
151 
152 // Baudrate change bugs in TI CC256x and CYW20704
153 #ifdef ENABLE_CC256X_BAUDRATE_CHANGE_FLOWCONTROL_BUG_WORKAROUND
154 #define ENABLE_BAUDRATE_CHANGE_FLOWCONTROL_BUG_WORKAROUND
155 static const uint8_t baud_rate_command_prefix[]   = { 0x01, 0x36, 0xff, 0x04};
156 #endif
157 
158 #ifdef ENABLE_CYPRESS_BAUDRATE_CHANGE_FLOWCONTROL_BUG_WORKAROUND
159 #ifdef ENABLE_BAUDRATE_CHANGE_FLOWCONTROL_BUG_WORKAROUND
160 #error "Please enable either ENABLE_CC256X_BAUDRATE_CHANGE_FLOWCONTROL_BUG_WORKAROUND or ENABLE_BAUDRATE_CHANGE_FLOWCONTROL_BUG_WORKAROUND"
161 #endif
162 #define ENABLE_BAUDRATE_CHANGE_FLOWCONTROL_BUG_WORKAROUND
163 static const uint8_t baud_rate_command_prefix[]   = { 0x01, 0x18, 0xfc, 0x06};
164 #endif
165 
166 #ifdef ENABLE_BAUDRATE_CHANGE_FLOWCONTROL_BUG_WORKAROUND
167 static const uint8_t local_version_event_prefix[] = { 0x04, 0x0e, 0x0c, 0x01, 0x01, 0x10};
168 static enum {
169     BAUDRATE_CHANGE_WORKAROUND_IDLE,
170     BAUDRATE_CHANGE_WORKAROUND_CHIPSET_DETECTED,
171     BAUDRATE_CHANGE_WORKAROUND_BAUDRATE_COMMAND_SENT,
172     BAUDRATE_CHANGE_WORKAROUND_DONE
173 } baudrate_change_workaround_state;
174 #endif
175 
176 static int hci_transport_h4_set_baudrate(uint32_t baudrate){
177     log_info("hci_transport_h4_set_baudrate %"PRIu32, baudrate);
178     return btstack_uart->set_baudrate(baudrate);
179 }
180 
181 static void hci_transport_h4_reset_statemachine(void){
182     h4_state = H4_W4_PACKET_TYPE;
183     read_pos = 0;
184     bytes_to_read = 1;
185 }
186 
187 static void hci_transport_h4_trigger_next_read(void){
188     // log_info("hci_transport_h4_trigger_next_read: %u bytes", bytes_to_read);
189     btstack_uart->receive_block(&hci_packet[read_pos], bytes_to_read);
190 }
191 
192 static void hci_transport_h4_packet_complete(void){
193 #ifdef ENABLE_BAUDRATE_CHANGE_FLOWCONTROL_BUG_WORKAROUND
194     if (baudrate_change_workaround_state == BAUDRATE_CHANGE_WORKAROUND_IDLE
195             && memcmp(hci_packet, local_version_event_prefix, sizeof(local_version_event_prefix)) == 0){
196 #ifdef ENABLE_CC256X_BAUDRATE_CHANGE_FLOWCONTROL_BUG_WORKAROUND
197                 if (little_endian_read_16(hci_packet, 11) == BLUETOOTH_COMPANY_ID_TEXAS_INSTRUMENTS_INC){
198                     // detect TI CC256x controller based on manufacturer
199                     log_info("Detected CC256x controller");
200                     baudrate_change_workaround_state = BAUDRATE_CHANGE_WORKAROUND_CHIPSET_DETECTED;
201                 } else {
202                     // work around not needed
203                     log_info("Bluetooth controller not by TI");
204                     baudrate_change_workaround_state = BAUDRATE_CHANGE_WORKAROUND_DONE;
205                 }
206 #endif
207 #ifdef ENABLE_CYPRESS_BAUDRATE_CHANGE_FLOWCONTROL_BUG_WORKAROUND
208                 if (little_endian_read_16(hci_packet, 11) == BLUETOOTH_COMPANY_ID_CYPRESS_SEMICONDUCTOR){
209                     // detect Cypress controller based on manufacturer
210                     log_info("Detected Cypress controller");
211                     baudrate_change_workaround_state = BAUDRATE_CHANGE_WORKAROUND_CHIPSET_DETECTED;
212                 } else {
213                     // work around not needed
214                     log_info("Bluetooth controller not by Cypress");
215                     baudrate_change_workaround_state = BAUDRATE_CHANGE_WORKAROUND_DONE;
216                 }
217 #endif
218             }
219 #endif
220     uint16_t packet_len = read_pos-1u;
221 
222     // reset state machine before delivering packet to stack as it might close the transport
223     hci_transport_h4_reset_statemachine();
224     hci_transport_h4_packet_handler(hci_packet[0], &hci_packet[1], packet_len);
225 }
226 
227 static void hci_transport_h4_block_read(void){
228 
229     read_pos += bytes_to_read;
230 
231     switch (h4_state) {
232         case H4_W4_PACKET_TYPE:
233             switch (hci_packet[0]){
234                 case HCI_EVENT_PACKET:
235                     bytes_to_read = HCI_EVENT_HEADER_SIZE;
236                     h4_state = H4_W4_EVENT_HEADER;
237                     break;
238                 case HCI_ACL_DATA_PACKET:
239                     bytes_to_read = HCI_ACL_HEADER_SIZE;
240                     h4_state = H4_W4_ACL_HEADER;
241                     break;
242                 case HCI_SCO_DATA_PACKET:
243                     bytes_to_read = HCI_SCO_HEADER_SIZE;
244                     h4_state = H4_W4_SCO_HEADER;
245                     break;
246 #ifdef ENABLE_EHCILL
247                 case EHCILL_GO_TO_SLEEP_IND:
248                 case EHCILL_GO_TO_SLEEP_ACK:
249                 case EHCILL_WAKE_UP_IND:
250                 case EHCILL_WAKE_UP_ACK:
251                     hci_transport_h4_ehcill_handle_command(hci_packet[0]);
252                     hci_transport_h4_reset_statemachine();
253                     break;
254 #endif
255                 default:
256                     log_error("hci_transport_h4: invalid packet type 0x%02x", hci_packet[0]);
257                     hci_transport_h4_reset_statemachine();
258                     break;
259             }
260             break;
261 
262         case H4_W4_EVENT_HEADER:
263             bytes_to_read = hci_packet[2];
264             // check Event length
265             if (bytes_to_read > (HCI_INCOMING_PACKET_BUFFER_SIZE - HCI_EVENT_HEADER_SIZE)){
266                 log_error("hci_transport_h4: invalid Event len %d - only space for %u", bytes_to_read, HCI_INCOMING_PACKET_BUFFER_SIZE - HCI_EVENT_HEADER_SIZE);
267                 hci_transport_h4_reset_statemachine();
268                 break;
269             }
270             h4_state = H4_W4_PAYLOAD;
271             break;
272 
273         case H4_W4_ACL_HEADER:
274             bytes_to_read = little_endian_read_16( hci_packet, 3);
275             // check ACL length
276             if (bytes_to_read > (HCI_INCOMING_PACKET_BUFFER_SIZE - HCI_ACL_HEADER_SIZE)){
277                 log_error("hci_transport_h4: invalid ACL payload len %d - only space for %u", bytes_to_read, HCI_INCOMING_PACKET_BUFFER_SIZE - HCI_ACL_HEADER_SIZE);
278                 hci_transport_h4_reset_statemachine();
279                 break;
280             }
281             h4_state = H4_W4_PAYLOAD;
282             break;
283 
284         case H4_W4_SCO_HEADER:
285             bytes_to_read = hci_packet[3];
286             // check SCO length
287             if (bytes_to_read > (HCI_INCOMING_PACKET_BUFFER_SIZE - HCI_SCO_HEADER_SIZE)){
288                 log_error("hci_transport_h4: invalid SCO payload len %d - only space for %u", bytes_to_read, HCI_INCOMING_PACKET_BUFFER_SIZE - HCI_SCO_HEADER_SIZE);
289                 hci_transport_h4_reset_statemachine();
290                 break;
291             }
292             h4_state = H4_W4_PAYLOAD;
293             break;
294 
295         case H4_W4_PAYLOAD:
296             hci_transport_h4_packet_complete();
297             break;
298 
299         case H4_OFF:
300             bytes_to_read = 0;
301             break;
302         default:
303             btstack_assert(false);
304             break;
305     }
306 
307 #ifdef ENABLE_BAUDRATE_CHANGE_FLOWCONTROL_BUG_WORKAROUND
308     if (baudrate_change_workaround_state == BAUDRATE_CHANGE_WORKAROUND_BAUDRATE_COMMAND_SENT){
309         baudrate_change_workaround_state = BAUDRATE_CHANGE_WORKAROUND_IDLE;
310         // avoid flowcontrol problem by reading expected hci command complete event of 7 bytes in a single block read
311         h4_state = H4_W4_PAYLOAD;
312         bytes_to_read = 7;
313     }
314 #endif
315 
316     // forward packet if payload size == 0
317     if (h4_state == H4_W4_PAYLOAD && bytes_to_read == 0u) {
318         hci_transport_h4_packet_complete();
319     }
320 
321     if (h4_state != H4_OFF) {
322         hci_transport_h4_trigger_next_read();
323     }
324 }
325 
326 static void hci_transport_h4_block_sent(void){
327 
328     static const uint8_t packet_sent_event[] = { HCI_EVENT_TRANSPORT_PACKET_SENT, 0};
329 
330     switch (tx_state){
331         case TX_W4_PACKET_SENT:
332             // packet fully sent, reset state
333 #ifdef ENABLE_EHCILL
334             ehcill_tx_len = 0;
335 #endif
336             tx_state = TX_IDLE;
337 
338 #ifdef ENABLE_EHCILL
339             // notify eHCILL engine
340             hci_transport_h4_ehcill_handle_packet_sent();
341 #endif
342             // notify upper stack that it can send again
343             hci_transport_h4_packet_handler(HCI_EVENT_PACKET, (uint8_t *) &packet_sent_event[0], sizeof(packet_sent_event));
344             break;
345 
346 #ifdef ENABLE_EHCILL
347         case TX_W4_EHCILL_SENT:
348         case TX_W4_WAKEUP:
349             hci_transport_h4_ehcill_handle_ehcill_command_sent();
350             break;
351 #endif
352 
353         default:
354             break;
355     }
356 }
357 
358 static int hci_transport_h4_can_send_now(uint8_t packet_type){
359     UNUSED(packet_type);
360     return tx_state == TX_IDLE;
361 }
362 
363 static int hci_transport_h4_send_packet(uint8_t packet_type, uint8_t * packet, int size){
364 
365     // store packet type before actual data and increase size
366     uint8_t * buffer = &packet[-1];
367     uint32_t  buffer_size = size + 1;
368     buffer[0] = packet_type;
369 
370 #ifdef ENABLE_BAUDRATE_CHANGE_FLOWCONTROL_BUG_WORKAROUND
371     if ((baudrate_change_workaround_state == BAUDRATE_CHANGE_WORKAROUND_CHIPSET_DETECTED)
372     && (memcmp(buffer, baud_rate_command_prefix, sizeof(baud_rate_command_prefix)) == 0)) {
373         log_info("Baud rate command detected, expect command complete event next");
374         baudrate_change_workaround_state = BAUDRATE_CHANGE_WORKAROUND_BAUDRATE_COMMAND_SENT;
375     }
376 #endif
377 
378 #ifdef ENABLE_EHCILL
379     // store request for later
380     ehcill_tx_len   = buffer_size;
381     ehcill_tx_data  = buffer;
382     switch (ehcill_state){
383         case EHCILL_STATE_SLEEP:
384             hci_transport_h4_ehcill_trigger_wakeup();
385             return 0;
386         case EHCILL_STATE_W2_SEND_SLEEP_ACK:
387             log_info("eHILL: send next packet, state EHCILL_STATE_W2_SEND_SLEEP_ACK");
388             return 0;
389         default:
390             break;
391     }
392 #endif
393 
394     // start sending
395     tx_state = TX_W4_PACKET_SENT;
396     btstack_uart->send_block(buffer, buffer_size);
397     return 0;
398 }
399 
400 static void hci_transport_h4_init(const void * transport_config){
401     // check for hci_transport_config_uart_t
402     if (!transport_config) {
403         log_error("hci_transport_h4: no config!");
404         return;
405     }
406     if (((hci_transport_config_t*)transport_config)->type != HCI_TRANSPORT_CONFIG_UART) {
407         log_error("hci_transport_h4: config not of type != HCI_TRANSPORT_CONFIG_UART!");
408         return;
409     }
410 
411     // extract UART config from transport config
412     hci_transport_config_uart_t * hci_transport_config_uart = (hci_transport_config_uart_t*) transport_config;
413     hci_transport_h4_uart_config.baudrate    = hci_transport_config_uart->baudrate_init;
414     hci_transport_h4_uart_config.flowcontrol = hci_transport_config_uart->flowcontrol;
415     hci_transport_h4_uart_config.parity      = hci_transport_config_uart->parity;
416     hci_transport_h4_uart_config.device_name = hci_transport_config_uart->device_name;
417 
418     // set state to off
419     tx_state = TX_OFF;
420     h4_state = H4_OFF;
421 
422     // setup UART driver
423     btstack_uart->init(&hci_transport_h4_uart_config);
424     btstack_uart->set_block_received(&hci_transport_h4_block_read);
425     btstack_uart->set_block_sent(&hci_transport_h4_block_sent);
426 }
427 
428 static int hci_transport_h4_open(void){
429     // open uart driver
430     int res = btstack_uart->open();
431     if (res != 0){
432         return res;
433     }
434 
435     // init rx + tx state machines
436     hci_transport_h4_reset_statemachine();
437     hci_transport_h4_trigger_next_read();
438     tx_state = TX_IDLE;
439 
440 #ifdef ENABLE_EHCILL
441     hci_transport_h4_ehcill_open();
442 #endif
443     return 0;
444 }
445 
446 static int hci_transport_h4_close(void){
447     // set state to off
448     tx_state = TX_OFF;
449     h4_state = H4_OFF;
450 
451     // close uart driver
452     return btstack_uart->close();
453 }
454 
455 static void hci_transport_h4_register_packet_handler(void (*handler)(uint8_t packet_type, uint8_t *packet, uint16_t size)){
456     hci_transport_h4_packet_handler = handler;
457 }
458 
459 static void dummy_handler(uint8_t packet_type, uint8_t *packet, uint16_t size){
460     UNUSED(packet_type);
461     UNUSED(packet);
462     UNUSED(size);
463 }
464 
465 //
466 // --- main part of eHCILL implementation ---
467 //
468 
469 #ifdef ENABLE_EHCILL
470 
471 static void hci_transport_h4_ehcill_emit_sleep_state(int sleep_active){
472     static int last_state = 0;
473     if (sleep_active == last_state) return;
474     last_state = sleep_active;
475 
476     log_info("hci_transport_h4_ehcill_emit_sleep_state: %u", sleep_active);
477     uint8_t event[3];
478     event[0] = HCI_EVENT_TRANSPORT_SLEEP_MODE;
479     event[1] = sizeof(event) - 2;
480     event[2] = sleep_active;
481     hci_transport_h4_packet_handler(HCI_EVENT_PACKET, &event[0], sizeof(event));
482 }
483 
484 static void hci_transport_h4_ehcill_wakeup_handler(void){
485 #ifdef ENABLE_LOG_EHCILL
486     log_info("eHCILL: UART wakeup received");
487 #endif
488     hci_transport_h4_ehcill_handle_command(EHCILL_WAKEUP_SIGNAL);
489 }
490 
491 static void hci_transport_h4_ehcill_open(void){
492     hci_transport_h4_ehcill_reset_statemachine();
493 
494     // find best sleep mode to use: wake on CTS, wake on RX, none
495     btstack_uart_sleep_mode = BTSTACK_UART_SLEEP_OFF;
496     int supported_sleep_modes = 0;
497     if (btstack_uart->get_supported_sleep_modes){
498         supported_sleep_modes = btstack_uart->get_supported_sleep_modes();
499     }
500     if (supported_sleep_modes & BTSTACK_UART_SLEEP_MASK_RTS_HIGH_WAKE_ON_CTS_PULSE){
501         log_info("eHCILL: using wake on CTS");
502         btstack_uart_sleep_mode = BTSTACK_UART_SLEEP_RTS_HIGH_WAKE_ON_CTS_PULSE;
503     } else if (supported_sleep_modes & BTSTACK_UART_SLEEP_MASK_RTS_LOW_WAKE_ON_RX_EDGE){
504         log_info("eHCILL: using wake on RX");
505         btstack_uart_sleep_mode = BTSTACK_UART_SLEEP_RTS_LOW_WAKE_ON_RX_EDGE;
506     } else {
507         log_info("eHCILL: UART driver does not provide compatible sleep mode");
508     }
509     if (btstack_uart->set_wakeup_handler){
510         btstack_uart->set_wakeup_handler(&hci_transport_h4_ehcill_wakeup_handler);
511     }
512 }
513 
514 static void hci_transport_h4_echill_send_wakeup_ind(void){
515 #ifdef ENABLE_LOG_EHCILL
516     log_info("eHCILL: send WAKEUP_IND");
517 #endif
518     // update state
519     tx_state     = TX_W4_WAKEUP;
520     ehcill_state = EHCILL_STATE_W4_WAKEUP_IND_OR_ACK;
521     ehcill_command_to_send = EHCILL_WAKE_UP_IND;
522     btstack_uart->send_block(&ehcill_command_to_send, 1);
523 }
524 
525 static int hci_transport_h4_ehcill_outgoing_packet_ready(void){
526     return ehcill_tx_len != 0;
527 }
528 
529 static void hci_transport_h4_ehcill_reset_statemachine(void){
530     ehcill_state = EHCILL_STATE_AWAKE;
531 }
532 
533 static void hci_transport_h4_ehcill_send_ehcill_command(void){
534 #ifdef ENABLE_LOG_EHCILL
535     log_info("eHCILL: send command %02x", ehcill_command_to_send);
536 #endif
537     tx_state = TX_W4_EHCILL_SENT;
538     if (ehcill_command_to_send == EHCILL_GO_TO_SLEEP_ACK){
539         ehcill_state = EHCILL_STATE_SLEEP;
540     }
541     btstack_uart->send_block(&ehcill_command_to_send, 1);
542 }
543 
544 static void hci_transport_h4_ehcill_sleep_ack_timer_handler(btstack_timer_source_t * timer){
545 	UNUSED(timer);
546 #ifdef ENABLE_LOG_EHCILL
547     log_info("eHCILL: timer triggered");
548 #endif
549     hci_transport_h4_ehcill_send_ehcill_command();
550 }
551 
552 static void hci_transport_h4_ehcill_sleep_ack_timer_setup(void){
553     // setup timer
554 #ifdef ENABLE_LOG_EHCILL
555     log_info("eHCILL: set timer for sending command %02x", ehcill_command_to_send);
556 #endif
557     btstack_run_loop_set_timer_handler(&ehcill_sleep_ack_timer, &hci_transport_h4_ehcill_sleep_ack_timer_handler);
558     btstack_run_loop_set_timer(&ehcill_sleep_ack_timer, 50);
559     btstack_run_loop_add_timer(&ehcill_sleep_ack_timer);
560 }
561 
562 static void hci_transport_h4_ehcill_trigger_wakeup(void){
563     switch (tx_state){
564         case TX_W2_EHCILL_SEND:
565         case TX_W4_EHCILL_SENT:
566             // wake up / sleep ack in progress, nothing to do now
567             return;
568         case TX_IDLE:
569         default:
570             // all clear, prepare for wakeup
571             break;
572     }
573     // UART needed again
574     hci_transport_h4_ehcill_emit_sleep_state(0);
575     if (btstack_uart_sleep_mode){
576         btstack_uart->set_sleep(BTSTACK_UART_SLEEP_OFF);
577     }
578     hci_transport_h4_echill_send_wakeup_ind();
579 }
580 
581 static void hci_transport_h4_ehcill_schedule_ehcill_command(uint8_t command){
582 #ifdef ENABLE_LOG_EHCILL
583     log_info("eHCILL: schedule eHCILL command %02x", command);
584 #endif
585     ehcill_command_to_send = command;
586     switch (tx_state){
587         case TX_IDLE:
588             if (ehcill_command_to_send == EHCILL_WAKE_UP_ACK){
589                 // send right away
590                 hci_transport_h4_ehcill_send_ehcill_command();
591             } else {
592                 // change state so BTstack cannot send and setup timer
593                 tx_state = TX_W2_EHCILL_SEND;
594                 hci_transport_h4_ehcill_sleep_ack_timer_setup();
595             }
596             break;
597         default:
598             break;
599     }
600 }
601 
602 static void hci_transport_h4_ehcill_handle_command(uint8_t action){
603     // log_info("hci_transport_h4_ehcill_handle: %x, state %u, defer_rx %u", action, ehcill_state, ehcill_defer_rx_size);
604     switch(ehcill_state){
605         case EHCILL_STATE_AWAKE:
606             switch(action){
607                 case EHCILL_GO_TO_SLEEP_IND:
608                     ehcill_state = EHCILL_STATE_W2_SEND_SLEEP_ACK;
609 #ifdef ENABLE_LOG_EHCILL
610                     log_info("eHCILL: Received GO_TO_SLEEP_IND RX");
611 #endif
612                     hci_transport_h4_ehcill_schedule_ehcill_command(EHCILL_GO_TO_SLEEP_ACK);
613                     break;
614                 default:
615                     break;
616             }
617             break;
618 
619         case EHCILL_STATE_W2_SEND_SLEEP_ACK:
620             switch(action){
621                 case EHCILL_WAKE_UP_IND:
622                     ehcill_state = EHCILL_STATE_AWAKE;
623                     hci_transport_h4_ehcill_emit_sleep_state(0);
624                     if (btstack_uart_sleep_mode){
625                         btstack_uart->set_sleep(BTSTACK_UART_SLEEP_OFF);
626                     }
627 #ifdef ENABLE_LOG_EHCILL
628                     log_info("eHCILL: Received WAKE_UP_IND RX");
629 #endif
630                     hci_transport_h4_ehcill_schedule_ehcill_command(EHCILL_WAKE_UP_ACK);
631                     break;
632 
633                 default:
634                     break;
635             }
636             break;
637 
638         case EHCILL_STATE_SLEEP:
639             switch(action){
640                 case EHCILL_WAKEUP_SIGNAL:
641                     hci_transport_h4_ehcill_emit_sleep_state(0);
642                     if (btstack_uart_sleep_mode){
643                         btstack_uart->set_sleep(BTSTACK_UART_SLEEP_OFF);
644                     }
645                     break;
646                 case EHCILL_WAKE_UP_IND:
647                     ehcill_state = EHCILL_STATE_AWAKE;
648                     hci_transport_h4_ehcill_emit_sleep_state(0);
649                     if (btstack_uart_sleep_mode){
650                         btstack_uart->set_sleep(BTSTACK_UART_SLEEP_OFF);
651                     }
652 #ifdef ENABLE_LOG_EHCILL
653                     log_info("eHCILL: Received WAKE_UP_IND RX");
654 #endif
655                     hci_transport_h4_ehcill_schedule_ehcill_command(EHCILL_WAKE_UP_ACK);
656                     break;
657 
658                 default:
659                     break;
660             }
661             break;
662 
663         case EHCILL_STATE_W4_WAKEUP_IND_OR_ACK:
664             switch(action){
665                 case EHCILL_WAKE_UP_IND:
666                 case EHCILL_WAKE_UP_ACK:
667 #ifdef ENABLE_LOG_EHCILL
668                     log_info("eHCILL: Received WAKE_UP (%02x)", action);
669 #endif
670                     tx_state = TX_W4_PACKET_SENT;
671                     ehcill_state = EHCILL_STATE_AWAKE;
672                     btstack_uart->send_block(ehcill_tx_data, ehcill_tx_len);
673                     break;
674                 default:
675                     break;
676             }
677             break;
678     }
679 }
680 
681 static void hci_transport_h4_ehcill_handle_packet_sent(void){
682 #ifdef ENABLE_LOG_EHCILL
683         log_info("eHCILL: handle packet sent, command to send %02x", ehcill_command_to_send);
684 #endif
685     // now, send pending ehcill command if neccessary
686     switch (ehcill_command_to_send){
687         case EHCILL_GO_TO_SLEEP_ACK:
688             hci_transport_h4_ehcill_sleep_ack_timer_setup();
689             break;
690         case EHCILL_WAKE_UP_IND:
691             hci_transport_h4_ehcill_send_ehcill_command();
692             break;
693         default:
694             break;
695     }
696 }
697 
698 static void hci_transport_h4_ehcill_handle_ehcill_command_sent(void){
699     tx_state = TX_IDLE;
700     int command = ehcill_command_to_send;
701     ehcill_command_to_send = 0;
702 
703 #ifdef ENABLE_LOG_EHCILL
704         log_info("eHCILL: handle eHCILL sent, command was %02x", command);
705 #endif
706 
707     if (command == EHCILL_GO_TO_SLEEP_ACK) {
708 #ifdef ENABLE_LOG_EHCILL
709         log_info("eHCILL: GO_TO_SLEEP_ACK sent, enter sleep mode");
710 #endif
711         // UART not needed after EHCILL_GO_TO_SLEEP_ACK was sent
712         if (btstack_uart_sleep_mode != BTSTACK_UART_SLEEP_OFF){
713             btstack_uart->set_sleep(btstack_uart_sleep_mode);
714         }
715         hci_transport_h4_ehcill_emit_sleep_state(1);
716     }
717     // already packet ready? then start wakeup
718     if (hci_transport_h4_ehcill_outgoing_packet_ready()){
719         hci_transport_h4_ehcill_emit_sleep_state(0);
720         if (btstack_uart_sleep_mode != BTSTACK_UART_SLEEP_OFF){
721             btstack_uart->set_sleep(BTSTACK_UART_SLEEP_OFF);
722         }
723         if (command != EHCILL_WAKE_UP_IND){
724             hci_transport_h4_echill_send_wakeup_ind();
725         }
726     }
727 }
728 
729 #endif
730 // --- end of eHCILL implementation ---------
731 
732 
733 // configure and return h4 singleton
734 static const hci_transport_t hci_transport_h4 = {
735         /* const char * name; */                                        "H4",
736         /* void   (*init) (const void *transport_config); */            &hci_transport_h4_init,
737         /* int    (*open)(void); */                                     &hci_transport_h4_open,
738         /* int    (*close)(void); */                                    &hci_transport_h4_close,
739         /* void   (*register_packet_handler)(void (*handler)(...); */   &hci_transport_h4_register_packet_handler,
740         /* int    (*can_send_packet_now)(uint8_t packet_type); */       &hci_transport_h4_can_send_now,
741         /* int    (*send_packet)(...); */                               &hci_transport_h4_send_packet,
742         /* int    (*set_baudrate)(uint32_t baudrate); */                &hci_transport_h4_set_baudrate,
743         /* void   (*reset_link)(void); */                               NULL,
744         /* void   (*set_sco_config)(uint16_t voice_setting, int num_connections); */ NULL,
745 };
746 
747 const hci_transport_t * hci_transport_h4_instance_for_uart(const btstack_uart_t * uart_driver){
748     btstack_uart = uart_driver;
749     return &hci_transport_h4;
750 }
751 
752 // @deprecated
753 const hci_transport_t * hci_transport_h4_instance(const btstack_uart_block_t * uart_driver) {
754     btstack_uart = (const btstack_uart_t *) uart_driver;
755     return &hci_transport_h4;
756 }
757