1 /******************************************************************************
2 *
3 * Copyright (C) 2014 Google, Inc.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at:
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 ******************************************************************************/
18
19 #define LOG_TAG "bt_hci_h4"
20
21 #include <assert.h>
22 #include <errno.h>
23 #include <string.h>
24 #include <unistd.h>
25
26 #include "hci_hal.h"
27 #include "osi/include/eager_reader.h"
28 #include "osi/include/log.h"
29 #include "osi/include/osi.h"
30 #include "osi/include/reactor.h"
31 #include "osi/include/thread.h"
32 #include "vendor.h"
33
34 #define HCI_HAL_SERIAL_BUFFER_SIZE 1026
35 #define HCI_BLE_EVENT 0x3e
36
37 // Increased HCI thread priority to keep up with the audio sub-system
38 // when streaming time sensitive data (A2DP).
39 #define HCI_THREAD_PRIORITY -19
40
41 #define BT_HCI_UNKNOWN_MESSAGE_TYPE_NUM 1010002
42
43 // Our interface and modules we import
44 static const hci_hal_t interface;
45 static const hci_hal_callbacks_t *callbacks;
46 static const vendor_t *vendor;
47
48 static thread_t *thread; // Not owned by us
49
50 static int uart_fd;
51 static eager_reader_t *uart_stream;
52 static serial_data_type_t current_data_type;
53 static bool stream_has_interpretation;
54 static bool stream_corruption_detected;
55 static uint8_t stream_corruption_bytes_to_ignore;
56
57 static void event_uart_has_bytes(eager_reader_t *reader, void *context);
58
59 // Interface functions
60
hal_init(const hci_hal_callbacks_t * upper_callbacks,thread_t * upper_thread)61 static bool hal_init(const hci_hal_callbacks_t *upper_callbacks, thread_t *upper_thread) {
62 assert(upper_callbacks != NULL);
63 assert(upper_thread != NULL);
64
65 callbacks = upper_callbacks;
66 thread = upper_thread;
67 return true;
68 }
69
hal_open()70 static bool hal_open() {
71 LOG_INFO(LOG_TAG, "%s", __func__);
72 // TODO(zachoverflow): close if already open / or don't reopen (maybe at the hci layer level)
73
74 int fd_array[CH_MAX];
75 int number_of_ports = vendor->send_command(VENDOR_OPEN_USERIAL, &fd_array);
76
77 if (number_of_ports != 1) {
78 LOG_ERROR(LOG_TAG, "%s opened the wrong number of ports: got %d, expected 1.", __func__, number_of_ports);
79 goto error;
80 }
81
82 uart_fd = fd_array[0];
83 if (uart_fd == INVALID_FD) {
84 LOG_ERROR(LOG_TAG, "%s unable to open the uart serial port.", __func__);
85 goto error;
86 }
87
88 uart_stream = eager_reader_new(uart_fd, &allocator_malloc, HCI_HAL_SERIAL_BUFFER_SIZE, SIZE_MAX, "hci_single_channel");
89 if (!uart_stream) {
90 LOG_ERROR(LOG_TAG, "%s unable to create eager reader for the uart serial port.", __func__);
91 goto error;
92 }
93
94 stream_has_interpretation = false;
95 stream_corruption_detected = false;
96 stream_corruption_bytes_to_ignore = 0;
97 eager_reader_register(uart_stream, thread_get_reactor(thread), event_uart_has_bytes, NULL);
98
99 // Raise thread priorities to keep up with audio
100 thread_set_priority(thread, HCI_THREAD_PRIORITY);
101 thread_set_priority(eager_reader_get_read_thread(uart_stream), HCI_THREAD_PRIORITY);
102
103 return true;
104
105 error:
106 interface.close();
107 return false;
108 }
109
hal_close()110 static void hal_close() {
111 LOG_INFO(LOG_TAG, "%s", __func__);
112
113 eager_reader_free(uart_stream);
114 vendor->send_command(VENDOR_CLOSE_USERIAL, NULL);
115 uart_fd = INVALID_FD;
116 }
117
read_data(serial_data_type_t type,uint8_t * buffer,size_t max_size)118 static size_t read_data(serial_data_type_t type, uint8_t *buffer, size_t max_size) {
119 if (type < DATA_TYPE_ACL || type > DATA_TYPE_EVENT) {
120 LOG_ERROR(LOG_TAG, "%s invalid data type: %d", __func__, type);
121 return 0;
122 } else if (!stream_has_interpretation) {
123 LOG_ERROR(LOG_TAG, "%s with no valid stream intepretation.", __func__);
124 return 0;
125 } else if (current_data_type != type) {
126 LOG_ERROR(LOG_TAG, "%s with different type than existing interpretation.", __func__);
127 return 0;
128 }
129
130 return eager_reader_read(uart_stream, buffer, max_size);
131 }
132
packet_finished(serial_data_type_t type)133 static void packet_finished(serial_data_type_t type) {
134 if (!stream_has_interpretation)
135 LOG_ERROR(LOG_TAG, "%s with no existing stream interpretation.", __func__);
136 else if (current_data_type != type)
137 LOG_ERROR(LOG_TAG, "%s with different type than existing interpretation.", __func__);
138
139 stream_has_interpretation = false;
140 }
141
transmit_data(serial_data_type_t type,uint8_t * data,uint16_t length)142 static uint16_t transmit_data(serial_data_type_t type, uint8_t *data, uint16_t length) {
143 assert(data != NULL);
144 assert(length > 0);
145
146 if (type < DATA_TYPE_COMMAND || type > DATA_TYPE_SCO) {
147 LOG_ERROR(LOG_TAG, "%s invalid data type: %d", __func__, type);
148 return 0;
149 }
150
151 // Write the signal byte right before the data
152 --data;
153 uint8_t previous_byte = *data;
154 *(data) = type;
155 ++length;
156
157 uint16_t transmitted_length = 0;
158 while (length > 0) {
159 ssize_t ret;
160 OSI_NO_INTR(ret = write(uart_fd, data + transmitted_length, length));
161 switch (ret) {
162 case -1:
163 LOG_ERROR(LOG_TAG, "In %s, error writing to the uart serial port: %s", __func__, strerror(errno));
164 goto done;
165 case 0:
166 // If we wrote nothing, don't loop more because we
167 // can't go to infinity or beyond
168 goto done;
169 default:
170 transmitted_length += ret;
171 length -= ret;
172 break;
173 }
174 }
175
176 done:;
177 // Be nice and restore the old value of that byte
178 *(data) = previous_byte;
179
180 // Remove the signal byte from our transmitted length, if it was actually written
181 if (transmitted_length > 0)
182 --transmitted_length;
183
184 return transmitted_length;
185 }
186
187 // Internal functions
188
189 // WORKAROUND:
190 // As exhibited by b/23934838, during result-heavy LE scans, the UART byte
191 // stream can get corrupted, leading to assertions caused by mis-interpreting
192 // the bytes following the corruption.
193 // This workaround looks for tell-tale signs of a BLE event and attempts to
194 // skip the correct amount of bytes in the stream to re-synchronize onto
195 // a packet boundary.
196 // Function returns true if |byte_read| has been processed by the workaround.
stream_corrupted_during_le_scan_workaround(const uint8_t byte_read)197 static bool stream_corrupted_during_le_scan_workaround(const uint8_t byte_read)
198 {
199 if (!stream_corruption_detected && byte_read == HCI_BLE_EVENT) {
200 LOG_ERROR(LOG_TAG, "%s HCI stream corrupted (message type 0x3E)!", __func__);
201 stream_corruption_detected = true;
202 return true;
203 }
204
205 if (stream_corruption_detected) {
206 if (stream_corruption_bytes_to_ignore == 0) {
207 stream_corruption_bytes_to_ignore = byte_read;
208 LOG_ERROR(LOG_TAG, "%s About to skip %d bytes...", __func__, stream_corruption_bytes_to_ignore);
209 } else {
210 --stream_corruption_bytes_to_ignore;
211 }
212
213 if (stream_corruption_bytes_to_ignore == 0) {
214 LOG_ERROR(LOG_TAG, "%s Back to our regularly scheduled program...", __func__);
215 stream_corruption_detected = false;
216 }
217 return true;
218 }
219
220 return false;
221 }
222
223 // See what data is waiting, and notify the upper layer
event_uart_has_bytes(eager_reader_t * reader,UNUSED_ATTR void * context)224 static void event_uart_has_bytes(eager_reader_t *reader, UNUSED_ATTR void *context) {
225 if (stream_has_interpretation) {
226 callbacks->data_ready(current_data_type);
227 } else {
228 uint8_t type_byte;
229 if (eager_reader_read(reader, &type_byte, 1) == 0) {
230 LOG_ERROR(LOG_TAG, "%s could not read HCI message type", __func__);
231 return;
232 }
233
234 if (stream_corrupted_during_le_scan_workaround(type_byte))
235 return;
236
237 if (type_byte < DATA_TYPE_ACL || type_byte > DATA_TYPE_EVENT) {
238 LOG_ERROR(LOG_TAG, "%s Unknown HCI message type 0x%x (min=0x%x max=0x%x). Aborting...",
239 __func__, type_byte, DATA_TYPE_ACL, DATA_TYPE_EVENT);
240 LOG_EVENT_INT(BT_HCI_UNKNOWN_MESSAGE_TYPE_NUM, type_byte);
241 assert(false && "Unknown HCI message type");
242 return;
243 }
244
245 stream_has_interpretation = true;
246 current_data_type = type_byte;
247 }
248 }
249
250 static const hci_hal_t interface = {
251 hal_init,
252
253 hal_open,
254 hal_close,
255
256 read_data,
257 packet_finished,
258 transmit_data,
259 };
260
hci_hal_h4_get_interface()261 const hci_hal_t *hci_hal_h4_get_interface() {
262 vendor = vendor_get_interface();
263 return &interface;
264 }
265
hci_hal_h4_get_test_interface(vendor_t * vendor_interface)266 const hci_hal_t *hci_hal_h4_get_test_interface(vendor_t *vendor_interface) {
267 vendor = vendor_interface;
268 return &interface;
269 }
270