1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
|
/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2018, Google Inc.
*
* device_enumerator.cpp - Enumeration and matching
*/
#include <fcntl.h>
#include <libudev.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include "device_enumerator.h"
#include "log.h"
#include "media_device.h"
/**
* \file device_enumerator.h
* \brief Enumerating and matching of media devices
*
* The purpose of device enumeration and matching is to find media
* devices in the system and map one or more media devices to a pipeline
* handler. During enumeration information about each media device is
* gathered, transformed and stored.
*
* The core of the enumeration is DeviceEnumerator which is responsible
* for all interactions with the operating system and the entry point
* for other parts of libcamera.
*
* The DeviceEnumerator can enumerate all or specific media devices in
* the system. When a new media device is added the enumerator creates a
* corresponding MediaDevice instance.
*
* The last functionality provided is the ability to search among the
* enumerate media devices for one matching information known to the
* searcher. This is done by populating and passing a DeviceMatch object
* to the DeviceEnumerator.
*
* \todo Add sysfs based device enumerator
* \todo Add support for hot-plug and hot-unplug.
*/
namespace libcamera {
/**
* \class DeviceMatch
* \brief Description of a media device search pattern
*
* The DeviceMatch class describes a media device using properties from
* the v4l2 struct media_device_info, entity names in the media graph or
* other properties which can be used to identify a media device.
*
* The description of a media device can then be passed to an enumerator
* to try and find a matching media device.
*/
/**
* \brief Construct a media device search pattern
*
* \param[in] driver The Linux device driver name who created the media device
*/
DeviceMatch::DeviceMatch(const std::string &driver)
: driver_(driver)
{
}
/**
* \brief Add a media entity name to the search pattern
*
* \param[in] entity The name of the entity in the media graph
*/
void DeviceMatch::add(const std::string &entity)
{
entities_.push_back(entity);
}
/**
* \brief Compare a search pattern with a media device
* \param[in] device The media device
*
* Matching is performed on the Linux device driver name and entity names
* from the media graph.
*
* \return true if the media device matches the search pattern, false otherwise
*/
bool DeviceMatch::match(const MediaDevice *device) const
{
if (driver_ != device->driver())
return false;
for (const std::string &name : entities_) {
bool found = false;
for (const MediaEntity *entity : device->entities()) {
if (name == entity->name()) {
found = true;
break;
}
}
if (!found)
return false;
}
return true;
}
/**
* \class DeviceEnumerator
* \brief Enumerate, interrogate, store and search media device information
*
* The DeviceEnumerator class is responsible for all interactions with
* the operation system when searching and interrogating media devices.
*
* It is possible to automatically search and add all media devices in
* the system or specify which media devices should be interrogated
* in order for a specialized application to open as few resources
* as possible to get hold of a specific camera.
*
* Once one or many media devices have been enumerated it is possible
* to search among them to try and find a matching device using a
* DeviceMatch object.
*
*/
/**
* \brief Create a new device enumerator matching the systems capabilities
*
* Create a enumerator based on resource available to the system. Not all
* different enumerator types are guaranteed to support all features.
*/
DeviceEnumerator *DeviceEnumerator::create()
{
DeviceEnumerator *enumerator;
/* TODO: add compile time checks to only try udev enumerator if libudev is available */
enumerator = new DeviceEnumeratorUdev();
if (!enumerator->init())
return enumerator;
/*
* NOTE: Either udev is not available or initialization of it
* failed, use/fallback on sysfs enumerator
*/
/* TODO: add a sysfs based enumerator */
return nullptr;
}
DeviceEnumerator::~DeviceEnumerator()
{
for (MediaDevice *dev : devices_) {
if (dev->busy())
LOG(Error) << "Removing device info while still in use";
delete dev;
}
}
/**
* \brief Add a media device to the enumerator
*
* \param[in] devnode path to the media device to add
*
* Opens the media device and quires its topology and other information.
*
* \return 0 on success none zero otherwise
*/
int DeviceEnumerator::addDevice(const std::string &devnode)
{
MediaDevice *media = new MediaDevice(devnode);
int ret = media->open();
if (ret < 0)
return ret;
ret = media->populate();
if (ret < 0) {
LOG(Info) << "Unable to populate media device " << devnode <<
" (" << strerror(-ret) << "), skipping";
return ret;
}
/* Associate entities to device node paths. */
for (MediaEntity *entity : media->entities()) {
if (entity->major() == 0 && entity->minor() == 0)
continue;
std::string devnode = lookupDevnode(entity->major(), entity->minor());
if (devnode.empty())
return -EINVAL;
ret = entity->setDeviceNode(devnode);
if (ret)
return ret;
}
devices_.push_back(media);
media->close();
return 0;
}
/**
* \brief Search available media devices for a pattern match
*
* \param[in] dm Search pattern
*
* Search in the enumerated media devices that are not already in use
* for a match described in \a dm. If a match is found and the caller
* intends to use it the caller is responsible to mark the MediaDevice
* object as in use and to release it when it's done with it.
*
* \return pointer to the matching MediaDevice, nullptr if no match is found
*/
MediaDevice *DeviceEnumerator::search(DeviceMatch &dm) const
{
for (MediaDevice *dev : devices_) {
if (dev->busy())
continue;
if (dm.match(dev))
return dev;
}
return nullptr;
}
/**
* \class DeviceEnumeratorUdev
* \brief Udev implementation of device enumeration
*
* Implementation of system enumeration functions using libudev.
*/
DeviceEnumeratorUdev::DeviceEnumeratorUdev()
: udev_(nullptr)
{
}
DeviceEnumeratorUdev::~DeviceEnumeratorUdev()
{
if (udev_)
udev_unref(udev_);
}
/**
* \brief Initialize the enumerator
*
* \retval 0 Initialized
* \retval -EBUSY Busy (already initialized)
* \retval -ENODEV Failed to talk to udev
*/
int DeviceEnumeratorUdev::init()
{
if (udev_)
return -EBUSY;
udev_ = udev_new();
if (!udev_)
return -ENODEV;
return 0;
}
/**
* \brief Enumerate all media devices using udev
*
* Find, enumerate and add all media devices in the system to the
* enumerator.
*
* \return 0 on success none zero otherwise
*/
int DeviceEnumeratorUdev::enumerate()
{
struct udev_enumerate *udev_enum = nullptr;
struct udev_list_entry *ents, *ent;
int ret;
udev_enum = udev_enumerate_new(udev_);
if (!udev_enum)
return -ENOMEM;
ret = udev_enumerate_add_match_subsystem(udev_enum, "media");
if (ret < 0)
goto done;
ret = udev_enumerate_scan_devices(udev_enum);
if (ret < 0)
goto done;
ents = udev_enumerate_get_list_entry(udev_enum);
if (!ents)
goto done;
udev_list_entry_foreach(ent, ents) {
struct udev_device *dev;
const char *devnode;
const char *syspath = udev_list_entry_get_name(ent);
dev = udev_device_new_from_syspath(udev_, syspath);
if (!dev) {
LOG(Warning) << "Failed to get device for '" <<
syspath << "', skipping";
continue;
}
devnode = udev_device_get_devnode(dev);
if (!devnode) {
udev_device_unref(dev);
ret = -ENODEV;
goto done;
}
addDevice(devnode);
udev_device_unref(dev);
}
done:
udev_enumerate_unref(udev_enum);
return ret >= 0 ? 0 : ret;
}
/**
* \brief Lookup device node from device number using udev
*
* Translate a device number (major, minor) to a device node path.
*
* \return device node path or empty string if lookup fails.
*
*/
std::string DeviceEnumeratorUdev::lookupDevnode(int major, int minor)
{
struct udev_device *device;
const char *name;
dev_t devnum;
std::string devnode = std::string();
devnum = makedev(major, minor);
device = udev_device_new_from_devnum(udev_, 'c', devnum);
if (!device)
return std::string();
name = udev_device_get_devnode(device);
if (name)
devnode = name;
udev_device_unref(device);
return devnode;
}
} /* namespace libcamera */
|
