Root/Documentation/video4linux/README.pvrusb2

1
2$Id$
3Mike Isely <isely@pobox.com>
4
5                pvrusb2 driver
6
7Background:
8
9  This driver is intended for the "Hauppauge WinTV PVR USB 2.0", which
10  is a USB 2.0 hosted TV Tuner. This driver is a work in progress.
11  Its history started with the reverse-engineering effort by Bj√∂rn
12  Danielsson <pvrusb2@dax.nu> whose web page can be found here:
13
14    http://pvrusb2.dax.nu/
15
16  From there Aurelien Alleaume <slts@free.fr> began an effort to
17  create a video4linux compatible driver. I began with Aurelien's
18  last known snapshot and evolved the driver to the state it is in
19  here.
20
21  More information on this driver can be found at:
22
23    http://www.isely.net/pvrusb2.html
24
25
26  This driver has a strong separation of layers. They are very
27  roughly:
28
29  1a. Low level wire-protocol implementation with the device.
30
31  1b. I2C adaptor implementation and corresponding I2C client drivers
32      implemented elsewhere in V4L.
33
34  1c. High level hardware driver implementation which coordinates all
35      activities that ensure correct operation of the device.
36
37  2. A "context" layer which manages instancing of driver, setup,
38      tear-down, arbitration, and interaction with high level
39      interfaces appropriately as devices are hotplugged in the
40      system.
41
42  3. High level interfaces which glue the driver to various published
43      Linux APIs (V4L, sysfs, maybe DVB in the future).
44
45  The most important shearing layer is between the top 2 layers. A
46  lot of work went into the driver to ensure that any kind of
47  conceivable API can be laid on top of the core driver. (Yes, the
48  driver internally leverages V4L to do its work but that really has
49  nothing to do with the API published by the driver to the outside
50  world.) The architecture allows for different APIs to
51  simultaneously access the driver. I have a strong sense of fairness
52  about APIs and also feel that it is a good design principle to keep
53  implementation and interface isolated from each other. Thus while
54  right now the V4L high level interface is the most complete, the
55  sysfs high level interface will work equally well for similar
56  functions, and there's no reason I see right now why it shouldn't be
57  possible to produce a DVB high level interface that can sit right
58  alongside V4L.
59
60  NOTE: Complete documentation on the pvrusb2 driver is contained in
61  the html files within the doc directory; these are exactly the same
62  as what is on the web site at the time. Browse those files
63  (especially the FAQ) before asking questions.
64
65
66Building
67
68  To build these modules essentially amounts to just running "Make",
69  but you need the kernel source tree nearby and you will likely also
70  want to set a few controlling environment variables first in order
71  to link things up with that source tree. Please see the Makefile
72  here for comments that explain how to do that.
73
74
75Source file list / functional overview:
76
77  (Note: The term "module" used below generally refers to loosely
78  defined functional units within the pvrusb2 driver and bears no
79  relation to the Linux kernel's concept of a loadable module.)
80
81  pvrusb2-audio.[ch] - This is glue logic that resides between this
82    driver and the msp3400.ko I2C client driver (which is found
83    elsewhere in V4L).
84
85  pvrusb2-context.[ch] - This module implements the context for an
86    instance of the driver. Everything else eventually ties back to
87    or is otherwise instanced within the data structures implemented
88    here. Hotplugging is ultimately coordinated here. All high level
89    interfaces tie into the driver through this module. This module
90    helps arbitrate each interface's access to the actual driver core,
91    and is designed to allow concurrent access through multiple
92    instances of multiple interfaces (thus you can for example change
93    the tuner's frequency through sysfs while simultaneously streaming
94    video through V4L out to an instance of mplayer).
95
96  pvrusb2-debug.h - This header defines a printk() wrapper and a mask
97    of debugging bit definitions for the various kinds of debug
98    messages that can be enabled within the driver.
99
100  pvrusb2-debugifc.[ch] - This module implements a crude command line
101    oriented debug interface into the driver. Aside from being part
102    of the process for implementing manual firmware extraction (see
103    the pvrusb2 web site mentioned earlier), probably I'm the only one
104    who has ever used this. It is mainly a debugging aid.
105
106  pvrusb2-eeprom.[ch] - This is glue logic that resides between this
107    driver the tveeprom.ko module, which is itself implemented
108    elsewhere in V4L.
109
110  pvrusb2-encoder.[ch] - This module implements all protocol needed to
111    interact with the Conexant mpeg2 encoder chip within the pvrusb2
112    device. It is a crude echo of corresponding logic in ivtv,
113    however the design goals (strict isolation) and physical layer
114    (proxy through USB instead of PCI) are enough different that this
115    implementation had to be completely different.
116
117  pvrusb2-hdw-internal.h - This header defines the core data structure
118    in the driver used to track ALL internal state related to control
119    of the hardware. Nobody outside of the core hardware-handling
120    modules should have any business using this header. All external
121    access to the driver should be through one of the high level
122    interfaces (e.g. V4L, sysfs, etc), and in fact even those high
123    level interfaces are restricted to the API defined in
124    pvrusb2-hdw.h and NOT this header.
125
126  pvrusb2-hdw.h - This header defines the full internal API for
127    controlling the hardware. High level interfaces (e.g. V4L, sysfs)
128    will work through here.
129
130  pvrusb2-hdw.c - This module implements all the various bits of logic
131    that handle overall control of a specific pvrusb2 device.
132    (Policy, instantiation, and arbitration of pvrusb2 devices fall
133    within the jurisdiction of pvrusb-context not here).
134
135  pvrusb2-i2c-chips-*.c - These modules implement the glue logic to
136    tie together and configure various I2C modules as they attach to
137    the I2C bus. There are two versions of this file. The "v4l2"
138    version is intended to be used in-tree alongside V4L, where we
139    implement just the logic that makes sense for a pure V4L
140    environment. The "all" version is intended for use outside of
141    V4L, where we might encounter other possibly "challenging" modules
142    from ivtv or older kernel snapshots (or even the support modules
143    in the standalone snapshot).
144
145  pvrusb2-i2c-cmd-v4l1.[ch] - This module implements generic V4L1
146    compatible commands to the I2C modules. It is here where state
147    changes inside the pvrusb2 driver are translated into V4L1
148    commands that are in turn send to the various I2C modules.
149
150  pvrusb2-i2c-cmd-v4l2.[ch] - This module implements generic V4L2
151    compatible commands to the I2C modules. It is here where state
152    changes inside the pvrusb2 driver are translated into V4L2
153    commands that are in turn send to the various I2C modules.
154
155  pvrusb2-i2c-core.[ch] - This module provides an implementation of a
156    kernel-friendly I2C adaptor driver, through which other external
157    I2C client drivers (e.g. msp3400, tuner, lirc) may connect and
158    operate corresponding chips within the pvrusb2 device. It is
159    through here that other V4L modules can reach into this driver to
160    operate specific pieces (and those modules are in turn driven by
161    glue logic which is coordinated by pvrusb2-hdw, doled out by
162    pvrusb2-context, and then ultimately made available to users
163    through one of the high level interfaces).
164
165  pvrusb2-io.[ch] - This module implements a very low level ring of
166    transfer buffers, required in order to stream data from the
167    device. This module is *very* low level. It only operates the
168    buffers and makes no attempt to define any policy or mechanism for
169    how such buffers might be used.
170
171  pvrusb2-ioread.[ch] - This module layers on top of pvrusb2-io.[ch]
172    to provide a streaming API usable by a read() system call style of
173    I/O. Right now this is the only layer on top of pvrusb2-io.[ch],
174    however the underlying architecture here was intended to allow for
175    other styles of I/O to be implemented with additional modules, like
176    mmap()'ed buffers or something even more exotic.
177
178  pvrusb2-main.c - This is the top level of the driver. Module level
179    and USB core entry points are here. This is our "main".
180
181  pvrusb2-sysfs.[ch] - This is the high level interface which ties the
182    pvrusb2 driver into sysfs. Through this interface you can do
183    everything with the driver except actually stream data.
184
185  pvrusb2-tuner.[ch] - This is glue logic that resides between this
186    driver and the tuner.ko I2C client driver (which is found
187    elsewhere in V4L).
188
189  pvrusb2-util.h - This header defines some common macros used
190    throughout the driver. These macros are not really specific to
191    the driver, but they had to go somewhere.
192
193  pvrusb2-v4l2.[ch] - This is the high level interface which ties the
194    pvrusb2 driver into video4linux. It is through here that V4L
195    applications can open and operate the driver in the usual V4L
196    ways. Note that **ALL** V4L functionality is published only
197    through here and nowhere else.
198
199  pvrusb2-video-*.[ch] - This is glue logic that resides between this
200    driver and the saa711x.ko I2C client driver (which is found
201    elsewhere in V4L). Note that saa711x.ko used to be known as
202    saa7115.ko in ivtv. There are two versions of this; one is
203    selected depending on the particular saa711[5x].ko that is found.
204
205  pvrusb2.h - This header contains compile time tunable parameters
206    (and at the moment the driver has very little that needs to be
207    tuned).
208
209
210  -Mike Isely
211  isely@pobox.com
212
213

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