About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Documentation / video4linux / README.pvrusb2




Custom Search

Based on kernel version 3.16. Page generated on 2014-08-06 21:41 EST.

1	
2	$Id$
3	Mike Isely <isely@pobox.com>
4	
5				    pvrusb2 driver
6	
7	Background:
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 Björn
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	
66	Building
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	
75	Source 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
Hide Line Numbers
About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Information is copyright its respective author. All material is available from the Linux Kernel Source distributed under a GPL License. This page is provided as a free service by mjmwired.net.