Documentation/video4linux/README.pvrusb2

   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 additonal 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