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diff --git a/Documentation/video4linux/README.pvrusb2 b/Documentation/video4linux/README.pvrusb2 new file mode 100644 index 000000000000..c73a32c34528 --- /dev/null +++ b/Documentation/video4linux/README.pvrusb2 @@ -0,0 +1,212 @@ + +$Id$ +Mike Isely <isely@pobox.com> + + pvrusb2 driver + +Background: + + This driver is intended for the "Hauppauge WinTV PVR USB 2.0", which + is a USB 2.0 hosted TV Tuner. This driver is a work in progress. + Its history started with the reverse-engineering effort by Björn + Danielsson <pvrusb2@dax.nu> whose web page can be found here: + + http://pvrusb2.dax.nu/ + + From there Aurelien Alleaume <slts@free.fr> began an effort to + create a video4linux compatible driver. I began with Aurelien's + last known snapshot and evolved the driver to the state it is in + here. + + More information on this driver can be found at: + + http://www.isely.net/pvrusb2.html + + + This driver has a strong separation of layers. They are very + roughly: + + 1a. Low level wire-protocol implementation with the device. + + 1b. I2C adaptor implementation and corresponding I2C client drivers + implemented elsewhere in V4L. + + 1c. High level hardware driver implementation which coordinates all + activities that ensure correct operation of the device. + + 2. A "context" layer which manages instancing of driver, setup, + tear-down, arbitration, and interaction with high level + interfaces appropriately as devices are hotplugged in the + system. + + 3. High level interfaces which glue the driver to various published + Linux APIs (V4L, sysfs, maybe DVB in the future). + + The most important shearing layer is between the top 2 layers. A + lot of work went into the driver to ensure that any kind of + conceivable API can be laid on top of the core driver. (Yes, the + driver internally leverages V4L to do its work but that really has + nothing to do with the API published by the driver to the outside + world.) The architecture allows for different APIs to + simultaneously access the driver. I have a strong sense of fairness + about APIs and also feel that it is a good design principle to keep + implementation and interface isolated from each other. Thus while + right now the V4L high level interface is the most complete, the + sysfs high level interface will work equally well for similar + functions, and there's no reason I see right now why it shouldn't be + possible to produce a DVB high level interface that can sit right + alongside V4L. + + NOTE: Complete documentation on the pvrusb2 driver is contained in + the html files within the doc directory; these are exactly the same + as what is on the web site at the time. Browse those files + (especially the FAQ) before asking questions. + + +Building + + To build these modules essentially amounts to just running "Make", + but you need the kernel source tree nearby and you will likely also + want to set a few controlling environment variables first in order + to link things up with that source tree. Please see the Makefile + here for comments that explain how to do that. + + +Source file list / functional overview: + + (Note: The term "module" used below generally refers to loosely + defined functional units within the pvrusb2 driver and bears no + relation to the Linux kernel's concept of a loadable module.) + + pvrusb2-audio.[ch] - This is glue logic that resides between this + driver and the msp3400.ko I2C client driver (which is found + elsewhere in V4L). + + pvrusb2-context.[ch] - This module implements the context for an + instance of the driver. Everything else eventually ties back to + or is otherwise instanced within the data structures implemented + here. Hotplugging is ultimately coordinated here. All high level + interfaces tie into the driver through this module. This module + helps arbitrate each interface's access to the actual driver core, + and is designed to allow concurrent access through multiple + instances of multiple interfaces (thus you can for example change + the tuner's frequency through sysfs while simultaneously streaming + video through V4L out to an instance of mplayer). + + pvrusb2-debug.h - This header defines a printk() wrapper and a mask + of debugging bit definitions for the various kinds of debug + messages that can be enabled within the driver. + + pvrusb2-debugifc.[ch] - This module implements a crude command line + oriented debug interface into the driver. Aside from being part + of the process for implementing manual firmware extraction (see + the pvrusb2 web site mentioned earlier), probably I'm the only one + who has ever used this. It is mainly a debugging aid. + + pvrusb2-eeprom.[ch] - This is glue logic that resides between this + driver the tveeprom.ko module, which is itself implemented + elsewhere in V4L. + + pvrusb2-encoder.[ch] - This module implements all protocol needed to + interact with the Conexant mpeg2 encoder chip within the pvrusb2 + device. It is a crude echo of corresponding logic in ivtv, + however the design goals (strict isolation) and physical layer + (proxy through USB instead of PCI) are enough different that this + implementation had to be completely different. + + pvrusb2-hdw-internal.h - This header defines the core data structure + in the driver used to track ALL internal state related to control + of the hardware. Nobody outside of the core hardware-handling + modules should have any business using this header. All external + access to the driver should be through one of the high level + interfaces (e.g. V4L, sysfs, etc), and in fact even those high + level interfaces are restricted to the API defined in + pvrusb2-hdw.h and NOT this header. + + pvrusb2-hdw.h - This header defines the full internal API for + controlling the hardware. High level interfaces (e.g. V4L, sysfs) + will work through here. + + pvrusb2-hdw.c - This module implements all the various bits of logic + that handle overall control of a specific pvrusb2 device. + (Policy, instantiation, and arbitration of pvrusb2 devices fall + within the jurisdiction of pvrusb-context not here). + + pvrusb2-i2c-chips-*.c - These modules implement the glue logic to + tie together and configure various I2C modules as they attach to + the I2C bus. There are two versions of this file. The "v4l2" + version is intended to be used in-tree alongside V4L, where we + implement just the logic that makes sense for a pure V4L + environment. The "all" version is intended for use outside of + V4L, where we might encounter other possibly "challenging" modules + from ivtv or older kernel snapshots (or even the support modules + in the standalone snapshot). + + pvrusb2-i2c-cmd-v4l1.[ch] - This module implements generic V4L1 + compatible commands to the I2C modules. It is here where state + changes inside the pvrusb2 driver are translated into V4L1 + commands that are in turn send to the various I2C modules. + + pvrusb2-i2c-cmd-v4l2.[ch] - This module implements generic V4L2 + compatible commands to the I2C modules. It is here where state + changes inside the pvrusb2 driver are translated into V4L2 + commands that are in turn send to the various I2C modules. + + pvrusb2-i2c-core.[ch] - This module provides an implementation of a + kernel-friendly I2C adaptor driver, through which other external + I2C client drivers (e.g. msp3400, tuner, lirc) may connect and + operate corresponding chips within the the pvrusb2 device. It is + through here that other V4L modules can reach into this driver to + operate specific pieces (and those modules are in turn driven by + glue logic which is coordinated by pvrusb2-hdw, doled out by + pvrusb2-context, and then ultimately made available to users + through one of the high level interfaces). + + pvrusb2-io.[ch] - This module implements a very low level ring of + transfer buffers, required in order to stream data from the + device. This module is *very* low level. It only operates the + buffers and makes no attempt to define any policy or mechanism for + how such buffers might be used. + + pvrusb2-ioread.[ch] - This module layers on top of pvrusb2-io.[ch] + to provide a streaming API usable by a read() system call style of + I/O. Right now this is the only layer on top of pvrusb2-io.[ch], + however the underlying architecture here was intended to allow for + other styles of I/O to be implemented with additonal modules, like + mmap()'ed buffers or something even more exotic. + + pvrusb2-main.c - This is the top level of the driver. Module level + and USB core entry points are here. This is our "main". + + pvrusb2-sysfs.[ch] - This is the high level interface which ties the + pvrusb2 driver into sysfs. Through this interface you can do + everything with the driver except actually stream data. + + pvrusb2-tuner.[ch] - This is glue logic that resides between this + driver and the tuner.ko I2C client driver (which is found + elsewhere in V4L). + + pvrusb2-util.h - This header defines some common macros used + throughout the driver. These macros are not really specific to + the driver, but they had to go somewhere. + + pvrusb2-v4l2.[ch] - This is the high level interface which ties the + pvrusb2 driver into video4linux. It is through here that V4L + applications can open and operate the driver in the usual V4L + ways. Note that **ALL** V4L functionality is published only + through here and nowhere else. + + pvrusb2-video-*.[ch] - This is glue logic that resides between this + driver and the saa711x.ko I2C client driver (which is found + elsewhere in V4L). Note that saa711x.ko used to be known as + saa7115.ko in ivtv. There are two versions of this; one is + selected depending on the particular saa711[5x].ko that is found. + + pvrusb2.h - This header contains compile time tunable parameters + (and at the moment the driver has very little that needs to be + tuned). + + + -Mike Isely + isely@pobox.com + |
