SN9C10x PC Camera Controllers
Driver for Linux
=============================
- Documentation -
Index
=====
1. Copyright
2. Disclaimer
3. License
4. Overview
5. Driver installation
6. Module loading
7. Module parameters
8. Optional device control through "sysfs"
9. Supported devices
10. How to add support for new image sensors
11. Notes for V4L2 application developers
12. Contact information
13. Credits
1. Copyright
============
Copyright (C) 2004 by Luca Risolia <luca.risolia@studio.unibo.it>
2. Disclaimer
=============
SONiX is a trademark of SONiX Technology Company Limited, inc.
This software is not sponsored or developed by SONiX.
3. License
==========
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
4. Overview
===========
This driver attempts to support the video and audio streaming capabilities of
the devices mounting the SONiX SN9C101, SN9C102 and SN9C103 (or SUI-102) PC
Camera Controllers.
It's worth to note that SONiX has never collaborated with the author during the
development of this project, despite several requests for enough detailed
specifications of the register tables, compression engine and video data format
of the above chips.
The driver relies on the Video4Linux2 and USB core modules. It has been
designed to run properly on SMP systems as well.
The latest version of the SN9C10x driver can be found at the following URL:
http://www.linux-projects.org/
Some of the features of the driver are:
- full compliance with the Video4Linux2 API (see also "Notes for V4L2
application developers" paragraph);
- available mmap or read/poll methods for video streaming through isochronous
data transfers;
- automatic detection of image sensor;
- support for any window resolutions and optional panning within the maximum
pixel area of image sensor;
- image downscaling with arbitrary scaling factors from 1, 2 and 4 in both
directions (see "Notes for V4L2 application developers" paragraph);
- two different video formats for uncompressed or compressed data (see also
"Notes for V4L2 application developers" paragraph);
- full support for the capabilities of many of the possible image sensors that
can be connected to the SN9C10x bridges, including, for istance, red, green,
blue and global gain adjustments and exposure (see "Supported devices"
paragraph for details);
- use of default color settings for sunlight conditions;
- dynamic I/O interface for both SN9C10x and image sensor control (see
"Optional device control through 'sysfs'" paragraph);
- dynamic driver control thanks to various module parameters (see "Module
parameters" paragraph);
- up to 64 cameras can be handled at the same time; they can be connected and
disconnected from the host many times without turning off the computer, if
your system supports hotplugging;
- no known bugs.
5. Module dependencies
======================
For it to work properly, the driver needs kernel support for Video4Linux and
USB.
The following options of the kernel configuration file must be enabled and
corresponding modules must be compiled:
# Multimedia devices
#
CONFIG_VIDEO_DEV=m
# USB support
#
CONFIG_USB=m
In addition, depending on the hardware being used, the modules below are
necessary:
# USB Host Controller Drivers
#
CONFIG_USB_EHCI_HCD=m
CONFIG_USB_UHCI_HCD=m
CONFIG_USB_OHCI_HCD=m
And finally:
# USB Multimedia devices
#
CONFIG_USB_SN9C102=m
6. Module loading
=================
To use the driver, it is necessary to load the "sn9c102" module into memory
after every other module required: "videodev", "usbcore" and, depending on
the USB host controller you have, "ehci-hcd", "uhci-hcd" or "ohci-hcd".
Loading can be done as shown below:
[root@localhost home]# modprobe sn9c102
At this point the devices should be recognized. You can invoke "dmesg" to
analyze kernel messages and verify that the loading process has gone well:
[user@localhost home]$ dmesg
7. Module parameters
====================
Module parameters are listed below:
-------------------------------------------------------------------------------
Name: video_nr
Type: int array (min = 0, max = 64)
Syntax: <-1|n[,...]>
Description: Specify V4L2 minor mode number:
-1 = use next available
n = use minor number n
You can specify up to 64 cameras this way.
For example:
video_nr=-1,2,-1 would assign minor number 2 to the second
recognized camera and use auto for the first one and for every
other camera.
Default: -1
-------------------------------------------------------------------------------
Name: debug
Type: int
Syntax: <n>
Description: Debugging information level, from 0 to 3:
0 = none (use carefully)
1 = critical errors
2 = significant informations
3 = more verbose messages
Level 3 is useful for testing only, when only one device
is used. It also shows some more informations about the
hardware being detected. This parameter can be changed at
runtime thanks to the /sys filesystem.
Default: 2
-------------------------------------------------------------------------------
8. Optional device control through "sysfs"
==========================================
It is possible to read and write both the SN9C10x and the image sensor
registers by using the "sysfs" filesystem interface.
Every time a supported device is recognized, a write-only file named "green" is
created in the /sys/class/video4linux/videoX directory. You can set the green
channel's gain by writing the desired value to it. The value may range from 0
to 15 for SN9C101 or SN9C102 bridges, from 0 to 127 for SN9C103 bridges.
Similarly, only for SN9C103 controllers, blue and red gain control files are
available in the same directory, for which accepted values may range from 0 to
127.
There are other four entries in the directory above for each registered camera:
"reg", "val", "i2c_reg" and "i2c_val". The first two files control the
SN9C10x bridge, while the other two control the sensor chip. "reg" and
"i2c_reg" hold the values of the current register index where the following
reading/writing operations are addressed at through "val" and "i2c_val". Their
use is not intended for end-users, unless you know what you are doing. Note
that "i2c_reg" and "i2c_val" won't be created if the sensor does not actually
support the standard I2C protocol. Also, remember that you must be logged in as
root before writing to them.
As an example, suppose we were to want to read the value contained in the
register number 1 of the sensor register table - which is usually the product
identifier - of the camera registered as "/dev/video0":
[root@localhost #] cd /sys/class/video4linux/video0
[root@localhost #] echo 1 > i2c_reg
[root@localhost #] cat i2c_val
Note that "cat" will fail if sensor registers cannot be read.
Now let's set the green gain's register of the SN9C101 or SN9C102 chips to 2:
[root@localhost #] echo 0x11 > reg
[root@localhost #] echo 2 > val
Note that the SN9C10x always returns 0 when some of its registers are read.
To avoid race conditions, all the I/O accesses to the files are serialized.
9. Supported devices
====================
None of the names of the companies as well as their products will be mentioned
here. They have never collaborated with the author, so no advertising.
From the point of view of a driver, what unambiguously identify a device are
its vendor and product USB identifiers. Below is a list of known identifiers of
devices mounting the SN9C10x PC camera controllers:
Vendor ID Product ID
--------- ----------
0x0c45 0x6001
0x0c45 0x6005
0x0c45 0x6009
0x0c45 0x600d
0x0c45 0x6024
0x0c45 0x6025
0x0c45 0x6028
0x0c45 0x6029
0x0c45 0x602a
0x0c45 0x602b
0x0c45 0x602c
0x0c45 0x6030
0x0c45 0x6080
0x0c45 0x6082
0x0c45 0x6083
0x0c45 0x6088
0x0c45 0x608a
0x0c45 0x608b
0x0c45 0x608c
0x0c45 0x608e
0x0c45 0x608f
0x0c45 0x60a0
0x0c45 0x60a2
0x0c45 0x60a3
0x0c45 0x60a8
0x0c45 0x60aa
0x0c45 0x60ab
0x0c45 0x60ac
0x0c45 0x60ae
0x0c45 0x60af
0x0c45 0x60b0
0x0c45 0x60b2
0x0c45 0x60b3
0x0c45 0x60b8
0x0c45 0x60ba
0x0c45 0x60bb
0x0c45 0x60bc
0x0c45 0x60be
The list above does not imply that all those devices work with this driver: up
until now only the ones that mount the following image sensors are supported;
kernel messages will always tell you whether this is the case:
Model Manufacturer
----- ------------
PAS106B PixArt Imaging Inc.
PAS202BCB PixArt Imaging Inc.
TAS5110C1B Taiwan Advanced Sensor Corporation
TAS5130D1B Taiwan Advanced Sensor Corporation
All the available control settings of each image sensor are supported through
the V4L2 interface.
If you think your camera is based on the above hardware and is not actually
listed in the above table, you may try to add the specific USB VendorID and
ProductID identifiers to the sn9c102_id_table[] in the file "sn9c102_sensor.h";
then compile, load the module again and look at the kernel output.
If this works, please send an email to the author reporting the kernel
messages, so that a new entry in the list of supported devices can be added.
Donations of new models for further testing and support would be much
appreciated. Non-available hardware won't be supported by the author of this
driver.
10. How to add support for new image sensors
============================================
It should be easy to write code for new sensors by using the small API that I
have created for this purpose, which is present in "sn9c102_sensor.h"
(documentation is included there). As an example, have a look at the code in
"sn9c102_pas106b.c", which uses the mentioned interface.
At the moment, possible unsupported image sensors are: HV7131x series (VGA),
MI03x series (VGA), OV7620 (VGA), OV7630 (VGA), CIS-VF10 (VGA).
11. Notes for V4L2 application developers
=========================================
This driver follows the V4L2 API specifications. In particular, it enforces two
rules:
- exactly one I/O method, either "mmap" or "read", is associated with each
file descriptor. Once it is selected, the application must close and reopen the
device to switch to the other I/O method;
- previously mapped buffer memory must always be unmapped before calling any
of the "VIDIOC_S_CROP", "VIDIOC_TRY_FMT" and "VIDIOC_S_FMT" ioctl's. The same
number of buffers as before will be allocated again to match the size of the
new video frames, so you have to map the buffers again before any I/O attempts
on them.
Consistently with the hardware limits, this driver also supports image
downscaling with arbitrary scaling factors from 1, 2 and 4 in both directions.
However, the V4L2 API specifications don't correctly define how the scaling
factor can be chosen arbitrarily by the "negotiation" of the "source" and
"target" rectangles. To work around this flaw, we have added the convention
that, during the negotiation, whenever the "VIDIOC_S_CROP" ioctl is issued, the
scaling factor is restored to 1.
This driver supports two different video formats: the first one is the "8-bit
Sequential Bayer" format and can be used to obtain uncompressed video data
from the device through the current I/O method, while the second one provides
"raw" compressed video data (without the initial and final frame headers). The
compression quality may vary from 0 to 1 and can be selected or queried thanks
to the VIDIOC_S_JPEGCOMP and VIDIOC_G_JPEGCOMP V4L2 ioctl's. For maximum
flexibility, the default active video format depends on how the image sensor
being used is initialized (as described in the documentation of the API for the
image sensors supplied by this driver).
12. Contact information
=======================
I may be contacted by e-mail at <luca.risolia@studio.unibo.it>.
I can accept GPG/PGP encrypted e-mail. My GPG key ID is 'FCE635A4'.
My public 1024-bit key should be available at any keyserver; the fingerprint
is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'.
13. Credits
===========
I would thank the following persons:
- Stefano Mozzi, who donated 45 EU;
- Luca Capello for the donation of a webcam;
- Mizuno Takafumi for the donation of a webcam;
- Carlos Eduardo Medaglia Dyonisio, who added the support for the PAS202BCB
image sensor.
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