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 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: 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 . 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.