Documentation/usb/zc0301.txt - SHIFTPHONES/kernel/common - Gitiles


                     ZC0301 Image Processor and Control Chip
                                 Driver for Linux
                     =======================================

                                - Documentation -


 Index
 =====
 1.  Copyright
 2.  Disclaimer
 3.  License
 4.  Overview and features
 5.  Module dependencies
 6.  Module loading
 7.  Module parameters
 8.  Supported devices
 9.  Notes for V4L2 application developers
 10. Contact information
 11. Credits


 1. Copyright
 ============
 Copyright (C) 2006 by Luca Risolia <luca.risolia@studio.unibo.it>


 2. Disclaimer
 =============
 This software is not developed or sponsored by Z-Star Microelectronics Corp.
 Trademarks are property of their respective owner.


 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 and features
 ========================
 This driver supports the video interface of the devices mounting the ZC0301
 Image Processor and Control Chip.

 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 ZC0301 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;
 - video format is standard JPEG;
 - full support for the capabilities of every possible image sensors that can
   be connected to the ZC0301 bridges, including, for istance, red, green,
   blue and global gain adjustments and exposure control (see "Supported
   devices" paragraph for details);
 - use of default color settings for sunlight conditions;
 - 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
   the system supports hotplugging;


 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

 The ZC0301 controller also provides a built-in microphone interface. It is
 supported by the USB Audio driver thanks to the ALSA API:

 	# Sound
 	#
 	CONFIG_SOUND=y

 	# Advanced Linux Sound Architecture
 	#
 	CONFIG_SND=m

 	# USB devices
 	#
 	CONFIG_SND_USB_AUDIO=m

 And finally:

 	# USB Multimedia devices
 	#
 	CONFIG_USB_ZC0301=m


 6. Module loading
 =================
 To use the driver, it is necessary to load the "zc0301" 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 zc0301

 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:           short 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
                 registered camera and use auto for the first one and for every
                 other camera.
 Default:        -1
 -------------------------------------------------------------------------------
 Name:           force_munmap
 Type:           bool array (min = 0, max = 64)
 Syntax:         <0|1[,...]>
 Description:    Force the application to unmap previously mapped buffer memory
                 before calling any VIDIOC_S_CROP or VIDIOC_S_FMT ioctl's. Not
                 all the applications support this feature. This parameter is
                 specific for each detected camera.
                 0 = do not force memory unmapping
                 1 = force memory unmapping (save memory)
 Default:        0
 -------------------------------------------------------------------------------
 Name:           debug
 Type:           ushort
 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 at the same time. It also shows some more informations
                 about the hardware being detected. This module parameter can be
                 changed at runtime thanks to the /sys filesystem interface.
 Default:        2
 -------------------------------------------------------------------------------


 8. 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 ZC0301 Image Processor and Control Chips:

 Vendor ID  Product ID
 ---------  ----------
 0x046d     0x08ae

 The following image sensors are supported:

 Model       Manufacturer
 -----       ------------
 PAS202BCB   PixArt Imaging, Inc.

 All the available control settings of each image sensor are supported through
 the V4L2 interface.


 9. 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;

 - although it is not mandatory, previously mapped buffer memory should always
 be unmapped before calling any "VIDIOC_S_CROP" or "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.


 10. Contact information
 =======================
 The author may be contacted by e-mail at <luca.risolia@studio.unibo.it>.

 GPG/PGP encrypted e-mail's are accepted. The GPG key ID of the author is
 'FCE635A4'; the public 1024-bit key should be available at any keyserver;
 the fingerprint is: '88E8 F32F 7244 68BA 3958  5D40 99DA 5D2A FCE6 35A4'.


 11. Credits
 ===========
 - Informations about the chip internals needed to enable the I2C protocol have
   been taken from the documentation of the ZC030x Video4Linux1 driver written
   by Andrew Birkett <andy@nobugs.org>;
 - Initialization values of the ZC0301 controller connected to the PAS202BCB
   image sensor have been taken from the SPCA5XX driver maintained by
   Michel Xhaard <mxhaard@magic.fr>.

	ZC0301 Image Processor and Control Chip
	Driver for Linux
	=======================================

	- Documentation -


	Index
	=====
	1. Copyright
	2. Disclaimer
	3. License
	4. Overview and features
	5. Module dependencies
	6. Module loading
	7. Module parameters
	8. Supported devices
	9. Notes for V4L2 application developers
	10. Contact information
	11. Credits


	1. Copyright
	============
	Copyright (C) 2006 by Luca Risolia <luca.risolia@studio.unibo.it>


	2. Disclaimer
	=============
	This software is not developed or sponsored by Z-Star Microelectronics Corp.
	Trademarks are property of their respective owner.


	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 and features
	========================
	This driver supports the video interface of the devices mounting the ZC0301
	Image Processor and Control Chip.

	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 ZC0301 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;
	- video format is standard JPEG;
	- full support for the capabilities of every possible image sensors that can
	be connected to the ZC0301 bridges, including, for istance, red, green,
	blue and global gain adjustments and exposure control (see "Supported
	devices" paragraph for details);
	- use of default color settings for sunlight conditions;
	- 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
	the system supports hotplugging;


	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

	The ZC0301 controller also provides a built-in microphone interface. It is
	supported by the USB Audio driver thanks to the ALSA API:

	# Sound
	#
	CONFIG_SOUND=y

	# Advanced Linux Sound Architecture
	#
	CONFIG_SND=m

	# USB devices
	#
	CONFIG_SND_USB_AUDIO=m

	And finally:

	# USB Multimedia devices
	#
	CONFIG_USB_ZC0301=m


	6. Module loading
	=================
	To use the driver, it is necessary to load the "zc0301" 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 zc0301

	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: short 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
	registered camera and use auto for the first one and for every
	other camera.
	Default: -1
	-------------------------------------------------------------------------------
	Name: force_munmap
	Type: bool array (min = 0, max = 64)
	Syntax: <0\|1[,...]>
	Description: Force the application to unmap previously mapped buffer memory
	before calling any VIDIOC_S_CROP or VIDIOC_S_FMT ioctl's. Not
	all the applications support this feature. This parameter is
	specific for each detected camera.
	0 = do not force memory unmapping
	1 = force memory unmapping (save memory)
	Default: 0
	-------------------------------------------------------------------------------
	Name: debug
	Type: ushort
	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 at the same time. It also shows some more informations
	about the hardware being detected. This module parameter can be
	changed at runtime thanks to the /sys filesystem interface.
	Default: 2
	-------------------------------------------------------------------------------


	8. 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 ZC0301 Image Processor and Control Chips:

	Vendor ID Product ID
	--------- ----------
	0x046d 0x08ae

	The following image sensors are supported:

	Model Manufacturer
	----- ------------
	PAS202BCB PixArt Imaging, Inc.

	All the available control settings of each image sensor are supported through
	the V4L2 interface.


	9. 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;

	- although it is not mandatory, previously mapped buffer memory should always
	be unmapped before calling any "VIDIOC_S_CROP" or "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.


	10. Contact information
	=======================
	The author may be contacted by e-mail at <luca.risolia@studio.unibo.it>.

	GPG/PGP encrypted e-mail's are accepted. The GPG key ID of the author is
	'FCE635A4'; the public 1024-bit key should be available at any keyserver;
	the fingerprint is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'.


	11. Credits
	===========
	- Informations about the chip internals needed to enable the I2C protocol have
	been taken from the documentation of the ZC030x Video4Linux1 driver written
	by Andrew Birkett <andy@nobugs.org>;
	- Initialization values of the ZC0301 controller connected to the PAS202BCB
	image sensor have been taken from the SPCA5XX driver maintained by
	Michel Xhaard <mxhaard@magic.fr>.