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+
+                    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 formats is standard JPEG in various compression qualities
+  (see also "Notes for V4L2 application developers" paragraph);
+- 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.
+
+This driver supports the standard JPEG video format. The current compression
+quality may vary from 0 to 3 and can be selected or queried thanks to the
+VIDIOC_S_JPEGCOMP and VIDIOC_G_JPEGCOMP V4L2 ioctl's.
+
+
+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 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 connected to the PAS202BCB image sensor
+  have been taken from the SPCA5XX driver maintained by
+  Michel Xhaard  <mxhaard@magic.fr>