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authorLuca Risolia <luca.risolia@studio.unibo.it>2006-02-06 11:29:35 -0500
committerGreg Kroah-Hartman <gregkh@suse.de>2006-03-20 17:49:52 -0500
commit60f780528f3ae603eb169a221628b93b6c6929f9 (patch)
tree535b75e9eafb445c7acd85ee350cdc0efbbcdecb /Documentation/usb/zc0301.txt
parentc4a1745aa09fc110afdefea0e5d025043e348bae (diff)
[PATCH] USB: Add ZC0301 Video4Linux2 driver
This patch adds a Video4Linux2 driver for ZC0301 Image Processor and Control Chip. Signed-off-by: Luca Risolia <luca.risolia@studio.unibo.it> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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1
2 ZC0301 Image Processor and Control Chip
3 Driver for Linux
4 =======================================
5
6 - Documentation -
7
8
9Index
10=====
111. Copyright
122. Disclaimer
133. License
144. Overview and features
155. Module dependencies
166. Module loading
177. Module parameters
188. Supported devices
199. Notes for V4L2 application developers
2010. Contact information
2111. Credits
22
23
241. Copyright
25============
26Copyright (C) 2006 by Luca Risolia <luca.risolia@studio.unibo.it>
27
28
292. Disclaimer
30=============
31This software is not developed or sponsored by Z-Star Microelectronics Corp.
32Trademarks are property of their respective owner.
33
34
353. License
36==========
37This program is free software; you can redistribute it and/or modify
38it under the terms of the GNU General Public License as published by
39the Free Software Foundation; either version 2 of the License, or
40(at your option) any later version.
41
42This program is distributed in the hope that it will be useful,
43but WITHOUT ANY WARRANTY; without even the implied warranty of
44MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
45GNU General Public License for more details.
46
47You should have received a copy of the GNU General Public License
48along with this program; if not, write to the Free Software
49Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
50
51
524. Overview and features
53========================
54This driver supports the video interface of the devices mounting the ZC0301
55Image Processor and Control Chip.
56
57The driver relies on the Video4Linux2 and USB core modules. It has been
58designed to run properly on SMP systems as well.
59
60The latest version of the ZC0301 driver can be found at the following URL:
61http://www.linux-projects.org/
62
63Some of the features of the driver are:
64
65- full compliance with the Video4Linux2 API (see also "Notes for V4L2
66 application developers" paragraph);
67- available mmap or read/poll methods for video streaming through isochronous
68 data transfers;
69- automatic detection of image sensor;
70- video formats is standard JPEG in various compression qualities
71 (see also "Notes for V4L2 application developers" paragraph);
72- full support for the capabilities of every possible image sensors that can
73 be connected to the ZC0301 bridges, including, for istance, red, green,
74 blue and global gain adjustments and exposure control (see "Supported
75 devices" paragraph for details);
76- use of default color settings for sunlight conditions;
77- dynamic driver control thanks to various module parameters (see "Module
78 parameters" paragraph);
79- up to 64 cameras can be handled at the same time; they can be connected and
80 disconnected from the host many times without turning off the computer, if
81 the system supports hotplugging;
82
83
845. Module dependencies
85======================
86For it to work properly, the driver needs kernel support for Video4Linux and
87USB.
88
89The following options of the kernel configuration file must be enabled and
90corresponding modules must be compiled:
91
92 # Multimedia devices
93 #
94 CONFIG_VIDEO_DEV=m
95
96 # USB support
97 #
98 CONFIG_USB=m
99
100In addition, depending on the hardware being used, the modules below are
101necessary:
102
103 # USB Host Controller Drivers
104 #
105 CONFIG_USB_EHCI_HCD=m
106 CONFIG_USB_UHCI_HCD=m
107 CONFIG_USB_OHCI_HCD=m
108
109The ZC0301 controller also provides a built-in microphone interface. It is
110supported by the USB Audio driver thanks to the ALSA API:
111
112 # Sound
113 #
114 CONFIG_SOUND=y
115
116 # Advanced Linux Sound Architecture
117 #
118 CONFIG_SND=m
119
120 # USB devices
121 #
122 CONFIG_SND_USB_AUDIO=m
123
124And finally:
125
126 # USB Multimedia devices
127 #
128 CONFIG_USB_ZC0301=m
129
130
1316. Module loading
132=================
133To use the driver, it is necessary to load the "zc0301" module into memory
134after every other module required: "videodev", "usbcore" and, depending on
135the USB host controller you have, "ehci-hcd", "uhci-hcd" or "ohci-hcd".
136
137Loading can be done as shown below:
138
139 [root@localhost home]# modprobe zc0301
140
141At this point the devices should be recognized. You can invoke "dmesg" to
142analyze kernel messages and verify that the loading process has gone well:
143
144 [user@localhost home]$ dmesg
145
146
1477. Module parameters
148====================
149Module parameters are listed below:
150-------------------------------------------------------------------------------
151Name: video_nr
152Type: short array (min = 0, max = 64)
153Syntax: <-1|n[,...]>
154Description: Specify V4L2 minor mode number:
155 -1 = use next available
156 n = use minor number n
157 You can specify up to 64 cameras this way.
158 For example:
159 video_nr=-1,2,-1 would assign minor number 2 to the second
160 registered camera and use auto for the first one and for every
161 other camera.
162Default: -1
163-------------------------------------------------------------------------------
164Name: force_munmap
165Type: bool array (min = 0, max = 64)
166Syntax: <0|1[,...]>
167Description: Force the application to unmap previously mapped buffer memory
168 before calling any VIDIOC_S_CROP or VIDIOC_S_FMT ioctl's. Not
169 all the applications support this feature. This parameter is
170 specific for each detected camera.
171 0 = do not force memory unmapping
172 1 = force memory unmapping (save memory)
173Default: 0
174-------------------------------------------------------------------------------
175Name: debug
176Type: ushort
177Syntax: <n>
178Description: Debugging information level, from 0 to 3:
179 0 = none (use carefully)
180 1 = critical errors
181 2 = significant informations
182 3 = more verbose messages
183 Level 3 is useful for testing only, when only one device
184 is used at the same time. It also shows some more informations
185 about the hardware being detected. This module parameter can be
186 changed at runtime thanks to the /sys filesystem interface.
187Default: 2
188-------------------------------------------------------------------------------
189
190
1918. Supported devices
192====================
193None of the names of the companies as well as their products will be mentioned
194here. They have never collaborated with the author, so no advertising.
195
196From the point of view of a driver, what unambiguously identify a device are
197its vendor and product USB identifiers. Below is a list of known identifiers of
198devices mounting the ZC0301 Image Processor and Control Chips:
199
200Vendor ID Product ID
201--------- ----------
2020x046d 0x08ae
203
204The following image sensors are supported:
205
206Model Manufacturer
207----- ------------
208PAS202BCB PixArt Imaging, Inc.
209
210All the available control settings of each image sensor are supported through
211the V4L2 interface.
212
213
2149. Notes for V4L2 application developers
215========================================
216This driver follows the V4L2 API specifications. In particular, it enforces two
217rules:
218
219- exactly one I/O method, either "mmap" or "read", is associated with each
220file descriptor. Once it is selected, the application must close and reopen the
221device to switch to the other I/O method;
222
223- although it is not mandatory, previously mapped buffer memory should always
224be unmapped before calling any "VIDIOC_S_CROP" or "VIDIOC_S_FMT" ioctl's.
225The same number of buffers as before will be allocated again to match the size
226of the new video frames, so you have to map the buffers again before any I/O
227attempts on them.
228
229This driver supports the standard JPEG video format. The current compression
230quality may vary from 0 to 3 and can be selected or queried thanks to the
231VIDIOC_S_JPEGCOMP and VIDIOC_G_JPEGCOMP V4L2 ioctl's.
232
233
23410. Contact information
235=======================
236The author may be contacted by e-mail at <luca.risolia@studio.unibo.it>.
237
238GPG/PGP encrypted e-mail's are accepted. The GPG key ID of the author is
239'FCE635A4'; the public 1024-bit key should be available at any keyserver;
240the fingerprint is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'.
241
242
24311. Credits
244===========
245- Informations about the chip internals to enable the I2C protocol have been
246 taken from the documentation of the ZC030x Video4Linux1 driver written by
247 Andrew Birkett <andy@nobugs.org>;
248- Initialization values of the ZC0301 connected to the PAS202BCB image sensor
249 have been taken from the SPCA5XX driver maintained by
250 Michel Xhaard <mxhaard@magic.fr>