Arm开发板上摄像头的移植有两种方法：第一，将驱动程序添加到内核，通过编译内核，烧写到板子上；第二种，通过动态加载摄像头驱动模块的方法进行硬件的驱动。作者首先在PC的linux系统进行摄像驱动程序的移植，保证驱动程序版本正确，然后将驱动程序编译成模块，通过文件系统挂载到板子，然后进行加载，进而创建摄像头设备节点。下面将具体介绍摄像头动态加载的过程。
移植过程所使用的摄像头型号ZC301P，arm板上的内核版本为2.6.9，开发板为pxa270，所采用的驱动程序包为spca5xx-20060501.tar.gz。
第一步，使用命令解压文件： tar zxvf spca5xx-20060501.tar.gz
进入spca5xx-20060501 ： cd spca5xx-20060501
第二步，修改Makefile文件：VERSION = 00.60.00
Makefile的内容如下，注释掉的为蓝色，红色表示修改过的内容：
CC =arm-linux-gcc
LD =arm-linux-ld
CVSVERSION = "$Experimental work Michel Xhaard && Reza Jelveh 03/02/2004"
DEFINES =
###
# The following flags enable experimental features.
# By default, these are enabled for development versions of the driver, and
# disabled for release versions.
# Optional: Enable driver debugging
DEFINES += -DSPCA50X_ENABLE_DEBUG
# Optional: Enable direct register read/write for PAC207 development
#DEFINES += -DSPCA5XX_ENABLE_REGISTERPLAY
###
# The following flags enable features that aren't yet implemented, and
# therefore are disabled by default.
# Optional: Enable compression
DEFINES += -DSPCA50X_ENABLE_COMPRESSION
###
# Rest of Makefile follows here. You probably won't need to touch this.
# Setup defines
DEFINES += -DCONFIG_USB_SPCA5XX_MODULE=1 -DMODULE -D__KERNEL__
DEFINES += -DVID_HARDWARE_SPCA5XX=0xFF -DSPCA5XX_VERSION=\"$(VERSION)\"
ifneq ($(shell uname -r | cut -d. -f1,2), 2.4)
ifneq ($(KERNELRELEASE),) # We were called by kbuild
CFLAGS += $(DEFINES)
obj-m += spca5xx.o
spca5xx-objs := drivers/usb/spca5xx.o drivers/usb/spcadecoder.o
else # We were called from command line
#KERNEL_VERSION = `uname -r`
KERNEL_VERSION = 2.6.9
#KERNELDIR := /lib/modules/$(KERNEL_VERSION)/build
KERNELDIR := /up-techpxa270/kernel/linux-2.6.9
PWD := $(shell pwd)
#MODULE_INSTALLDIR = /lib/modules/$(KERNEL_VERSION)/kernel/drivers/usb/media/
MODULE_INSTALLDIR =/root/modules/
# Targets, don't change!
default:
@echo ' Building SPCA5XX driver for 2.5/2.6 kernel.'
@echo ' Remember: you must have read/write access to your kernel source tree.'
$(MAKE) -C $(KERNELDIR) SUBDIRS=$(PWD) CC=$(CC) modules
install:
mkdir -p $(MODULE_INSTALLDIR)
rm -f $(MODULE_INSTALLDIR)spca50x.ko
rm -f $(MODULE_INSTALLDIR)et61x.ko
install -c -m 0644 spca5xx.ko $(MODULE_INSTALLDIR)
/sbin/depmod -ae
uninstall:
rm -f $(MODULE_INSTALLDIR)/spca5xx.ko
/sbin/depmod -aq
endif
else # kernel version test
#############################################################################
# For Linux 2.4 users.
# Change the following lines according to your system configuration.
# It is important to configure your particular source tree ("make dep") before
# compiling this module!
#############################################################################
###
# This makefile will build the spca50x driver module external to the kernel
# source tree. It makes it easier to swap kernels.
#KERNEL_VERSION = `uname -r`
KERNEL_VERSION = 2.4.x
###
# Location of the header files (most importantly the config files)
# for the kernel you want to build the module against.
# This should be correct for the currently installed kernel on your machine.
#KINCLUDE = /lib/modules/$(KERNEL_VERSION)/build/include
KINCLUDE =/up-techpxa270/kernel/linux2.4.x
KERNEL_ACFILE = $(KINCLUDE)/linux/autoconf.h
KERNEL_MODVERSIONSFILE = $(KINCLUDE)/linux/modversions.h
#MODULE_INSTALLDIR = /lib/modules/$(KERNEL_VERSION)/kernel/drivers/usb/
MODULE_INSTALLDIR =/root/modules/
# Detect module versioning support
ifneq ($(strip $(shell grep 'define CONFIG_MODVERSIONS 1' $(KERNEL_ACFILE))),)
DEFINES += -DMODVERSIONS -include $(KERNEL_MODVERSIONSFILE)
endif
# Detect SMP support
ifneq ($(strip $(shell grep 'define CONFIG_SMP 1' $(KERNEL_ACFILE))),)
DEFINES += -D__SMP__ -DSMP
endif
# Setup the tools
#CC = gcc
#LD = ld
CC =arm-linux-gcc
LD =arm-linux-gcc
# Setup compiler warnings
WARNINGS = -Wall -Wpointer-arith
WARNINGS += -Wcast-align -Wwrite-strings -Wstrict-prototypes
WARNINGS += -Wuninitialized -Wreturn-type -Wunused -Wparentheses
# Setup compiler flags
CFLAGS = -O2 -fomit-frame-pointer -fno-strict-aliasing -pipe
CFLAGS += -mpreferred-stack-boundary=2
CFLAGS += -I$(KINCLUDE) -Idrivers/usb
# Setup link flags
LDFLAGS = --strip-debug -r
# Setup the list of files to be included in a distribution
DIST_FILES = CHANGELOG \
README \
Makefile \
drivers/usb/Config.in \
drivers/usb/spcadecoder.c \
drivers/usb/spcadecoder.h \
drivers/usb/spcagamma.h \
drivers/usb/spcaCompat.h \
drivers/usb/spcausb.h \
drivers/usb/spca500_init.h \
drivers/usb/spca501_init.h \
drivers/usb/sp5xxfw2.dat \
drivers/usb/sp5xxfw2.h \
drivers/usb/spca505_init.h \
drivers/usb/spca506.h \
drivers/usb/spca508_init.h \
drivers/usb/spca561.h \
drivers/usb/sonix.h \
drivers/usb/cs2102.h \
drivers/usb/hv7131b.h \
drivers/usb/icm105a.h \
drivers/usb/hv7131c.h \
drivers/usb/hdcs2020.h \
drivers/usb/pb0330.h \
drivers/usb/tas5130c.h \
drivers/usb/zc3xx.h\
drivers/usb/tv8532.h\
drivers/usb/cxlib.h\
drivers/usb/sn9cxxx.h\
drivers/usb/cx11646.h\
drivers/usb/pac207.h\
drivers/usb/spca5xx.c \
drivers/usb/spca5xx.h
OBJS = drivers/usb/spcadecoder.o \
drivers/usb/spca5xx.o
BINARY = spca5xx.o
###
# Targets follow here
binary: $(OBJS)
@echo Linking $(BINARY)
@$(LD) $(LDFLAGS) -o $(BINARY) $(OBJS)
install: binary
@echo Installing.. Your root password may be required.
su -c "make install-root"
install-root:
@echo Installing..
@mkdir -p /lib/modules/`uname -r`/kernel/drivers/usb
@rm -f /lib/modules/`uname -r`/kernel/drivers/usb/spca50x.o
@rm -f /lib/modules/`uname -r`/kernel/drivers/usb/et61x.o
@cp spca5xx.o /lib/modules/`uname -r`/kernel/drivers/usb/spca5xx.o
@/sbin/depmod
dist: clean binary
@echo Making distributable archives
@rm -f spca5xx-src-$(VERSION).tar.gz
@tar zcf spca5xx-src-$(VERSION).tar.gz $(DIST_FILES)
@rm -f spca5xx-module-$(VERSION).tar.gz
@cp $(BINARY) spca5xx-$(VERSION).o
@tar zcf spca5xx-module-$(VERSION).tar.gz spca5xx-$(VERSION).o README
@rm spca5xx-$(VERSION).o
.c.o: Makefile $*.c
@echo Compiling $*.c
@$(CC) $(CFLAGS) $(WARNINGS) $(DEFINES) -c $*.c -o $*.o
###
# Dependencies follow here
drivers/usb/spca5xx.o: drivers/usb/spca5xx.h \
drivers/usb/spcaCompat.h \
drivers/usb/spcausb.h \
drivers/usb/sonix.h \
drivers/usb/spca500_init.h \
drivers/usb/spca501_init.h \
drivers/usb/sp5xxfw2.h \
drivers/usb/spca505_init.h \
drivers/usb/spca506.h \
drivers/usb/spca508_init.h \
drivers/usb/spca561.h \
drivers/usb/zc3xx.h\
drivers/usb/tv8532.h\
drivers/usb/cx11646.h\
drivers/usb/mr97311.h\
drivers/usb/sn9cxxx.h\
drivers/usb/pac207.h\
drivers/usb/spcadecoder.o: drivers/usb/spcadecoder.h \
drivers/usb/spcagamma.h \
endif # End kernel version test
##############################################################################
# OTHER TARGETS
##############################################################################
clean:
rm -r -f drivers/usb/*.o drivers/usb/.spcadecoder.o.cmd \
drivers/usb/.spca5xx.o.cmd *.o *.ko *.mod.* .[a-z]* core *.i
##############################################################################
关于修改Makefile文件做几点说明：1Makefile文件针对不同内核回编译成不同的目标文件，该Makefile前部分是针对2.6的内核，后部分针对2.4的内核，用户根据自己的内核进行修改，我修改的是2.6.9的内核，关于2.4.x是表示2.4的某个版本，只是一个代号，用户自己根据实际修改。2修改的东西，主要有两个，一是gcc变成arm-linux-gcc；二是内核路径，注意这是交叉编译环境的内核路径，即arm-linux的内核路径，非pc上linux系统的内核。3 在Makefile文件修改之后，如果你的arm-linux从未编译，需要先编译内核，然后在make。MODULE_INSTALLDIR 这个是你编译生成的模块放在哪个路径，可以不用改，当然为了方便，最好改成你想要的文件夹下，文件夹权限要改成可读写的。
第三步： make
编译成功后，会在模块MODULE_INSTALLDIR 路径生成spca5xx.ko,spca5xx.o等目标文件。
第四步：将你的目标文件spca5xx.ko(2.6内核)或者spca5xx.o(2.4内核)挂载到arm开发板上
第五步：在开发板上进入挂载的文件夹下 insmod spca5xx.ko
第六步： 插上摄像头，测试摄像头
不出意外情况下，在/dev/下会有video0设备符，或者是/dev/v4l/video0
第七步： cat /dev/video0 > a.jpg 看看是否有文件a.jpg
按 ctrl+C 退出，将a.jpg拷贝到pc linux下通过gqview软件进行查看，也可以编一个图像采集小程序，抓取一帧保存成文件，然后到pclinux下进行查看。gqview软件下得麻烦，我是写了个小程序，将jpg文件保存下来，到pc linux
下直接看的，很方便。
当然，也有意外，摄像头驱动加载之后，不能使用摄像头，下一篇文章将会介绍一个特殊情况。我也是被这个问题卡了一两天，问了一个技术达人才解决的。前面过程网上很多，我是将过程再细化一些，供初学者参考，共同进步。
内核中数据成员的使用)
linux启动过程)
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