网络摄像头4 cmos 0v9650，driver

将ov9650的驱动编译进内核
 Device Drivers  ---> <*> Multimedia support  --->  <*>   OV9650 on the S3C2440 driver

查看这项的help，可知符号
Symbol: S3C2440_CAMERA [=y]    
在目录/opt/FriendlyArm/mini2440/linux-2.6.32.2/drivers/media/video的Makefile里面找到以下2行

obj-$(CONFIG_S3C2440_CAMERA) += s3c2440camera.o
s3c2440camera-objs    :=    s3c2440_ov9650.o sccb.o s3c2440camif.o

可见0v9650的驱动由3个c文件构成，如下
s3c2440camif.c
s3c2440_ov9650.c
sccb.c
还有两个h文件
s3c2440camif.h
sccb.h
(并且可如果编译成模块的话，生成s3c2440camera.ko)

其中
s3c2440camif.c用于从cmos接口获取图像数据和将数据传输到进程空间(在有app读取时)。比如创建misc设备，设备名字是camera。在misc中仅实现3个方法open,read,release。没有ioctl(和mmap)，所以在网络摄像头2里所看到的来自app的ioctl会失败。
s3c2440_ov9650.c 读取和配置ov9650寄存器。通过iic接口传输数据。设备地址是60(#define OV9650_SCCB_ADDR    0x60).比如进行初始化和product id获取.
sccb.c 定义了去读ov9650的寄存器的具体方法，是时序模拟的iic。而s3c2440_ov9650.c里是调用这些具体方法去读写ov9650的寄存器的。
**************************************************************硬件连接******************************************
cmos ov9650的引脚

2440处理器cmos接口

用于传输ov9650的寄存器配置信息即工作参数,ov9650<--->2440
电源控制,ov9650<---2440
用户ov9650传输捕获的图像数据,ov9650--->2440

查看ov9650的spec可知其输出的数据格式


**************************************************************驱动分析****************************************************

/*
 * camif_init()
 */
static int __init camif_init(void)
{
	int ret;
	struct s3c2440camif_dev * pdev;
	struct clk * camif_upll_clk;

	printk(KERN_ALERT"initializing s3c2440 camera interface......\n");

	pdev = &camera;

	/* set gpio-j to camera mode. */
	s3c2410_gpio_cfgpin(S3C2440_GPJ0, S3C2440_GPJ0_CAMDATA0);
	s3c2410_gpio_cfgpin(S3C2440_GPJ1, S3C2440_GPJ1_CAMDATA1);
	s3c2410_gpio_cfgpin(S3C2440_GPJ2, S3C2440_GPJ2_CAMDATA2);
	s3c2410_gpio_cfgpin(S3C2440_GPJ3, S3C2440_GPJ3_CAMDATA3);
	s3c2410_gpio_cfgpin(S3C2440_GPJ4, S3C2440_GPJ4_CAMDATA4);
	s3c2410_gpio_cfgpin(S3C2440_GPJ5, S3C2440_GPJ5_CAMDATA5);
	s3c2410_gpio_cfgpin(S3C2440_GPJ6, S3C2440_GPJ6_CAMDATA6);
	s3c2410_gpio_cfgpin(S3C2440_GPJ7, S3C2440_GPJ7_CAMDATA7);
	s3c2410_gpio_cfgpin(S3C2440_GPJ8, S3C2440_GPJ8_CAMPCLK);
	s3c2410_gpio_cfgpin(S3C2440_GPJ9, S3C2440_GPJ9_CAMVSYNC);
	s3c2410_gpio_cfgpin(S3C2440_GPJ10, S3C2440_GPJ10_CAMHREF);
	s3c2410_gpio_cfgpin(S3C2440_GPJ11, S3C2440_GPJ11_CAMCLKOUT);
	s3c2410_gpio_cfgpin(S3C2440_GPJ12, S3C2440_GPJ12_CAMRESET);

	/* init camera's virtual memory. */
	if (!request_mem_region((unsigned long)S3C2440_PA_CAMIF, S3C2440_SZ_CAMIF, CARD_NAME))
	{
		ret = -EBUSY;
		goto error1;
	}

	/* remap the virtual memory. */
	camif_base_addr = (unsigned long)ioremap_nocache((unsigned long)S3C2440_PA_CAMIF, S3C2440_SZ_CAMIF);
	if (camif_base_addr == (unsigned long)NULL)
	{
		ret = -EBUSY;
		goto error2;
	}

	/* init camera clock. */
	pdev->clk = clk_get(NULL, "camif");
	if (IS_ERR(pdev->clk))
	{
		ret = -ENOENT;
		goto error3;
	}
	clk_enable(pdev->clk);

	camif_upll_clk = clk_get(NULL, "camif-upll");
	clk_set_rate(camif_upll_clk, 24000000);
	mdelay(100);

	/* init reference counter and its mutex. */
	mutex_init(&pdev->rcmutex);
	pdev->rc = 0;

	/* init image input source. */
	pdev->input = 0;

	/* init camif state and its lock. */
	pdev->state = CAMIF_STATE_FREE;

	/* init command code, command lock and the command wait queue. */
	pdev->cmdcode = CAMIF_CMD_NONE;
	init_waitqueue_head(&pdev->cmdqueue);

	/* register to videodev layer. */
	if (misc_register(&misc) < 0)
	{
		ret = -EBUSY;
		goto error4;
	}
	printk(KERN_ALERT"s3c2440 camif init done\n");
	
	sccb_init();
	hw_reset_camif();
	has_ov9650 = s3c2440_ov9650_init() >= 0;
	s3c2410_gpio_setpin(S3C2410_GPG(4), 1);
	return 0;

error4:
	clk_put(pdev->clk);
error3:
	iounmap((void *)camif_base_addr);
error2:
	release_mem_region((unsigned long)S3C2440_PA_CAMIF, S3C2440_SZ_CAMIF);
	
error1:
	return ret;
}