OV9650摄像头驱动学习

\drivers\media\video\s3c2440camif.c

\drivers\media\video\s3c2440_ov9650.c

\drivers\media\video\sccb.c

硬件连接

I2C总线连接

I2CSCL ——GPE14

I2CSDA——GPE15

Sccb.h

#define SIO_C S3C2410_GPE14

#define SIO_D S3C2410_GPE15

#define State(x) s3c2410_gpio_getpin(x)

#define High(x) do{s3c2410_gpio_setpin(x,1); smp_mb();}while(0)

#define Low(x) do{s3c2410_gpio_setpin(x,0); smp_mb();}while(0)

#define WAIT_STABLE() do{udelay(10);}while(0)

#define WAIT_CYCLE() do{udelay(90);}while(0)

#define CFG_READ(x) do{s3c2410_gpio_cfgpin(x,S3C2410_GPIO_INPUT);smp_mb();}while(0)

#define CFG_WRITE(x) do{s3c2410_gpio_cfgpin(x,S3C2410_GPIO_OUTPUT);smp_mb();}while(0)

void sccb_write(u8 IdAddr, u8 SubAddr, u8 data);

u8 sccb_read(u8 IdAddr, u8 SubAddr);

CFG_WRITE(x)把GPIO设置为输出

CFG_READ(x)把GPIO设置为输入

High(x) 把GPIO设置为高电平

Low(x) 把GPIO设置为低电平

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Sccb.c

把SCL和Data都拉高，即为默认初始化状态电平

int sccb_init(void)

{

CFG_WRITE(SIO_C);

CFG_WRITE(SIO_D);

High(SIO_C);

High(SIO_D);

WAIT_STABLE();

return 0;

}

由上面的图可以看出，CLK高电平时，DATA拉低，即为START

static void __inline__ sccb_start(void)

{

CFG_WRITE(SIO_D);

Low(SIO_D);

WAIT_STABLE();

}

使用到一个信号量

static DECLARE_MUTEX(bus_lock);

void sccb_write(u8 IdAddr, u8 SubAddr, u8 data)

{

down(&bus_lock);

sccb_start();

sccb_write_byte(IdAddr);

sccb_write_byte(SubAddr);

sccb_write_byte(data);

sccb_stop();

up (&bus_lock);

}

首先把信号量数值降低，表示自己使用，如果此时信号量不大于0，表示bus正在使用，驱动会在此等待，知道信号量大于0，然后，将其减1，此时bus对外界不可用。最后再把信号量加1，表示bus可用。

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

摄像头接口初始化：

/*

* camif_init()

*/

static int __init camif_init(void)

{

配置CAMIF的GPIO接口功能

/* 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);

申请CAMIF的寄存器区域，由于OS的系统统一管理，所以，需要确定，该寄存器区域没有被别的进程获取，所以要申请。

/* init camera's virtual memory. */

if (!request_mem_region((unsigned long)S3C2440_PA_CAMIF, S3C2440_SZ_CAMIF, CARD_NAME))

{

ret = -EBUSY;

goto error1;

}

申请到了寄存器区域，相当于物理地址可用，然后，再将该物理地址映射到虚拟地址。

/* 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;

}

获取CAMIF的时钟，使用24M

/* 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);

初始化CAMIF的状态

/* init camif state and its lock. */

pdev->state = CAMIF_STATE_FREE;

CAMIF DEV的状态：

/* for s3c2440camif_dev->state field. */

enum

{

CAMIF_STATE_FREE = 0, // not openned

CAMIF_STATE_READY = 1, // openned, but standby

CAMIF_STATE_PREVIEWING = 2, // in previewing

CAMIF_STATE_CODECING = 3 // in capturing

};

注册杂项设备：

/* register to videodev layer. */

if (misc_register(&misc) < 0)

{

ret = -EBUSY;

goto error4;

}

printk(KERN_ALERT"s3c2440 camif init done\n");

初始化SCCB接口，Serial Camera Control Bus，其实是I2C接口

sccb_init();

硬件复位CAMIF

hw_reset_camif();

其实是软件复位，对CIGCTRL寄存器配置软件复位

/* software reset camera interface. */

static void __inline__ hw_reset_camif(void)

{

u32 cigctrl;

cigctrl = (1<<30)|(1<<29);

iowrite32(cigctrl, S3C244X_CIGCTRL);

mdelay(10);

cigctrl = (1<<29);

iowrite32(cigctrl, S3C244X_CIGCTRL);

mdelay(10);

}

检测是否存在OV9650，GPG4连的是LCD_PWR，不知道为什么？

has_ov9650 = s3c2440_ov9650_init() >= 0;

s3c2410_gpio_setpin(S3C2410_GPG4, 1);

OV9650的初始化：

int s3c2440_ov9650_init(void)

{

printk(KERN_ALERT"Loading OV9650 driver.........\n");

/* power on. */

ov9650_poweron();

mdelay(100);

/* check device. */

if (ov9650_check() == 0 && ov9650_check() == 0)

{

printk(KERN_ERR"No OV9650 found!!!\n");

return -ENODEV;

}

show_ov9650_product_id();

ov9650_init_regs();

printk("ov9650 init done!\n");

return 0;

}

OV9650上电，这里对GPG12设置为输出，这里使用的虽然是中断引脚，但似乎没有用中断，这是一个电源控制引脚，PWDN，0：power on，1：power down

static void __inline__ ov9650_poweron(void)

{

s3c2410_gpio_cfgpin(S3C2410_GPG12, S3C2410_GPG12_OUTP);

s3c2410_gpio_setpin(S3C2410_GPG12, 0);

mdelay(20);

}

OV9650检测，读取OV9650的Manu ID

static int __inline__ ov9650_check(void)

{

u32 mid;

mid = sccb_read(OV9650_SCCB_ADDR, 0x1c)<<8;

mid |= sccb_read(OV9650_SCCB_ADDR, 0x1d);

printk("SCCB address 0x%02X, manufacture ID 0x%04X, expect 0x%04X\n", OV9650_SCCB_ADDR, mid, OV9650_MANUFACT_ID);

return (mid==OV9650_MANUFACT_ID)?1:0;

}

#define OV9650_SCCB_ADDR 0x60

#define OV9650_MANUFACT_ID 0x7FA2

#define OV9650_PRODUCT_ID 0x9650

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

摄像头接口打开：

/*

* camif_open()

*/

static int camif_open(struct inode *inode, struct file *file)

{

首先判断是否存在OV9650 camera是文件开始的一个static变量。

struct s3c2440camif_dev *pdev;

struct s3c2440camif_fh *fh;

int ret;

if (!has_ov9650) {

return -ENODEV;

}

pdev = &camera;

为file handle分配内存

fh = kzalloc(sizeof(*fh),GFP_KERNEL); // alloc memory for filehandle

设置设备状态为open and standby，初始化CAMIF的配置。

pdev->state = CAMIF_STATE_READY;

init_camif_config(fh);

对CAMIF进行配置，最后更新一下配置

/* config camif when master-open camera.*/

static void init_camif_config(struct s3c2440camif_fh * fh)

{

struct s3c2440camif_dev * pdev;

pdev = fh->dev;

pdev->input = 0; // FIXME, the default input image format, see inputs[] for detail.

/* the source image size (input from external camera). */

pdev->srcHsize = 1280; // FIXME, the OV9650's horizontal output pixels.

pdev->srcVsize = 1024; // FIXME, the OV9650's verical output pixels.

/* the windowed image size. */

pdev->wndHsize = 1280;

pdev->wndVsize = 1024;

/* codec-path target(output) image size. */

pdev->coTargetHsize = pdev->wndHsize;

pdev->coTargetVsize = pdev->wndVsize;

/* preview-path target(preview) image size. */

pdev->preTargetHsize = 640;

pdev->preTargetVsize = 512;

update_camif_config(fh, CAMIF_CMD_STOP);

}

由于设备状态是CAMIF_STATE_READY所以，直接更新寄存器。

/* update camera interface with the new config. */

static void update_camif_config (struct s3c2440camif_fh * fh, u32 cmdcode)

{

struct s3c2440camif_dev * pdev;

pdev = fh->dev;

switch (pdev->state)

{

case CAMIF_STATE_READY:

update_camif_regs(fh->dev); // config the regs directly.

break;

case CAMIF_STATE_PREVIEWING:

/* camif is previewing image. */

disable_irq(IRQ_S3C2440_CAM_P); // disable cam-preview irq.

/* source image format. */

if (cmdcode & CAMIF_CMD_SFMT)

{

// ignore it, nothing to do now.

}

/* target image format. */

if (cmdcode & CAMIF_CMD_TFMT)

{

/* change target image format only. */

pdev->cmdcode |= CAMIF_CMD_TFMT;

}

不知为什么要等待VSYNC为L？然后对寄存器进行配置。

/* update camif registers, called only when camif ready, or ISR. */

static void __inline__ update_camif_regs(struct s3c2440camif_dev * pdev)

{

if (!in_irq())

{

while(1) // wait until VSYNC is 'L'

{

barrier();

if ((ioread32(S3C244X_CICOSTATUS)&(1<<28)) == 0)

break;

}

}

/* WARNING: don't change the statement sort below!!! */

update_source_fmt_regs(pdev);

update_target_wnd_regs(pdev);

update_target_fmt_regs(pdev);

update_target_zoom_regs(pdev);

}

初始化CAMIF的DMA内存。

ret = init_image_buffer(); // init image buffer.

这里为DMA分配内存，按页分配，内存管理的知识需要学习？

/* init image buffer (only when the camif is first open). */

static int __inline__ init_image_buffer(void)

{

int size1, size2;

unsigned long size;

unsigned int order;

/* size1 is the max image size of codec path. */

size1 = MAX_C_WIDTH * MAX_C_HEIGHT * 16 / 8;

/* size2 is the max image size of preview path. */

size2 = MAX_P_WIDTH * MAX_P_HEIGHT * 16 / 8;

size = (size1 > size2)?size1:size2;

order = get_order(size); //获取需要分配字节的2的阶数，内存按页分配

img_buff[0].order = order;

img_buff[0].virt_base = __get_free_pages(GFP_KERNEL|GFP_DMA, img_buff[0].order);

if (img_buff[0].virt_base == (unsigned long)NULL)

{

goto error0;

}

img_buff[0].phy_base = img_buff[0].virt_base - PAGE_OFFSET + PHYS_OFFSET; // the DMA address.

申请中断，分别为Codec的中断和Preview的中断

request_irq(IRQ_S3C2440_CAM_C, on_camif_irq_c, IRQF_DISABLED, "CAM_C", pdev);

request_irq(IRQ_S3C2440_CAM_P, on_camif_irq_p, IRQF_DISABLED, "CAM_P", pdev);

使能时钟，软件复位，更新CAMIF的配置。

clk_enable(pdev->clk); // and enable camif clock.

soft_reset_camif();

file->private_data = fh;

fh->dev = pdev;

update_camif_config(fh, 0);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

摄像头接口读取函数：

static ssize_t camif_read(struct file *file, char __user *data, size_t count, loff_t *ppos)

{

int i;

struct s3c2440camif_fh * fh;

struct s3c2440camif_dev * pdev;

fh = file->private_data;

pdev = fh->dev;

if (start_capture(pdev, 0) != 0) //此处是捕获一张图片，所以会阻塞在此，直至中断发生。

{

return -ERESTARTSYS;

}

//中断已经发生，数据已经更新。

disable_irq(IRQ_S3C2440_CAM_C);

disable_irq(IRQ_S3C2440_CAM_P);

for (i = 0; i < 4; i++)

{

if (img_buff.state != CAMIF_BUFF_INVALID) //如果数据已经更新，移动数据

{

copy_to_user(data, (void *)img_buff.virt_base, count);

img_buff.state = CAMIF_BUFF_INVALID; //设置数据无效

}

}

enable_irq(IRQ_S3C2440_CAM_P); //重新使能中断

enable_irq(IRQ_S3C2440_CAM_C);

return count;

}

开始捕获函数，设置window offset

/* start image capture.

*

* param 'stream' means capture pictures streamly or capture only one picture.

*/

static int start_capture(struct s3c2440camif_dev * pdev, int stream)

{

int ret;

u32 ciwdofst;

u32 ciprscctrl;

u32 ciimgcpt;

ciwdofst = ioread32(S3C244X_CIWDOFST); //window offset

ciwdofst |= (1<<30) // Clear the overflow indication flag of input CODEC FIFO Y

|(1<<15) // Clear the overflow indication flag of input CODEC FIFO Cb

|(1<<14) // Clear the overflow indication flag of input CODEC FIFO Cr

|(1<<13) // Clear the overflow indication flag of input PREVIEW FIFO Cb

|(1<<12); // Clear the overflow indication flag of input PREVIEW FIFO Cr

iowrite32(ciwdofst, S3C244X_CIWDOFST);

ciprscctrl = ioread32(S3C244X_CIPRSCCTRL); //Preview main scale control开始prev

ciprscctrl |= 1<<15; // preview scaler start

iowrite32(ciprscctrl, S3C244X_CIPRSCCTRL);

pdev->state = CAMIF_STATE_PREVIEWING;

ciimgcpt = (1<<31) // camera interface global capture enable

|(1<<29); // capture enable for preview scaler.

iowrite32(ciimgcpt, S3C244X_CIIMGCPT); //Image capture enable开始捕获

//如果是捕获视频的话，会一直循环这样，只是数据到什么地方了呢？

ret = 0;

if (stream == 0)

{

pdev->cmdcode = CAMIF_CMD_STOP;

//如果是捕获图片的话，那么只会中断一次，然后STOP，在此阻塞，等待中断发生

ret = wait_event_interruptible(pdev->cmdqueue, pdev->cmdcode == CAMIF_CMD_NONE);

}

return ret;

}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

摄像头接口中断服务P path函数：

/*

* ISR: service for P-path interrupt.

*/

static irqreturn_t on_camif_irq_p(int irq, void * dev)

{

u32 ciprstatus;

u32 frame;

struct s3c2440camif_dev * pdev;

ciprstatus = ioread32(S3C244X_CIPRSTATUS); 检查状态

if ((ciprstatus & (1<<21))== 0)

{

return IRQ_RETVAL(IRQ_NONE);

}

pdev = (struct s3c2440camif_dev *)dev;

/* valid img_buff[x] just DMAed. */

frame = (ciprstatus&(3<<26))>>26; 计算帧数？

frame = (frame+4-1)%4;

img_buff[frame].state = CAMIF_BUFF_RGB565;

if (pdev->cmdcode & CAMIF_CMD_STOP) 查看有没有CMD

{

stop_capture(pdev);

pdev->state = CAMIF_STATE_READY;

}

else

{

if (pdev->cmdcode & CAMIF_CMD_P2C)

{

camif_c2p(pdev);

}

if (pdev->cmdcode & CAMIF_CMD_WND)

{

update_target_wnd_regs(pdev);

}

if (pdev->cmdcode & CAMIF_CMD_TFMT)

{

update_target_fmt_regs(pdev);

}

if (pdev->cmdcode & CAMIF_CMD_ZOOM)

{

update_target_zoom_regs(pdev);

}

invalid_image_buffer();

}

pdev->cmdcode = CAMIF_CMD_NONE; 最后将CMD置为NONE，然后唤醒Read中的queue

wake_up(&pdev->cmdqueue);

return IRQ_RETVAL(IRQ_HANDLED);

}

配置目标格式寄存器

/* update registers:

* PREVIEW path:

* CIPRCLRSA1 ~ CIPRCLRSA4

* CIPRTRGFMT

* CIPRCTRL

* CIPRSCCTRL

* CIPRTAREA

* CODEC path:

* CICOYSA1 ~ CICOYSA4

* CICOCBSA1 ~ CICOCBSA4

* CICOCRSA1 ~ CICOCRSA4

* CICOTRGFMT

* CICOCTRL

* CICOTAREA

*/

static void __inline__ update_target_fmt_regs(struct s3c2440camif_dev * pdev)

{

u32 ciprtrgfmt;

u32 ciprctrl;

u32 ciprscctrl;

u32 mainBurstSize, remainedBurstSize;

/* CIPRCLRSA1 ~ CIPRCLRSA4. */

iowrite32(img_buff[0].phy_base, S3C244X_CIPRCLRSA1); DMA的地址

iowrite32(img_buff[1].phy_base, S3C244X_CIPRCLRSA2);

iowrite32(img_buff[2].phy_base, S3C244X_CIPRCLRSA3);

iowrite32(img_buff[3].phy_base, S3C244X_CIPRCLRSA4);

/* CIPRTRGFMT. */

ciprtrgfmt = (pdev->preTargetHsize<<16) // horizontal pixel number of target image

|(0<<14) // don't mirror or rotation.

|(pdev->preTargetVsize<<0); // vertical pixel number of target image

iowrite32(ciprtrgfmt, S3C244X_CIPRTRGFMT);

/* CIPRCTRL. */

calc_burst_size(2, pdev->preTargetHsize, &mainBurstSize, &remainedBurstSize);

ciprctrl = (mainBurstSize<<19)|(remainedBurstSize<<14);

iowrite32(ciprctrl, S3C244X_CIPRCTRL);

/* CIPRSCCTRL. */

ciprscctrl = ioread32(S3C244X_CIPRSCCTRL);

ciprscctrl &= 1<<15; // clear all other info except 'preview scaler start'.

ciprscctrl |= 0<<30; // 16-bits RGB

iowrite32(ciprscctrl, S3C244X_CIPRSCCTRL); // 16-bit RGB

/* CIPRTAREA. */

iowrite32(pdev->preTargetHsize * pdev->preTargetVsize, S3C244X_CIPRTAREA);

}

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