linux GT2005攝像頭驅動源代碼分析

由於近期在研究Android的一些視頻通話的一些技術，所以很快就發現實現攝像頭的驅動成爲必須研究的課題。下面是在telechips公司提供的Android SDK中已經包含的GT2005型號sensor的部分驅動代碼。雖然已經有了比較完善的驅動代碼，但是我TCC8902板子上的GT2005攝像頭還是沒能preview出圖像來，最近一直在試圖進行各種方法的調試和分析。最後覺得硬着頭皮來好好研究GT2005 camera的driver，我會分幾期來進行分析，如果有不正確的地方，非常歡迎指正。

 

下面的代碼是GT2005_2mp.h（GT2005 2百萬像素攝像頭頭文件）

/*
 * drivers/media/video/tcc83xx/GT2005_2mp.h
 *
 * Register definitions for the GT2005 CameraChip.
 *
 * Author: zzau ([email protected])
 *
 * Copyright (C) 2008 Telechips, Inc.
 *
 * This file is licensed under the terms of the GNU General Public License
 * version 2. This program is licensed "as is" without any warranty of any
 * kind, whether express or implied.
 */
#include <mach/globals.h>
#include "sensor_if.h"

#ifndef GT2005_H
#define GT2005_H

/* The MT9D112 I2C sensor chip has a fixed slave address of 0x78. */
#define SENSOR_I2C_ADDR     0x78                            //[suting] : 攝像頭涉及I2C總線協議

#define REG_TERM 0x0000 /* terminating list entry for reg */
#define VAL_TERM 0x0000 /* terminating list entry for val */

//CLOCK
#define CKC_CAMERA_MCLK             240000
#define CKC_CAMERA_MCLK_SRC         DIRECTPLL1
#define CKC_CAMERA_SCLK             480000
#define CKC_CAMERA_SCLK_SRC         DIRECTPLL2

#define FRAMESKIP_COUNT_FOR_CAPTURE 3

// ZOOM Setting!!
#define PRV_W           800
#define PRV_H           600
#define PRV_ZOFFX       8
#define PRV_ZOFFY       6

#define CAP_W           1600
#define CAP_H           1200
#define CAP_ZOFFX       16
#define CAP_ZOFFY       12

#define CAM_2XMAX_ZOOM_STEP     25
#define CAM_CAPCHG_WIDTH        800


struct sensor_reg {                     //[suting]: register number and number hold
    unsigned short reg;
    unsigned short val;
};

struct capture_size {                       //[suting] : width and height
    unsigned long width;
    unsigned long height;
};

extern struct capture_size sensor_sizes[];
extern void sensor_init_fnc(SENSOR_FUNC_TYPE *sensor_func);

#endif /* GT2005_H */

 

從上面的代碼可以看出，GT2005攝像頭涉及到了I2C總線協議，因爲它在發送命令和接受數據時，都是通過I2C總線的方式來完成的。

上面比較重要的數據結構是：

（1）struct sensor_reg ，它提供的是一個鍵值對：寄存器號 、 寄存器的值，這樣定義的目的是在進行初始化等各種操作時，能夠很方便的由寄存器號獲得寄存器值，進行I2C總線的讀寫。

（2）struct capture_size ，它定義了capture後的image的width、heigth。

（3）extern void sensor_init_fnc(SENSOR_FUNC_TYPE *sensor_func);

這個函數用於註冊GT2005_2mp.c中實際提供給上層應用程序的接口函數。

SENSOR_FUNC_TYPE類型是在 sensor_if.c/.h中定義的。

 

下面是GT2005_2mp.c 實現文件

#include <linux/delay.h>
#include <asm/system.h>
#include <mach/hardware.h>
#include <asm/io.h>
#include "sensor_if.h"
#include "cam.h"
#include "tcc_cam_i2c.h"

#if defined(CONFIG_ARCH_TCC92X) || defined(CONFIG_ARCH_TCC93XX)
#include <mach/bsp.h>
#elif defined(CONFIG_ARCH_TCC79X)
#include <mach/tcc79x.h>
#endif

//省略了一些註釋掉的代嗎
//................

/* Array of image sizes supported by GT2005.  These must be ordered from
 * smallest image size to largest.
 */
struct capture_size sensor_sizes[] = {
    { 1600, 1200 }, /* UXGA */
    { 1280,  960 }, /* SXGA */
    { 1024,  768 }, /* XGA */
    {  800,  600 }, /* SVGA */
    {  640,  480 }, /* VGA */
    {  320,  240 }, /* QVGA */
    {  176,  144 }, /* QCIF */
};
/* 上面這個結構主要是用於保存capture size，它每個數據項必須按從小到大來排列，因爲在sensor_if.c的sensor_find_size()函數中，需要使用這個struct的定義，根據app給出的capture size，協商出最合適的size */

/* register initialization tables for sensor */
/* common sensor register initialization for all image sizes, pixel formats,
 * and frame rates
 */
/* ....省略，後面是一些寄存器的鍵值對定義，主要用於寄存器的初始化，指定對應的image size / pixel format / frmae rate ,這些都可以通過GT2005的數據手冊獲得 */

/* .....省略,接下來的是一些針對camera的不同屬性的寄存器定義，比如：white balance / brightness / special effect等等 */

static int write_regs(const struct sensor_reg reglist[])            //[suting]: write register list
{

    int err;
    int err_cnt = 0;
    unsigned char data[132];
    unsigned char bytes;
    const struct sensor_reg *next = reglist;

    while (!((next->reg == REG_TERM) && (next->val == VAL_TERM)))
    {

        if(next->reg == REG_TERM && next->val != VAL_TERM)
        {
            mdelay(next->val*2);
            printk("Sensor init Delay[%d]!!!! /n", next->val);
            next++;
        }
        else
        {
            bytes = 0;
            data[bytes]= next->reg>>8;     bytes++;
            data[bytes]= (u8)next->reg&0xff;     bytes++;

            data[bytes]= next->val;      bytes++;

                err = DDI_I2C_Write(data, 2, bytes-2);              //[suting] : DDI_I2C_Write

            if (err)
            {
                err_cnt++;
                if(err_cnt >= 3)
                {
                    printk("ERROR: Sensor I2C !!!! /n");
                    return err;
                }
            }
            else
            {
                err_cnt = 0;
                next++;
            }
        }
    }

    return 0;
}

/* 上面這個函數主要用於寫寄存器，它被下面很多的接口函數所調用 */

static int sensor_open(void)
{
    int id = 0;
    int id1 = 0;
    sensor_power_disable();
    sensor_delay(10);

    sensor_power_enable();
    sensor_delay(10);

    sensor_powerdown_disable();
    sensor_delay(10);

    sensor_powerdown_enable();
    sensor_delay(10);

    sensor_reset_low();
    sensor_delay(10);

    CIF_Open();                                             //[suting] : open CIF
    sensor_delay(40);

    sensor_reset_high();
    sensor_delay(15);

    printk("init sensor GT2005 !!!! /n");
    DDI_I2C_Read(0x0000, 2, &id, 1);
    DDI_I2C_Read(0x0001, 2, &id1, 1);
    printk("read sensor ID : %x%x/n", id, id1);
    return write_regs(sensor_reg_common[0]);                //[suting]: write_regs for initialization
}

static int sensor_close(void)
{
    CIF_ONOFF(OFF);                                         //[suting] : close CIF

    sensor_reset_low();
    sensor_power_disable();
    sensor_powerdown_disable();

    CIF_Close();
    msleep(5);

    return 0;
}

static int sensor_preview(void)
{
    printk("sensor_preview/r/n");
    return write_regs(sensor_reg_common[1]);                //[suting] : write_regs for preview
}

static int sensor_capture(void)
{
    printk("sensor_capture/r/n");
    return write_regs(sensor_reg_common[2]);                //[suting] : write_regs for capture
}

static int sensor_capturecfg(int width, int height)
{
    return 0;
}

/* 上面就是幾個比較有代表性的接口函數 */

void sensor_init_fnc(SENSOR_FUNC_TYPE *sensor_func)         //[suting] just like register callback functions
{
    sensor_func->Open        = sensor_open;
    sensor_func->Close       = sensor_close;

    sensor_func->Set_Preview     = sensor_preview;
    sensor_func->Set_Capture     = sensor_capture;
    sensor_func->Set_CaptureCfg = sensor_capturecfg;

    sensor_func->Set_Zoom    = sensor_zoom;
    sensor_func->Set_AF      = sensor_autofocus;
    sensor_func->Set_Effect  = sensor_effect;
    sensor_func->Set_Flip    = sensor_flip;
    sensor_func->Set_ISO     = sensor_iso;
    sensor_func->Set_ME      = sensor_me;
    sensor_func->Set_WB      = sensor_wb;
    sensor_func->Set_Bright  = sensor_bright;
    sensor_func->Set_Scene   = sensor_scene;

    sensor_func->Check_ESD   = sensor_check_esd;
    sensor_func->Check_Luma  = sensor_check_luma;
}

/* 上面就是註冊所有的接口函數 */