ARM嵌入式之lcd驱动程序之显示图片

内核版本：linux-3.4.2                   lcd：4.3

上代码之前我得讲解一些基本的知识点，LCD驱动我们只需要写硬件这一块的代码就可以了，下面有三个函数内核已经帮我们写好了，我们只需要调用就可以了，这几个函数实现了内核层和应用成数据的传递，有兴趣的朋友去分析一下源码，我里驱动写好了我们可以选择动态加载驱动或者直接静态编译进内核，这个的区别在前文中我讲解的非常清楚了，希望朋友一定要去看一下，Linux驱动静态编译和动态编译方法详解

这个代码相对有点复杂，朋友们一定要仔细分析。驱动程序如下：

lcd.c文件如下：

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include

#include
#include
#include

#include

static int s3c_lcdfb_setcolreg(unsigned int regno, unsigned int red,
    unsigned int green, unsigned int blue,
    unsigned int transp, struct fb_info *info);

struct lcd_regs {
unsigned long  lcdcon1;
unsigned long  lcdcon2;
unsigned long  lcdcon3;
unsigned long  lcdcon4;
unsigned long  lcdcon5;
    unsigned long lcdsaddr1;
    unsigned long lcdsaddr2;
    unsigned long lcdsaddr3;
    unsigned long redlut;
    unsigned long greenlut;
    unsigned long bluelut;
    unsigned long reserved[9];
    unsigned long dithmode;
    unsigned long tpal;
    unsigned long lcdintpnd;
    unsigned long lcdsrcpnd;
    unsigned long lcdintmsk;
    unsigned long lpcsel;
};


static struct fb_ops s3c_lcdfb_ops = {
.owner  = THIS_MODULE,
.fb_setcolreg  = s3c_lcdfb_setcolreg,
.fb_fillrect  = cfb_fillrect,          
.fb_copyarea  = cfb_copyarea,
.fb_imageblit  = cfb_imageblit,
};

static struct fb_info *s3c_lcd;
static volatile unsigned long *gpbcon;
static volatile unsigned long *gpbdat;
static volatile unsigned long *gpccon;
static volatile unsigned long *gpdcon;
static volatile unsigned long *gpgcon;
static volatile struct lcd_regs* lcd_regs;
static u32 pseudo_palette[16];

static inline unsigned int chan_to_field(unsigned int chan, struct fb_bitfield *bf)
{
chan &= 0xffff;
chan >>= 16 - bf->length;
return chan << bf->offset;
}

static int s3c_lcdfb_setcolreg(unsigned int regno, unsigned int red,
    unsigned int green, unsigned int blue,
    unsigned int transp, struct fb_info *info)
{
unsigned int val;

if (regno > 16)
return 1;


val  = chan_to_field(red,&info->var.red);
val |= chan_to_field(green, &info->var.green);
val |= chan_to_field(blue,&info->var.blue);

//((u32 *)(info->pseudo_palette))[regno] = val;
pseudo_palette[regno] = val;
return 0;
}

static int lcd_init(void)
{

s3c_lcd = framebuffer_alloc(0, NULL);



strcpy(s3c_lcd->fix.id, "mylcd");
s3c_lcd->fix.smem_len = 480*272*16/8;
s3c_lcd->fix.type     = FB_TYPE_PACKED_PIXELS;
s3c_lcd->fix.visual   = FB_VISUAL_TRUECOLOR;
s3c_lcd->fix.line_length = 480*2;


s3c_lcd->var.xres           = 480;
s3c_lcd->var.yres           = 272;
s3c_lcd->var.xres_virtual   = 480;
s3c_lcd->var.yres_virtual   = 272;
s3c_lcd->var.bits_per_pixel = 16;


s3c_lcd->var.red.offset     = 11;
s3c_lcd->var.red.length     = 5;

s3c_lcd->var.green.offset   = 5;
s3c_lcd->var.green.length   = 6;

s3c_lcd->var.blue.offset    = 0;
s3c_lcd->var.blue.length    = 5;

s3c_lcd->var.activate       = FB_ACTIVATE_NOW;


s3c_lcd->fbops              = &s3c_lcdfb_ops;


s3c_lcd->pseudo_palette = pseudo_palette;
//s3c_lcd->screen_base  = ;   
s3c_lcd->screen_size   = 480*272*16/8;



gpbcon = ioremap(0x56000010, 8);
gpbdat = gpbcon+1;
gpccon = ioremap(0x56000020, 4);
gpdcon = ioremap(0x56000030, 4);
gpgcon = ioremap(0x56000060, 4);

    *gpccon  = 0xaaaaaaaa;  
*gpdcon  = 0xaaaaaaaa;  

*gpbcon &= ~(3);  
*gpbcon |= 1;
*gpbdat &= ~1;    

*gpgcon |= (3<<8);


lcd_regs = ioremap(0x4D000000, sizeof(struct lcd_regs));


lcd_regs->lcdcon1  = (4<<8) | (3<<5) | (0x0c<<1);

#if 1

lcd_regs->lcdcon2  = (1<<24) | (271<<14) | (1<<6) | (9);


lcd_regs->lcdcon3 = (1<<19) | (479<<8) | (1);


lcd_regs->lcdcon4 = 40;

#else
lcd_regs->lcdcon2 = S3C2410_LCDCON2_VBPD(5) | \
S3C2410_LCDCON2_LINeval_r(319) | \
S3C2410_LCDCON2_VFPD(3) | \
S3C2410_LCDCON2_VSPW(1);


lcd_regs->lcdcon3 = S3C2410_LCDCON3_HBPD(10) | \
S3C2410_LCDCON3_HOZVAL(239) | \
S3C2410_LCDCON3_HFPD(1);


lcd_regs->lcdcon4 = S3C2410_LCDCON4_MVAL(13) | \
S3C2410_LCDCON4_HSPW(0);

#endif

lcd_regs->lcdcon5 = (1<<11) | (0<<10) | (1<<9) | (1<<8) | (1<<0);


s3c_lcd->screen_base = dma_alloc_writecombine(NULL, s3c_lcd->fix.smem_len, &s3c_lcd->fix.smem_start, GFP_KERNEL);

lcd_regs->lcdsaddr1  = (s3c_lcd->fix.smem_start >> 1) & ~(3<<30);
lcd_regs->lcdsaddr2  = ((s3c_lcd->fix.smem_start + s3c_lcd->fix.smem_len) >> 1) & 0x1fffff;
lcd_regs->lcdsaddr3  = (480*16/16);  

//s3c_lcd->fix.smem_start = xxx;  

lcd_regs->lcdcon1 |= (1<<0);
lcd_regs->lcdcon5 |= (1<<3);
*gpbdat |= 1;    


register_framebuffer(s3c_lcd);

return 0;
}

static void lcd_exit(void)
{
unregister_framebuffer(s3c_lcd);
lcd_regs->lcdcon1 &= ~(1<<0);
*gpbdat &= ~1;    
dma_free_writecombine(NULL, s3c_lcd->fix.smem_len, s3c_lcd->screen_base, s3c_lcd->fix.smem_start);
iounmap(lcd_regs);
iounmap(gpbcon);
iounmap(gpccon);
iounmap(gpdcon);
iounmap(gpgcon);
framebuffer_release(s3c_lcd);
}

module_init(lcd_init);
module_exit(lcd_exit);
MODULE_LICENSE("GPL");

测试程序怎么编写就看你的应用程序了，但是框架是不变的如下：下面是在Lcd上显示一幅图片,用到了libjpeg库，这个地方可以不用关注，主要是看看应用程序怎么调用驱动程序的，我总结有如下当函数：

static int FBDeviceInit(void)    

static int FBShowPixel(int iX, int iY, unsigned int dwColor)  

static int FBCleanScreen(unsigned int dwBackColor)      

#include
#include "jpeglib.h"
#include
#include
#include
#include
#include
#include
#include
#include
#include

#define FB_DEVICE_NAME "/dev/fb0"
#define DBG_PRINTF printf

static int g_fd;
static struct fb_var_screeninfo g_tFBVar;
static struct fb_fix_screeninfo g_tFBFix;
static unsigned char *g_pucFBMem;
static unsigned int g_dwScreenSize;

static unsigned int g_dwLineWidth;
static unsigned int g_dwPixelWidth;

static int FBDeviceInit(void)
{
int ret;

g_fd = open(FB_DEVICE_NAME, O_RDWR);  
if (0 > g_fd)
{
DBG_PRINTF("can't open %s\n", FB_DEVICE_NAME);
}

ret = ioctl(g_fd, FBIOGET_VSCREENINFO, &g_tFBVar);  
if (ret < 0)
{
DBG_PRINTF("can't get fb's var\n");
return -1;
}


ret = ioctl(g_fd, FBIOGET_FSCREENINFO, &g_tFBFix);   
if (ret < 0)
{
DBG_PRINTF("can't get fb's fix\n");
return -1;
}

g_dwScreenSize = g_tFBVar.xres * g_tFBVar.yres * g_tFBVar.bits_per_pixel / 8;  
g_pucFBMem = (unsigned char *)mmap(NULL , g_dwScreenSize, PROT_READ | PROT_WRITE, MAP_SHARED, g_fd, 0);                                          
if (0 > g_pucFBMem)
{
DBG_PRINTF("can't mmap\n");
return -1;
}

g_dwLineWidth  = g_tFBVar.xres * g_tFBVar.bits_per_pixel / 8;
g_dwPixelWidth = g_tFBVar.bits_per_pixel / 8;

return 0;
}

static int FBShowPixel(int iX, int iY, unsigned int dwColor)  
{
unsigned char *pucFB;
unsigned short *pwFB16bpp;
unsigned int *pdwFB32bpp;
unsigned short wColor16bpp;
int iRed;
int iGreen;
int iBlue;

if ((iX >= g_tFBVar.xres) || (iY >= g_tFBVar.yres))
{
DBG_PRINTF("out of region\n");
return -1;
}

pucFB      = g_pucFBMem + g_dwLineWidth * iY + g_dwPixelWidth * iX;
pwFB16bpp  = (unsigned short *)pucFB;
pdwFB32bpp = (unsigned int *)pucFB;

switch (g_tFBVar.bits_per_pixel)
{
case 8:
{
*pucFB = (unsigned char)dwColor;
break;
}
case 16:
{
iRed   = (dwColor >> (16+3)) & 0x1f;
iGreen = (dwColor >> (8+2)) & 0x3f;
iBlue  = (dwColor >> 3) & 0x1f;
wColor16bpp = (iRed << 11) | (iGreen << 5) | iBlue;
*pwFB16bpp  = wColor16bpp;
break;
}
case 32:
{
*pdwFB32bpp = dwColor;
break;
}
default :
{
DBG_PRINTF("can't support %d bpp\n", g_tFBVar.bits_per_pixel);
return -1;
}
}

return 0;
}

static int FBCleanScreen(unsigned int dwBackColor)
{
unsigned char *pucFB;
unsigned short *pwFB16bpp;
unsigned int *pdwFB32bpp;
unsigned short wColor16bpp;
int iRed;
int iGreen;
int iBlue;
int i = 0;

pucFB      = g_pucFBMem;
pwFB16bpp  = (unsigned short *)pucFB;
pdwFB32bpp = (unsigned int *)pucFB;


switch (g_tFBVar.bits_per_pixel)
{
case 8:
{
memset(g_pucFBMem, dwBackColor, g_dwScreenSize);
break;
}
case 16:
{
iRed   = (dwBackColor >> (16+3)) & 0x1f;
iGreen = (dwBackColor >> (8+2)) & 0x3f;
iBlue  = (dwBackColor >> 3) & 0x1f;
wColor16bpp = (iRed << 11) | (iGreen << 5) | iBlue;
while (i < g_dwScreenSize)
{
*pwFB16bpp  = wColor16bpp;
pwFB16bpp++;
i += 2;
}
break;
}
case 32:
{
while (i < g_dwScreenSize)
{
*pdwFB32bpp  = dwBackColor;
pdwFB32bpp++;
i += 4;
}
break;
}
default :
{
DBG_PRINTF("can't support %d bpp\n", g_tFBVar.bits_per_pixel);
return -1;
}
}


return 0;
}


static int FBShowLine(int iXStart, int iXEnd, int iY, unsigned char *pucRGBArray)
{
int i = iXStart * 3;
int iX;
unsigned int dwColor;


if (iY >= g_tFBVar.yres)
return -1;


if (iXStart >= g_tFBVar.xres)
return -1;


if (iXEnd >= g_tFBVar.xres)
{
iXEnd = g_tFBVar.xres;
}

for (iX = iXStart; iX < iXEnd; iX++)
{

dwColor = (pucRGBArray[i]<<16) + (pucRGBArray[i+1]<<8) + (pucRGBArray[i+2]<<0);
i += 3;
FBShowPixel(iX, iY, dwColor);
}
return 0;
}



int main(int argc, char **argv)
{
struct jpeg_decompress_struct cinfo;
struct jpeg_error_mgr jerr;
FILE * infile;
int row_stride;
unsigned char *buffer;

if (argc != 2)
{
printf("Usage: \n");
printf("%s \n", argv[0]);
return -1;
}

if (FBDeviceInit())
{
return -1;
}

FBCleanScreen(0);

// 分配和初始化一个decompression结构体
cinfo.err = jpeg_std_error(&jerr);
jpeg_create_decompress(&cinfo);

// 指定源文件
if ((infile = fopen(argv[1], "rb")) == NULL) {
fprintf(stderr, "can't open %s\n", argv[1]);
return -1;
}
jpeg_stdio_src(&cinfo, infile);

// 用jpeg_read_header获得jpg信息
jpeg_read_header(&cinfo, TRUE);

printf("image_width = %d\n", cinfo.image_width);
printf("image_height = %d\n", cinfo.image_height);
printf("num_components = %d\n", cinfo.num_components);

// 设置解压参数,比如放大、缩小
printf("enter scale M/N:\n");
scanf("%d/%d", &cinfo.scale_num, &cinfo.scale_denom);
printf("scale to : %d/%d\n", cinfo.scale_num, cinfo.scale_denom);

// 启动解压：jpeg_start_decompress
jpeg_start_decompress(&cinfo);


printf("output_width = %d\n", cinfo.output_width);
printf("output_height = %d\n", cinfo.output_height);
printf("output_components = %d\n", cinfo.output_components);

// 一行的数据长度
row_stride = cinfo.output_width * cinfo.output_components;
buffer = malloc(row_stride);

// 循环调用jpeg_read_scanlines来一行一行地获得解压的数据
while (cinfo.output_scanline < cinfo.output_height) 
{
(void) jpeg_read_scanlines(&cinfo, &buffer, 1);

// 写到LCD去
FBShowLine(0, cinfo.output_width, cinfo.output_scanline, buffer);
}

free(buffer);
jpeg_finish_decompress(&cinfo);
jpeg_destroy_decompress(&cinfo);

return 0;
}