经过前面两篇文章的基础知识的讲解，现在我们开始写驱动程序，具体代码如下，文件名lcd.c
1. 分配一个fb_info结构体: 使用framebuffer_alloc
2. 设置：各种参数的设置 3. 注册: register_framebuffer 4. 硬件相关的操作；#include#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include //定义LCD控制器结构体，这样很方便初始化LCD寄存器static 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 tconsel;};static struct fb_info *s3c_lcd;static u32 pseudo_pal[16]; //假的调色板/* from pxafb.c */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) //调色板大于16 return 1; /* 用red,green,blue三原色构造出val */ val = chan_to_field(red, &info->var.red); val |= chan_to_field(green, &info->var.green); val |= chan_to_field(blue, &info->var.blue); pseudo_pal[regno] = val; return 0;}//对显存的操作static struct fb_ops s3c_lcd_fb_ops = { .owner = THIS_MODULE, .fb_setcolreg = s3c_lcdfb_setcolreg, .fb_fillrect = cfb_fillrect, .fb_copyarea = cfb_copyarea, .fb_imageblit = cfb_imageblit,};//LCD背光使能引脚 address:0x56000010 GPB0输出static volatile unsigned long *GPBCON = NULL; static volatile unsigned long *GPBDAT = NULL; //LCD电源电路 address:0x56000060 GPG4 输出static volatile unsigned long *GPGCON = NULL;static volatile unsigned long *GPGDAT = NULL;//VD3,4,5,6,7 -> B -> GPC11,12,13,14,15引脚 address:0x56000020//VLINE -> GPC2//VFRAME -> GPC3static volatile unsigned long *GPCCON = NULL;static volatile unsigned long *GPCDAT = NULL;//VD10,11,12,13,14,15 -> G -> GPD2,3,4,5,6,7引脚 address:0x56000030//VD19,20,21,22,23 -> R -> GPD11,12,13,14,15引脚static volatile unsigned long *GPDCON = NULL;static volatile unsigned long *GPDDAT = NULL;static struct lcd_regs *lcd_regs = NULL;static int __init lcd_init(void) //入口函数{ /* 1.分配一个fb_info结构体 */ /* 原型: struct fb_info *framebuffer_alloc(size_t size, struct device *dev) * 其中的size表示大小，内核在分配结构体的同时会额外的分配一些内存空间 原来 * 分配的空间中有一个指针，指向这个额外的内存空间，里面存放私有数据。这里我 * 们不需要,所以size为0，指针为空 */ s3c_lcd = framebuffer_alloc(0, NULL); /* 2. 设置 */ /* 2.1 设置固定参数fix*/ strcpy(s3c_lcd->fix.id, "mylcd"); //设置名字 s3c_lcd->fix.smem_len = 480*272*16/8; //设置framebuffer显存的长度 s3c_lcd->fix.type = FB_TYPE_PACKED_PIXELS; //设置显示格式 s3c_lcd->fix.visual = FB_VISUAL_TRUECOLOR; //TFT是真彩色 s3c_lcd->fix.line_length = 480*2; //行长度，单位是字节 /* 2.2 设置可变参数 */ s3c_lcd->var.xres = 480; //x方向的分辨率 s3c_lcd->var.yres = 272; //y方向的分辨率 s3c_lcd->var.xres_virtual = 480; //x方向的虚拟分辨率 s3c_lcd->var.yres_virtual = 272; //y方向的虚拟分辨率 s3c_lcd->var.bits_per_pixel = 16; //每个像素多少位: 16位 /* RGB:565 */ //设置fb缓存的R位域 s3c_lcd->var.red.offset = 11; s3c_lcd->var.red.length = 5; //设置fb缓存的G位域 s3c_lcd->var.green.offset = 5; s3c_lcd->var.green.length = 6; //设置fb缓存的B位域 s3c_lcd->var.blue.offset = 0; s3c_lcd->var.blue.length = 5; //使用默认值 s3c_lcd->var.activate = FB_ACTIVATE_NOW; /* 2.3 设置操作函数 */ s3c_lcd->fbops = &s3c_lcd_fb_ops; /* 其他设置 */ s3c_lcd->pseudo_palette = pseudo_pal; //设置调色板 s3c_lcd->screen_size = 480*272*16/8; //虚拟显存的长度 /* 硬件相关的操作 */ /* 配置GPIO用于LCD */ GPBCON = ioremap(0x56000010,8); GPBDAT = GPBCON + 1; GPCCON = ioremap(0x56000020,4); GPDCON = ioremap(0x56000030,4); GPGCON = ioremap(0x56000060,4); GPGDAT = GPGCON + 1; //GPIO管脚用于VD[7:0],LCDVF[2:0],VM,VFRAME,VLINE,VCLK,LEND *GPCCON = 0xaaaaaaaa; //GPIO管脚用于VD[23:8] *GPDCON = 0xaaaaaaaa; *GPBCON &= ~(0x03); //GPB0设置为输出引脚 ：KEYBOARD *GPBCON |= (0x01); *GPBDAT &= ~(0x01); //输出低电平，先不要开启背光 *GPGCON |= (0x03 << 8); //GPG4设置LCD_PWREN,电源使能引脚 *GPGDAT |= (0x01 << 4); //GPG4引脚输出高电平 /* 根据LCD手册设置LCD控制器，比如VCLK的频率等 */ lcd_regs = ioremap(0X4D000000,sizeof(struct lcd_regs)); /* 设置频率等参数 * CLKVAL : bit[17:8] VCLK = HCLK / [(CLKVAL+1) x 2 * HCLK:dmesg查看内核信息，100MHz * VCLK = 100MHz / [(CLKVAL+1) x 2 * VCLK:查看LCD手册,5MHz (P11页) * 5MHz = 100MHz / [(CLKVAL+1) x 2 * CLKVAL = 9MHz * PNRMODE : bit[6:5] 设置LCD显示模式 * 0b11 = TFT LCD panel * BPPMODE : bit[4:1] 设置BPP模式 * 0b1100 = 16 bpp for TFT * ENVID : bit[0] 设置是否输出视频格式 * 1 = Enable the video output and the LCD control signal * 0 = Disable the video output and the LCD control signal */ lcd_regs -> lcdcon1 = (0x09<<8)|(0x03<<5)|(0x0c<<1); /* 垂直方向的时间参数；可以结合LCD手册和主控芯片手册的LCD控制器章节计算以下参数； * VBPD : bit[31:24],VSYNC时钟之后过多长时间才发出第一行数据,设置为1； * LINEVAL : bit[23:14],多少行,设置为271； * VFPD : bit[13:6],发出最后一行之后，再过多长时间才发出VSYNC信号，设置为1； * VSPW : bit[5:0],VSYNC有效信号的保持时间，设置为9； */ lcd_regs -> lcdcon2 = (0x01<<24)|(0x10f<<14)|(0x01<<6)|(0x09<<0); /* 水平方向的时间参数 * HBPD：bit[25:19],HSYNC时钟信号之后过多长时间才发出第一个有效像素数据，设置为1； * HOZVAL：bit[18:8],一行有多少个有效像素，设置为479； * HFPD：bit[7:0],发出最后一个有效像素之后，再过多长时间才发出HSYNC信号，设置为1； */ lcd_regs -> lcdcon3 = (0x01<<19)|(0x1DF<<8)|(0x01<<0); /* 水平方向的时间参数 * HSPW: bit[7:0],HSYNC时钟信号的宽度，设置为40； */ lcd_regs -> lcdcon4 = (0x28<<0); /* 信号的极性设置 * FRM565：bit[11],设置为 1 = 5:6:5 Format * INVVCLK：bit[10],设置为 0 = The video data is fetched at VCLK falling edge * INVVLINE：bit[9],This bit indicates the VLINE/HSYNC pulse polarity,设置为1 = Inverted * INVVFRAME:bit[8],This bit indicates the VFRAME/VSYNC pulse polarity,设置为1 = Inverted * INVVD:bit[7],This bit indicates the VD (video data) pulse polarity,设置为0 = Normal * INVVDEN：bit[6],This bit indicates the VDEN signal polarity,设置为0 = normal * INVPWREN:bit[5],This bit indicates the PWREN signal polarity,设置为0 = normal * PWREN:bit[3], LCD_PWREN output signal enable/disable,设置为0 = Disable PWREN signal * BSWP：bit[1],Byte swap control bit,设置为0 = Swap Disable * HWSWP:bit[0],Half-Word swap control bit,设置为1 = Swap Enable */ lcd_regs -> lcdcon5 = (1<<11)|(0<<10)|(1<<9)|(1<<8)|(1<<0); /* 分配(framebuffer)显存，告诉LCD控制器显存地址 */ //返回显存的虚拟地址 s3c_lcd->screen_base = dma_alloc_writecombine(NULL,s3c_lcd->fix.smem_len,&s3c_lcd->fix.smem_start,GFP_KERNEL); /* Frame buffer start address 1 register */ lcd_regs -> lcdsaddr1 = (s3c_lcd->fix.smem_start>>1) & ~(3<<30) ; //Frame buffer start address 2 register lcd_regs -> lcdsaddr2 = ((s3c_lcd->fix.smem_start+s3c_lcd->fix.smem_len)>>1) & 0x1fffff; //Virtual screen address set lcd_regs -> lcdsaddr3 = 480*16/16; //一行的长度，单位half words，2字节 有疑问 /* 启动LCD */ lcd_regs -> lcdcon1 |= (0x01<<0); //使能LCD控制器 lcd_regs -> lcdcon5 |= (1<<3); //使能LCD本身 *GPBDAT |= (0x01); //输出高电平，开启LCD背光灯 /* 注册 */ register_framebuffer(s3c_lcd); return 0;}static void __exit lcd_exit(void){ unregister_framebuffer(s3c_lcd); /* 关闭LCD */ lcd_regs -> lcdcon1 &= ~(0x01>>0); //关闭LCD本身 *GPBDAT &= ~(0x01); //输出低电平，关闭LCD背光灯 //释放显存 dma_alloc_writecombine(NULL,s3c_lcd->fix.smem_len,s3c_lcd->screen_base,s3c_lcd->fix.smem_start); //取消映射端口 iounmap(lcd_regs); iounmap(GPBCON); iounmap(GPCCON); iounmap(GPDCON); iounmap(GPGDAT); iounmap(GPGCON); framebuffer_release(s3c_lcd);}module_init(lcd_init);module_exit(lcd_exit);MODULE_LICENSE("GPL");MODULE_DESCRIPTION("LCD drivers by Cai haitao");
测试：
1.make menuconfig去掉原来的LCD驱动程序；
Device Drivers Graphics support <M> S3C2410 LCD framebuffer support2. make uImage
uImage 文件里面已经不包含LCD驱动；
make modules
将cfbcopyarea.ko，cfbfillrect.ko，cfbimgblt.ko三个文件拷贝开发板；
3. 使用新的uImage启动开发板
下载uImage的方法： reboot-->按任意键进入菜单模式，输入： nfs 30000000 192.168.1.123:/work/nfs_root/first_fs/uImage 然后bootm 30000000启动开发板4. 加载驱动程序
insmod cfbcopyarea.ko insmod cfbfillrect.ko insmod cfbimgblt.ko insmod lcd.ko5.
echo hello > /dev/tty1 // 可以在LCD上看见hello
cat lcd.ko > /dev/fb0 // 花屏