ARM+LINUX移植攻略（十六）Linux驱动移植之LCD

努力成为linux kernel hacker的人李万鹏原创作品，为梦而战。转载请标明出处

http://blog.csdn.net/woshixingaaa/archive/2011/05/21/6436681.aspx

LCD屏驱动移植
1.修改arch/arm/mach-s3c2440/mach-smdk2440.c如下程序：修改这里的时序，并把.lpcsel = ((0xCE6) & ~7) | 1<<4,修改为.lpcsel = 0,

static struct s3c2410fb_display smdk2440_lcd_cfg __initdata = {

	.lcdcon5	= S3C2410_LCDCON5_FRM565 |
			  S3C2410_LCDCON5_INVVLINE |
			  S3C2410_LCDCON5_INVVFRAME |
			  S3C2410_LCDCON5_PWREN |
			  S3C2410_LCDCON5_HWSWP,

	.type		= S3C2410_LCDCON1_TFT,

	.width		= 240,
	.height		= 320,

	.pixclock	= 270000, /* HCLK 100 MHz, divisor 10 */
	.xres		= 320,
	.yres		= 240,
	.bpp		= 16,
	.left_margin	= 8,
	.right_margin	= 5,
	.hsync_len	= 63,
	.upper_margin	= 15,
	.lower_margin	= 3,
	.vsync_len	= 5,
};

static struct s3c2410fb_mach_info smdk2440_fb_info __initdata = {
	.displays	= &smdk2440_lcd_cfg,
	.num_displays	= 1,
	.default_display = 0,

#if 0
	/* currently setup by downloader */
	.gpccon		= 0xaa940659,
	.gpccon_mask	= 0xffffffff,
	.gpcup		= 0x0000ffff,
	.gpcup_mask	= 0xffffffff,
	.gpdcon		= 0xaa84aaa0,
	.gpdcon_mask	= 0xffffffff,
	.gpdup		= 0x0000faff,
	.gpdup_mask	= 0xffffffff,
#endif

//	.lpcsel		= ((0xCE6) & ~7) | 1<<4,
	.lpcsel 	= 0,
};

这里主要介绍一下pixclock的计算方法：
首先看如下两个公式，一个是S3C2440手册里的，一个是drivers/video/s3c2410fb.c中的：
VCLK(Hz)=HCLK/(CLKVAL*2)
int clkdiv = s3c2410fb_calc_pixclk(fbi, var->pixclock) / 2;
(clkdiv+1)*2 = clk*pixclk/10^12;
clkdiv = clk*pixclk/10^12/2-1
这里的clk就是HCLK，然后计算得出pixclk与VCLK的关系
(HCLK/VCLK/2-1) = clk*pixclk/10^12/2-1
1/VCLK = pixclk/10^12
VCLK*pixclk = 10^12

添加开机logo，小企鹅：

Graphics support  ---> 
                <*> Support for frame buffer devices
                <*> S3C2410 LCD framebuffer support ,multi support! 
                Console display driver support  --->
                        <*> Framebuffer Console support  
                Logo configuration  --->  
                        [*] Bootup logo 
                                [*]   Standard 224-color Linux logo

显示如下：