LCD驱动移植

内核里已经有很完善的 LCD 驱动了,只要根据所用的 LCD 进行简单的修改。
#vi arch/arm/mach-s3c2440/mach-smdk2440.c

修改smdk2440_lcd_cfg函数和smdk2440_fb_info函数，设置LCD参数，我的是SONY3.5寸(X35)TFT屏。如下：

参照mini2440源码：

首先定义：

#define LCD_WIDTH 240
#define LCD_HEIGHT 320
#define LCD_PIXCLOCK 170000
#define LCD_RIGHT_MARGIN 25
#define LCD_LEFT_MARGIN 0
#define LCD_HSYNC_LEN 4
#define LCD_UPPER_MARGIN 0
#define LCD_LOWER_MARGIN 4
#define LCD_VSYNC_LEN 9
#define LCD_CON5 (S3C2410_LCDCON5_FRM565 | S3C2410_LCDCON5_INVVDEN | S3C2410_LCDCON5_INVVFRAME | S3C2410_LCDCON5_INVVLINE | S3C2410_LCDCON5_INVVCLK | S3C2410_LCDCON5_HWSWP )

然后修改smdk2440_lcd_cfg函数和smdk2440_fb_info函数。

static struct s3c2410fb_display mini2440_lcd_cfg __initdata = {

#if !defined (LCD_CON5)
    .lcdcon5 = S3C2410_LCDCON5_FRM565 |
              S3C2410_LCDCON5_INVVLINE |
              S3C2410_LCDCON5_INVVFRAME |
              S3C2410_LCDCON5_PWREN |
              S3C2410_LCDCON5_HWSWP,
#else
    .lcdcon5 = LCD_CON5,
#endif

    .type = S3C2410_LCDCON1_TFT,

    .width = LCD_WIDTH,
    .height = LCD_HEIGHT,

    .pixclock = LCD_PIXCLOCK,
    .xres = LCD_WIDTH,
    .yres = LCD_HEIGHT,
    .bpp = 16,
    .left_margin = LCD_LEFT_MARGIN + 1,
    .right_margin = LCD_RIGHT_MARGIN + 1,
    .hsync_len = LCD_HSYNC_LEN + 1,
    .upper_margin = LCD_UPPER_MARGIN + 1,
    .lower_margin = LCD_LOWER_MARGIN + 1,
    .vsync_len = LCD_VSYNC_LEN + 1,
};

 

static struct s3c2410fb_mach_info mini2440_fb_info __initdata = {
    .displays = &mini2440_lcd_cfg,
    .num_displays = 1,
    .default_display = 0,

    .gpccon = 0xaa955699,
    .gpccon_mask = 0xffc003cc,
    .gpcup = 0x0000ffff,
    .gpcup_mask = 0xffffffff,

    .gpdcon = 0xaa95aaa1,
    .gpdcon_mask = 0xffc0fff0,
    .gpdup = 0x0000faff,
    .gpdup_mask = 0xffffffff,


    .lpcsel = 0xf82,
};

打开LCD的背光，如不打开就无法观测LCD是否正常工作。由开发板原理图可以看到LCD的背光电源LCD_PWR接到S3C2440的GPG4引脚上，故在mach-smdk2440.c中作如下修改：

static void __init smdk2440_machine_init(void)
{
    s3c24xx_fb_set_platdata(&smdk2440_fb_info);

    //添加下面两句代码
    s3c2410_gpio_cfgpin(S3C2410_GPG(4), S3C2410_GPIO_OUTPUT);
    s3c2410_gpio_setpin(S3C2410_GPG(4),1);

    s3c_i2c0_set_platdata(NULL);
    platform_add_devices(smdk2440_devices, ARRAY_SIZE(smdk2440_devices));
    smdk_machine_init();
}

linux-2.6.32以上版本需要在mach-smdk2440.c中加入头文件，否则提示找不到函数。

#include <linux/gpio.h>

配置内核,支持 LCD:
Device Drivers:
  Graphics Support --->
     <*>support for frame buffer devices --->
         [*] Enable frameware EDID
         [*] Enable Vidoe Mode Handling Helpers
         <*> S3C24X0 LCD framebuffer support
     Console display driver support --->
         <*> Framebuffer Console Support
     [*] Bootup Logo --->
         <*> Standard 224-color Linux logo
启动时LCD上显示可爱的小企鹅，终端输出:
Console: switching to colour frame buffer device 40x30
fb0: s3c2410fb frame buffer device

板子启动后，查看硬件信息：

cat /proc/devices

可以看到：29 fb

mknod /dev/fb0 c 29 0