本篇目的：添加背光驱动，添加LCD驱动。
本篇参考：
(1)背光添加：http://singleboy./blog/static/5490019452183748863/
(2)LCD驱动：http://singleboy./blog/static/5490019452113914540/
9.1 背光驱动添加
LCD的背光控制引脚是GPG4，这里我们先用0/1的方式开关LCD背光，以后再修改为PWM控制。
（1）进入到Linux源码文件夹，并在drivers/video/backlight/下建立一个背光驱动。
root@ubuntu:~#cd linux-4.9.2/
root@ubuntu:~/linux-4.9.2#vim drivers/video/backlight/mini2440_backlight.c
（2）添加驱动源码
#include <linux/errno.h>#include <linux/kernel.h>#include <linux/module.h>#include <linux/slab.h>#include <linux/input.h>#include <linux/init.h>#include <linux/serio.h>#include <linux/delay.h>#include <linux/clk.h>#include <linux/miscdevice.h>#include <linux/gpio.h>#include <asm/io.h>#include <asm/irq.h>#include <asm/uaccess.h>#include <mach/regs-clock.h>#include <mach/gpio-samsung.h>#include <mach/regs-gpio.h>#include <linux/cdev.h>#define DEVICE_NAME "backlight"#define DEVICE_MINOR 5static long mini2440_backlight_ioctl(structfile *file,unsigned int cmd,unsigned long arg){switch(cmd){case 0:gpio_set_value(S3C2410_GPG(4), 0);printk(DEVICE_NAME "turn off!\n");return 0;case 1:gpio_set_value(S3C2410_GPG(4), 1);printk(DEVICE_NAME " turn on!\n");return 0;default:return -EINVAL;}}static struct file_operations dev_fops ={.owner =THIS_MODULE,.unlocked_ioctl= mini2440_backlight_ioctl,};static struct miscdevice misc ={.minor = DEVICE_MINOR,.name =DEVICE_NAME,.fops =&dev_fops,};static int __init dev_init(void){int ret;ret =misc_register(&misc);if(ret < 0){printk("Register misc device fiald!");returnret;}gpio_direction_output(S3C2410_GPG(4), 1);return ret;}static void __exit dev_exit(void){misc_deregister(&misc);}module_init(dev_init);module_exit(dev_exit);MODULE_LICENSE("GPL");MODULE_AUTHOR("ubuntu");MODULE_DESCRIPTION("Backlight control formini2440");
注意，linux4.9的GPIO驱动与linux2.6的GPIO驱动不同，
初始化并设置IO输出模式是：gpio_direction_output(S3C2410_GPG(4), 1);
IO电平状态设置是：gpio_set_value(S3C2410_GPG(4),0);
（3）添加make menu菜单
root@ubuntu:~/linux-4.9.2#vim drivers/video/backlight/Kconfig
定位到第11行，添加红色部分代码
#
# Backlight& LCD drivers configuration
#
menuconfigBACKLIGHT_LCD_SUPPORT
bool "Backlight & LCD devicesupport"
help
Enable this to be able to choose thedrivers for controlling the
backlight and the LCD panel on someplatforms, for example on PDAs.
config BACKLIGHT_MINI2440
tristate"Backlight support for mini2440 from FriendlyARM"
depends onBACKLIGHT_LCD_SUPPORT
help
backlight driver forMINI2440 from FriendlyARM
if BACKLIGHT_LCD_SUPPORT
#
# LCD
#
configLCD_CLASS_DEVICE
（4）修改makefile
root@ubuntu:~/linux-4.9.2#vim drivers/video/backlight/Makefile
在第24行，加入红色部分
obj-$(CONFIG_BACKLIGHT_88PM860X) += 88pm860x_bl.o
obj-$(CONFIG_BACKLIGHT_AAT2870) += aat2870_bl.o
obj-$(CONFIG_BACKLIGHT_ADP5520) += adp5520_bl.o
obj-$(CONFIG_BACKLIGHT_MINI2440) += mini2440_backlight.o
obj-$(CONFIG_BACKLIGHT_ADP8860) += adp8860_bl.o
obj-$(CONFIG_BACKLIGHT_ADP8870) += adp8870_bl.o
（5）在menuconfig中开启背光驱动。
root@ubuntu:~/linux-4.9.2#make menuconfig
在界面中找到
DeviceDrivers --->
Graphicssupport --->
[*] Backlight & LCD device support --->
就可以找到该配置选项，如图
选中后，保存退出。
9.2 添加LCD驱动
（1）修改mach-mini2440.c
root@ubuntu:~/linux-4.9.2# vim arch/arm/mach-s3c24xx/mach-mini2440.c
将从第112行
taticstruct s3c2410fb_display mini2440_lcd_cfg __initdata = {
开始，到154行
.lpcsel = ((0xCE6) & ~7) | 1<<4,
};
的代码全部删除
添加如下代码
#if defined(CONFIG_FB_S3C2410_N240320)#define LCD_WIDTH 240#define LCD_HEIGHT 320#define LCD_PIXCLOCK 100000#define LCD_RIGHT_MARGIN 36#define LCD_LEFT_MARGIN 19#define LCD_HSYNC_LEN 5#define LCD_UPPER_MARGIN 1#define LCD_LOWER_MARGIN 5#define LCD_VSYNC_LEN 1#elif defined(CONFIG_FB_S3C2410_W320240)#define LCD_WIDTH 320#define LCD_HEIGHT 240#define LCD_PIXCLOCK 170000#define LCD_RIGHT_MARGIN 0x44#define LCD_LEFT_MARGIN 0x04#define LCD_HSYNC_LEN 0x01#define LCD_UPPER_MARGIN 10#define LCD_LOWER_MARGIN 4#define LCD_VSYNC_LEN 1#define LCD_CON5 (S3C2410_LCDCON5_FRM565 |S3C2410_LCDCON5_INVVFRAME | S3C2410_LCDCON5_INVVLINE | S3C2410_LCDCON5_HWSWP )#elif defined(CONFIG_FB_S3C2410_N480272)#define LCD_WIDTH 480#define LCD_HEIGHT 272#define LCD_PIXCLOCK 100000#define LCD_RIGHT_MARGIN 36#define LCD_LEFT_MARGIN 19#define LCD_HSYNC_LEN 5#define LCD_UPPER_MARGIN 1#define LCD_LOWER_MARGIN 5#define LCD_VSYNC_LEN 1#elif defined(CONFIG_FB_S3C2410_TFT640480)#define LCD_WIDTH 640#define LCD_HEIGHT 480#define LCD_PIXCLOCK 40000#define LCD_RIGHT_MARGIN 67#define LCD_LEFT_MARGIN 40#define LCD_HSYNC_LEN 31#define LCD_UPPER_MARGIN 5#define LCD_LOWER_MARGIN 25#define LCD_VSYNC_LEN 1#elif defined(CONFIG_FB_S3C2410_T240320)#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 1#define LCD_LOWER_MARGIN 4#define LCD_VSYNC_LEN 1#define LCD_CON5 (S3C2410_LCDCON5_FRM565 |S3C2410_LCDCON5_INVVDEN | S3C2410_LCDCON5_INVVFRAME | S3C2410_LCDCON5_INVVLINE| S3C2410_LCDCON5_INVVCLK | S3C2410_LCDCON5_HWSWP )#elif defined(CONFIG_FB_S3C2410_X240320)#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 )#elif defined(CONFIG_FB_S3C2410_TFT800480)#define LCD_WIDTH 800#define LCD_HEIGHT 480#define LCD_PIXCLOCK 40000#define LCD_RIGHT_MARGIN 67#define LCD_LEFT_MARGIN 40#define LCD_HSYNC_LEN 31#define LCD_UPPER_MARGIN 25#define LCD_LOWER_MARGIN 5#define LCD_VSYNC_LEN 1#elif defined(CONFIG_FB_S3C2410_VGA1024768)#define LCD_WIDTH 1024#define LCD_HEIGHT 768#define LCD_PIXCLOCK 80000#define LCD_RIGHT_MARGIN 15#define LCD_LEFT_MARGIN 199#define LCD_HSYNC_LEN 15#define LCD_UPPER_MARGIN 1#define LCD_LOWER_MARGIN 1#define LCD_VSYNC_LEN 1#define LCD_CON5 (S3C2410_LCDCON5_FRM565 |S3C2410_LCDCON5_HWSWP)#endif
保存退出
（2）修改drivers/video/fbdev/Kconfig
root@ubuntu:~/linux-4.9.2# vim drivers/video/fbdev/Kconfig
在2073行附近加入红色部分代码
config FB_S3C2410_DEBUG
bool "S3C2410 lcddebug messages"
depends on FB_S3C2410
help
Turn on debuggingmessages. Note that you can set/unset at run time
through sysfs
choice
prompt "LCD select"
depends on FB_S3C2410
help
S3C24x0 LCD size select
config FB_S3C2410_W320240
boolean "3.5 inch 320X240 TFT Landscape LCD"
depends on FB_S3C2410
help
3.5 inch 320X240 TFT Landscape LCD
config FB_S3C2410_T240320
boolean "3.5 inch 240X320 Toppoly LCD"
depends on FB_S3C2410
help
3.5 inch 240X320 Toppoly LCD
config FB_S3C2410_X240320
boolean "3.5 inch 240X320 LCD(ACX502BMU)"
depends on FB_S3C2410
help
3.5 inch 240X320 LCD(ACX502BMU)
config FB_S3C2410_N240320
boolean "3.5 inch 240X320 NEC LCD"
depends on FB_S3C2410
help
3.5 inch 240x320 NEC LCD
config FB_S3C2410_N480272
boolean "4.3 inch 480X272 NEC LCD"
depends on FB_S3C2410
help
config FB_S3C2410_TFT640480
boolean "8 inch 640X480 L80 LCD"
depends on FB_S3C2410
help
8inch 640X480 LCD
config FB_S3C2410_TFT800480
boolean "7 inch 800x480 TFT LCD"
depends on FB_S3C2410
help
7inch 800x480 TFT LCD
config FB_S3C2410_VGA1024768
boolean "VGA 1024x768"
depends on FB_S3C2410
help
VGA 1024x768
endchoice
config FB_NUC900
tristate "NUC900LCD framebuffer support"
depends on FB&& ARCH_W90X900
select FB_CFB_FILLRECT
select FB_CFB_COPYAREA
selectFB_CFB_IMAGEBLIT
---help---
Frame buffer driverfor the built-in LCD controller in the Nuvoton
NUC900 processor
保存退出
（3）配置
root@ubuntu:~/linux-4.9.2# make menuconfig
现在，我们在命令行输入:makemenuconfig 进入内核配置，依次按下面的子菜单项选择：
Device Drivers --->
Graphics support --->
Frame buffer devices --->
<*> Support forframe buffer devices ---> //这行选中，不用进入
LCD select (3.5inch 240X320 Toppoly LCD) ---> //进入
(X) 3.5 inch 240X320 LCD(ACX502BMU) //根据自己开发板的屏幕型号选择，我的是X35
按空格或者回车键选择我们需要的 LCD 型号，然后退出保存内核配置。
9.3 编译测试
root@ubuntu:~/linux-4.9.2#make -j8
root@ubuntu:~/linux-4.9.2#./mkuImage.sh
重新启动开发板，可以看到屏幕上出现了小企鹅，并且下面打印了启动信息。
