1. LCD背光驱动移植
建立LCD背光驱动文件，进入linux-2.6.37/ drivers/video，新建文件mini2440_backlight.c
（vi mini2440_backlight.c）
文件名：linux-2.6.37/drivers/video/mini2440_backlight.c，内容如下：
//================================jyb365==========
#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 <plat/regs-timer.h>
#include <mach/regs-gpio.h>
#include <linux/cdev.h>
#undef DEBUG
//#define DEBUG
#ifdef DEBUG
#define DPRINTK(x...) {printk(__FUNCTION__"(%d): ",__LINE__);printk(##x);}
#else
#define DPRINTK(x...) (void)(0)
#endif
//;定义背光驱动的名称为backligh，将会出现在/dev/backlight
#define DEVICE_NAME "backlight"
//;定义背光变量bl_state，以记录背光的开关状态
static unsigned int bl_state;
//;设置背光开关的函数，主要是翻转背光变量bl_state
static inline void set_bl(int state)
{
bl_state = !!state; //翻转bl_state 变量
s3c2410_gpio_setpin(S3C2410_GPG(4), bl_state); //把结果写入背光所用的寄存器GPG4
}
//;获取背光状态
static inline unsigned int get_bl(void)
{
return bl_state;
}
//;从应用程序读取参数，并传递到内核中
static ssize_t dev_write(struct file *file, const char *buffer, size_t count, loff_t * ppos)
{
unsigned char ch;
int ret;
if (count == 0) {
return count;
}
//;使用copy_from_user 函数从用户层/应用层读取参数
ret = copy_from_user(&ch, buffer, sizeof ch) ? -EFAULT : 0;
if (ret) {
return ret;
}
ch &= 0x01; //判断奇数还是偶数
set_bl(ch); //设置背光状态
return count;
}
//;把内核参数传递给用户层/应用层的读函数
static ssize_t dev_read(struct file *filp, char *buffer, size_t count, loff_t *ppos)
{
int ret;
unsigned char str[] = {'0', '1' };
if (count == 0) {
return 0;
}
//;使用copy_to_user 函数把内核参数传递到用户层/应用层
ret = copy_to_user(buffer, str + get_bl(), sizeof(unsigned char) ) ? -EFAULT : 0;
if (ret) {
return ret;
}
return sizeof(unsigned char);
}
//;设备操作集
static struct file_operations dev_fops = {
owner: THIS_MODULE,
read:dev_read,
write: dev_write,
};
static struct miscdevice misc = {
.minor = MISC_DYNAMIC_MINOR,
.name = DEVICE_NAME,
.fops = &dev_fops,
};
//;设备初始化，内核启动时就有效
static int __init dev_init(void)
{
int ret;
ret = misc_register(&misc);
printk (DEVICE_NAME"\tinitialized\n");
//;初始化背光所用的端口GPG4 为输出
s3c2410_gpio_cfgpin(S3C2410_GPG(4), S3C2410_GPIO_OUTPUT);
//;启动内核时打开背光
set_bl(1);
return ret;
}
static void __exit dev_exit(void)
{
misc_deregister(&misc);
}
module_init(dev_init); //注册背光驱动模块
module_exit(dev_exit); //卸载背光驱动模块
MODULE_LICENSE("GPL");
MODULE_AUTHOR("FriendlyARM Inc.");
//================================
