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#include <linux/config.h>
#include <linux/module.h>
#include <linux/version.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <asm/hardware.h>
#include <asm/delay.h>
#include <asm/uaccess.h>
#include <asm-arm/arch-s3c2410/regs-gpio.h>
#include <asm/io.h>
#include <asm-arm/arch-s3c2410/irqs.h>
#include <asm-arm/irq.h>
#include <linux/interrupt.h>
#include <linux/wait.h>
#define BUTTON_IRQ1 IRQ_EINT16
#define BUTTON_IRQ2 IRQ_EINT17
#define DEVICE_NAME "button"
static int buttonMajor=0;//用来存放主设备号
#define BUTTONMINOR 0//次设备号
#define MAX_BUTTON_BUF 16
#define BUTTONSTATUS_1 16
#define BUTTONSTATUS_2 17
static unsigned char buttonRead(void);
static int flag=0;
typedef struct {
unsigned int buttonStatus; //按键状态
unsigned char buf[MAX_BUTTON_BUF]; //按键缓冲区
unsigned int head,tail; //按键缓冲区头和尾
wait_queue_head_t wq; //等待队列
} BUTTON_DEV;
static BUTTON_DEV buttondev;
#define BUF_HEAD (buttondev.buf[buttondev.head])
#define BUF_TAIL (buttondev.buf[buttondev.tail])
#define INCBUF(x,mod) ((++(x)) & ((mod)-1)) //移动缓冲区指针,可限定x的值在0~(mod-1)范围
static void (*buttonEvent)(void);
static void buttonEvent_dummy(void) {}
static void buttonEvent_1(void)
{
if(buttondev.buttonStatus==BUTTONSTATUS_2) {
BUF_HEAD=BUTTONSTATUS_2;//按键状态存储到缓冲区中
}
else {
BUF_HEAD=BUTTONSTATUS_1;
}
buttondev.head=INCBUF(buttondev.head,MAX_BUTTON_BUF);//移动缓冲区指针
flag=1;
wake_up_interruptible(&(buttondev.wq));//唤醒等待队列中的读进程
printk("buttonEvent_1\n");
}
static irqreturn_t isr_button(int irq,void *dev_id,struct pt_regs *regs)//中断处理函数
{
printk("Occured key board Inetrrupt,irq=%d\n",irq-44);
switch (irq) {
case BUTTON_IRQ1:buttondev.buttonStatus=BUTTONSTATUS_1;
break;
case BUTTON_IRQ2:buttondev.buttonStatus=BUTTONSTATUS_2;
break;
default:break;
}
buttonEvent();
return 0;
}
static int button_open(struct inode *inode,struct file *filp)
{
int ret;
buttondev.head=buttondev.tail=0;
buttonEvent=buttonEvent_1;
ret=request_irq(BUTTON_IRQ1,isr_button,SA_INTERRUPT,DEVICE_NAME,NULL);//中断线注册,SA_INTERRUPT表示一个"快
//速"中断处理 快速中断(那些使用 SA_INTERRUPT 被请求的)执行时禁止所有在当前处理器上的其他中断
if(ret) {
printk("BUTTON_IRQ1: could not register interrupt\n");
return ret;
}
ret=request_irq(BUTTON_IRQ2,isr_button,SA_INTERRUPT,DEVICE_NAME,NULL);
if(ret) {
printk("BUTTON_IRQ2: could not register interrupt\n");
return ret;
}
return 0;
}
static int button_release(struct inode *inode,struct file *filp)
{
buttonEvent=buttonEvent_dummy;
free_irq(BUTTON_IRQ1,NULL);//注销中断处理
free_irq(BUTTON_IRQ2,NULL);
return 0;
}
static ssize_t button_read(struct file *filp,char *buffer,size_t count,loff_t *ppos)
{
static unsigned char button_ret;
retry:
printk("retry start\n");
if(buttondev.head!=buttondev.tail) {
button_ret=buttonRead();//得到缓冲区中一个unsigned char值
copy_to_user(buffer,(char *)&button_ret,sizeof(unsigned char));//把button_ret值复制到用户空间
printk("the button_ret is 0x%x\n",button_ret);
return sizeof(unsigned char);
}
else {//若无数据
if(filp->f_flags & O_NONBLOCK)//非阻塞
return -EAGAIN;
printk("sleep\n");
//interruptible_sleep_on(&(buttondev.wq));//为安全起见,最好不要调用该睡眠函数
wait_event_interruptible(buttondev.wq,flag);//等待被唤醒
flag=0;
printk("sleep_after\n");
if(signal_pending(current))//若是被信号唤醒则返回-ERESTARTSYS错误码
{
printk("rturn -ERESTARTSYS\n");
return -ERESTARTSYS;
}
goto retry;//若是阻塞的,则阻塞
}
return sizeof(unsigned char);
}
static struct file_operations button_fops= {//这个结构用来连接设备操作到设备编号上
.owner = THIS_MODULE,
.open = button_open,
.read = button_read,
.release = button_release,
};
static int __init s3c2410_button_init(void) //模块初始化
{
int ret;
set_irq_type(BUTTON_IRQ1,IRQT_FALLING);
set_irq_type(BUTTON_IRQ2,IRQT_FALLING);
buttonEvent=buttonEvent_dummy;//此处不解 为何在初始化中，把它架空了？？
ret=register_chrdev(0,DEVICE_NAME,&button_fops);//注册字符设备(第一个参数为0表示动态分配一个主设备号)
if(ret<0) {
printk("button: can't get major number\n");
return ret;
}
buttonMajor=ret;//存放主设备号
#ifdef CONFIG_DEVFS_FS
devfs_mk_cdev(MKDEV(buttonMajor,BUTTONMINOR),S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP,DEVICE_NAME);//创建设备文件
//主次编号, 需要将其转换为一个 dev_t, 使用MKDEV(int major, int minor);
#endif
//buttondev.head=buttondev.tail=0;
buttondev.buttonStatus=BUTTONSTATUS_1;
init_waitqueue_head(&(buttondev.wq));//初始化等待队列
//将自旋锁初始化为未锁，等待队列初始化为空的双向循环链表。
printk(DEVICE_NAME"initialized\n");
return 0;
}
static unsigned char buttonRead(void)//得到缓冲区一个unsigned char类型的字符 并把tail指向下一个（循环）缓冲区单元
{
unsigned char button_ret;
button_ret=BUF_TAIL;
buttondev.tail=INCBUF(buttondev.tail,MAX_BUTTON_BUF);
return button_ret;
}
static void __exit s3c2410_button_eixt(void)
{
#ifdef CONFIG_DEVFS_FS
devfs_remove(DEVICE_NAME);//移除设备文件
#endif
unregister_chrdev(buttonMajor,DEVICE_NAME);//卸载设备
}
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Kision");
MODULE_DESCRIPTION ("the first char device driver");
module_init(s3c2410_button_init);
module_exit(s3c2410_button_eixt);
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