Linux下的一个使用中断的按键驱动程序
时间：2009-04-09 来源：yuanfu
以下是一个使用中断的按键驱动程序。内核采用2.6.15.1，编译器采用3.4.3（release版本的）。在arm2410开发板上测试通过。
#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_IRQ IRQ_EINT1 //申请的中断号
#define DEVICE_NAME "button" //设备名字
#define BUTTONMINOR 0
DECLARE_WAIT_QUEUE_HEAD(wq); //申请等待队列并初始化
static unsigned char key_down_cnt=0; //中断计数
static int ev_press=0; //唤醒等待的条件
static int button_Major; //设备号
static irqreturn_t button_irq_ser(int irq,void *dev_id,struct pt_regs *regs) //中断服务程序
{
key_down_cnt++; //来一次，中断计数加一
ev_press = 1; //表示中断发生了
wake_up_interruptible(&wq); //唤醒休眠的进程
return 0;
}
static int s3c2410_button_open(struct inode *inode,struct file *filp) //open 函数
{
int ret;
ret= request_irq(BUTTON_IRQ,button_irq_ser,SA_INTERRUPT,DEVICE_NAME,NULL); //注册中断
if(ret<0)
{
printk("could not register interrupt !");
return ret;
}
printk("interrupt register successed");
return 0;
}
static int s3c2410_button_release(struct inode *inode,struct file *filp) //关闭设备
{
free_irq(BUTTON_IRQ,NULL); //释放中断
return 0;
}
//读设备
static ssize_t s3c2410_button_read(struct file *filp,char __user *buff,size_t count,loff_t *offp)
{
//printk("sleep\n");
//如果ev_press = 0,则继续休眠
wait_event_interruptible(wq,ev_press);
//若执行到这儿，ev_press = 1
printk("wake up \n");
//清除ev_press
ev_press = 0;
//拷贝key_down_cnt 到用户空间
copy_to_user(buff,(const void *)&key_down_cnt,sizeof(char));
printk("process is waked up after");
// key_down_cnt = 0;
return sizeof(unsigned char);
}
static struct file_operations s3c2410_button_flops = {
.owner = THIS_MODULE,
.open = s3c2410_button_open,
.read = s3c2410_button_read,
.release = s3c2410_button_release,
};
//模块初始化
static int __init s3c2410_button_init(void)
{
int ret;
set_irq_type(BUTTON_IRQ,IRQT_FALLING); //设置触发中断的类型，下降沿触发
ev_press = 0; //初始化ev_press
//注册设备，返回主设备号
ret=register_chrdev(0,DEVICE_NAME,&s3c2410_button_flops);
if(ret<0)
{
printk(DEVICE_NAME"can not register the number!");
return ret;
}
button_Major = ret;
//建立设备节点
#ifdef CONFIG_DEVFS_FS
devfs_mk_cdev(MKDEV(button_Major,BUTTONMINOR),S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP,DEVICE_NAME);
#endif
printk("button_init initialized successed!\n");
return 0;
}
//卸载模块
static void __exit s3c2410_button_exit(void)
{
#ifdef CONFIG_DEVFS_FS
devfs_remove(DEVICE_NAME);
#endif
unregister_chrdev(button_Major,DEVICE_NAME);
}
MODULE_LICENSE("GPL");
MODULE_AUTHOR("YUAF");
MODULE_DESCRIPTION("the s3c2410 key interrupt driver");
module_init(s3c2410_button_init);
module_exit(s3c2410_button_exit);
在使用等待队列的时候，必须得初始化。
Init_waitqueue_head(&(buttondev.wq);
也可以用 DECLARE_WAIT_QUEUE_HEAD(buttondev.wq),初始化和申明都在这条语句里面。若不初始化，则会出现：
Unable to handle kernel NULL pointer dereference at virtual address 00000004
pgd = c3e64000
[00000004] *pgd=3381c031, *pte=00000000, *ppte=00000000
Internal error: Oops: 817 [#2]
Modules linked in: button
CPU: 0
PC is at prepare_to_wait+0x54/0x9c
LR is at prepare_to_wait+0x38/0x9c
pc : [<c0053c44>] lr : [<c0053c28>] Not tainted
sp : c3ecdee0 ip : c3ecdee0 fp : c3ecdefc
r10: c0378d00 r9 : c3ecc000 r8 : bf000e24
r7 : 00000001 r6 : 40000013 r5 : bf000e48 r4 : c3ecdf14
r3 : 00000000 r2 : c3ecdf20 r1 : c3ecc000 r0 : 00000001
Flags: nZCv IRQs off FIQs on Mode SVC_32 Segment user
Control: C000717F Table: 33E64000 DAC: 00000015
Process test (pid: 828, stack limit = 0xc3ecc194)
Stack: (0xc3ecdee0 to 0xc3ece000)
dee0: c3ecdf10 c3ecdf14 c3ecc000 becf4e8c c3ecdf4c c3ecdf00 bf0002e0 c0053c00
df00: 00000000 c03f7080 c0053db8 c3ecdf20 c3ecdf20 00000000 c03f7080 c0053db8
df20: 00000000 c3ecdf20 00000001 c0378d00 becf4e8c 00000000 c3ecdf78 c3ecc000
df40: c3ecdf74 c3ecdf50 c007dee4 bf0001e0 c0378d20 c0378d00 c3ecdf78 00000000
df60: 00000000 40137e60 c3ecdfa4 c3ecdf78 c007e268 c007de34 00000000 00000000
df80: 00000000 becf4ed4 40020c34 000082c4 00000003 c0024104 00000000 c3ecdfa8
dfa0: c0023f80 c007e22c becf4ed4 40020c34 00000003 becf4e8c 00000001 becf4e8c
dfc0: becf4ed4 40020c34 000082c4 00000001 00008438 401377ec 40137e60 becf4eb8
dfe0: 400e1ef0 becf4e8c 000084a0 400e1ef4 60000010 00000003 00000000 00000000
Backtrace:
[<c0053bf0>] (prepare_to_wait+0x0/0x9c) from [<bf0002e0>] (button_read+0x110/0x1b4 [button])
r7 = BECF4E8C r6 = C3ECC000 r5 = C3ECDF14 r4 = C3ECDF10
[<bf0001d0>] (button_read+0x0/0x1b4 [button]) from [<c007dee4>] (vfs_read+0xc0/0x17c)
[<c007de24>] (vfs_read+0x0/0x17c) from [<c007e268>] (sys_read+0x4c/0x74)
[<c007e21c>] (sys_read+0x0/0x74) from [<c0023f80>] (ret_fast_syscall+0x0/0x2c)
r8 = C0024104 r7 = 00000003 r6 = 000082C4 r5 = 40020C34
r4 = BECF4ED4
Code: 05953000 0584300c e3cd1d7f e3c1103f (05832004)
<6>note: test[828] exited with preempt_count 1
Segmentation fault。
出现这种错误，可知内核是因为非法地址访问出错，使用了空指针。
测试程序如下：
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
int main()
{
int retval;
int fileno;
int ts, maxfd;
int ret= 0,i,j;
int number=0;
fileno = open("/dev/button",O_RDWR);
if (fileno == -1) {
printf("open device led errr!\n");
return 0;
}
printf("open success\n");
while(1) {
read(fileno,&number,1);
printf("key=%d\n",number);
}
close(fileno);
return 0;
}
仍需解决的问题：按键消抖的问题，这个程序，按一下，有时会出现多次中断。
这是网上的一个驱动程序。也能测试通过。程序中注释是自己添加的。
/**********************start*******************************/
#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>
//申请的中断号
#define BUTTON_IRQ1 IRQ_EINT16
#define BUTTON_IRQ2 IRQ_EINT17
//设备名字
#define DEVICE_NAME "button"
static int buttonMajor=0;
#define BUTTONMINOR 0
//缓冲区长度
#define MAX_BUTTON_BUF 16
#define BUTTONSTATUS_1 1
#define BUTTONSTATUS_2 2
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]) //缓冲区头
#define BUF_TAIL (buttondev.buf[buttondev.tail]) //缓冲区尾
#define INCBUF(x,mod) ((++(x)) & ((mod)-1)) //移动缓冲区指针，建立了环形队列
static void (*buttonEvent)(void); //定义了一个返回值为void,不带参数的函数指针
static void buttonEvent_dummy(void) {}
static void buttonEvent_1(void)
{
if(buttondev.buttonStatus==BUTTONSTATUS_2) {
BUF_HEAD=BUTTONSTATUS_2; //保存的是哪一个发生了中断
}
else {
BUF_HEAD=BUTTONSTATUS_1;
}
/*移动缓冲区指针，也就是为判断中断buttondev.head!=buttondev.tail是否发生提供了依据*/
buttondev.head=INCBUF(buttondev.head,MAX_BUTTON_BUF);
//唤醒等待的标志位
flag=1;
//唤醒休眠的进程
wake_up_interruptible(&(buttondev.wq));
printk("buttonEvent_1\n");
}
//中断服务程序
static irqreturn_t isr_button(int irq,void *dev_id,struct pt_regs *regs)
{
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;
//注册中断
ret=request_irq(BUTTON_IRQ1,isr_button,SA_INTERRUPT,DEVICE_NAME,NULL);
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;
}
//关闭设备
static int button_release(struct inode *inode,struct file *filp)
{
buttonEvent=buttonEvent_dummy;
free_irq(BUTTON_IRQ1,NULL);
free_irq(BUTTON_IRQ2,NULL);
return 0;
}
//设备读程序
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) { //判断是否发生了中断
button_ret=buttonRead(); //无效中断发生条件
//拷贝数据到用户空间
copy_to_user(buffer,(char *)&button_ret,sizeof(unsigned char));
printk("the button_ret is 0x%x\n",button_ret);
//返回
return sizeof(unsigned char);
}
else {//没有发生中断
if(filp->f_flags & O_NONBLOCK)
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
//等待发生中断
wait_event_interruptible(buttondev.wq,flag);
flag=0;
printk("sleep_after\n");
if(signal_pending(current))
{
printk("rturn -ERESTARTSYS\n");
return -ERESTARTSYS;
}
goto retry;
}
return sizeof(unsigned char);
}
static struct file_operations button_fops= {
.owner = THIS_MODULE,
.open = button_open,
.read = button_read,
.release = button_release,
};
//模块初始化
static int __init s3c2410_button_init(void)
{
int ret;
set_irq_type(BUTTON_IRQ1,IRQT_FALLING);
set_irq_type(BUTTON_IRQ2,IRQT_FALLING);
buttonEvent=buttonEvent_dummy;
ret=register_chrdev(0,DEVICE_NAME,&button_fops);
if(ret<0) {
printk("button: can't get major number\n");
return ret;
}
buttonMajor=ret;
#ifdef CONFIG_DEVFS_FS
devfs_mk_cdev(MKDEV(buttonMajor,BUTTONMINOR),S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP,DEVICE_NAME);
#endif
//buttondev.head=buttondev.tail=0;
buttondev.buttonStatus=BUTTONSTATUS_1;
init_waitqueue_head(&(buttondev.wq));
printk(DEVICE_NAME"initialized\n");
return 0;
}
//移动指针
static unsigned char buttonRead(void)
{
unsigned char button_ret;
button_ret=BUF_TAIL;
buttondev.tail=INCBUF(buttondev.tail,MAX_BUTTON_BUF);
return button_ret;
}
//卸载模块时调用
static void __exit s3c2410_button_eixt(void)
{
#ifdef CONFIG_DEVFS_FS
devfs_remove(DEVICE_NAME);
#endif
unregister_chrdev(buttonMajor,DEVICE_NAME);
}
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Kision");
MODULE_DEscrīptION ("the first char device driver");
module_init(s3c2410_button_init);
module_exit(s3c2410_button_eixt);
/*************************end***************************/
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