按键驱动分析：
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/poll.h>
#include <linux/irq.h>
#include <asm/irq.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <asm/uaccess.h>
#include <linux/gpio.h>
#include <mach/regs-gpio.h>
#include <mach/hardware.h>
#include <linux/platform_device.h>
#include <linux/cdev.h>
#include <linux/miscdevice.h>
#include <linux/miscdevice.h>
//#include <linux/time.h> #include <linux/device.h> struct class *key_class;//udev机制自动创建文件结点 #define USING_TASKLET
//struct timespec start_time;
//struct timespec end_time;
static int key_major = ; struct key_irq_desc {
// unsigned int irq;//对拥鼻暗膇 irq 号
int pin; //对应的管脚
int pin_setting;//将邋邋GPIO口设置为外部中断源
int number;
char *name;
}; /* 用来指定按键所用的外部中断引脚及中断触发方式, 名字 */
static struct key_irq_desc key_irqs [] = {
{S5PV210_GPH0(), S3C_GPIO_SFN(0xf), , "KEY1"}, /* K1 */
{S5PV210_GPH0(), S3C_GPIO_SFN(0xf), , "KEY2"}, /* K2 */
{S5PV210_GPH0(), S3C_GPIO_SFN(0xf), , "KEY3"}, /* K3 */
{S5PV210_GPH0(), S3C_GPIO_SFN(0xf), , "KEY4"}, /* K4 */
{S5PV210_GPH0(), S3C_GPIO_SFN(0xf), , "KEY5"}, /* K5 */
}; /* 按键被按下的次数(准确地说，是发生中断的次数) */
static volatile int key_values[] = {, , , , }; /* 等待队列:
* 当没有按键被按下时，如果有进程调用key_read函数，
* 它将休眠
*/
static DECLARE_WAIT_QUEUE_HEAD(key_waitq); //初始化一个等待队列头key_waitq /* 中断事件标志, 中断服务程序将它置1，key_read将它清0 */
static volatile int ev_press = ;//按下为1，抬起为0 #ifdef USING_TASKLET
static struct tasklet_struct key_tasklet;
static void key_do_tasklet(unsigned long);
//DECLARE_TASKLET(key_tasklet, key_do_tasklet, 0);//在init中初始化 static void key_do_tasklet(unsigned long data)
{
printk("key_do_tasklet\n");
}
#endif static irqreturn_t key_interrupt(int irq, void *dev_id)
{
printk("in the key_interrupt before wake_up!!\n");
// clock_gettime(CLOCK_REALTIME, &start_time);
// printk("%d\n%d\n",start_time.tvsec,start_time.tv_nsec);
struct key_irq_desc *key_irqs = (struct key_irq_desc *)dev_id;//see at request_irq
int up = gpio_get_value(key_irqs->pin); printk("<1>up=%d\n",up);
if (up)
key_values[key_irqs->number] = (key_irqs->number + ) + 0x80;
else
key_values[key_irqs->number] += ; ev_press = ; /* 表示中断发生了 */
wake_up_interruptible(&key_waitq); /* 唤醒休眠的进程 */
printk("in the key_interrupt after wake_up!!\n");
#ifdef USING_TASKLET
tasklet_schedule(&key_tasklet);//调度key_do_tasklet
#endif return IRQ_RETVAL(IRQ_HANDLED);
// clock_gettime(CLOCK_REALTIME, &end_time);
// printf("%d\n%d\n",end_time.tvsec,end_time.tv_nsec);
} /* 应用程序对设备文件/dev/key执行open(...)时，
* 就会调用key_open函数
*/
static int key_open(struct inode *inode, struct file *file)
{
printk("in the key_open!\n");
int i;
int err;
int irq; for (i = ; i < sizeof(key_irqs)/sizeof(key_irqs[]); i++) {
// 注册中断处理函数
s3c_gpio_cfgpin(key_irqs[i].pin,key_irqs[i].pin_setting);//配置邋邋GPIO口
irq=gpio_to_irq(key_irqs[i].pin);
err = request_irq(irq, key_interrupt, IRQ_TYPE_EDGE_BOTH,
key_irqs[i].name, (void *)&key_irqs[i]);// 设备ID号
//set_irq_type(key_irqs[i].irq, IRQ_TYPE_EDGE_FALLING);//<linux/irq.h> 下降沿触发
// IRQ_TYPE_EDGE_RISING, IRQ_TYPE_EDGE_BOTH, IRQ_TYPE_EDGE_HIGH,
// IRQ_TYPE_EDGE_LOW
if (err)
break;
}
if (err) {
// 释放已经注册的中断
i--;
for (; i >= ; i--) {
irq=gpio_to_irq(key_irqs[i].pin);
disable_irq(irq);
free_irq(irq, (void *)&key_irqs[i]);
}
return -EBUSY;
} return ;
} /* 应用程序对设备文件/dev/key执行close(...)时，
* 就会调用key_close函数
*/
static int key_close(struct inode *inode, struct file *file)
{
int i;
int irq;
for (i = ; i < sizeof(key_irqs)/sizeof(key_irqs[]); i++) {
irq=gpio_to_irq(key_irqs[i].pin);
// 释放已经注册的中断
disable_irq(irq);
free_irq(irq, (void *)&key_irqs[i]);
//释放gpio口
gpio_free(key_irqs[i].pin);
} return ;
} /* 应用程序对设备文件/dev/key执行read(...)时，
* 就会调用key_read函数
*/
static int key_read(struct file *filp, char __user *buff,
size_t count, loff_t *offp)
{
printk("in the key_read before wait_event!!\n"); unsigned long err; if (!ev_press) {
if (filp->f_flags & O_NONBLOCK)
return -EAGAIN;//如果是阻塞访问则直接返回
else
{
/* 如果ev_press等于0，休眠,直到key_waitq被唤醒,并且ev_press为真*/
wait_event_interruptible(key_waitq, ev_press); printk("(1)in the key_read after wait_event!!\n");
}
} printk("(2)in the key_read after wait_event!!\n");
/* 执行到这里时，ev_press等于1，将它清0 */
ev_press = ; /* 将按键状态复制给用户，并清0 */
//copy_to_user(void __user * to,const void * from,unsigned long n)
err = copy_to_user(buff, (const void *)key_values, min(sizeof(key_values), count));
memset((void *)key_values, , sizeof(key_values));//清零 return err ? -EFAULT : min(sizeof(key_values), count);
} /**************************************************
* 当用户程序调用select函数时，本函数被调用
* 如果有按键数据，则select函数会立刻返回
* 如果没有按键数据，本函数使用poll_wait等待
**************************************************/
static unsigned int key_poll(struct file *file,
struct poll_table_struct *wait)
{
printk("in the key_poll!!\n");
unsigned int mask = ;
poll_wait(file, &key_waitq, wait);//将等待队列添加到poll_table
if (ev_press)
mask |= POLLIN | POLLRDNORM;/*数据可获得*/ return mask;//mask=0;休眠timeout
} /* 这个结构是字符设备驱动程序的核心
* 当应用程序操作设备文件时所调用的open、read、write等函数，
* 最终会调用这个结构中的对应函数
*/
static struct file_operations key_fops = {
.owner = THIS_MODULE, /* 这是一个宏，指向编译模块时自动创建的__this_module变量 */
.open = key_open,
.release = key_close,
.read = key_read,
.poll = key_poll,
}; /*
* Set up the cdev structure for a device.
*/
static void key_setup_cdev(struct cdev *dev, int minor,
struct file_operations *fops)
{
int err, devno = MKDEV(key_major, minor); cdev_init(dev, fops);
dev->owner = THIS_MODULE;
dev->ops = fops;
err = cdev_add (dev, devno, );
/* Fail gracefully if need be */
if (err)
printk (KERN_NOTICE "Error %d adding key%d", err, minor);
} /*
* We export one key device. There's no need for us to maintain any
* special housekeeping info, so we just deal with raw cdev.
*/
static struct cdev key_cdev; /*
* 执行"insmod key_drv.ko" 命令时就会调用这个函数
*/
static int __init userkey_init(void)
//static int key_init(void)
{
int result;
dev_t dev = MKDEV(key_major, );
char dev_name[]="key"; /*request gpio*/
int ret;
int i=;
for(i=;i<;i++)
{
ret = gpio_request(key_irqs[i].pin, "KEY");
if (ret)
{
printk("%s:request GPIO %d for KEY failed,ret= %d\n",dev_name,key_irqs[i],ret);
}
} /* Figure out our device number. */
if (key_major)
result = register_chrdev_region(dev, , dev_name);
else {
result = alloc_chrdev_region(&dev, , , dev_name);
key_major = MAJOR(dev);
}
if (result < ) {
printk(KERN_WARNING "key: unable to get major %d\n", key_major);
return result;
}
if (key_major == )
key_major = result; #ifdef USING_TASKLET
tasklet_init(&key_tasklet, key_do_tasklet, );//初始化底半部机制tasklet
#endif
/* Now set up cdev. */
key_setup_cdev(&key_cdev, , &key_fops); /*udev自动创建文件结点*/
key_class = class_create(THIS_MODULE, "key_class");
device_create(key_class, NULL, dev, NULL,dev_name); printk("key device installed, with major %d\n", key_major);
printk("The device name is: /dev/%s\n", dev_name); return ;
} /*
* 执行rmod key_drv”命令时就会调用这个函数
*/
static void __exit userkey_exit(void)
{ device_destroy(key_class, key_cdev.dev);
class_destroy(key_class);
cdev_del(&key_cdev);
unregister_chrdev_region(MKDEV(key_major, ), ); #ifdef USING_TASKLET
tasklet_kill(&key_tasklet);
#endif
printk("key device uninstalled\n");
} /* 这两行指定驱动程序的初始化函数和卸载函数 */
module_init(userkey_init);
module_exit(userkey_exit); /* 描述驱动程序的一些信息，不是必须的 */
MODULE_AUTHOR("mhb@SEU"); // 驱动程序的作者
MODULE_DESCRIPTION("KEY Driver"); // 一些描述信息
MODULE_LICENSE("Dual BSD/GPL"); // 遵循的协议
测试实例代码：
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/select.h>
#include <sys/time.h>
#include <errno.h> int main(void)
{ int i;
int key_fd;
int key_value[]={,,,,}; /*打开键盘设备文件*/
key_fd = open("/dev/key", );
printf("key_fd=%d!!\n",key_fd);
if (key_fd < ) {
perror("open device key");
exit();
}
for (;;) {
fd_set rds;
int ret; FD_ZERO(&rds);
FD_SET(key_fd, &rds); /*使用系统调用select检查是否能够从/dev/key设备读取数据*/
ret = select(key_fd + , &rds, NULL, NULL, NULL); /*读取出错则退出程序*/
if (ret < ) {
perror("select");
exit();
} if (ret == ) {
printf("Timeout.\n");
}
/*能够读取到数据*/
else if (FD_ISSET(key_fd, &rds)) {
/*开始读取键盘驱动发出的数据，注意key_value和键盘驱动中定义为一致的类型*/
int ret = read(key_fd, key_value, sizeof key_value);
if (ret != sizeof key_value) {
if (errno != EAGAIN)
perror("read key\n");
continue;
} else {
/*打印键值*/
for (i = ; i < ; i++)
printf("K%d %s, key value = 0x%02x\n", \
i+, (key_value[i] & 0x80) ? "released": \
key_value[i] ? "pressed down" : "", key_value[i]);
key_value[i] = ;
} }
} /*关闭设备文件句柄*/
close(key_fd);
return ;
}
输出：
/*output
[root@FORLINX210]# insmod int_key_drv.ko
[ 27.114321] key device installed, with major 247
[ 27.118175] The device name is: /dev/key
[root@FORLINX210]# ./key_test
[ 30.396897] in the key_open!
[ 30.398527] in the key_poll!!
key_fd=3!!
[ 33.959336] in the key_interrupt before wake_up!!
[ 33.962558] up=0
[ 33.964379] in the key_interrupt after wake_up!!
[ 33.968974] key_do_tasklet
[ 33.971669] in the key_poll!!
[ 33.974631] in the key_read before wait_event!!
[ 33.979124] (2)in the key_read after wait_event!!
[ 33.983897] in the key_poll!!
K1 pressed down, key value = 0x01
K2 , key value = 0x00
K3 , key value = 0x00
K4 , key value = 0x00
K5 , key value = 0x00
[ 37.173298] in the key_interrupt before wake_up!!
[ 37.176516] up=1
[ 37.178338] in the key_interrupt after wake_up!!
[ 37.182932] key_do_tasklet
[ 37.185625] in the key_poll!!
[ 37.188582] in the key_read before wait_event!!
[ 37.193085] (2)in the key_read after wait_event!!
[ 37.197830] in the key_poll!!
K1 released, key value = 0x81
K2 , key value = 0x00
K3 , key value = 0x00
K4 , key value = 0x00
K5 , key value = 0x00
[ 42.013178] in the key_interrupt before wake_up!!
[ 42.016393] up=0
[ 42.018213] in the key_interrupt after wake_up!!
[ 42.022808] key_do_tasklet
[ 42.025501] in the key_poll!!
[ 42.028457] in the key_read before wait_event!!
[ 42.032961] (2)in the key_read after wait_event!!
[ 42.037702] in the key_poll!!
K1 , key value = 0x00
K2 pressed down, key value = 0x01
K3 , key value = 0x00
K4 , key value = 0x00
K5 , key value = 0x00
[ 51.785335] in the key_interrupt before wake_up!!
[ 51.788557] up=1
[ 51.790377] in the key_interrupt after wake_up!!
[ 51.794971] key_do_tasklet
[ 51.797664] in the key_poll!!
[ 51.800603] in the key_read before wait_event!!
[ 51.805127] (2)in the key_read after wait_event!!
[ 51.809867] in the key_poll!!
K1 , key value = 0x00
K2 released, key value = 0x82
K3 , key value = 0x00
K4 , key value = 0x00
K5 , key value = 0x00
*/