内核驱动 - 阻塞型驱动

1、定义“等待队列头部”     wait_queue_head_t key_q; 2、初始化“等待队列头部”     init_waitqueue_head(&key_q); 3、等待事件发生     wait_event(key_q, key_num); 4、唤醒等待事件     wake_up(&key_q);

查询按键状态

key.c

#include <linux/module.h>
#include <linux/device.h>
#include <linux/miscdevice.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <linux/sched.h>

#define	GPH0CON 0xE0200C00
#define	GPH0DAT 0xE0200C04
#define DEVICE_NAME	"tqkey"

#define	LEDCON 0xE0200060
#define LEDDAT 0xE0200064

volatile unsigned int *led_config;
volatile unsigned int *led_data;
volatile unsigned int *key_data;

unsigned int key_num;

//等待队列
wait_queue_head_t key_q;

//1、定义工作
struct work_struct *work;

//(定时器)1、定义定时器结构体
struct timer_list buttons_timer;

void work_func(struct work_struct *work)
{
	/*启动定时器*/   /*延时 1s/10=100ms */
	mod_timer(&buttons_timer, jiffies + (HZ / 10));
}

//(定时器)5、函数
static void buttons_timer_function(unsigned long data)
{
	unsigned int key_val;
	volatile unsigned short leddata;
	key_val = readw(key_data) & 0x03;  //GPH0_0 Key_1引角  //GPH0_0 Key_2引角
	if(key_val == 2)	//按键按下为低电平
	{
		leddata = 0xFF;  //点亮LED
		key_num = 1;
	}
	else if(key_val == 1)	//按键按下为低电平
	{
		leddata = 0x00;  //熄灭LED
		key_num = 2;
	}
	writel(leddata, led_data);

	//唤醒等待队列
	wake_up(&key_q);
}

void timer_init(void)
{
	//(定时器)2、初始化
	init_timer(&buttons_timer);
	buttons_timer.function = &buttons_timer_function;

	//(定时器)3、向内核注册定时器
	add_timer(&buttons_timer);
}

static irqreturn_t key_int(int irq, void *dev_id)
{
	//3、提交下半部至内核默认工作队列keventd_wq 
	schedule_work(work);
	return 0;
}

void key_hw_init(void)
{
	volatile unsigned short data;
	volatile unsigned int *gpio_config;
	gpio_config = (volatile unsigned int *)ioremap(GPH0CON, 4);
	data = readw(gpio_config);		//读出原有寄存器中的值
	data &= ~0xFF;
	data |= 0xFF;
	writew(data, gpio_config);
	printk("key_hw_init!\n");

	
	led_config = (volatile unsigned int *)ioremap(LEDCON, 4);	//物理地址转换为虚拟地址
	writel(0x00011000, led_config);

	led_data = (volatile unsigned int *)ioremap(LEDDAT, 4);
	writel(0xFF, led_data);

	key_data = (volatile unsigned int *)ioremap(GPH0DAT, 4);
}

/*static long key_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	return -EINVAL;
}*/

static int key_open(struct inode *inode, struct file *file)
{
	return 0;
}

static int key_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{
	//进入等待队列睡眠
	wait_event(key_q, key_num);  /*当key_num为true，即当按键按下时唤醒*/
	
	if (copy_to_user(buf, &key_num, 4))
	{
		key_num = 0;
		return 4;
	}
	else
	{
		key_num = 0;
		return 0;
	}
}


static struct file_operations key_fops =
{
	.owner = THIS_MODULE,
	//.unlocked_ioctl = key_ioctl,
	.open = key_open,
	.read = key_read,
	.release = NULL,
};

struct miscdevice key_miscdev = 
{
	.minor = 200,
	.name = DEVICE_NAME,
	.fops = &key_fops,
};

//注册函数
static int __init button_init(void)
{
	int ret = 0;

	misc_register(&key_miscdev);

	//注册中断处理程序
	ret = request_irq(IRQ_EINT0, key_int, IRQF_TRIGGER_FALLING, DEVICE_NAME, 0);
	ret = request_irq(IRQ_EINT1, key_int, IRQF_TRIGGER_FALLING, DEVICE_NAME, 0);

	//硬件初始化
	key_hw_init();

	//2、工作初始化
	work = kmalloc(sizeof(struct work_struct), GFP_KERNEL);
	//(注：GFP_KERNEL是内核内存分配时最常用的，无内存可用时可引起休眠)
	INIT_WORK(work, work_func);  //创建工作，关联工作函数

	//内核定时器初始化
	timer_init();

	//初始化等待队列
	init_waitqueue_head(&key_q);
	
	return 0;
}

//注销函数
static void __exit button_exit(void)
{
	misc_deregister(&key_miscdev);

	//注销中断程序
	free_irq(IRQ_EINT0, 0);
}

module_init(button_init);
module_exit(button_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jerry.Gou");
MODULE_DESCRIPTION("TQ210 button driver");

key_app.c

/*********************************************
*File name :key_app.c
*Author    :JerryGou
*Date      :2017/10/23
*Function  :通过read函数，获取内核中是那个按键按下
*********************************************/
  
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>

int main()
{
	int fd;
	int buf = 0;
	fd = open("/dev/tqkey", 0);

	if (fd < 0)
		printf("open fail\n");

	read(fd, &buf, 4);
	printf("num is %d\n", buf);
	close(fd);
	return 0;
}