linux驱动之key中断方式读键值

来源：互联网发布：影音先锋网络主播视频编辑：程序博客网时间：2024/06/05 11:43

内核版本：linux-2.6.32.2

开发板：mini2440

参考韦东山的视频，编写代码，对于其源码稍有改动，以适合linux-2.6.32.2版本。代码如下：

#include <linux/module.h>#include <linux/kernel.h>#include <linux/fs.h>#include <linux/init.h>#include <linux/delay.h>#include <asm/uaccess.h>#include <asm/irq.h>#include <mach/io.h>#include <asm/io.h>#include <mach/regs-gpio.h>#include <mach/hardware.h>#include <linux/device.h>#include <linux/gpio.h>#include <linux/interrupt.h>#include <linux/wait.h>#include <linux/sched.h>#include <linux/irq.h>#define DEVICE_NAME "key_1"static struct class *leds_class;//static struct device *leds_class_devs;static DECLARE_WAIT_QUEUE_HEAD(button_waitq);/* 中断事件标志, 中断服务程序将它置1，third_drv_read将它清0 */static volatile int ev_press = 0;struct pin_desc{unsigned int pin;unsigned int key_val;};/* 键值: 按下时, 0x01, 0x02, 0x03, 0x04 *//* 键值: 松开时, 0x81, 0x82, 0x83, 0x84 */static unsigned char key_val;struct pin_desc pins_desc[3] = {{S3C2410_GPG(0), 0x01},{S3C2410_GPG(3), 0x02},{S3C2410_GPG(5), 0x03},};/*  * 确定按键值  */  static unsigned char key_val;static irqreturn_t button_irq(int irq, void *dev_id){struct pin_desc * pindesc = (struct pin_desc *)dev_id;unsigned int pinval;pinval = s3c2410_gpio_getpin(pindesc->pin);if (pinval){/* 松开 */key_val = 0x80 | pindesc->key_val;}else{/* 按下 */key_val = pindesc->key_val;}    ev_press = 1;                  /* 表示中断发生了 */    wake_up_interruptible(&button_waitq);   /* 唤醒休眠的进程 */return IRQ_RETVAL(IRQ_HANDLED);} static int mini2440_key_open(struct inode *inode, struct file *file){/**   配置中断。*/    request_irq(IRQ_EINT8, button_irq,IRQ_TYPE_EDGE_BOTH,"s1",&pins_desc[0]);request_irq(IRQ_EINT11,button_irq,IRQ_TYPE_EDGE_BOTH,"s2",&pins_desc[1]);request_irq(IRQ_EINT13,button_irq,IRQ_TYPE_EDGE_BOTH,"s3",&pins_desc[2]);    return 0;}static ssize_t mini2440_key_read(struct file *file, char __user *buf, size_t size, loff_t *ppos){if (size != 1)return -EINVAL;/* 如果没有按键动作, 休眠 */wait_event_interruptible(button_waitq, ev_press);/* 如果有按键动作, 返回键值 */copy_to_user(buf, &key_val, 1);ev_press = 0;return 1;}int mini2440_key_close(struct inode *inode, struct file *file){free_irq(IRQ_EINT8, &pins_desc[0]);free_irq(IRQ_EINT11,&pins_desc[1]);free_irq(IRQ_EINT13,&pins_desc[2]);return 0;}static struct file_operations mini2440_key_fops = {    .owner  =   THIS_MODULE,    /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */    .open   =   mini2440_key_open,        .read   =   mini2440_key_read,.release =   mini2440_key_close,};/* * 执行insmod命令时就会调用这个函数  */int ret;static int mini2440_key_init(void){    ret = register_chrdev(0, DEVICE_NAME, &mini2440_key_fops); leds_class = class_create(THIS_MODULE,DEVICE_NAME);device_create(leds_class, NULL, MKDEV(ret, 0), NULL, "button"); /* /dev/button */     return 0;}/* * 执行rmmod命令时就会调用这个函数  */static void mini2440_key_exit(void){    /* 卸载驱动程序 */    unregister_chrdev(ret, DEVICE_NAME);device_destroy(leds_class,MKDEV(ret, 0));class_destroy(leds_class);}/* 这两行指定驱动程序的初始化函数和卸载函数 */module_init(mini2440_key_init);module_exit(mini2440_key_exit);/* 描述驱动程序的一些信息，不是必须的 */MODULE_LICENSE("GPL");

linux应用测试程序

#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <stdio.h>#include <unistd.h>int main(int argc, char **argv){int fd;unsigned char key_val;fd = open("/dev/button", O_RDWR);if (fd < 0){printf("can't open!\n");}while (1){read(fd, &key_val, 1);printf("key_val = 0x%x\n", key_val);sleep(5);}return 0;}

对于该案例，linux相关的指令：

查看cpu占有率：top

查看进程：ps

查看中断源：cat proc/interrupts

注意：实际测试中，键值返回很慢，有时按下的键值返回不了，暂时还不知道原因，mark下

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