查询方式按键驱动

艾恩凝 2021/3/23

序

按键和led差不多，只不过按键换成了读取操作

程序

驱动程序

#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 <asm/io.h>
#include <asm/arch/regs-gpio.h>
#include <asm/hardware.h>

#define BUTTON_MAJOR_NUMBER 200
#define DEVICE_NAME  "button_drv"

static struct class *button_drv_class;
static struct class_device	*button_drv_class_dev;

volatile unsigned long *GPFCON;
volatile unsigned long *GPFDAT;

volatile unsigned long *GPGCON;
volatile unsigned long *GPGDAT;


static int button_drv_open(struct inode *inode,struct file *file){
    *GPFCON &= ~((0x3<<(0*2)) | (0x3<<(2*2)));
    *GPGCON &= ~((0x3<<(3*2)) | (0x3<<(11*2)));
    return 0;
}

static ssize_t button_drv_read(struct file *file, const char __user *buf, size_t count, loff_t * ppos){
    unsigned char key_vals[4];
	if (count != sizeof(key_vals))
		return -EINVAL;
	key_vals[0] = (*GPFDAT & (1<<0)) ? 1 : 0;
	key_vals[1] = (*GPFDAT & (1<<2)) ? 1 : 0;

	key_vals[2] = (*GPGDAT & (1<<3)) ? 1 : 0;
	key_vals[3] = (*GPGDAT & (1<<11)) ? 1 : 0;

	copy_to_user(buf, key_vals, sizeof(key_vals));
    return sizeof(key_vals);
}

static struct file_operations button_drv_fops = {
    .owner  =   THIS_MODULE,  
    .open   =   button_drv_open,   
	.read	=	button_drv_read,	   
};

static int  button_drv_init(void){
    register_chrdev(BUTTON_MAJOR_NUMBER,DEVICE_NAME, &button_drv_fops);//register tell kernel
    button_drv_class = class_create(THIS_MODULE, DEVICE_NAME);
    button_drv_class_dev = class_device_create(button_drv_class, NULL, MKDEV(BUTTON_MAJOR_NUMBER, 0), NULL, DEVICE_NAME);
   
    GPFCON = (volatile unsigned long *)ioremap(0x56000050, 16);
	GPFDAT = GPFCON + 1;

    GPGCON = (volatile unsigned long *)ioremap(0x56000060, 16);
	GPGDAT = GPGCON + 1;
   
    return 0;
}

static void  button_drv_exit(void){
    unregister_chrdev(BUTTON_MAJOR_NUMBER, DEVICE_NAME);//unregister tell kernel
    class_device_unregister(button_drv_class_dev);
	class_destroy(button_drv_class);
	iounmap(GPFCON);
	iounmap(GPGCON);
}

module_init(button_drv_init);
module_exit(button_drv_exit);
MODULE_AUTHOR("https://aeneag.xyz");
MODULE_VERSION("0.1");
MODULE_DESCRIPTION("S3C2440 Button Driver");
MODULE_LICENSE("GPL");

测试程序

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>

int main(int argc, char **argv)
{
	int fd;
	unsigned char key_vals[4];
	int cnt = 0;
	printf("please use ./test_button_drv  /dev/button_drv");
	fd = open(argv[1], O_RDWR);
	if (fd < 0)
	{
		printf("can't open!\n");
	}

	while (1)
	{
		read(fd, key_vals, sizeof(key_vals));
		if (!key_vals[0] || !key_vals[1] || !key_vals[2] || !key_vals[3])
		{
			printf("%04d key pressed: %d %d %d %d\n", cnt++, key_vals[0], key_vals[1], key_vals[2], key_vals[3]);
		}
	}

	return 0;
}

慢慢搞

    

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