字符设备驱动(一)

最新推荐文章于 2020-09-27 15:00:44 发布

原创最新推荐文章于 2020-09-27 15:00:44 发布 · 812 阅读

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#字符驱动 #嵌入式 #编程 #c

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本文介绍如何使用Linux内核实现GPIO驱动，通过控制GPIO口实现LED的点亮与熄灭，包括初始化设备、配置GPIO口为输出、读取并处理用户输入以控制LED状态。

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框架图：

#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>

static struct class *firstdrv_class;
static struct class_device *firstdrv_class_dev;

volatile unsigned long *gpfcon=NULL;
volatile unsigned long *gpfdat=NULL;


static int first_drv_open(struct inode *inode,struct file *filp)
{
	//printk("fist_drv_open\n");
	/*配置GPF4、5、6为输出*/
	//清零
	*gpfcon &= ~((0x3<<(4*2))|(0x3<<(5*2))|(0x3<<(6*2)));
	//设置为输出口
	*gpfcon |=((0x1<<(4*2))|(0x1<<(5*2))|(0x1<<(6*2)));

	return 0;
}
static ssize_t first_drv_write(struct file *filp,const char __user *buf,size_t count,loff_t *ppos)
{
	int val;

	copy_from_user(&val,buf,count);//copy_to_user();

	if (val==1)
	{
		//点灯
		*gpfdat &=~((1<<4)|(1<<5)|(1<<6));
	}
	else
	{
		//灭灯
		*gpfdat |=(1<<4)|(1<<5)|(1<<6);
	}


	//printk("fist_drv_write\n");
	return 0;
}
static struct file_operations first_drv_fops={
	.owner=THIS_MODULE,
	.open=first_drv_open,
	.write=first_drv_write,

};

int major;
static int first_drv_init(void)
{
//register_chrdev(111,"first_drv",&first_drv_fops);
// if first args 0, the sysytm auto give the dervice number
	major=register_chrdev(0,"first_drv",&first_drv_fops);
	
	firstdrv_class=class_create(THIS_MODULE,"firstdrv");
	if(IS_ERR(firstdrv_class))
		return PTR_ERR(firstdrv_class);

	firstdrv_class_dev=class_device_create(firstdrv_class,NULL,MKDEV(major,0),NULL,"xyz");
	if(unlikely(IS_ERR(firstdrv_class_dev)))
		return PTR_ERR(firstdrv_class_dev);

	/*虚拟地址映射*/
	gpfcon=(volatile unsigned long *)ioremap(0x56000050,16);
	gpfdat=gpfcon+1;
	return 0;
	
}

static void first_drv_exit(void)
{
	unregister_chrdev(major,"first_drv");
	
	class_device_unregister(firstdrv_class_dev);
	class_destroy(firstdrv_class);
	iounmap(gpfcon);
	
}
module_init(first_drv_init);
module_exit(first_drv_exit);

MODULE_LICENSE("GPL");