编写LED灯的驱动，使用GPIO子系统，里面添加按键的中断处理
1.应用程序发送指令控制发光二极管亮灭
2.按键1按下，led1电位反转；按键2按下，led2电位反转；按键3按下，led3电位反转
//头文件
#ifndef __LED_H__
#define __LED_H__
//功能码
#define LED_ON _IOW('l',1,int)
#define LED_OFF _IOW('l',0,int)
#endif
//应用程序实现LED的亮灭
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include "led.h"
int main(int argc, const char *argv[])
{
int a,b;
while(1)
{
int fd_led = open("/dev/myled0",O_RDWR);
if(fd_led < 0)
{
printf("打开设备文件失败\n");
exit(-1);
}
printf("请输入要控制的灯:1 2 3>>");
scanf("%d",&b);
printf("输入控制命令:0熄灭 1开灯>>>");
scanf("%d",&a);
switch(a)
{
case 1:
ioctl(fd_led,LED_ON,&b);
break;
case 0:
ioctl(fd_led,LED_OFF,&b);
break;
}
close(fd_led);
}
return 0;
}
//驱动程序
#include <linux/init.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/gpio.h>
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/io.h>
#include<linux/of_irq.h>
#include<linux/interrupt.h>
#include "led.h"
/* leds{
led1-gpios=<&gpioe 10 0>;//10表示引脚编号 0表示默认
led2-gpios=<&gpiof 10 0>;
led3-gpios=<&gpioe 8 0>;
};*/
struct device_node *dnode1;
struct device_node *dnode2;
struct gpio_desc *gpiono1;
struct gpio_desc *gpiono2;
struct gpio_desc *gpiono3;
struct cdev *cdev;
int major=168;
int minor=0;
struct class *cls;
struct device *dev;
dev_t devno;
int i;
unsigned int irqno[3]; //软中断号
//中断处理函数
irqreturn_t myirq_handler(int irqno, void *dev_id)
{
unsigned int id=(unsigned int)dev_id;
switch(id)
{
case 0:
printk("KEY1_INTERRUPT\n");
gpiod_set_value(gpiono1,!gpiod_get_value(gpiono1));
break;
case 1:
printk("KEY2_INTERRUPT\n");
gpiod_set_value(gpiono2,!gpiod_get_value(gpiono2));
break;
case 2:
printk("KEY3_INTERRUPT\n");
gpiod_set_value(gpiono3,!gpiod_get_value(gpiono3));
break;
}
return IRQ_HANDLED;
}
/*********************封装操作方法***************************/
int mycdev_open(struct inode *inode, struct file *file)
{
//printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
return 0;
}
long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
int which;
copy_from_user(&which,(void *)arg,4);
switch(cmd)
{
case LED_ON: // 亮灯
switch(which)
{
case 1:
gpiod_set_value(gpiono1, 1);
break;
case 2:
gpiod_set_value(gpiono2, 1);
break;
case 3:
gpiod_set_value(gpiono3, 1);
break;
}
break;
case LED_OFF:
switch(which)
{
case 1:
gpiod_set_value(gpiono1, 0);
break;
case 2:
gpiod_set_value(gpiono2, 0);
break;
case 3:
gpiod_set_value(gpiono3, 0);
}
break;
}
//printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
return 0;
}
int mycdev_close(struct inode *inode, struct file *file)
{
//printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
return 0;
}
/***********************************************************************/
//定义一个操作方法结构体变量并初始化
struct file_operations fops =
{
.open = mycdev_open,
.release = mycdev_close,
.unlocked_ioctl = mycdev_ioctl,
};
static int __init mycdev_init(void)
{
int ret,i;
//1.申请对象空间 cdev_alloc
cdev = cdev_alloc();
if(cdev == NULL)
{
printk("申请对象空间失败\n");
ret=-EFAULT;
goto out1;
}
printk("申请对象空间成功\n");
//2.初始化对象 cdev_init
cdev_init(cdev,&fops);
printk("初始化对象成功\n");
//3.申请设备号 register_chrdev_region()或clloc_chrdev_region()
if(major != 0) //静态申请
{
ret=register_chrdev_region(MKDEV(major,minor),3,"myled");
if(ret)
{
printk("申请静态设备号失败\n");
goto out2;
}
printk("申请静态设备号成功major=%d\n",major);
}
else //动态申请
{
ret=alloc_chrdev_region(&devno,minor,3,"myled");
if(ret)
{
printk("申请动态设备号失败\n");
goto out2;
}
major=MAJOR(devno);
minor=MINOR(devno);
printk("申请动态设备号成功major=%d\n",major);
}
//4.注册驱动对象 cdev_add()
ret=cdev_add(cdev,MKDEV(major,minor),3);
if(ret)
{
printk("注册驱动对象失败\n");
goto out3;
}
printk("注册驱动对象成功\n");
//5.向上提交目录 class_create()
cls=class_create(THIS_MODULE,"myled");
if(IS_ERR(cls))
{
printk("向上提交目录失败\n");
ret = -PTR_ERR(cls);
goto out4;
}
printk("向上提交目录成功\n");
//6.向上提交设备信息 device_create()
for(i=0;i<3;i++)
{
dev=device_create(cls,NULL,MKDEV(major,i),NULL,"myled%d",i);
if(IS_ERR(dev))
{
printk("向上提交设备节点失败\n");
ret = -PTR_ERR(dev);
goto out5;
}
}
printk("向上提交设备信息成功\n");
// 根据设备树节点的路径解析设备树信息
dnode1 = of_find_node_by_path("/leds");
if (dnode1 == NULL)
{
printk("解析设备树节点led失败\n");
return -EFAULT;
}
printk("解析设备树节点led成功\n");
// 申请gpio_desc对象并设置输出为低电平
gpiono1 = gpiod_get_from_of_node(dnode1, "led1-gpios", 0, GPIOD_OUT_LOW, NULL);
if (IS_ERR(gpiono1))
{
printk("申请gpio1对象失败\n");
return -PTR_ERR(gpiono1);
}
printk("申请gpio1对象成功\n");
gpiono2 = gpiod_get_from_of_node(dnode1, "led2-gpios", 0, GPIOD_OUT_LOW, NULL);
if (IS_ERR(gpiono2))
{
printk("申请gpio2对象失败\n");
return -PTR_ERR(gpiono2);
}
printk("申请gpio2对象成功\n");
gpiono3 = gpiod_get_from_of_node(dnode1, "led3-gpios", 0, GPIOD_OUT_LOW, NULL);
if (IS_ERR(gpiono3))
{
printk("申请gpio3对象失败\n");
return -PTR_ERR(gpiono3);
}
printk("申请gpio3对象成功\n");
// 根据设备树节点的路径解析设备树信息
dnode2 = of_find_node_by_path("/myirq");
if (dnode2 == NULL)
{
printk("解析设备树节点myirq失败\n");
return -EFAULT;
}
printk("解析设备树节点myirq成功\n");
for(i=0;i<3;i++)
{
//获取软中断号
irqno[i]=irq_of_parse_and_map(dnode2,i);
if(!irqno[i])
{
printk("软中断号irqno[%d]获取失败\n",i);
return -ENXIO;
}
printk("软中断号获取成功irqno[%d]=%d\n",i,irqno[i]);
//注册中断
ret=request_irq(irqno[i],myirq_handler,IRQF_TRIGGER_FALLING,"key",(void *)i);
if(ret)
{
printk("注册驱动失败\n");
return ret;
}
printk("key%d中断注册成功\n",i);
}
return 0;
out5:
for(--i;i>=0;i--)
{
//销毁上面提交的设备信息
device_destroy(cls,MKDEV(major,i));
}
class_destroy(cls);
out4:
cdev_del(cdev);
out3:
unregister_chrdev_region(MKDEV(major,minor),3);
out2:
kfree(cdev);
out1:
return ret;
}
static void __exit mycdev_exit(void)
{
// 灭灯
gpiod_set_value(gpiono1, 0);
gpiod_set_value(gpiono2, 0);
gpiod_set_value(gpiono3, 0);
// 释放gpio编号
gpiod_put(gpiono1);
gpiod_put(gpiono2);
gpiod_put(gpiono3);
//注销中断
for(i=0;i<3;i++)
{
free_irq(irqno[i],NULL);
}
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");
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文章来源：https://www.toymoban.com/news/detail-622576.html
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