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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LED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

功能函数

#include<stdlib.h>
#include<stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include<unistd.h>
#include<string.h>
#include<sys/ioctl.h>//功能码
#define LED_ON _IOW('l',1,int)
#define LED_OFF _IOW('l',0,int)int main(int argc, char const *argv[])
{char buf[128] = {0};int a,b;int fd;while (1){printf("请输入要控制的灯：0(led1) 1(led2) 2(led3)\n");scanf("%d",&a);if(a == 0){fd = open("/dev/myled0", O_RDWR);if (fd < 0){printf("打开设备文件失败\n");exit(-1);}}else if(a == 1){fd = open("/dev/myled1", O_RDWR);if (fd < 0){printf("打开设备文件失败\n");exit(-1);}}else if(a == 2){int fd = open("/dev/myled2", O_RDWR);if (fd < 0){printf("打开设备文件失败\n");exit(-1);}}printf("请输入控制命令:0(关闭) 1(开灯)>");scanf("%d",&b);switch(b){case 1:ioctl(fd,LED_ON);break;case 0:ioctl(fd,LED_OFF);break;}close(fd);}return 0;
}

驱动代码

#include <linux/of_irq.h>
#include <linux/interrupt.h>
#include <linux/of_gpio.h>
#include <linux/gpio.h>
#include <linux/init.h>
#include <linux/module.h>
#include<linux/fs.h>
#include<linux/io.h>
#include<linux/device.h>//功能码
#define LED_ON _IOW('l',1,int)
#define LED_OFF _IOW('l',0,int)unsigned int major;//定义一个变量保存主设备号char kbuf[128]={0};
struct class *cls;
struct device*device;struct device_node *dev_led;
struct device_node *dev;
unsigned int irqno1,irqno2,irqno3;
struct gpio_desc *gpiono1;
struct gpio_desc *gpiono2;
struct gpio_desc *gpiono3;/*myirq{interrupt-parent=<&gpiof>;//引用中断父节点interrupts=<9 0>,<7 0>,<8 0>;//声明和中断父节点的关系 9表示索引号，0表示默认设置
};
*///中断处理函数
irqreturn_t myirq_handler1(int irq,void *dev)
{gpiod_set_value(gpiono1, !gpiod_get_value(gpiono1)); // LED1return IRQ_HANDLED;
}
irqreturn_t myirq_handler2(int irq,void *dev)
{gpiod_set_value(gpiono2, !gpiod_get_value(gpiono2)); // LED2return IRQ_HANDLED;
}
irqreturn_t myirq_handler3(int irq,void *dev)
{gpiod_set_value(gpiono3, !gpiod_get_value(gpiono3)); // LED3return IRQ_HANDLED;
}//封装操作方法
int mycdev_open(struct inode *inode, struct file *file)
{int a = inode->i_rdev;//获取当前设备文件对应的设备号file->private_data=(void*)MINOR(a);//将次设备号保存到当前文件的file结构中printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);return 0;
}long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{unsigned int a=(unsigned int)file->private_data;switch(a){case 0:if(cmd == LED_ON)gpiod_set_value(gpiono1,1);elsegpiod_set_value(gpiono1,0);break;   case 1:if(cmd == LED_ON)gpiod_set_value(gpiono2,1);elsegpiod_set_value(gpiono2,0);break; case 2:if(cmd == LED_ON)gpiod_set_value(gpiono3,1);elsegpiod_set_value(gpiono3,0);break;                          }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且初始化
struct file_operations fops={.open=mycdev_open,.release=mycdev_close,.unlocked_ioctl = mycdev_ioctl,
};static int __init mycdev_init(void)
{int i;// 字符设备驱动注册major = register_chrdev(0, "mychrdev", &fops);if (major < 0){printk("字符设备驱动注册失败\n");return major;}printk("字符设备驱动注册成功:major=%d\n", major);// 向上提交目录cls = class_create(THIS_MODULE, "myled");if (IS_ERR(cls)){printk("向上提交目录失败\n");return -PTR_ERR(cls);}printk("向上提交目录信息成功\n");// 向上提交设备节点信息for (i = 0; i < 3; i++){device = device_create(cls, NULL, MKDEV(major, i), NULL, "myled%d", i);if (IS_ERR(device)){printk("向上提交设备节点信息失败\n");return -PTR_ERR(device);}}printk("向上提交设备节点成功\n");int ret1,ret2,ret3;//解析按键的设备树节点dev = of_find_node_by_path("/myirq");if(dev==NULL){printk("解析设备树节点失败\n");return -EFAULT;}printk("解析设备树节点成功\n");//根据设备树节点的路径解析设备树信息dev_led = of_find_node_by_path("/leds");if(dev_led==NULL){printk("解析设备树信息失败\n");return -EFAULT;}printk("解析设备树信息成功\n");//根据设备树节点解析出软中断号irqno1 = irq_of_parse_and_map(dev,0);//按键1索引号为0irqno2 = irq_of_parse_and_map(dev,1);//按键2索引号为1irqno3 = irq_of_parse_and_map(dev,2);//按键3索引号为2if(!irqno1|!irqno1|!irqno2){printk("解析软中断号失败\n");return -ENXIO;}printk("解析软中断号成功 irqno=%d %d %d\n",irqno1,irqno2,irqno3);//注册中断ret1 = request_irq(irqno1,myirq_handler1,IRQF_TRIGGER_FALLING,"key1",NULL);ret2 = request_irq(irqno2,myirq_handler2,IRQF_TRIGGER_FALLING,"key2",NULL);ret3 = request_irq(irqno3,myirq_handler3,IRQF_TRIGGER_FALLING,"key3",NULL);if(ret1|ret2|ret3){printk("注册中断失败\n");return -EFAULT;}printk("注册中断成功\n");//根据解析到的设备树信息解析出led的gpio编号// 申请gpio_desc对象并设置输出为低电平gpiono1 = gpiod_get_from_of_node(dev_led, "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(dev_led, "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(dev_led, "led3-gpios", 0, GPIOD_OUT_LOW, NULL);if (IS_ERR(gpiono3)){printk("申请gpio对象失败\n");return -PTR_ERR(gpiono3);}printk("申请gpio3对象成功\n");return 0;
}
static void __exit mycdev_exit(void)
{//销毁设备节点信息int i;for(i=0;i<3;i++){device_destroy(cls,MKDEV(major,i));}//销毁目录信息class_destroy(cls);//注销字符设备驱动unregister_chrdev(major,"mychrdev");//注销中断free_irq(irqno1,NULL);free_irq(irqno2,NULL);free_irq(irqno3,NULL);// 灭灯gpiod_set_value(gpiono1, 0);// 释放gpio编号gpiod_put(gpiono1);gpiod_set_value(gpiono2, 0);gpiod_put(gpiono2);gpiod_set_value(gpiono3, 0);gpiod_put(gpiono3);}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");