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

驱动程序

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/device.h>
#include <linux/of_irq.h>
#include <linux/interrupt.h>
#include <linux/of_gpio.h>//功能码
#define LED_ON _IO('l',1)
#define LED_OFF _IO('l',0)// 定义一个变量保存主设备号
unsigned int major;
char kbuf[128] = {0};
unsigned int led1;
unsigned int led2;
unsigned int led3;struct class *cls;
struct device *dev;
struct device_node *devn;
unsigned int irqno1;
unsigned int irqno2;
unsigned int irqno3;// 中断处理函数
irqreturn_t myirq_handle1(int irq, void *dev)
{printk("key1 press\n");gpio_set_value(led1, !gpio_get_value(led1));return IRQ_HANDLED;
}
irqreturn_t myirq_handle2(int irq, void *dev)
{printk("key2 press\n");gpio_set_value(led2, !gpio_get_value(led2));return IRQ_HANDLED;
}
irqreturn_t myirq_handle3(int irq, void *dev)
{printk("key3 press\n");gpio_set_value(led3, !gpio_get_value(led3));return IRQ_HANDLED;
}int mycdev_open(struct inode *inode, struct file *file)
{int a = inode->i_rdev;file->private_data = (void *)MINOR(a);printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);return 0;
}ssize_t mycdev_read(struct file *file, char *ubuf, size_t size, loff_t *loff)
{printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);unsigned long ret;if (size > sizeof(kbuf)){size = sizeof(kbuf);}ret = copy_to_user(ubuf, kbuf, size);if (ret){printk("copy_to_user failed\n");return ret;}return 0;
}ssize_t mycdev_write(struct file *file, const char *ubuf, size_t size, loff_t *loff)
{printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);if (size > sizeof(kbuf)){size = sizeof(kbuf);}long ret;ret = copy_from_user(kbuf, ubuf, size);if (ret){printk("copy_from_user failed\n");return -EIO;}return 0;
}int mycdev_close(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)
{unsigned int a = (unsigned int)file->private_data;switch (a){case 0:switch (cmd){case LED_ON:gpio_set_value(led1, 1);break;case LED_OFF:gpio_set_value(led1, 0);break;}break;case 1:switch (cmd){case LED_ON:gpio_set_value(led2, 1);break;case LED_OFF:gpio_set_value(led2, 0);break;}break;case 2:switch (cmd){case LED_ON:gpio_set_value(led3, 1);break;case LED_OFF:gpio_set_value(led3, 0);break;}break;}return 0;
}
struct file_operations fops = {.open = mycdev_open,.read = mycdev_read,.write = mycdev_write,.release = mycdev_close,.unlocked_ioctl = mycdev_ioctl,
};
int irq_init(void)
{int ret;// 解析按键的设备树节点devn = of_find_node_by_path("/myirq");if (NULL == devn){printk("解析设备树节点失败\n");return -EFAULT;}printk("解析设备树节点成功\n");// 根据设备树节点解析出软中断号irqno1 = irq_of_parse_and_map(devn, 0);if (!irqno1){printk("解析软中断号失败\n");return -ENXIO;}printk("解析软中断号成功 irqno1=%d\n", irqno1);irqno2 = irq_of_parse_and_map(devn, 1);if (!irqno2){printk("解析软中断号失败\n");return -ENXIO;}printk("解析软中断号成功 irqno2=%d\n", irqno2);irqno3 = irq_of_parse_and_map(devn, 2);if (!irqno3){printk("解析软中断号失败\n");return -ENXIO;}printk("解析软中断号成功 irqno3=%d\n", irqno3);// 注册中断ret = request_irq(irqno1, myirq_handle1, IRQF_TRIGGER_FALLING, "key1", NULL);if (ret){printk("注册中断失败\n");return ret;}printk("注册中断成功\n");ret = request_irq(irqno2, myirq_handle2, IRQF_TRIGGER_FALLING, "key2", NULL);if (ret){printk("注册中断失败\n");return ret;}printk("注册中断成功\n");ret = request_irq(irqno3, myirq_handle3, IRQF_TRIGGER_FALLING, "key3", NULL);if (ret){printk("注册中断失败\n");return ret;}printk("注册中断成功\n");return 0;
}static int __init mycdev_init(void)
{int i, ret;irq_init();devn = of_find_node_by_path("/leds");if (NULL == devn){printk("解析设备树节点失败\n");return -EFAULT;}printk("解析设备树节点成功\n");// 根据解析到的设备树节点指针解析出LED的gpio编号led1 = of_get_named_gpio(devn, "led1-gpios", 0);if (led1 < 0){printk("解析led1编号失败\n");return led1;}printk("解析led1编号成功\n");// 申请led编号ret = gpio_request(led1, NULL);if (ret){printk("申请led编号失败\n");return ret;}printk("申请led编号成功\n");led2 = of_get_named_gpio(devn, "led2-gpios", 0);if (led2 < 0){printk("解析led2编号失败\n");return led2;}printk("解析led1编号成功\n");// 申请led编号ret = gpio_request(led2, NULL);if (ret){printk("申请led编号失败\n");return ret;}printk("申请led编号成功\n");led3 = of_get_named_gpio(devn, "led3-gpios", 0);if (led3 < 0){printk("解析led3编号失败\n");return led3;}printk("解析led3编号成功\n");// 申请led编号ret = gpio_request(led3, NULL);if (ret){printk("申请led编号失败\n");return ret;}printk("申请led编号成功\n");// 注册字符设备驱动major = register_chrdev(0, "mychrdev", &fops);if (major < 0){printk("register error\n");return major;}printk("register success\n");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");for (i = 0; i < 3; i++){dev = device_create(cls, NULL, MKDEV(major, i), NULL, "myled%d", i);if (IS_ERR(dev)){printk("向上提交结点设备信息失败\n");return -PTR_ERR(dev);}}printk("向上提交设备节点成功\n");return 0;
}static void __exit mycdev_exit(void)
{// 注销中断free_irq(irqno1, NULL);free_irq(irqno2, NULL);free_irq(irqno3, NULL);// 释放led编号gpio_put(led1);gpio_put(led2);gpio_put(led3);// 销毁节点信息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, "mycdev");
}module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

应用程序

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
//功能码
#define LED_ON _IO('l',1)
#define LED_OFF _IO('l',0)int main(int argc, char const *argv[])
{int a, b, c;char buf[128] = {0};printf("invoking open\n");int fd1 = open("/dev/myled0", O_RDWR);if (fd1 < 0){printf("open file failed");exit(-1);}int fd2 = open("/dev/myled1", O_RDWR);if (fd2 < 0){printf("open file failed");exit(-1);}int fd3 = open("/dev/myled2", O_RDWR);if (fd3 < 0){printf("open file failed");exit(-1);}while (1){printf("请选择LED灯1（LED1）2(LED2) 3(LED3)>");scanf("%d", &b);printf("请输入控制指令：0（关灯） 1（开灯）>");scanf("%d", &a);switch (b){case 1:switch (a){case 1:ioctl(fd1, LED_ON);break;case 0:ioctl(fd1, LED_OFF);break;}break;case 2:switch (a){case 1:ioctl(fd2, LED_ON);break;case 0:ioctl(fd2, LED_OFF);break;}break;case 3:switch (a){case 1:ioctl(fd3, LED_ON);break;case 0:ioctl(fd3, LED_OFF);break;}break;}}printf("invoking close\n");close(fd1);close(fd2);close(fd3);return 0;
}