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/ {
	led {
		status = "okay";
		compatible = "led";
		gpios = <&pio 0 0 GPIO_ACTIVE_LOW>;
		pinctrl-names = "default";
	};
};

&pio {
    led_pins: led_pins {
        pins = "PA0";
    };
};

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/device.h>
#include <linux/of.h>
#include <linux/gpio.h>
#include <linux/of_gpio.h>


#define CDEV_NAME "led"
#define LED_NODE_PATH "/led"
#define LED_NODE_PROPERTY "gpios"

int major = -1;
int gpionum = -1;
struct class *cls = NULL;
struct device *dev = NULL;
struct device_node *led_node = NULL;
char kbuf[128] = {0};

ssize_t my_write (struct file *file, const char __user *ubuf, size_t size, loff_t *offset)
{
	size = size > sizeof(kbuf)  ? sizeof(kbuf) : size;
	if(copy_from_user(kbuf, ubuf, size))
	{
		printk("copy data from user failed!\n");
		return -EINVAL;
	}

	if(kbuf[0] == '1')
	{
		gpio_set_value(gpionum,1); //设置高电平
	}
	else
	{
		gpio_set_value(gpionum,0); //设置低电平
	}
	return size;
}

struct file_operations fops = {
	.write = my_write,
};

int gpio_init(void)
{
	//获取节点
	led_node = of_find_node_by_path(LED_NODE_PATH);
	if(led_node == NULL)
	{
		printk("find node %s failed!\n",LED_NODE_PATH );
		return -ENODEV;
	}

	//获取gpio编号
	gpionum = of_get_named_gpio(led_node, LED_NODE_PROPERTY, 0);
	if(gpionum < 0)
	{
		printk("get property %s failed!\n",LED_NODE_PROPERTY );
		return -EINVAL;
	}

	//申请GPIO
	if(gpio_request(gpionum,NULL))
	{
		printk("request gpio failed!\n");
		return -EINVAL;
	}

	
	//设置GPIO为输出
	if(gpio_direction_output(gpionum, 0))
	{
		printk("set gpio direction failed!\n");
		return -EINVAL;
	}
	return 0;
}

static int __init mydev_init(void)
{
	//注册字符设备
	major = register_chrdev(0,CDEV_NAME,&fops);
	if(major < 0)
	{
		printk("register chardev failed! \n");
		return -1;
	}
	
	//自动创建设备节点
	//提交目录信息
	cls = class_create(THIS_MODULE,CDEV_NAME);
	if(IS_ERR(cls))
	{
		printk("auto create node failed! \n");
		return PTR_ERR(cls);
	}
	
	//提交设备信息
	dev = device_create(cls,NULL,MKDEV(major,0),NULL,CDEV_NAME);
	{
		if(IS_ERR(dev))
		{
			printk("device create failed! \n");
			return PTR_ERR(dev);
		}
	}
	
	gpio_init();
    return 0;
}

void gpio_deinit(void)
{
	gpio_set_value(gpionum,0);
	gpio_free(gpionum);
}

static void __exit mydev_exit(void)
{
	gpio_deinit();
	device_destroy(cls, MKDEV(major,0));
	class_destroy(cls);
	unregister_chrdev(major,CDEV_NAME);
}

module_init(mydev_init);
module_exit(mydev_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("yuan u1232@qq.com");
MODULE_VERSION("1.0");

KERNELDIR:=/home/test/lc/buildroot/output/build/linux-5.4.99/  #内核源码路径

ARCH=arm
CROSS_COMPILE=/home/test/lc/buildroot/output/host/bin/arm-buildroot-linux-gnueabi-
export  ARCH  CROSS_COMPILE

obj-m += led.o

module:
	make -C $(KERNELDIR) M=$(CURDIR) ARCH=arm modules
clean:
	make -C $(KERNELDIR) M=$(CURDIR) ARCH=arm clean

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

int main()
{
	int fd = open("/dev/led",O_RDWR);
	if(fd == -1)
	{
		printf("open failed");
		return -1;
	}
	while(1)
	{
		write(fd,"1",1);
		sleep(1);
		write(fd,"0",1);
		sleep(1);
	}
	close(fd);
	return 0;
}