Linux char device to handle with IRQ

#include <linux/module.h>
#include <linux/kernel.h>    /* printk() */
#include <linux/moduleparam.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <linux/fs.h>
#include <linux/gfp.h>
#include <linux/cdev.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h> 
#include <linux/semaphore.h>


DECLARE_WAIT_QUEUE_HEAD(hq);
static int irq_num;

static int x=0;
//spinlock_t mLock = SPIN_LOCK_UNLOCKED;
unsigned long flags;
static DEFINE_SPINLOCK(mLock);

static irqreturn_t fpga_irq_handle(int irq, void *dev_id)

{
    wake_up(&hq);
//    printk(KERN_DEBUG "Interrupt\n");
        return IRQ_HANDLED;
}

    static ssize_t
fpga_read(struct file *file, char __user *buf,size_t count,loff_t *ppos)
{
    wait_event(hq,x);    
    return 0;
}

static struct file_operations fpga_fops =
{
    .owner = THIS_MODULE,
    .read = fpga_read,
};

static struct cdev *fpga_cdev;
#define DEVNAME "fpga-irq"

static int
fpga_init (void)
{
    int  res;
    struct device_node * np = NULL;
    res = request_irq(irq_num, fpga_irq_handle, 0, DEVNAME,0  );
    if (res ) {
        printk (KERN_INFO "failed to request IRQ%u: %d\n",irq_num, res);
        return res;   

    }
    printk("OK to request IRQ: %u\n",irq_num);
    if(register_chrdev_region(MKDEV(230,0),1,"fpga"))
    {
        printk (KERN_INFO "alloc chrdev error.\n");
        return -1;
    }
    fpga_cdev=cdev_alloc();
    if(!fpga_cdev)
    {
        printk (KERN_INFO "cdev alloc error.\n");
        return -1;
    }
    fpga_cdev->ops = &fpga_fops;
    fpga_cdev->owner = THIS_MODULE;

    if(cdev_add(fpga_cdev,MKDEV(230,0),1))
    {
        printk (KERN_INFO "cdev add error.\n");
        return -1;
    }

    return 0;

}

static void
fpga_cleanup (void)
{

    printk (KERN_INFO "hello unloaded succefully.\n");
    free_irq(irq_num,fpga_irq_handle);

}

module_init (fpga_init);
module_exit (fpga_cleanup);
MODULE_LICENSE("GPL");

obj-m += fpga.o

all:
    make -C /path/to/kernel  M=$(PWD) ARCH=arm64 CROSS_COMPILE=/opt/fsl-imx-xwayland/4.14-sumo/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-   modules

clean:
    make -C /path/to/kernel M=$(PWD)  ARCH=arm64 CROSS_COMPILE=/opt/fsl-imx-xwayland/4.14-sumo/sysroots/x86_64-pokysdk-linux/usr/bin/aarch64-poky-linux/aarch64-poky-linux-  modules  clean

#include<stdio.h>
#include<fcntl.h>
#include<unistd.h>
#include<sys/ioctl.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <pthread.h>


void *thread_isr(void *p)
{
    char buf[100];
    int fd,led_fd;
    fd=open("/dev/fpga",O_RDONLY);
    led_fd=open("/sys/class/gpio/gpio100/value",O_WRONLY);

    while(1)
    {
        write(led_fd,"1",1);        
        read(fd,buf,1);
        write(led_fd,"0",1);
        usleep(400);
        
    //    printf("Interrupt handler\n");
        write(led_fd,"1",1);
        
        
    }

}

int main()
{
    pthread_t t1;
    puts("start");
    pthread_create(&t1,NULL,thread_isr,NULL);
    while (1)
        sleep(500);
    return 1;
}

$CC test.c -o test -lpthread  -g -O2
scp test root@a.b.c.d:/home/root #a.b.c.d is the target ip address

insmod fpga.ko
mknod /dev/fpga c 230 0
echo  100 > /sys/class/gpio/export 
echo "out" > /sys/class/gpio/gpio100/direction
echo 1 > /sys/class/gpio/gpio100/value
echo 0 > /sys/class/gpio/gpio100/value