#include <linux/module.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/mutex.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/tty.h>
#include <linux/kmod.h>
#include <linux/gfp.h>
#include <asm/pgtable.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/mman.h>
#include <linux/memblock.h>
#include <linux/memblock.h>
#include <linux/pagemap.h>

#define WEIGHT_ADDR 0x4307F000		// 权重加载的内存地址处
#define MEM_ACCESS_RELEASE_PHYS_ADDR _IOR('M', 0, unsigned int)	// 自定义ioctl命令，用于释放预留内存

static int major = 0;
static struct class *mem_operation_class;

static int check_page_reserved(unsigned long addr)
{
    struct page *page;

    page = pfn_to_page(addr >> PAGE_SHIFT);  // 将虚拟地址转换为页面索引，然后得到页面结构
    if (PageReserved(page)) {
        printk(KERN_INFO "Page at address 0x%lx is reserved.\n", addr);
		return 0;
    } else {
        printk(KERN_INFO "Page at address 0x%lx is not reserved.\n", addr);
		return -1;
    }
}

static int mem_operation_drv_open (struct inode *node, struct file *file)
{
	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
	return 0;
}

static int mem_operation_drv_close (struct inode *node, struct file *file)
{
	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
	return 0;
}

static int mem_operation_drv_mmap(struct file *file, struct vm_area_struct *vma)
{
	unsigned long phy = WEIGHT_ADDR;

	if(check_page_reserved(WEIGHT_ADDR) < 0)
			return -EINVAL;

	/* 设置属性: cache, buffer */
	vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);

	/* map */
	if (remap_pfn_range(vma, vma->vm_start, phy >> PAGE_SHIFT,
			    vma->vm_end - vma->vm_start, vma->vm_page_prot)) {
		printk("mmap remap_pfn_range failed\n");
		return -ENOBUFS;
	}

	return 0;
}

static long mem_operation_drv_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    int ret = 0;

    switch (cmd) {
    case MEM_ACCESS_RELEASE_PHYS_ADDR: {
		unsigned int mem_size;

		if (get_user(mem_size, (unsigned long __user *)arg))
			return -EFAULT;

		if(check_page_reserved(WEIGHT_ADDR) < 0)
			return -EINVAL;

		memblock_free(WEIGHT_ADDR, mem_size);
		free_reserved_area(__va(WEIGHT_ADDR), __va(WEIGHT_ADDR + mem_size), -1, "wakeup_source");
		printk("release phy addr: 0x%x, size: %d\n", WEIGHT_ADDR, mem_size);
        break;
    }
    default:
        ret = -EINVAL;
        break;
    }

    return ret;
}

static struct file_operations mem_operation_drv = {
	.owner	 = THIS_MODULE,
	.open    = mem_operation_drv_open,
	.release = mem_operation_drv_close,
	.mmap    = mem_operation_drv_mmap,
	.unlocked_ioctl = mem_operation_drv_ioctl,
};

static int __init mem_operation_init(void)
{
	int err;

	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
	major = register_chrdev(0, "mem_operation", &mem_operation_drv);  /* /dev/mem_operation */

	mem_operation_class = class_create(THIS_MODULE, "mem_operation_class");
	err = PTR_ERR(mem_operation_class);
	if (IS_ERR(mem_operation_class)) {
		printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
		unregister_chrdev(major, "mem_operation");
		return -1;
	}

	device_create(mem_operation_class, NULL, MKDEV(major, 0), NULL, "mem_operation"); /* 设备节点： /dev/mem_operation */

	return 0;
}

static void __exit mem_operation_exit(void)
{
	printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
	device_destroy(mem_operation_class, MKDEV(major, 0));
	class_destroy(mem_operation_class);
	unregister_chrdev(major, "mem_operation");
}

module_init(mem_operation_init);
module_exit(mem_operation_exit);
MODULE_LICENSE("GPL");