// SPDX-License-Identifier: GPL-2.0-only/* * arc_hostlink.c: Pseudo-driver for Metaware provided "hostlink" facility * * Allows Linux userland access to host in absence of any peripherals. * * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) */ #include <linux/fs.h>		/* file_operations */#include <linux/miscdevice.h>#include <linux/mm.h>		/* VM_IO */#include <linux/module.h>#include <linux/uaccess.h> static unsigned char __HOSTLINK__[4 * PAGE_SIZE] __aligned(PAGE_SIZE); static int arc_hl_mmap(struct file *fp, struct vm_area_struct *vma){	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); 	if (io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,			       vma->vm_end - vma->vm_start,			       vma->vm_page_prot)) {		pr_warn("Hostlink buffer mmap ERROR\n");		return -EAGAIN;	}	return 0;} static long arc_hl_ioctl(struct file *file, unsigned int cmd,			unsigned long arg){	/* we only support, returning the physical addr to mmap in user space */	put_user((unsigned int)__HOSTLINK__, (int __user *)arg);	return 0;} static const struct file_operations arc_hl_fops = {	.unlocked_ioctl	= arc_hl_ioctl,	.mmap		= arc_hl_mmap,}; static struct miscdevice arc_hl_dev = {	.minor	= MISC_DYNAMIC_MINOR,	.name	= "hostlink",	.fops	= &arc_hl_fops}; static int __init arc_hl_init(void){	pr_info("ARC Hostlink driver mmap at 0x%p\n", __HOSTLINK__);	return misc_register(&arc_hl_dev);}module_init(arc_hl_init);