1/*
2 * arc_hostlink.c: Pseudo-driver for Metaware provided "hostlink" facility
3 *
4 * Allows Linux userland access to host in absence of any peripherals.
5 *
6 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13#include <linux/fs.h>		/* file_operations */
14#include <linux/miscdevice.h>
15#include <linux/mm.h>		/* VM_IO */
16#include <linux/module.h>
17#include <linux/uaccess.h>
18
19static unsigned char __HOSTLINK__[4 * PAGE_SIZE] __aligned(PAGE_SIZE);
20
21static int arc_hl_mmap(struct file *fp, struct vm_area_struct *vma)
22{
23	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
24
25	if (io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
26			       vma->vm_end - vma->vm_start,
27			       vma->vm_page_prot)) {
28		pr_warn("Hostlink buffer mmap ERROR\n");
29		return -EAGAIN;
30	}
31	return 0;
32}
33
34static long arc_hl_ioctl(struct file *file, unsigned int cmd,
35			unsigned long arg)
36{
37	/* we only support, returning the physical addr to mmap in user space */
38	put_user((unsigned int)__HOSTLINK__, (int __user *)arg);
39	return 0;
40}
41
42static const struct file_operations arc_hl_fops = {
43	.unlocked_ioctl	= arc_hl_ioctl,
44	.mmap		= arc_hl_mmap,
45};
46
47static struct miscdevice arc_hl_dev = {
48	.minor	= MISC_DYNAMIC_MINOR,
49	.name	= "hostlink",
50	.fops	= &arc_hl_fops
51};
52
53static int __init arc_hl_init(void)
54{
55	pr_info("ARC Hostlink driver mmap at 0x%p\n", __HOSTLINK__);
56	return misc_register(&arc_hl_dev);
57}
58module_init(arc_hl_init);
59