1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * arc_hostlink.c: Pseudo-driver for Metaware provided "hostlink" facility
4 *
5 * Allows Linux userland access to host in absence of any peripherals.
6 *
7 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
8 */
9
10 #include <linux/fs.h> /* file_operations */
11 #include <linux/miscdevice.h>
12 #include <linux/mm.h> /* VM_IO */
13 #include <linux/module.h>
14 #include <linux/uaccess.h>
15
16 static unsigned char __HOSTLINK__[4 * PAGE_SIZE] __aligned(PAGE_SIZE);
17
18 static int arc_hl_mmap(struct file *fp, struct vm_area_struct *vma)
19 {
20 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
21
22 if (io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
23 vma->vm_end - vma->vm_start,
24 vma->vm_page_prot)) {
25 pr_warn("Hostlink buffer mmap ERROR\n");
26 return -EAGAIN;
27 }
28 return 0;
29 }
30
31 static long arc_hl_ioctl(struct file *file, unsigned int cmd,
32 unsigned long arg)
33 {
34 /* we only support, returning the physical addr to mmap in user space */
35 put_user((unsigned int)__HOSTLINK__, (int __user *)arg);
36 return 0;
37 }
38
39 static const struct file_operations arc_hl_fops = {
40 .unlocked_ioctl = arc_hl_ioctl,
41 .mmap = arc_hl_mmap,
42 };
43
44 static struct miscdevice arc_hl_dev = {
45 .minor = MISC_DYNAMIC_MINOR,
46 .name = "hostlink",
47 .fops = &arc_hl_fops
48 };
49
50 static int __init arc_hl_init(void)
51 {
52 pr_info("ARC Hostlink driver mmap at 0x%p\n", __HOSTLINK__);
53 return misc_register(&arc_hl_dev);
54 }
55 module_init(arc_hl_init);
56
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