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, addr: vma->vm_start, pfn: vma->vm_pgoff, |
23 | size: vma->vm_end - vma->vm_start, |
24 | prot: 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(misc: &arc_hl_dev); |
54 | } |
55 | module_init(arc_hl_init); |
56 | |