WIP FPC-III support
[linux/fpc-iii.git] / arch / arc / kernel / arc_hostlink.c
blob08c5196efe0a00d7fab00f6dd532c1b8a0bdc3d0
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * arc_hostlink.c: Pseudo-driver for Metaware provided "hostlink" facility
5 * Allows Linux userland access to host in absence of any peripherals.
7 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
8 */
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>
16 static unsigned char __HOSTLINK__[4 * PAGE_SIZE] __aligned(PAGE_SIZE);
18 static int arc_hl_mmap(struct file *fp, struct vm_area_struct *vma)
20 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
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;
28 return 0;
31 static long arc_hl_ioctl(struct file *file, unsigned int cmd,
32 unsigned long arg)
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;
39 static const struct file_operations arc_hl_fops = {
40 .unlocked_ioctl = arc_hl_ioctl,
41 .mmap = arc_hl_mmap,
44 static struct miscdevice arc_hl_dev = {
45 .minor = MISC_DYNAMIC_MINOR,
46 .name = "hostlink",
47 .fops = &arc_hl_fops
50 static int __init arc_hl_init(void)
52 pr_info("ARC Hostlink driver mmap at 0x%p\n", __HOSTLINK__);
53 return misc_register(&arc_hl_dev);
55 module_init(arc_hl_init);