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// 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);
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