// SPDX-License-Identifier: GPL-2.0-only
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/*
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* arc_hostlink.c: Pseudo-driver for Metaware provided "hostlink" facility
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*
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* Allows Linux userland access to host in absence of any peripherals.
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*
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*/
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#include <linux/fs.h> /* file_operations */
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#include <linux/miscdevice.h>
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#include <linux/mm.h> /* VM_IO */
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#include <linux/module.h>
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#include <linux/uaccess.h>
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static unsigned char __HOSTLINK__[4 * PAGE_SIZE] __aligned(PAGE_SIZE);
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static int arc_hl_mmap(struct file *fp, struct vm_area_struct *vma)
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{
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vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
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if (io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
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vma->vm_end - vma->vm_start,
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vma->vm_page_prot)) {
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pr_warn("Hostlink buffer mmap ERROR\n");
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return -EAGAIN;
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}
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return 0;
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}
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static long arc_hl_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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/* we only support, returning the physical addr to mmap in user space */
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put_user((unsigned int)__HOSTLINK__, (int __user *)arg);
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return 0;
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}
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static const struct file_operations arc_hl_fops = {
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.unlocked_ioctl = arc_hl_ioctl,
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.mmap = arc_hl_mmap,
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};
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static struct miscdevice arc_hl_dev = {
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.minor = MISC_DYNAMIC_MINOR,
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.name = "hostlink",
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.fops = &arc_hl_fops
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};
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static int __init arc_hl_init(void)
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{
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pr_info("ARC Hostlink driver mmap at 0x%p\n", __HOSTLINK__);
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return misc_register(&arc_hl_dev);
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}
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module_init(arc_hl_init);
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