1/*
 2 * Copyright © 2014 Intel Corporation
 3 *
 4 * Permission is hereby granted, free of charge, to any person obtaining a
 5 * copy of this software and associated documentation files (the "Software"),
 6 * to deal in the Software without restriction, including without limitation
 7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 8 * and/or sell copies of the Software, and to permit persons to whom the
 9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21 * IN THE SOFTWARE.
22 *
23 */
24
25#include <linux/mm.h>
26#include <linux/io-mapping.h>
27
28#include <asm/pgtable.h>
29
30#include "i915_drv.h"
31
32struct remap_pfn {
33	struct mm_struct *mm;
34	unsigned long pfn;
35	pgprot_t prot;
36};
37
38static int remap_pfn(pte_t *pte, pgtable_t token,
39		     unsigned long addr, void *data)
40{
41	struct remap_pfn *r = data;
42
43	/* Special PTE are not associated with any struct page */
44	set_pte_at(r->mm, addr, pte, pte_mkspecial(pfn_pte(r->pfn, r->prot)));
45	r->pfn++;
46
47	return 0;
48}
49
50/**
51 * remap_io_mapping - remap an IO mapping to userspace
52 * @vma: user vma to map to
53 * @addr: target user address to start at
54 * @pfn: physical address of kernel memory
55 * @size: size of map area
56 * @iomap: the source io_mapping
57 *
58 *  Note: this is only safe if the mm semaphore is held when called.
59 */
60int remap_io_mapping(struct vm_area_struct *vma,
61		     unsigned long addr, unsigned long pfn, unsigned long size,
62		     struct io_mapping *iomap)
63{
64	struct remap_pfn r;
65	int err;
66
67	GEM_BUG_ON((vma->vm_flags &
68		    (VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP)) !=
69		   (VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP));
70
71	/* We rely on prevalidation of the io-mapping to skip track_pfn(). */
72	r.mm = vma->vm_mm;
73	r.pfn = pfn;
74	r.prot = __pgprot((pgprot_val(iomap->prot) & _PAGE_CACHE_MASK) |
75			  (pgprot_val(vma->vm_page_prot) & ~_PAGE_CACHE_MASK));
76
77	err = apply_to_page_range(r.mm, addr, size, remap_pfn, &r);
78	if (unlikely(err)) {
79		zap_vma_ptes(vma, addr, (r.pfn - pfn) << PAGE_SHIFT);
80		return err;
81	}
82
83	return 0;
84}