1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright © 2008 Ingo Molnar
4 */
5
6 #include <asm/iomap.h>
7 #include <asm/memtype.h>
8 #include <linux/export.h>
9 #include <linux/highmem.h>
10
11 static int is_io_mapping_possible(resource_size_t base, unsigned long size)
12 {
13 #if !defined(CONFIG_X86_PAE) && defined(CONFIG_PHYS_ADDR_T_64BIT)
14 /* There is no way to map greater than 1 << 32 address without PAE */
15 if (base + size > 0x100000000ULL)
16 return 0;
17 #endif
18 return 1;
19 }
20
21 int iomap_create_wc(resource_size_t base, unsigned long size, pgprot_t *prot)
22 {
23 enum page_cache_mode pcm = _PAGE_CACHE_MODE_WC;
24 int ret;
25
26 if (!is_io_mapping_possible(base, size))
27 return -EINVAL;
28
29 ret = memtype_reserve_io(base, base + size, &pcm);
30 if (ret)
31 return ret;
32
33 *prot = __pgprot(__PAGE_KERNEL | cachemode2protval(pcm));
34 /* Filter out unsupported __PAGE_KERNEL* bits: */
35 pgprot_val(*prot) &= __default_kernel_pte_mask;
36
37 return 0;
38 }
39 EXPORT_SYMBOL_GPL(iomap_create_wc);
40
41 void iomap_free(resource_size_t base, unsigned long size)
42 {
43 memtype_free_io(base, base + size);
44 }
45 EXPORT_SYMBOL_GPL(iomap_free);
46
47 void __iomem *__iomap_local_pfn_prot(unsigned long pfn, pgprot_t prot)
48 {
49 /*
50 * For non-PAT systems, translate non-WB request to UC- just in
51 * case the caller set the PWT bit to prot directly without using
52 * pgprot_writecombine(). UC- translates to uncached if the MTRR
53 * is UC or WC. UC- gets the real intention, of the user, which is
54 * "WC if the MTRR is WC, UC if you can't do that."
55 */
56 if (!pat_enabled() && pgprot2cachemode(prot) != _PAGE_CACHE_MODE_WB)
57 prot = __pgprot(__PAGE_KERNEL |
58 cachemode2protval(_PAGE_CACHE_MODE_UC_MINUS));
59
60 /* Filter out unsupported __PAGE_KERNEL* bits: */
61 pgprot_val(prot) &= __default_kernel_pte_mask;
62
63 return (void __force __iomem *)__kmap_local_pfn_prot(pfn, prot);
64 }
65 EXPORT_SYMBOL_GPL(__iomap_local_pfn_prot);
66
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