x86/mm/iomap_32.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * Copyright © 2008 Ingo Molnar
0004  */
0005
0006 #include <asm/iomap.h>
0007 #include <asm/memtype.h>
0008 #include <linux/export.h>
0009 #include <linux/highmem.h>
0010
0011 static int is_io_mapping_possible(resource_size_t base, unsigned long size)
0012 {
0013 #if !defined(CONFIG_X86_PAE) && defined(CONFIG_PHYS_ADDR_T_64BIT)
0014     /* There is no way to map greater than 1 << 32 address without PAE */
0015     if (base + size > 0x100000000ULL)
0016         return 0;
0017 #endif
0018     return 1;
0019 }
0020
0021 int iomap_create_wc(resource_size_t base, unsigned long size, pgprot_t *prot)
0022 {
0023     enum page_cache_mode pcm = _PAGE_CACHE_MODE_WC;
0024     int ret;
0025
0026     if (!is_io_mapping_possible(base, size))
0027         return -EINVAL;
0028
0029     ret = memtype_reserve_io(base, base + size, &pcm);
0030     if (ret)
0031         return ret;
0032
0033     *prot = __pgprot(__PAGE_KERNEL | cachemode2protval(pcm));
0034     /* Filter out unsupported __PAGE_KERNEL* bits: */
0035     pgprot_val(*prot) &= __default_kernel_pte_mask;
0036
0037     return 0;
0038 }
0039 EXPORT_SYMBOL_GPL(iomap_create_wc);
0040
0041 void iomap_free(resource_size_t base, unsigned long size)
0042 {
0043     memtype_free_io(base, base + size);
0044 }
0045 EXPORT_SYMBOL_GPL(iomap_free);
0046
0047 void __iomem *__iomap_local_pfn_prot(unsigned long pfn, pgprot_t prot)
0048 {
0049     /*
0050      * For non-PAT systems, translate non-WB request to UC- just in
0051      * case the caller set the PWT bit to prot directly without using
0052      * pgprot_writecombine(). UC- translates to uncached if the MTRR
0053      * is UC or WC. UC- gets the real intention, of the user, which is
0054      * "WC if the MTRR is WC, UC if you can't do that."
0055      */
0056     if (!pat_enabled() && pgprot2cachemode(prot) != _PAGE_CACHE_MODE_WB)
0057         prot = __pgprot(__PAGE_KERNEL |
0058                 cachemode2protval(_PAGE_CACHE_MODE_UC_MINUS));
0059
0060     /* Filter out unsupported __PAGE_KERNEL* bits: */
0061     pgprot_val(prot) &= __default_kernel_pte_mask;
0062
0063     return (void __force __iomem *)__kmap_local_pfn_prot(pfn, prot);
0064 }
0065 EXPORT_SYMBOL_GPL(__iomap_local_pfn_prot);