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