lib/ioremap.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Re-map IO memory to kernel address space so that we can access it.
   4  * This is needed for high PCI addresses that aren't mapped in the
   5  * 640k-1MB IO memory area on PC's
   6  *
   7  * (C) Copyright 1995 1996 Linus Torvalds
   8  */
   9 #include <linux/vmalloc.h>
  10 #include <linux/mm.h>
  11 #include <linux/sched.h>
  12 #include <linux/io.h>
  13 #include <linux/export.h>
  14 #include <asm/cacheflush.h>
  15 #include <asm/pgtable.h>
  16
  17 #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
  18 static int __read_mostly ioremap_p4d_capable;
  19 static int __read_mostly ioremap_pud_capable;
  20 static int __read_mostly ioremap_pmd_capable;
  21 static int __read_mostly ioremap_huge_disabled;
  22
  23 static int __init set_nohugeiomap(char *str)
  24 {
  25         ioremap_huge_disabled = 1;
  26         return 0;
  27 }
  28 early_param("nohugeiomap", set_nohugeiomap);
  29
  30 void __init ioremap_huge_init(void)
  31 {
  32         if (!ioremap_huge_disabled) {
  33                 if (arch_ioremap_pud_supported())
  34                         ioremap_pud_capable = 1;
  35                 if (arch_ioremap_pmd_supported())
  36                         ioremap_pmd_capable = 1;
  37         }
  38 }
  39
  40 static inline int ioremap_p4d_enabled(void)
  41 {
  42         return ioremap_p4d_capable;
  43 }
  44
  45 static inline int ioremap_pud_enabled(void)
  46 {
  47         return ioremap_pud_capable;
  48 }
  49
  50 static inline int ioremap_pmd_enabled(void)
  51 {
  52         return ioremap_pmd_capable;
  53 }
  54
  55 #else   /* !CONFIG_HAVE_ARCH_HUGE_VMAP */
  56 static inline int ioremap_p4d_enabled(void) { return 0; }
  57 static inline int ioremap_pud_enabled(void) { return 0; }
  58 static inline int ioremap_pmd_enabled(void) { return 0; }
  59 #endif  /* CONFIG_HAVE_ARCH_HUGE_VMAP */
  60
  61 static int ioremap_pte_range(pmd_t *pmd, unsigned long addr,
  62                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
  63 {
  64         pte_t *pte;
  65         u64 pfn;
  66
  67         pfn = phys_addr >> PAGE_SHIFT;
  68         pte = pte_alloc_kernel(pmd, addr);
  69         if (!pte)
  70                 return -ENOMEM;
  71         do {
  72                 BUG_ON(!pte_none(*pte));
  73                 set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot));
  74                 pfn++;
  75         } while (pte++, addr += PAGE_SIZE, addr != end);
  76         return 0;
  77 }
  78
  79 static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr,
  80                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
  81 {
  82         pmd_t *pmd;
  83         unsigned long next;
  84
  85         phys_addr -= addr;
  86         pmd = pmd_alloc(&init_mm, pud, addr);
  87         if (!pmd)
  88                 return -ENOMEM;
  89         do {
  90                 next = pmd_addr_end(addr, end);
  91
  92                 if (ioremap_pmd_enabled() &&
  93                     ((next - addr) == PMD_SIZE) &&
  94                     IS_ALIGNED(phys_addr + addr, PMD_SIZE) &&
  95                     pmd_free_pte_page(pmd)) {
  96                         if (pmd_set_huge(pmd, phys_addr + addr, prot))
  97                                 continue;
  98                 }
  99
 100                 if (ioremap_pte_range(pmd, addr, next, phys_addr + addr, prot))
 101                         return -ENOMEM;
 102         } while (pmd++, addr = next, addr != end);
 103         return 0;
 104 }
 105
 106 static inline int ioremap_pud_range(p4d_t *p4d, unsigned long addr,
 107                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
 108 {
 109         pud_t *pud;
 110         unsigned long next;
 111
 112         phys_addr -= addr;
 113         pud = pud_alloc(&init_mm, p4d, addr);
 114         if (!pud)
 115                 return -ENOMEM;
 116         do {
 117                 next = pud_addr_end(addr, end);
 118
 119                 if (ioremap_pud_enabled() &&
 120                     ((next - addr) == PUD_SIZE) &&
 121                     IS_ALIGNED(phys_addr + addr, PUD_SIZE) &&
 122                     pud_free_pmd_page(pud)) {
 123                         if (pud_set_huge(pud, phys_addr + addr, prot))
 124                                 continue;
 125                 }
 126
 127                 if (ioremap_pmd_range(pud, addr, next, phys_addr + addr, prot))
 128                         return -ENOMEM;
 129         } while (pud++, addr = next, addr != end);
 130         return 0;
 131 }
 132
 133 static inline int ioremap_p4d_range(pgd_t *pgd, unsigned long addr,
 134                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
 135 {
 136         p4d_t *p4d;
 137         unsigned long next;
 138
 139         phys_addr -= addr;
 140         p4d = p4d_alloc(&init_mm, pgd, addr);
 141         if (!p4d)
 142                 return -ENOMEM;
 143         do {
 144                 next = p4d_addr_end(addr, end);
 145
 146                 if (ioremap_p4d_enabled() &&
 147                     ((next - addr) == P4D_SIZE) &&
 148                     IS_ALIGNED(phys_addr + addr, P4D_SIZE)) {
 149                         if (p4d_set_huge(p4d, phys_addr + addr, prot))
 150                                 continue;
 151                 }
 152
 153                 if (ioremap_pud_range(p4d, addr, next, phys_addr + addr, prot))
 154                         return -ENOMEM;
 155         } while (p4d++, addr = next, addr != end);
 156         return 0;
 157 }
 158
 159 int ioremap_page_range(unsigned long addr,
 160                        unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
 161 {
 162         pgd_t *pgd;
 163         unsigned long start;
 164         unsigned long next;
 165         int err;
 166
 167         might_sleep();
 168         BUG_ON(addr >= end);
 169
 170         start = addr;
 171         phys_addr -= addr;
 172         pgd = pgd_offset_k(addr);
 173         do {
 174                 next = pgd_addr_end(addr, end);
 175                 err = ioremap_p4d_range(pgd, addr, next, phys_addr+addr, prot);
 176                 if (err)
 177                         break;
 178         } while (pgd++, addr = next, addr != end);
 179
 180         flush_cache_vmap(start, end);
 181
 182         return err;
 183 }