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 int ioremap_try_huge_pmd(pmd_t *pmd, unsigned long addr,
  80                                 unsigned long end, phys_addr_t phys_addr,
  81                                 pgprot_t prot)
  82 {
  83         if (!ioremap_pmd_enabled())
  84                 return 0;
  85
  86         if ((end - addr) != PMD_SIZE)
  87                 return 0;
  88
  89         if (!IS_ALIGNED(phys_addr, PMD_SIZE))
  90                 return 0;
  91
  92         if (pmd_present(*pmd) && !pmd_free_pte_page(pmd, addr))
  93                 return 0;
  94
  95         return pmd_set_huge(pmd, phys_addr, prot);
  96 }
  97
  98 static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr,
  99                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
 100 {
 101         pmd_t *pmd;
 102         unsigned long next;
 103
 104         phys_addr -= addr;
 105         pmd = pmd_alloc(&init_mm, pud, addr);
 106         if (!pmd)
 107                 return -ENOMEM;
 108         do {
 109                 next = pmd_addr_end(addr, end);
 110
 111                 if (ioremap_try_huge_pmd(pmd, addr, next, phys_addr + addr, prot))
 112                         continue;
 113
 114                 if (ioremap_pte_range(pmd, addr, next, phys_addr + addr, prot))
 115                         return -ENOMEM;
 116         } while (pmd++, addr = next, addr != end);
 117         return 0;
 118 }
 119
 120 static int ioremap_try_huge_pud(pud_t *pud, unsigned long addr,
 121                                 unsigned long end, phys_addr_t phys_addr,
 122                                 pgprot_t prot)
 123 {
 124         if (!ioremap_pud_enabled())
 125                 return 0;
 126
 127         if ((end - addr) != PUD_SIZE)
 128                 return 0;
 129
 130         if (!IS_ALIGNED(phys_addr, PUD_SIZE))
 131                 return 0;
 132
 133         if (pud_present(*pud) && !pud_free_pmd_page(pud, addr))
 134                 return 0;
 135
 136         return pud_set_huge(pud, phys_addr, prot);
 137 }
 138
 139 static inline int ioremap_pud_range(p4d_t *p4d, unsigned long addr,
 140                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
 141 {
 142         pud_t *pud;
 143         unsigned long next;
 144
 145         phys_addr -= addr;
 146         pud = pud_alloc(&init_mm, p4d, addr);
 147         if (!pud)
 148                 return -ENOMEM;
 149         do {
 150                 next = pud_addr_end(addr, end);
 151
 152                 if (ioremap_try_huge_pud(pud, addr, next, phys_addr + addr, prot))
 153                         continue;
 154
 155                 if (ioremap_pmd_range(pud, addr, next, phys_addr + addr, prot))
 156                         return -ENOMEM;
 157         } while (pud++, addr = next, addr != end);
 158         return 0;
 159 }
 160
 161 static inline int ioremap_p4d_range(pgd_t *pgd, unsigned long addr,
 162                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
 163 {
 164         p4d_t *p4d;
 165         unsigned long next;
 166
 167         phys_addr -= addr;
 168         p4d = p4d_alloc(&init_mm, pgd, addr);
 169         if (!p4d)
 170                 return -ENOMEM;
 171         do {
 172                 next = p4d_addr_end(addr, end);
 173
 174                 if (ioremap_p4d_enabled() &&
 175                     ((next - addr) == P4D_SIZE) &&
 176                     IS_ALIGNED(phys_addr + addr, P4D_SIZE)) {
 177                         if (p4d_set_huge(p4d, phys_addr + addr, prot))
 178                                 continue;
 179                 }
 180
 181                 if (ioremap_pud_range(p4d, addr, next, phys_addr + addr, prot))
 182                         return -ENOMEM;
 183         } while (p4d++, addr = next, addr != end);
 184         return 0;
 185 }
 186
 187 int ioremap_page_range(unsigned long addr,
 188                        unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
 189 {
 190         pgd_t *pgd;
 191         unsigned long start;
 192         unsigned long next;
 193         int err;
 194
 195         might_sleep();
 196         BUG_ON(addr >= end);
 197
 198         start = addr;
 199         phys_addr -= addr;
 200         pgd = pgd_offset_k(addr);
 201         do {
 202                 next = pgd_addr_end(addr, end);
 203                 err = ioremap_p4d_range(pgd, addr, next, phys_addr+addr, prot);
 204                 if (err)
 205                         break;
 206         } while (pgd++, addr = next, addr != end);
 207
 208         flush_cache_vmap(start, end);
 209
 210         return err;
 211 }