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Linux/lib/ioremap.c

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

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