arch/nios2/mm/ioremap.c

   1 /*
   2  * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
   3  * Copyright (C) 2009 Wind River Systems Inc
   4  *   Implemented by fredrik.markstrom@gmail.com and ivarholmqvist@gmail.com
   5  * Copyright (C) 2004 Microtronix Datacom Ltd.
   6  *
   7  * This file is subject to the terms and conditions of the GNU General Public
   8  * License. See the file "COPYING" in the main directory of this archive
   9  * for more details.
  10  */
  11
  12 #include <linux/export.h>
  13 #include <linux/sched.h>
  14 #include <linux/mm.h>
  15 #include <linux/slab.h>
  16 #include <linux/vmalloc.h>
  17 #include <linux/io.h>
  18
  19 #include <asm/cacheflush.h>
  20 #include <asm/tlbflush.h>
  21
  22 static inline void remap_area_pte(pte_t *pte, unsigned long address,
  23                                 unsigned long size, unsigned long phys_addr,
  24                                 unsigned long flags)
  25 {
  26         unsigned long end;
  27         unsigned long pfn;
  28         pgprot_t pgprot = __pgprot(_PAGE_GLOBAL | _PAGE_PRESENT | _PAGE_READ
  29                                 | _PAGE_WRITE | flags);
  30
  31         address &= ~PMD_MASK;
  32         end = address + size;
  33         if (end > PMD_SIZE)
  34                 end = PMD_SIZE;
  35         if (address >= end)
  36                 BUG();
  37         pfn = PFN_DOWN(phys_addr);
  38         do {
  39                 if (!pte_none(*pte)) {
  40                         pr_err("remap_area_pte: page already exists\n");
  41                         BUG();
  42                 }
  43                 set_pte(pte, pfn_pte(pfn, pgprot));
  44                 address += PAGE_SIZE;
  45                 pfn++;
  46                 pte++;
  47         } while (address && (address < end));
  48 }
  49
  50 static inline int remap_area_pmd(pmd_t *pmd, unsigned long address,
  51                                 unsigned long size, unsigned long phys_addr,
  52                                 unsigned long flags)
  53 {
  54         unsigned long end;
  55
  56         address &= ~PGDIR_MASK;
  57         end = address + size;
  58         if (end > PGDIR_SIZE)
  59                 end = PGDIR_SIZE;
  60         phys_addr -= address;
  61         if (address >= end)
  62                 BUG();
  63         do {
  64                 pte_t *pte = pte_alloc_kernel(pmd, address);
  65
  66                 if (!pte)
  67                         return -ENOMEM;
  68                 remap_area_pte(pte, address, end - address, address + phys_addr,
  69                         flags);
  70                 address = (address + PMD_SIZE) & PMD_MASK;
  71                 pmd++;
  72         } while (address && (address < end));
  73         return 0;
  74 }
  75
  76 static int remap_area_pages(unsigned long address, unsigned long phys_addr,
  77                                 unsigned long size, unsigned long flags)
  78 {
  79         int error;
  80         pgd_t *dir;
  81         unsigned long end = address + size;
  82
  83         phys_addr -= address;
  84         dir = pgd_offset(&init_mm, address);
  85         flush_cache_all();
  86         if (address >= end)
  87                 BUG();
  88         do {
  89                 pud_t *pud;
  90                 pmd_t *pmd;
  91
  92                 error = -ENOMEM;
  93                 pud = pud_alloc(&init_mm, dir, address);
  94                 if (!pud)
  95                         break;
  96                 pmd = pmd_alloc(&init_mm, pud, address);
  97                 if (!pmd)
  98                         break;
  99                 if (remap_area_pmd(pmd, address, end - address,
 100                         phys_addr + address, flags))
 101                         break;
 102                 error = 0;
 103                 address = (address + PGDIR_SIZE) & PGDIR_MASK;
 104                 dir++;
 105         } while (address && (address < end));
 106         flush_tlb_all();
 107         return error;
 108 }
 109
 110 #define IS_MAPPABLE_UNCACHEABLE(addr) (addr < 0x20000000UL)
 111
 112 /*
 113  * Map some physical address range into the kernel address space.
 114  */
 115 void __iomem *ioremap(unsigned long phys_addr, unsigned long size)
 116 {
 117         struct vm_struct *area;
 118         unsigned long offset;
 119         unsigned long last_addr;
 120         void *addr;
 121
 122         /* Don't allow wraparound or zero size */
 123         last_addr = phys_addr + size - 1;
 124
 125         if (!size || last_addr < phys_addr)
 126                 return NULL;
 127
 128         /* Don't allow anybody to remap normal RAM that we're using */
 129         if (phys_addr > PHYS_OFFSET && phys_addr < virt_to_phys(high_memory)) {
 130                 char *t_addr, *t_end;
 131                 struct page *page;
 132
 133                 t_addr = __va(phys_addr);
 134                 t_end = t_addr + (size - 1);
 135                 for (page = virt_to_page(t_addr);
 136                         page <= virt_to_page(t_end); page++)
 137                         if (!PageReserved(page))
 138                                 return NULL;
 139         }
 140
 141         /*
 142          * Map uncached objects in the low part of address space to
 143          * CONFIG_NIOS2_IO_REGION_BASE
 144          */
 145         if (IS_MAPPABLE_UNCACHEABLE(phys_addr) &&
 146             IS_MAPPABLE_UNCACHEABLE(last_addr))
 147                 return (void __iomem *)(CONFIG_NIOS2_IO_REGION_BASE + phys_addr);
 148
 149         /* Mappings have to be page-aligned */
 150         offset = phys_addr & ~PAGE_MASK;
 151         phys_addr &= PAGE_MASK;
 152         size = PAGE_ALIGN(last_addr + 1) - phys_addr;
 153
 154         /* Ok, go for it */
 155         area = get_vm_area(size, VM_IOREMAP);
 156         if (!area)
 157                 return NULL;
 158         addr = area->addr;
 159         if (remap_area_pages((unsigned long) addr, phys_addr, size, 0)) {
 160                 vunmap(addr);
 161                 return NULL;
 162         }
 163         return (void __iomem *) (offset + (char *)addr);
 164 }
 165 EXPORT_SYMBOL(ioremap);
 166
 167 /*
 168  * iounmap unmaps nearly everything, so be careful
 169  * it doesn't free currently pointer/page tables anymore but it
 170  * wasn't used anyway and might be added later.
 171  */
 172 void iounmap(void __iomem *addr)
 173 {
 174         struct vm_struct *p;
 175
 176         if ((unsigned long) addr > CONFIG_NIOS2_IO_REGION_BASE)
 177                 return;
 178
 179         p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
 180         if (!p)
 181                 pr_err("iounmap: bad address %p\n", addr);
 182         kfree(p);
 183 }
 184 EXPORT_SYMBOL(iounmap);