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TOMOYO Linux Cross Reference
Linux/arch/nios2/mm/ioremap.c

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  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                         unsigned long cacheflag)
117 {
118         struct vm_struct *area;
119         unsigned long offset;
120         unsigned long last_addr;
121         void *addr;
122 
123         /* Don't allow wraparound or zero size */
124         last_addr = phys_addr + size - 1;
125 
126         if (!size || last_addr < phys_addr)
127                 return NULL;
128 
129         /* Don't allow anybody to remap normal RAM that we're using */
130         if (phys_addr > PHYS_OFFSET && phys_addr < virt_to_phys(high_memory)) {
131                 char *t_addr, *t_end;
132                 struct page *page;
133 
134                 t_addr = __va(phys_addr);
135                 t_end = t_addr + (size - 1);
136                 for (page = virt_to_page(t_addr);
137                         page <= virt_to_page(t_end); page++)
138                         if (!PageReserved(page))
139                                 return NULL;
140         }
141 
142         /*
143          * Map uncached objects in the low part of address space to
144          * CONFIG_NIOS2_IO_REGION_BASE
145          */
146         if (IS_MAPPABLE_UNCACHEABLE(phys_addr) &&
147             IS_MAPPABLE_UNCACHEABLE(last_addr) &&
148             !(cacheflag & _PAGE_CACHED))
149                 return (void __iomem *)(CONFIG_NIOS2_IO_REGION_BASE + phys_addr);
150 
151         /* Mappings have to be page-aligned */
152         offset = phys_addr & ~PAGE_MASK;
153         phys_addr &= PAGE_MASK;
154         size = PAGE_ALIGN(last_addr + 1) - phys_addr;
155 
156         /* Ok, go for it */
157         area = get_vm_area(size, VM_IOREMAP);
158         if (!area)
159                 return NULL;
160         addr = area->addr;
161         if (remap_area_pages((unsigned long) addr, phys_addr, size,
162                 cacheflag)) {
163                 vunmap(addr);
164                 return NULL;
165         }
166         return (void __iomem *) (offset + (char *)addr);
167 }
168 EXPORT_SYMBOL(__ioremap);
169 
170 /*
171  * __iounmap unmaps nearly everything, so be careful
172  * it doesn't free currently pointer/page tables anymore but it
173  * wasn't used anyway and might be added later.
174  */
175 void __iounmap(void __iomem *addr)
176 {
177         struct vm_struct *p;
178 
179         if ((unsigned long) addr > CONFIG_NIOS2_IO_REGION_BASE)
180                 return;
181 
182         p = remove_vm_area((void *) (PAGE_MASK & (unsigned long __force) addr));
183         if (!p)
184                 pr_err("iounmap: bad address %p\n", addr);
185         kfree(p);
186 }
187 EXPORT_SYMBOL(__iounmap);
188 

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