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Linux/arch/unicore32/mm/ioremap.c

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  1 /*
  2  * linux/arch/unicore32/mm/ioremap.c
  3  *
  4  * Code specific to PKUnity SoC and UniCore ISA
  5  *
  6  * Copyright (C) 2001-2010 GUAN Xue-tao
  7  *
  8  * This program is free software; you can redistribute it and/or modify
  9  * it under the terms of the GNU General Public License version 2 as
 10  * published by the Free Software Foundation.
 11  *
 12  *
 13  * Re-map IO memory to kernel address space so that we can access it.
 14  *
 15  * This allows a driver to remap an arbitrary region of bus memory into
 16  * virtual space.  One should *only* use readl, writel, memcpy_toio and
 17  * so on with such remapped areas.
 18  *
 19  * Because UniCore only has a 32-bit address space we can't address the
 20  * whole of the (physical) PCI space at once.  PCI huge-mode addressing
 21  * allows us to circumvent this restriction by splitting PCI space into
 22  * two 2GB chunks and mapping only one at a time into processor memory.
 23  * We use MMU protection domains to trap any attempt to access the bank
 24  * that is not currently mapped.  (This isn't fully implemented yet.)
 25  */
 26 #include <linux/module.h>
 27 #include <linux/errno.h>
 28 #include <linux/mm.h>
 29 #include <linux/vmalloc.h>
 30 #include <linux/io.h>
 31 
 32 #include <asm/cputype.h>
 33 #include <asm/cacheflush.h>
 34 #include <asm/mmu_context.h>
 35 #include <asm/pgalloc.h>
 36 #include <asm/tlbflush.h>
 37 #include <asm/sizes.h>
 38 
 39 #include <mach/map.h>
 40 #include "mm.h"
 41 
 42 /*
 43  * Used by ioremap() and iounmap() code to mark (super)section-mapped
 44  * I/O regions in vm_struct->flags field.
 45  */
 46 #define VM_UNICORE_SECTION_MAPPING      0x80000000
 47 
 48 int ioremap_page(unsigned long virt, unsigned long phys,
 49                  const struct mem_type *mtype)
 50 {
 51         return ioremap_page_range(virt, virt + PAGE_SIZE, phys,
 52                                   __pgprot(mtype->prot_pte));
 53 }
 54 EXPORT_SYMBOL(ioremap_page);
 55 
 56 /*
 57  * Section support is unsafe on SMP - If you iounmap and ioremap a region,
 58  * the other CPUs will not see this change until their next context switch.
 59  * Meanwhile, (eg) if an interrupt comes in on one of those other CPUs
 60  * which requires the new ioremap'd region to be referenced, the CPU will
 61  * reference the _old_ region.
 62  *
 63  * Note that get_vm_area_caller() allocates a guard 4K page, so we need to
 64  * mask the size back to 4MB aligned or we will overflow in the loop below.
 65  */
 66 static void unmap_area_sections(unsigned long virt, unsigned long size)
 67 {
 68         unsigned long addr = virt, end = virt + (size & ~(SZ_4M - 1));
 69         pgd_t *pgd;
 70 
 71         flush_cache_vunmap(addr, end);
 72         pgd = pgd_offset_k(addr);
 73         do {
 74                 pmd_t pmd, *pmdp = pmd_offset((pud_t *)pgd, addr);
 75 
 76                 pmd = *pmdp;
 77                 if (!pmd_none(pmd)) {
 78                         /*
 79                          * Clear the PMD from the page table, and
 80                          * increment the kvm sequence so others
 81                          * notice this change.
 82                          *
 83                          * Note: this is still racy on SMP machines.
 84                          */
 85                         pmd_clear(pmdp);
 86 
 87                         /*
 88                          * Free the page table, if there was one.
 89                          */
 90                         if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_TABLE)
 91                                 pte_free_kernel(&init_mm, pmd_page_vaddr(pmd));
 92                 }
 93 
 94                 addr += PGDIR_SIZE;
 95                 pgd++;
 96         } while (addr < end);
 97 
 98         flush_tlb_kernel_range(virt, end);
 99 }
100 
101 static int
102 remap_area_sections(unsigned long virt, unsigned long pfn,
103                     size_t size, const struct mem_type *type)
104 {
105         unsigned long addr = virt, end = virt + size;
106         pgd_t *pgd;
107 
108         /*
109          * Remove and free any PTE-based mapping, and
110          * sync the current kernel mapping.
111          */
112         unmap_area_sections(virt, size);
113 
114         pgd = pgd_offset_k(addr);
115         do {
116                 pmd_t *pmd = pmd_offset((pud_t *)pgd, addr);
117 
118                 set_pmd(pmd, __pmd(__pfn_to_phys(pfn) | type->prot_sect));
119                 pfn += SZ_4M >> PAGE_SHIFT;
120                 flush_pmd_entry(pmd);
121 
122                 addr += PGDIR_SIZE;
123                 pgd++;
124         } while (addr < end);
125 
126         return 0;
127 }
128 
129 void __iomem *__uc32_ioremap_pfn_caller(unsigned long pfn,
130         unsigned long offset, size_t size, unsigned int mtype, void *caller)
131 {
132         const struct mem_type *type;
133         int err;
134         unsigned long addr;
135         struct vm_struct *area;
136 
137         /*
138          * High mappings must be section aligned
139          */
140         if (pfn >= 0x100000 && (__pfn_to_phys(pfn) & ~SECTION_MASK))
141                 return NULL;
142 
143         /*
144          * Don't allow RAM to be mapped
145          */
146         if (pfn_valid(pfn)) {
147                 WARN(1, "BUG: Your driver calls ioremap() on\n"
148                         "system memory.  This leads to architecturally\n"
149                         "unpredictable behaviour, and ioremap() will fail in\n"
150                         "the next kernel release. Please fix your driver.\n");
151                 return NULL;
152         }
153 
154         type = get_mem_type(mtype);
155         if (!type)
156                 return NULL;
157 
158         /*
159          * Page align the mapping size, taking account of any offset.
160          */
161         size = PAGE_ALIGN(offset + size);
162 
163         area = get_vm_area_caller(size, VM_IOREMAP, caller);
164         if (!area)
165                 return NULL;
166         addr = (unsigned long)area->addr;
167 
168         if (!((__pfn_to_phys(pfn) | size | addr) & ~PMD_MASK)) {
169                 area->flags |= VM_UNICORE_SECTION_MAPPING;
170                 err = remap_area_sections(addr, pfn, size, type);
171         } else
172                 err = ioremap_page_range(addr, addr + size, __pfn_to_phys(pfn),
173                                          __pgprot(type->prot_pte));
174 
175         if (err) {
176                 vunmap((void *)addr);
177                 return NULL;
178         }
179 
180         flush_cache_vmap(addr, addr + size);
181         return (void __iomem *) (offset + addr);
182 }
183 
184 void __iomem *__uc32_ioremap_caller(unsigned long phys_addr, size_t size,
185         unsigned int mtype, void *caller)
186 {
187         unsigned long last_addr;
188         unsigned long offset = phys_addr & ~PAGE_MASK;
189         unsigned long pfn = __phys_to_pfn(phys_addr);
190 
191         /*
192          * Don't allow wraparound or zero size
193          */
194         last_addr = phys_addr + size - 1;
195         if (!size || last_addr < phys_addr)
196                 return NULL;
197 
198         return __uc32_ioremap_pfn_caller(pfn, offset, size, mtype, caller);
199 }
200 
201 /*
202  * Remap an arbitrary physical address space into the kernel virtual
203  * address space. Needed when the kernel wants to access high addresses
204  * directly.
205  *
206  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
207  * have to convert them into an offset in a page-aligned mapping, but the
208  * caller shouldn't need to know that small detail.
209  */
210 void __iomem *
211 __uc32_ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
212                   unsigned int mtype)
213 {
214         return __uc32_ioremap_pfn_caller(pfn, offset, size, mtype,
215                         __builtin_return_address(0));
216 }
217 EXPORT_SYMBOL(__uc32_ioremap_pfn);
218 
219 void __iomem *
220 __uc32_ioremap(unsigned long phys_addr, size_t size)
221 {
222         return __uc32_ioremap_caller(phys_addr, size, MT_DEVICE,
223                         __builtin_return_address(0));
224 }
225 EXPORT_SYMBOL(__uc32_ioremap);
226 
227 void __iomem *
228 __uc32_ioremap_cached(unsigned long phys_addr, size_t size)
229 {
230         return __uc32_ioremap_caller(phys_addr, size, MT_DEVICE_CACHED,
231                         __builtin_return_address(0));
232 }
233 EXPORT_SYMBOL(__uc32_ioremap_cached);
234 
235 void __uc32_iounmap(volatile void __iomem *io_addr)
236 {
237         void *addr = (void *)(PAGE_MASK & (unsigned long)io_addr);
238         struct vm_struct *vm;
239 
240         /*
241          * If this is a section based mapping we need to handle it
242          * specially as the VM subsystem does not know how to handle
243          * such a beast. We need the lock here b/c we need to clear
244          * all the mappings before the area can be reclaimed
245          * by someone else.
246          */
247         vm = find_vm_area(addr);
248         if (vm && (vm->flags & VM_IOREMAP) &&
249                 (vm->flags & VM_UNICORE_SECTION_MAPPING))
250                 unmap_area_sections((unsigned long)vm->addr, vm->size);
251 
252         vunmap(addr);
253 }
254 EXPORT_SYMBOL(__uc32_iounmap);
255 

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