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
  48int 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}
  54EXPORT_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 */
  66static 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
 101static int
 102remap_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
 129void __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                printk(KERN_WARNING "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                WARN_ON(1);
 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
 184void __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 */
 210void __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}
 217EXPORT_SYMBOL(__uc32_ioremap_pfn);
 218
 219void __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}
 225EXPORT_SYMBOL(__uc32_ioremap);
 226
 227void __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}
 233EXPORT_SYMBOL(__uc32_ioremap_cached);
 234
 235void __uc32_iounmap(volatile void __iomem *io_addr)
 236{
 237        void *addr = (void *)(PAGE_MASK & (unsigned long)io_addr);
 238        struct vm_struct **p, *tmp;
 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        write_lock(&vmlist_lock);
 248        for (p = &vmlist ; (tmp = *p) ; p = &tmp->next) {
 249                if ((tmp->flags & VM_IOREMAP) && (tmp->addr == addr)) {
 250                        if (tmp->flags & VM_UNICORE_SECTION_MAPPING) {
 251                                unmap_area_sections((unsigned long)tmp->addr,
 252                                                    tmp->size);
 253                        }
 254                        break;
 255                }
 256        }
 257        write_unlock(&vmlist_lock);
 258
 259        vunmap(addr);
 260}
 261EXPORT_SYMBOL(__uc32_iounmap);
 262