arch/unicore32/mm/ioremap.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/arch/unicore32/mm/ioremap.c
   4  *
   5  * Code specific to PKUnity SoC and UniCore ISA
   6  *
   7  * Copyright (C) 2001-2010 GUAN Xue-tao
   8  *
   9  * Re-map IO memory to kernel address space so that we can access it.
  10  *
  11  * This allows a driver to remap an arbitrary region of bus memory into
  12  * virtual space.  One should *only* use readl, writel, memcpy_toio and
  13  * so on with such remapped areas.
  14  *
  15  * Because UniCore only has a 32-bit address space we can't address the
  16  * whole of the (physical) PCI space at once.  PCI huge-mode addressing
  17  * allows us to circumvent this restriction by splitting PCI space into
  18  * two 2GB chunks and mapping only one at a time into processor memory.
  19  * We use MMU protection domains to trap any attempt to access the bank
  20  * that is not currently mapped.  (This isn't fully implemented yet.)
  21  */
  22 #include <linux/module.h>
  23 #include <linux/errno.h>
  24 #include <linux/mm.h>
  25 #include <linux/vmalloc.h>
  26 #include <linux/io.h>
  27
  28 #include <asm/cputype.h>
  29 #include <asm/cacheflush.h>
  30 #include <asm/mmu_context.h>
  31 #include <asm/pgalloc.h>
  32 #include <asm/tlbflush.h>
  33 #include <linux/sizes.h>
  34
  35 #include <mach/map.h>
  36 #include "mm.h"
  37
  38 /*
  39  * Used by ioremap() and iounmap() code to mark (super)section-mapped
  40  * I/O regions in vm_struct->flags field.
  41  */
  42 #define VM_UNICORE_SECTION_MAPPING      0x80000000
  43
  44 int ioremap_page(unsigned long virt, unsigned long phys,
  45                  const struct mem_type *mtype)
  46 {
  47         return ioremap_page_range(virt, virt + PAGE_SIZE, phys,
  48                                   __pgprot(mtype->prot_pte));
  49 }
  50 EXPORT_SYMBOL(ioremap_page);
  51
  52 /*
  53  * Section support is unsafe on SMP - If you iounmap and ioremap a region,
  54  * the other CPUs will not see this change until their next context switch.
  55  * Meanwhile, (eg) if an interrupt comes in on one of those other CPUs
  56  * which requires the new ioremap'd region to be referenced, the CPU will
  57  * reference the _old_ region.
  58  *
  59  * Note that get_vm_area_caller() allocates a guard 4K page, so we need to
  60  * mask the size back to 4MB aligned or we will overflow in the loop below.
  61  */
  62 static void unmap_area_sections(unsigned long virt, unsigned long size)
  63 {
  64         unsigned long addr = virt, end = virt + (size & ~(SZ_4M - 1));
  65         pgd_t *pgd;
  66
  67         flush_cache_vunmap(addr, end);
  68         pgd = pgd_offset_k(addr);
  69         do {
  70                 pmd_t pmd, *pmdp = pmd_offset((pud_t *)pgd, addr);
  71
  72                 pmd = *pmdp;
  73                 if (!pmd_none(pmd)) {
  74                         /*
  75                          * Clear the PMD from the page table, and
  76                          * increment the kvm sequence so others
  77                          * notice this change.
  78                          *
  79                          * Note: this is still racy on SMP machines.
  80                          */
  81                         pmd_clear(pmdp);
  82
  83                         /*
  84                          * Free the page table, if there was one.
  85                          */
  86                         if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_TABLE)
  87                                 pte_free_kernel(&init_mm, pmd_page_vaddr(pmd));
  88                 }
  89
  90                 addr += PGDIR_SIZE;
  91                 pgd++;
  92         } while (addr < end);
  93
  94         flush_tlb_kernel_range(virt, end);
  95 }
  96
  97 static int
  98 remap_area_sections(unsigned long virt, unsigned long pfn,
  99                     size_t size, const struct mem_type *type)
 100 {
 101         unsigned long addr = virt, end = virt + size;
 102         pgd_t *pgd;
 103
 104         /*
 105          * Remove and free any PTE-based mapping, and
 106          * sync the current kernel mapping.
 107          */
 108         unmap_area_sections(virt, size);
 109
 110         pgd = pgd_offset_k(addr);
 111         do {
 112                 pmd_t *pmd = pmd_offset((pud_t *)pgd, addr);
 113
 114                 set_pmd(pmd, __pmd(__pfn_to_phys(pfn) | type->prot_sect));
 115                 pfn += SZ_4M >> PAGE_SHIFT;
 116                 flush_pmd_entry(pmd);
 117
 118                 addr += PGDIR_SIZE;
 119                 pgd++;
 120         } while (addr < end);
 121
 122         return 0;
 123 }
 124
 125 void __iomem *__uc32_ioremap_pfn_caller(unsigned long pfn,
 126         unsigned long offset, size_t size, unsigned int mtype, void *caller)
 127 {
 128         const struct mem_type *type;
 129         int err;
 130         unsigned long addr;
 131         struct vm_struct *area;
 132
 133         /*
 134          * High mappings must be section aligned
 135          */
 136         if (pfn >= 0x100000 && (__pfn_to_phys(pfn) & ~SECTION_MASK))
 137                 return NULL;
 138
 139         /*
 140          * Don't allow RAM to be mapped
 141          */
 142         if (pfn_valid(pfn)) {
 143                 WARN(1, "BUG: Your driver calls ioremap() on\n"
 144                         "system memory.  This leads to architecturally\n"
 145                         "unpredictable behaviour, and ioremap() will fail in\n"
 146                         "the next kernel release. Please fix your driver.\n");
 147                 return NULL;
 148         }
 149
 150         type = get_mem_type(mtype);
 151         if (!type)
 152                 return NULL;
 153
 154         /*
 155          * Page align the mapping size, taking account of any offset.
 156          */
 157         size = PAGE_ALIGN(offset + size);
 158
 159         area = get_vm_area_caller(size, VM_IOREMAP, caller);
 160         if (!area)
 161                 return NULL;
 162         addr = (unsigned long)area->addr;
 163
 164         if (!((__pfn_to_phys(pfn) | size | addr) & ~PMD_MASK)) {
 165                 area->flags |= VM_UNICORE_SECTION_MAPPING;
 166                 err = remap_area_sections(addr, pfn, size, type);
 167         } else
 168                 err = ioremap_page_range(addr, addr + size, __pfn_to_phys(pfn),
 169                                          __pgprot(type->prot_pte));
 170
 171         if (err) {
 172                 vunmap((void *)addr);
 173                 return NULL;
 174         }
 175
 176         flush_cache_vmap(addr, addr + size);
 177         return (void __iomem *) (offset + addr);
 178 }
 179
 180 void __iomem *__uc32_ioremap_caller(unsigned long phys_addr, size_t size,
 181         unsigned int mtype, void *caller)
 182 {
 183         unsigned long last_addr;
 184         unsigned long offset = phys_addr & ~PAGE_MASK;
 185         unsigned long pfn = __phys_to_pfn(phys_addr);
 186
 187         /*
 188          * Don't allow wraparound or zero size
 189          */
 190         last_addr = phys_addr + size - 1;
 191         if (!size || last_addr < phys_addr)
 192                 return NULL;
 193
 194         return __uc32_ioremap_pfn_caller(pfn, offset, size, mtype, caller);
 195 }
 196
 197 /*
 198  * Remap an arbitrary physical address space into the kernel virtual
 199  * address space. Needed when the kernel wants to access high addresses
 200  * directly.
 201  *
 202  * NOTE! We need to allow non-page-aligned mappings too: we will obviously
 203  * have to convert them into an offset in a page-aligned mapping, but the
 204  * caller shouldn't need to know that small detail.
 205  */
 206 void __iomem *
 207 __uc32_ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
 208                   unsigned int mtype)
 209 {
 210         return __uc32_ioremap_pfn_caller(pfn, offset, size, mtype,
 211                         __builtin_return_address(0));
 212 }
 213 EXPORT_SYMBOL(__uc32_ioremap_pfn);
 214
 215 void __iomem *
 216 __uc32_ioremap(unsigned long phys_addr, size_t size)
 217 {
 218         return __uc32_ioremap_caller(phys_addr, size, MT_DEVICE,
 219                         __builtin_return_address(0));
 220 }
 221 EXPORT_SYMBOL(__uc32_ioremap);
 222
 223 void __uc32_iounmap(volatile void __iomem *io_addr)
 224 {
 225         void *addr = (void *)(PAGE_MASK & (unsigned long)io_addr);
 226         struct vm_struct *vm;
 227
 228         /*
 229          * If this is a section based mapping we need to handle it
 230          * specially as the VM subsystem does not know how to handle
 231          * such a beast. We need the lock here b/c we need to clear
 232          * all the mappings before the area can be reclaimed
 233          * by someone else.
 234          */
 235         vm = find_vm_area(addr);
 236         if (vm && (vm->flags & VM_IOREMAP) &&
 237                 (vm->flags & VM_UNICORE_SECTION_MAPPING))
 238                 unmap_area_sections((unsigned long)vm->addr, vm->size);
 239
 240         vunmap(addr);
 241 }
 242 EXPORT_SYMBOL(__uc32_iounmap);