1 // SPDX-License-Identifier: GPL-2.0 <<
2 /* 1 /*
3 * Copyright (C) 2020-2022 Loongson Technology !! 2 * arch/i386/mm/ioremap.c
>> 3 *
>> 4 * Re-map IO memory to kernel address space so that we can access it.
>> 5 * This is needed for high PCI addresses that aren't mapped in the
>> 6 * 640k-1MB IO memory area on PC's
>> 7 *
>> 8 * (C) Copyright 1995 1996 Linus Torvalds
4 */ 9 */
5 10
>> 11 #include <linux/vmalloc.h>
>> 12 #include <linux/init.h>
>> 13 #include <linux/slab.h>
6 #include <asm/io.h> 14 #include <asm/io.h>
7 #include <asm-generic/early_ioremap.h> !! 15 #include <asm/pgalloc.h>
>> 16 #include <asm/fixmap.h>
>> 17 #include <asm/cacheflush.h>
>> 18 #include <asm/tlbflush.h>
>> 19 #include <asm/pgtable.h>
8 20
9 void __init __iomem *early_ioremap(u64 phys_ad !! 21 static inline void remap_area_pte(pte_t * pte, unsigned long address, unsigned long size,
>> 22 unsigned long phys_addr, unsigned long flags)
10 { 23 {
11 return ((void __iomem *)TO_CACHE(phys_ !! 24 unsigned long end;
>> 25 unsigned long pfn;
>> 26
>> 27 address &= ~PMD_MASK;
>> 28 end = address + size;
>> 29 if (end > PMD_SIZE)
>> 30 end = PMD_SIZE;
>> 31 if (address >= end)
>> 32 BUG();
>> 33 pfn = phys_addr >> PAGE_SHIFT;
>> 34 do {
>> 35 if (!pte_none(*pte)) {
>> 36 printk("remap_area_pte: page already exists\n");
>> 37 BUG();
>> 38 }
>> 39 set_pte(pte, pfn_pte(pfn, __pgprot(_PAGE_PRESENT | _PAGE_RW |
>> 40 _PAGE_DIRTY | _PAGE_ACCESSED | flags)));
>> 41 address += PAGE_SIZE;
>> 42 pfn++;
>> 43 pte++;
>> 44 } while (address && (address < end));
12 } 45 }
13 46
14 void __init early_iounmap(void __iomem *addr, !! 47 static inline int remap_area_pmd(pmd_t * pmd, unsigned long address, unsigned long size,
>> 48 unsigned long phys_addr, unsigned long flags)
15 { 49 {
>> 50 unsigned long end;
16 51
>> 52 address &= ~PGDIR_MASK;
>> 53 end = address + size;
>> 54 if (end > PGDIR_SIZE)
>> 55 end = PGDIR_SIZE;
>> 56 phys_addr -= address;
>> 57 if (address >= end)
>> 58 BUG();
>> 59 do {
>> 60 pte_t * pte = pte_alloc_kernel(&init_mm, pmd, address);
>> 61 if (!pte)
>> 62 return -ENOMEM;
>> 63 remap_area_pte(pte, address, end - address, address + phys_addr, flags);
>> 64 address = (address + PMD_SIZE) & PMD_MASK;
>> 65 pmd++;
>> 66 } while (address && (address < end));
>> 67 return 0;
17 } 68 }
18 69
19 void *early_memremap_ro(resource_size_t phys_a !! 70 static int remap_area_pages(unsigned long address, unsigned long phys_addr,
>> 71 unsigned long size, unsigned long flags)
20 { 72 {
21 return early_memremap(phys_addr, size) !! 73 int error;
>> 74 pgd_t * dir;
>> 75 unsigned long end = address + size;
>> 76
>> 77 phys_addr -= address;
>> 78 dir = pgd_offset(&init_mm, address);
>> 79 flush_cache_all();
>> 80 if (address >= end)
>> 81 BUG();
>> 82 spin_lock(&init_mm.page_table_lock);
>> 83 do {
>> 84 pmd_t *pmd;
>> 85 pmd = pmd_alloc(&init_mm, dir, address);
>> 86 error = -ENOMEM;
>> 87 if (!pmd)
>> 88 break;
>> 89 if (remap_area_pmd(pmd, address, end - address,
>> 90 phys_addr + address, flags))
>> 91 break;
>> 92 error = 0;
>> 93 address = (address + PGDIR_SIZE) & PGDIR_MASK;
>> 94 dir++;
>> 95 } while (address && (address < end));
>> 96 spin_unlock(&init_mm.page_table_lock);
>> 97 flush_tlb_all();
>> 98 return error;
>> 99 }
>> 100
>> 101 /*
>> 102 * Generic mapping function (not visible outside):
>> 103 */
>> 104
>> 105 /*
>> 106 * Remap an arbitrary physical address space into the kernel virtual
>> 107 * address space. Needed when the kernel wants to access high addresses
>> 108 * directly.
>> 109 *
>> 110 * NOTE! We need to allow non-page-aligned mappings too: we will obviously
>> 111 * have to convert them into an offset in a page-aligned mapping, but the
>> 112 * caller shouldn't need to know that small detail.
>> 113 */
>> 114 void * __ioremap(unsigned long phys_addr, unsigned long size, unsigned long flags)
>> 115 {
>> 116 void * addr;
>> 117 struct vm_struct * area;
>> 118 unsigned long offset, last_addr;
>> 119
>> 120 /* Don't allow wraparound or zero size */
>> 121 last_addr = phys_addr + size - 1;
>> 122 if (!size || last_addr < phys_addr)
>> 123 return NULL;
>> 124
>> 125 /*
>> 126 * Don't remap the low PCI/ISA area, it's always mapped..
>> 127 */
>> 128 if (phys_addr >= 0xA0000 && last_addr < 0x100000)
>> 129 return phys_to_virt(phys_addr);
>> 130
>> 131 /*
>> 132 * Don't allow anybody to remap normal RAM that we're using..
>> 133 */
>> 134 if (phys_addr < virt_to_phys(high_memory)) {
>> 135 char *t_addr, *t_end;
>> 136 struct page *page;
>> 137
>> 138 t_addr = __va(phys_addr);
>> 139 t_end = t_addr + (size - 1);
>> 140
>> 141 for(page = virt_to_page(t_addr); page <= virt_to_page(t_end); page++)
>> 142 if(!PageReserved(page))
>> 143 return NULL;
>> 144 }
>> 145
>> 146 /*
>> 147 * Mappings have to be page-aligned
>> 148 */
>> 149 offset = phys_addr & ~PAGE_MASK;
>> 150 phys_addr &= PAGE_MASK;
>> 151 size = PAGE_ALIGN(last_addr+1) - phys_addr;
>> 152
>> 153 /*
>> 154 * Ok, go for it..
>> 155 */
>> 156 area = get_vm_area(size, VM_IOREMAP);
>> 157 if (!area)
>> 158 return NULL;
>> 159 area->phys_addr = phys_addr;
>> 160 addr = area->addr;
>> 161 if (remap_area_pages((unsigned long) addr, phys_addr, size, flags)) {
>> 162 vunmap(addr);
>> 163 return NULL;
>> 164 }
>> 165 return (void *) (offset + (char *)addr);
22 } 166 }
23 167
24 void *early_memremap_prot(resource_size_t phys !! 168
25 unsigned long prot_val) !! 169 /**
>> 170 * ioremap_nocache - map bus memory into CPU space
>> 171 * @offset: bus address of the memory
>> 172 * @size: size of the resource to map
>> 173 *
>> 174 * ioremap_nocache performs a platform specific sequence of operations to
>> 175 * make bus memory CPU accessible via the readb/readw/readl/writeb/
>> 176 * writew/writel functions and the other mmio helpers. The returned
>> 177 * address is not guaranteed to be usable directly as a virtual
>> 178 * address.
>> 179 *
>> 180 * This version of ioremap ensures that the memory is marked uncachable
>> 181 * on the CPU as well as honouring existing caching rules from things like
>> 182 * the PCI bus. Note that there are other caches and buffers on many
>> 183 * busses. In particular driver authors should read up on PCI writes
>> 184 *
>> 185 * It's useful if some control registers are in such an area and
>> 186 * write combining or read caching is not desirable:
>> 187 *
>> 188 * Must be freed with iounmap.
>> 189 */
>> 190
>> 191 void *ioremap_nocache (unsigned long phys_addr, unsigned long size)
26 { 192 {
27 return early_memremap(phys_addr, size) !! 193 unsigned long last_addr;
>> 194 void *p = __ioremap(phys_addr, size, _PAGE_PCD);
>> 195 if (!p)
>> 196 return p;
>> 197
>> 198 /* Guaranteed to be > phys_addr, as per __ioremap() */
>> 199 last_addr = phys_addr + size - 1;
>> 200
>> 201 if (last_addr < virt_to_phys(high_memory)) {
>> 202 struct page *ppage = virt_to_page(__va(phys_addr));
>> 203 unsigned long npages;
>> 204
>> 205 phys_addr &= PAGE_MASK;
>> 206
>> 207 /* This might overflow and become zero.. */
>> 208 last_addr = PAGE_ALIGN(last_addr);
>> 209
>> 210 /* .. but that's ok, because modulo-2**n arithmetic will make
>> 211 * the page-aligned "last - first" come out right.
>> 212 */
>> 213 npages = (last_addr - phys_addr) >> PAGE_SHIFT;
>> 214
>> 215 if (change_page_attr(ppage, npages, PAGE_KERNEL_NOCACHE) < 0) {
>> 216 iounmap(p);
>> 217 p = NULL;
>> 218 }
>> 219 global_flush_tlb();
>> 220 }
>> 221
>> 222 return p;
>> 223 }
>> 224
>> 225 void iounmap(void *addr)
>> 226 {
>> 227 struct vm_struct *p;
>> 228 if (addr <= high_memory)
>> 229 return;
>> 230 p = remove_vm_area((void *) (PAGE_MASK & (unsigned long) addr));
>> 231 if (!p) {
>> 232 printk("__iounmap: bad address %p\n", addr);
>> 233 return;
>> 234 }
>> 235
>> 236 if (p->flags && p->phys_addr < virt_to_phys(high_memory)) {
>> 237 change_page_attr(virt_to_page(__va(p->phys_addr)),
>> 238 p->size >> PAGE_SHIFT,
>> 239 PAGE_KERNEL);
>> 240 global_flush_tlb();
>> 241 }
>> 242 kfree(p);
>> 243 }
>> 244
>> 245 void __init *bt_ioremap(unsigned long phys_addr, unsigned long size)
>> 246 {
>> 247 unsigned long offset, last_addr;
>> 248 unsigned int nrpages;
>> 249 enum fixed_addresses idx;
>> 250
>> 251 /* Don't allow wraparound or zero size */
>> 252 last_addr = phys_addr + size - 1;
>> 253 if (!size || last_addr < phys_addr)
>> 254 return NULL;
>> 255
>> 256 /*
>> 257 * Don't remap the low PCI/ISA area, it's always mapped..
>> 258 */
>> 259 if (phys_addr >= 0xA0000 && last_addr < 0x100000)
>> 260 return phys_to_virt(phys_addr);
>> 261
>> 262 /*
>> 263 * Mappings have to be page-aligned
>> 264 */
>> 265 offset = phys_addr & ~PAGE_MASK;
>> 266 phys_addr &= PAGE_MASK;
>> 267 size = PAGE_ALIGN(last_addr) - phys_addr;
>> 268
>> 269 /*
>> 270 * Mappings have to fit in the FIX_BTMAP area.
>> 271 */
>> 272 nrpages = size >> PAGE_SHIFT;
>> 273 if (nrpages > NR_FIX_BTMAPS)
>> 274 return NULL;
>> 275
>> 276 /*
>> 277 * Ok, go for it..
>> 278 */
>> 279 idx = FIX_BTMAP_BEGIN;
>> 280 while (nrpages > 0) {
>> 281 set_fixmap(idx, phys_addr);
>> 282 phys_addr += PAGE_SIZE;
>> 283 --idx;
>> 284 --nrpages;
>> 285 }
>> 286 return (void*) (offset + fix_to_virt(FIX_BTMAP_BEGIN));
>> 287 }
>> 288
>> 289 void __init bt_iounmap(void *addr, unsigned long size)
>> 290 {
>> 291 unsigned long virt_addr;
>> 292 unsigned long offset;
>> 293 unsigned int nrpages;
>> 294 enum fixed_addresses idx;
>> 295
>> 296 virt_addr = (unsigned long)addr;
>> 297 if (virt_addr < fix_to_virt(FIX_BTMAP_BEGIN))
>> 298 return;
>> 299 offset = virt_addr & ~PAGE_MASK;
>> 300 nrpages = PAGE_ALIGN(offset + size - 1) >> PAGE_SHIFT;
>> 301
>> 302 idx = FIX_BTMAP_BEGIN;
>> 303 while (nrpages > 0) {
>> 304 clear_fixmap(idx);
>> 305 --idx;
>> 306 --nrpages;
>> 307 }
28 } 308 }
29 309
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