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   1 /*
   2  *  linux/arch/arm/mm/consistent.c
   3  *
   4  *  Copyright (C) 2000-2004 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  *  DMA uncached mapping support.
  11  */
  12 #include <linux/module.h>
  13 #include <linux/mm.h>
  14 #include <linux/slab.h>
  15 #include <linux/errno.h>
  16 #include <linux/list.h>
  17 #include <linux/init.h>
  18 #include <linux/device.h>
  19 #include <linux/dma-mapping.h>
  20
  21 #include <asm/memory.h>
  22 #include <asm/cacheflush.h>
  23 #include <asm/tlbflush.h>
  24 #include <asm/sizes.h>
  25
  26 /* Sanity check size */
  27 #if (CONSISTENT_DMA_SIZE % SZ_2M)
  28 #error "CONSISTENT_DMA_SIZE must be multiple of 2MiB"
  29 #endif
  30
  31 #define CONSISTENT_END  (0xffe00000)
  32 #define CONSISTENT_BASE (CONSISTENT_END - CONSISTENT_DMA_SIZE)
  33
  34 #define CONSISTENT_OFFSET(x)    (((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)
  35 #define CONSISTENT_PTE_INDEX(x) (((unsigned long)(x) - CONSISTENT_BASE) >> PGDIR_SHIFT)
  36 #define NUM_CONSISTENT_PTES (CONSISTENT_DMA_SIZE >> PGDIR_SHIFT)
  37
  38
  39 /*
  40  * These are the page tables (2MB each) covering uncached, DMA consistent allocations
  41  */
  42 static pte_t *consistent_pte[NUM_CONSISTENT_PTES];
  43 static DEFINE_SPINLOCK(consistent_lock);
  44
  45 /*
  46  * VM region handling support.
  47  *
  48  * This should become something generic, handling VM region allocations for
  49  * vmalloc and similar (ioremap, module space, etc).
  50  *
  51  * I envisage vmalloc()'s supporting vm_struct becoming:
  52  *
  53  *  struct vm_struct {
  54  *    struct vm_region  region;
  55  *    unsigned long     flags;
  56  *    struct page       **pages;
  57  *    unsigned int      nr_pages;
  58  *    unsigned long     phys_addr;
  59  *  };
  60  *
  61  * get_vm_area() would then call vm_region_alloc with an appropriate
  62  * struct vm_region head (eg):
  63  *
  64  *  struct vm_region vmalloc_head = {
  65  *      .vm_list        = LIST_HEAD_INIT(vmalloc_head.vm_list),
  66  *      .vm_start       = VMALLOC_START,
  67  *      .vm_end         = VMALLOC_END,
  68  *  };
  69  *
  70  * However, vmalloc_head.vm_start is variable (typically, it is dependent on
  71  * the amount of RAM found at boot time.)  I would imagine that get_vm_area()
  72  * would have to initialise this each time prior to calling vm_region_alloc().
  73  */
  74 struct vm_region {
  75         struct list_head        vm_list;
  76         unsigned long           vm_start;
  77         unsigned long           vm_end;
  78         struct page             *vm_pages;
  79         int                     vm_active;
  80 };
  81
  82 static struct vm_region consistent_head = {
  83         .vm_list        = LIST_HEAD_INIT(consistent_head.vm_list),
  84         .vm_start       = CONSISTENT_BASE,
  85         .vm_end         = CONSISTENT_END,
  86 };
  87
  88 static struct vm_region *
  89 vm_region_alloc(struct vm_region *head, size_t size, gfp_t gfp)
  90 {
  91         unsigned long addr = head->vm_start, end = head->vm_end - size;
  92         unsigned long flags;
  93         struct vm_region *c, *new;
  94
  95         new = kmalloc(sizeof(struct vm_region), gfp);
  96         if (!new)
  97                 goto out;
  98
  99         spin_lock_irqsave(&consistent_lock, flags);
 100
 101         list_for_each_entry(c, &head->vm_list, vm_list) {
 102                 if ((addr + size) < addr)
 103                         goto nospc;
 104                 if ((addr + size) <= c->vm_start)
 105                         goto found;
 106                 addr = c->vm_end;
 107                 if (addr > end)
 108                         goto nospc;
 109         }
 110
 111  found:
 112         /*
 113          * Insert this entry _before_ the one we found.
 114          */
 115         list_add_tail(&new->vm_list, &c->vm_list);
 116         new->vm_start = addr;
 117         new->vm_end = addr + size;
 118         new->vm_active = 1;
 119
 120         spin_unlock_irqrestore(&consistent_lock, flags);
 121         return new;
 122
 123  nospc:
 124         spin_unlock_irqrestore(&consistent_lock, flags);
 125         kfree(new);
 126  out:
 127         return NULL;
 128 }
 129
 130 static struct vm_region *vm_region_find(struct vm_region *head, unsigned long addr)
 131 {
 132         struct vm_region *c;
 133
 134         list_for_each_entry(c, &head->vm_list, vm_list) {
 135                 if (c->vm_active && c->vm_start == addr)
 136                         goto out;
 137         }
 138         c = NULL;
 139  out:
 140         return c;
 141 }
 142
 143 #ifdef CONFIG_HUGETLB_PAGE
 144 #error ARM Coherent DMA allocator does not (yet) support huge TLB
 145 #endif
 146
 147 static void *
 148 __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
 149             pgprot_t prot)
 150 {
 151         struct page *page;
 152         struct vm_region *c;
 153         unsigned long order;
 154         u64 mask = ISA_DMA_THRESHOLD, limit;
 155
 156         if (!consistent_pte[0]) {
 157                 printk(KERN_ERR "%s: not initialised\n", __func__);
 158                 dump_stack();
 159                 return NULL;
 160         }
 161
 162         if (dev) {
 163                 mask = dev->coherent_dma_mask;
 164
 165                 /*
 166                  * Sanity check the DMA mask - it must be non-zero, and
 167                  * must be able to be satisfied by a DMA allocation.
 168                  */
 169                 if (mask == 0) {
 170                         dev_warn(dev, "coherent DMA mask is unset\n");
 171                         goto no_page;
 172                 }
 173
 174                 if ((~mask) & ISA_DMA_THRESHOLD) {
 175                         dev_warn(dev, "coherent DMA mask %#llx is smaller "
 176                                  "than system GFP_DMA mask %#llx\n",
 177                                  mask, (unsigned long long)ISA_DMA_THRESHOLD);
 178                         goto no_page;
 179                 }
 180         }
 181
 182         /*
 183          * Sanity check the allocation size.
 184          */
 185         size = PAGE_ALIGN(size);
 186         limit = (mask + 1) & ~mask;
 187         if ((limit && size >= limit) ||
 188             size >= (CONSISTENT_END - CONSISTENT_BASE)) {
 189                 printk(KERN_WARNING "coherent allocation too big "
 190                        "(requested %#x mask %#llx)\n", size, mask);
 191                 goto no_page;
 192         }
 193
 194         order = get_order(size);
 195
 196         if (mask != 0xffffffff)
 197                 gfp |= GFP_DMA;
 198
 199         page = alloc_pages(gfp, order);
 200         if (!page)
 201                 goto no_page;
 202
 203         /*
 204          * Invalidate any data that might be lurking in the
 205          * kernel direct-mapped region for device DMA.
 206          */
 207         {
 208                 unsigned long kaddr = (unsigned long)page_address(page);
 209                 memset(page_address(page), 0, size);
 210                 dmac_flush_range(kaddr, kaddr + size);
 211         }
 212
 213         /*
 214          * Allocate a virtual address in the consistent mapping region.
 215          */
 216         c = vm_region_alloc(&consistent_head, size,
 217                             gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
 218         if (c) {
 219                 pte_t *pte;
 220                 struct page *end = page + (1 << order);
 221                 int idx = CONSISTENT_PTE_INDEX(c->vm_start);
 222                 u32 off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
 223
 224                 pte = consistent_pte[idx] + off;
 225                 c->vm_pages = page;
 226
 227                 split_page(page, order);
 228
 229                 /*
 230                  * Set the "dma handle"
 231                  */
 232                 *handle = page_to_dma(dev, page);
 233
 234                 do {
 235                         BUG_ON(!pte_none(*pte));
 236
 237                         /*
 238                          * x86 does not mark the pages reserved...
 239                          */
 240                         SetPageReserved(page);
 241                         set_pte_ext(pte, mk_pte(page, prot), 0);
 242                         page++;
 243                         pte++;
 244                         off++;
 245                         if (off >= PTRS_PER_PTE) {
 246                                 off = 0;
 247                                 pte = consistent_pte[++idx];
 248                         }
 249                 } while (size -= PAGE_SIZE);
 250
 251                 /*
 252                  * Free the otherwise unused pages.
 253                  */
 254                 while (page < end) {
 255                         __free_page(page);
 256                         page++;
 257                 }
 258
 259                 return (void *)c->vm_start;
 260         }
 261
 262         if (page)
 263                 __free_pages(page, order);
 264  no_page:
 265         *handle = ~0;
 266         return NULL;
 267 }
 268
 269 /*
 270  * Allocate DMA-coherent memory space and return both the kernel remapped
 271  * virtual and bus address for that space.
 272  */
 273 void *
 274 dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
 275 {
 276         if (arch_is_coherent()) {
 277                 void *virt;
 278
 279                 virt = kmalloc(size, gfp);
 280                 if (!virt)
 281                         return NULL;
 282                 *handle =  virt_to_dma(dev, virt);
 283
 284                 return virt;
 285         }
 286
 287         return __dma_alloc(dev, size, handle, gfp,
 288                            pgprot_noncached(pgprot_kernel));
 289 }
 290 EXPORT_SYMBOL(dma_alloc_coherent);
 291
 292 /*
 293  * Allocate a writecombining region, in much the same way as
 294  * dma_alloc_coherent above.
 295  */
 296 void *
 297 dma_alloc_writecombine(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
 298 {
 299         return __dma_alloc(dev, size, handle, gfp,
 300                            pgprot_writecombine(pgprot_kernel));
 301 }
 302 EXPORT_SYMBOL(dma_alloc_writecombine);
 303
 304 static int dma_mmap(struct device *dev, struct vm_area_struct *vma,
 305                     void *cpu_addr, dma_addr_t dma_addr, size_t size)
 306 {
 307         unsigned long flags, user_size, kern_size;
 308         struct vm_region *c;
 309         int ret = -ENXIO;
 310
 311         user_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 312
 313         spin_lock_irqsave(&consistent_lock, flags);
 314         c = vm_region_find(&consistent_head, (unsigned long)cpu_addr);
 315         spin_unlock_irqrestore(&consistent_lock, flags);
 316
 317         if (c) {
 318                 unsigned long off = vma->vm_pgoff;
 319
 320                 kern_size = (c->vm_end - c->vm_start) >> PAGE_SHIFT;
 321
 322                 if (off < kern_size &&
 323                     user_size <= (kern_size - off)) {
 324                         vma->vm_flags |= VM_RESERVED;
 325                         ret = remap_pfn_range(vma, vma->vm_start,
 326                                               page_to_pfn(c->vm_pages) + off,
 327                                               user_size << PAGE_SHIFT,
 328                                               vma->vm_page_prot);
 329                 }
 330         }
 331
 332         return ret;
 333 }
 334
 335 int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
 336                       void *cpu_addr, dma_addr_t dma_addr, size_t size)
 337 {
 338         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 339         return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
 340 }
 341 EXPORT_SYMBOL(dma_mmap_coherent);
 342
 343 int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma,
 344                           void *cpu_addr, dma_addr_t dma_addr, size_t size)
 345 {
 346         vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
 347         return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
 348 }
 349 EXPORT_SYMBOL(dma_mmap_writecombine);
 350
 351 /*
 352  * free a page as defined by the above mapping.
 353  * Must not be called with IRQs disabled.
 354  */
 355 void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t handle)
 356 {
 357         struct vm_region *c;
 358         unsigned long flags, addr;
 359         pte_t *ptep;
 360         int idx;
 361         u32 off;
 362
 363         WARN_ON(irqs_disabled());
 364
 365         if (arch_is_coherent()) {
 366                 kfree(cpu_addr);
 367                 return;
 368         }
 369
 370         size = PAGE_ALIGN(size);
 371
 372         spin_lock_irqsave(&consistent_lock, flags);
 373         c = vm_region_find(&consistent_head, (unsigned long)cpu_addr);
 374         if (!c)
 375                 goto no_area;
 376
 377         c->vm_active = 0;
 378         spin_unlock_irqrestore(&consistent_lock, flags);
 379
 380         if ((c->vm_end - c->vm_start) != size) {
 381                 printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
 382                        __func__, c->vm_end - c->vm_start, size);
 383                 dump_stack();
 384                 size = c->vm_end - c->vm_start;
 385         }
 386
 387         idx = CONSISTENT_PTE_INDEX(c->vm_start);
 388         off = CONSISTENT_OFFSET(c->vm_start) & (PTRS_PER_PTE-1);
 389         ptep = consistent_pte[idx] + off;
 390         addr = c->vm_start;
 391         do {
 392                 pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep);
 393                 unsigned long pfn;
 394
 395                 ptep++;
 396                 addr += PAGE_SIZE;
 397                 off++;
 398                 if (off >= PTRS_PER_PTE) {
 399                         off = 0;
 400                         ptep = consistent_pte[++idx];
 401                 }
 402
 403                 if (!pte_none(pte) && pte_present(pte)) {
 404                         pfn = pte_pfn(pte);
 405
 406                         if (pfn_valid(pfn)) {
 407                                 struct page *page = pfn_to_page(pfn);
 408
 409                                 /*
 410                                  * x86 does not mark the pages reserved...
 411                                  */
 412                                 ClearPageReserved(page);
 413
 414                                 __free_page(page);
 415                                 continue;
 416                         }
 417                 }
 418
 419                 printk(KERN_CRIT "%s: bad page in kernel page table\n",
 420                        __func__);
 421         } while (size -= PAGE_SIZE);
 422
 423         flush_tlb_kernel_range(c->vm_start, c->vm_end);
 424
 425         spin_lock_irqsave(&consistent_lock, flags);
 426         list_del(&c->vm_list);
 427         spin_unlock_irqrestore(&consistent_lock, flags);
 428
 429         kfree(c);
 430         return;
 431
 432  no_area:
 433         spin_unlock_irqrestore(&consistent_lock, flags);
 434         printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n",
 435                __func__, cpu_addr);
 436         dump_stack();
 437 }
 438 EXPORT_SYMBOL(dma_free_coherent);
 439
 440 /*
 441  * Initialise the consistent memory allocation.
 442  */
 443 static int __init consistent_init(void)
 444 {
 445         pgd_t *pgd;
 446         pmd_t *pmd;
 447         pte_t *pte;
 448         int ret = 0, i = 0;
 449         u32 base = CONSISTENT_BASE;
 450
 451         do {
 452                 pgd = pgd_offset(&init_mm, base);
 453                 pmd = pmd_alloc(&init_mm, pgd, base);
 454                 if (!pmd) {
 455                         printk(KERN_ERR "%s: no pmd tables\n", __func__);
 456                         ret = -ENOMEM;
 457                         break;
 458                 }
 459                 WARN_ON(!pmd_none(*pmd));
 460
 461                 pte = pte_alloc_kernel(pmd, base);
 462                 if (!pte) {
 463                         printk(KERN_ERR "%s: no pte tables\n", __func__);
 464                         ret = -ENOMEM;
 465                         break;
 466                 }
 467
 468                 consistent_pte[i++] = pte;
 469                 base += (1 << PGDIR_SHIFT);
 470         } while (base < CONSISTENT_END);
 471
 472         return ret;
 473 }
 474
 475 core_initcall(consistent_init);
 476
 477 /*
 478  * Make an area consistent for devices.
 479  * Note: Drivers should NOT use this function directly, as it will break
 480  * platforms with CONFIG_DMABOUNCE.
 481  * Use the driver DMA support - see dma-mapping.h (dma_sync_*)
 482  */
 483 void consistent_sync(void *vaddr, size_t size, int direction)
 484 {
 485         unsigned long start = (unsigned long)vaddr;
 486         unsigned long end   = start + size;
 487
 488         switch (direction) {
 489         case DMA_FROM_DEVICE:           /* invalidate only */
 490                 dmac_inv_range(start, end);
 491                 break;
 492         case DMA_TO_DEVICE:             /* writeback only */
 493                 dmac_clean_range(start, end);
 494                 break;
 495         case DMA_BIDIRECTIONAL:         /* writeback and invalidate */
 496                 dmac_flush_range(start, end);
 497                 break;
 498         default:
 499                 BUG();
 500         }
 501 }
 502 EXPORT_SYMBOL(consistent_sync);