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