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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/io.h>
  23 #include <asm/tlbflush.h>
  24
  25 #define CONSISTENT_BASE (0xffc00000)
  26 #define CONSISTENT_END  (0xffe00000)
  27 #define CONSISTENT_OFFSET(x)    (((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)
  28
  29 /*
  30  * This is the page table (2MB) covering uncached, DMA consistent allocations
  31  */
  32 static pte_t *consistent_pte;
  33 static DEFINE_SPINLOCK(consistent_lock);
  34
  35 /*
  36  * VM region handling support.
  37  *
  38  * This should become something generic, handling VM region allocations for
  39  * vmalloc and similar (ioremap, module space, etc).
  40  *
  41  * I envisage vmalloc()'s supporting vm_struct becoming:
  42  *
  43  *  struct vm_struct {
  44  *    struct vm_region  region;
  45  *    unsigned long     flags;
  46  *    struct page       **pages;
  47  *    unsigned int      nr_pages;
  48  *    unsigned long     phys_addr;
  49  *  };
  50  *
  51  * get_vm_area() would then call vm_region_alloc with an appropriate
  52  * struct vm_region head (eg):
  53  *
  54  *  struct vm_region vmalloc_head = {
  55  *      .vm_list        = LIST_HEAD_INIT(vmalloc_head.vm_list),
  56  *      .vm_start       = VMALLOC_START,
  57  *      .vm_end         = VMALLOC_END,
  58  *  };
  59  *
  60  * However, vmalloc_head.vm_start is variable (typically, it is dependent on
  61  * the amount of RAM found at boot time.)  I would imagine that get_vm_area()
  62  * would have to initialise this each time prior to calling vm_region_alloc().
  63  */
  64 struct vm_region {
  65         struct list_head        vm_list;
  66         unsigned long           vm_start;
  67         unsigned long           vm_end;
  68         struct page             *vm_pages;
  69 };
  70
  71 static struct vm_region consistent_head = {
  72         .vm_list        = LIST_HEAD_INIT(consistent_head.vm_list),
  73         .vm_start       = CONSISTENT_BASE,
  74         .vm_end         = CONSISTENT_END,
  75 };
  76
  77 static struct vm_region *
  78 vm_region_alloc(struct vm_region *head, size_t size, gfp_t gfp)
  79 {
  80         unsigned long addr = head->vm_start, end = head->vm_end - size;
  81         unsigned long flags;
  82         struct vm_region *c, *new;
  83
  84         new = kmalloc(sizeof(struct vm_region), gfp);
  85         if (!new)
  86                 goto out;
  87
  88         spin_lock_irqsave(&consistent_lock, flags);
  89
  90         list_for_each_entry(c, &head->vm_list, vm_list) {
  91                 if ((addr + size) < addr)
  92                         goto nospc;
  93                 if ((addr + size) <= c->vm_start)
  94                         goto found;
  95                 addr = c->vm_end;
  96                 if (addr > end)
  97                         goto nospc;
  98         }
  99
 100  found:
 101         /*
 102          * Insert this entry _before_ the one we found.
 103          */
 104         list_add_tail(&new->vm_list, &c->vm_list);
 105         new->vm_start = addr;
 106         new->vm_end = addr + size;
 107
 108         spin_unlock_irqrestore(&consistent_lock, flags);
 109         return new;
 110
 111  nospc:
 112         spin_unlock_irqrestore(&consistent_lock, flags);
 113         kfree(new);
 114  out:
 115         return NULL;
 116 }
 117
 118 static struct vm_region *vm_region_find(struct vm_region *head, unsigned long addr)
 119 {
 120         struct vm_region *c;
 121
 122         list_for_each_entry(c, &head->vm_list, vm_list) {
 123                 if (c->vm_start == addr)
 124                         goto out;
 125         }
 126         c = NULL;
 127  out:
 128         return c;
 129 }
 130
 131 #ifdef CONFIG_HUGETLB_PAGE
 132 #error ARM Coherent DMA allocator does not (yet) support huge TLB
 133 #endif
 134
 135 static void *
 136 __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
 137             pgprot_t prot)
 138 {
 139         struct page *page;
 140         struct vm_region *c;
 141         unsigned long order;
 142         u64 mask = ISA_DMA_THRESHOLD, limit;
 143
 144         if (!consistent_pte) {
 145                 printk(KERN_ERR "%s: not initialised\n", __func__);
 146                 dump_stack();
 147                 return NULL;
 148         }
 149
 150         if (dev) {
 151                 mask = dev->coherent_dma_mask;
 152
 153                 /*
 154                  * Sanity check the DMA mask - it must be non-zero, and
 155                  * must be able to be satisfied by a DMA allocation.
 156                  */
 157                 if (mask == 0) {
 158                         dev_warn(dev, "coherent DMA mask is unset\n");
 159                         goto no_page;
 160                 }
 161
 162                 if ((~mask) & ISA_DMA_THRESHOLD) {
 163                         dev_warn(dev, "coherent DMA mask %#llx is smaller "
 164                                  "than system GFP_DMA mask %#llx\n",
 165                                  mask, (unsigned long long)ISA_DMA_THRESHOLD);
 166                         goto no_page;
 167                 }
 168         }
 169
 170         /*
 171          * Sanity check the allocation size.
 172          */
 173         size = PAGE_ALIGN(size);
 174         limit = (mask + 1) & ~mask;
 175         if ((limit && size >= limit) ||
 176             size >= (CONSISTENT_END - CONSISTENT_BASE)) {
 177                 printk(KERN_WARNING "coherent allocation too big "
 178                        "(requested %#x mask %#llx)\n", size, mask);
 179                 goto no_page;
 180         }
 181
 182         order = get_order(size);
 183
 184         if (mask != 0xffffffff)
 185                 gfp |= GFP_DMA;
 186
 187         page = alloc_pages(gfp, order);
 188         if (!page)
 189                 goto no_page;
 190
 191         /*
 192          * Invalidate any data that might be lurking in the
 193          * kernel direct-mapped region for device DMA.
 194          */
 195         {
 196                 unsigned long kaddr = (unsigned long)page_address(page);
 197                 memset(page_address(page), 0, size);
 198                 dmac_flush_range(kaddr, kaddr + size);
 199         }
 200
 201         /*
 202          * Allocate a virtual address in the consistent mapping region.
 203          */
 204         c = vm_region_alloc(&consistent_head, size,
 205                             gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
 206         if (c) {
 207                 pte_t *pte = consistent_pte + CONSISTENT_OFFSET(c->vm_start);
 208                 struct page *end = page + (1 << order);
 209
 210                 c->vm_pages = page;
 211
 212                 /*
 213                  * Set the "dma handle"
 214                  */
 215                 *handle = page_to_dma(dev, page);
 216
 217                 do {
 218                         BUG_ON(!pte_none(*pte));
 219
 220                         set_page_count(page, 1);
 221                         /*
 222                          * x86 does not mark the pages reserved...
 223                          */
 224                         SetPageReserved(page);
 225                         set_pte(pte, mk_pte(page, prot));
 226                         page++;
 227                         pte++;
 228                 } while (size -= PAGE_SIZE);
 229
 230                 /*
 231                  * Free the otherwise unused pages.
 232                  */
 233                 while (page < end) {
 234                         set_page_count(page, 1);
 235                         __free_page(page);
 236                         page++;
 237                 }
 238
 239                 return (void *)c->vm_start;
 240         }
 241
 242         if (page)
 243                 __free_pages(page, order);
 244  no_page:
 245         *handle = ~0;
 246         return NULL;
 247 }
 248
 249 /*
 250  * Allocate DMA-coherent memory space and return both the kernel remapped
 251  * virtual and bus address for that space.
 252  */
 253 void *
 254 dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
 255 {
 256         return __dma_alloc(dev, size, handle, gfp,
 257                            pgprot_noncached(pgprot_kernel));
 258 }
 259 EXPORT_SYMBOL(dma_alloc_coherent);
 260
 261 /*
 262  * Allocate a writecombining region, in much the same way as
 263  * dma_alloc_coherent above.
 264  */
 265 void *
 266 dma_alloc_writecombine(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
 267 {
 268         return __dma_alloc(dev, size, handle, gfp,
 269                            pgprot_writecombine(pgprot_kernel));
 270 }
 271 EXPORT_SYMBOL(dma_alloc_writecombine);
 272
 273 static int dma_mmap(struct device *dev, struct vm_area_struct *vma,
 274                     void *cpu_addr, dma_addr_t dma_addr, size_t size)
 275 {
 276         unsigned long flags, user_size, kern_size;
 277         struct vm_region *c;
 278         int ret = -ENXIO;
 279
 280         user_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 281
 282         spin_lock_irqsave(&consistent_lock, flags);
 283         c = vm_region_find(&consistent_head, (unsigned long)cpu_addr);
 284         spin_unlock_irqrestore(&consistent_lock, flags);
 285
 286         if (c) {
 287                 unsigned long off = vma->vm_pgoff;
 288
 289                 kern_size = (c->vm_end - c->vm_start) >> PAGE_SHIFT;
 290
 291                 if (off < kern_size &&
 292                     user_size <= (kern_size - off)) {
 293                         vma->vm_flags |= VM_RESERVED;
 294                         ret = remap_pfn_range(vma, vma->vm_start,
 295                                               page_to_pfn(c->vm_pages) + off,
 296                                               user_size << PAGE_SHIFT,
 297                                               vma->vm_page_prot);
 298                 }
 299         }
 300
 301         return ret;
 302 }
 303
 304 int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
 305                       void *cpu_addr, dma_addr_t dma_addr, size_t size)
 306 {
 307         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 308         return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
 309 }
 310 EXPORT_SYMBOL(dma_mmap_coherent);
 311
 312 int dma_mmap_writecombine(struct device *dev, struct vm_area_struct *vma,
 313                           void *cpu_addr, dma_addr_t dma_addr, size_t size)
 314 {
 315         vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
 316         return dma_mmap(dev, vma, cpu_addr, dma_addr, size);
 317 }
 318 EXPORT_SYMBOL(dma_mmap_writecombine);
 319
 320 /*
 321  * free a page as defined by the above mapping.
 322  */
 323 void dma_free_coherent(struct device *dev, size_t size, void *cpu_addr, dma_addr_t handle)
 324 {
 325         struct vm_region *c;
 326         unsigned long flags, addr;
 327         pte_t *ptep;
 328
 329         size = PAGE_ALIGN(size);
 330
 331         spin_lock_irqsave(&consistent_lock, flags);
 332
 333         c = vm_region_find(&consistent_head, (unsigned long)cpu_addr);
 334         if (!c)
 335                 goto no_area;
 336
 337         if ((c->vm_end - c->vm_start) != size) {
 338                 printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
 339                        __func__, c->vm_end - c->vm_start, size);
 340                 dump_stack();
 341                 size = c->vm_end - c->vm_start;
 342         }
 343
 344         ptep = consistent_pte + CONSISTENT_OFFSET(c->vm_start);
 345         addr = c->vm_start;
 346         do {
 347                 pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep);
 348                 unsigned long pfn;
 349
 350                 ptep++;
 351                 addr += PAGE_SIZE;
 352
 353                 if (!pte_none(pte) && pte_present(pte)) {
 354                         pfn = pte_pfn(pte);
 355
 356                         if (pfn_valid(pfn)) {
 357                                 struct page *page = pfn_to_page(pfn);
 358
 359                                 /*
 360                                  * x86 does not mark the pages reserved...
 361                                  */
 362                                 ClearPageReserved(page);
 363
 364                                 __free_page(page);
 365                                 continue;
 366                         }
 367                 }
 368
 369                 printk(KERN_CRIT "%s: bad page in kernel page table\n",
 370                        __func__);
 371         } while (size -= PAGE_SIZE);
 372
 373         flush_tlb_kernel_range(c->vm_start, c->vm_end);
 374
 375         list_del(&c->vm_list);
 376
 377         spin_unlock_irqrestore(&consistent_lock, flags);
 378
 379         kfree(c);
 380         return;
 381
 382  no_area:
 383         spin_unlock_irqrestore(&consistent_lock, flags);
 384         printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n",
 385                __func__, cpu_addr);
 386         dump_stack();
 387 }
 388 EXPORT_SYMBOL(dma_free_coherent);
 389
 390 /*
 391  * Initialise the consistent memory allocation.
 392  */
 393 static int __init consistent_init(void)
 394 {
 395         pgd_t *pgd;
 396         pmd_t *pmd;
 397         pte_t *pte;
 398         int ret = 0;
 399
 400         do {
 401                 pgd = pgd_offset(&init_mm, CONSISTENT_BASE);
 402                 pmd = pmd_alloc(&init_mm, pgd, CONSISTENT_BASE);
 403                 if (!pmd) {
 404                         printk(KERN_ERR "%s: no pmd tables\n", __func__);
 405                         ret = -ENOMEM;
 406                         break;
 407                 }
 408                 WARN_ON(!pmd_none(*pmd));
 409
 410                 pte = pte_alloc_kernel(pmd, CONSISTENT_BASE);
 411                 if (!pte) {
 412                         printk(KERN_ERR "%s: no pte tables\n", __func__);
 413                         ret = -ENOMEM;
 414                         break;
 415                 }
 416
 417                 consistent_pte = pte;
 418         } while (0);
 419
 420         return ret;
 421 }
 422
 423 core_initcall(consistent_init);
 424
 425 /*
 426  * Make an area consistent for devices.
 427  */
 428 void consistent_sync(void *vaddr, size_t size, int direction)
 429 {
 430         unsigned long start = (unsigned long)vaddr;
 431         unsigned long end   = start + size;
 432
 433         switch (direction) {
 434         case DMA_FROM_DEVICE:           /* invalidate only */
 435                 dmac_inv_range(start, end);
 436                 break;
 437         case DMA_TO_DEVICE:             /* writeback only */
 438                 dmac_clean_range(start, end);
 439                 break;
 440         case DMA_BIDIRECTIONAL:         /* writeback and invalidate */
 441                 dmac_flush_range(start, end);
 442                 break;
 443         default:
 444                 BUG();
 445         }
 446 }
 447 EXPORT_SYMBOL(consistent_sync);