linux/arch/metag/kernel/dma.c
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   1/*
   2 *  Meta version derived from arch/powerpc/lib/dma-noncoherent.c
   3 *    Copyright (C) 2008 Imagination Technologies Ltd.
   4 *
   5 *  PowerPC version derived from arch/arm/mm/consistent.c
   6 *    Copyright (C) 2001 Dan Malek (dmalek@jlc.net)
   7 *
   8 *  Copyright (C) 2000 Russell King
   9 *
  10 * Consistent memory allocators.  Used for DMA devices that want to
  11 * share uncached memory with the processor core.  The function return
  12 * is the virtual address and 'dma_handle' is the physical address.
  13 * Mostly stolen from the ARM port, with some changes for PowerPC.
  14 *                                              -- Dan
  15 *
  16 * Reorganized to get rid of the arch-specific consistent_* functions
  17 * and provide non-coherent implementations for the DMA API. -Matt
  18 *
  19 * Added in_interrupt() safe dma_alloc_coherent()/dma_free_coherent()
  20 * implementation. This is pulled straight from ARM and barely
  21 * modified. -Matt
  22 *
  23 * This program is free software; you can redistribute it and/or modify
  24 * it under the terms of the GNU General Public License version 2 as
  25 * published by the Free Software Foundation.
  26 */
  27
  28#include <linux/sched.h>
  29#include <linux/kernel.h>
  30#include <linux/errno.h>
  31#include <linux/export.h>
  32#include <linux/string.h>
  33#include <linux/types.h>
  34#include <linux/highmem.h>
  35#include <linux/dma-mapping.h>
  36#include <linux/slab.h>
  37
  38#include <asm/tlbflush.h>
  39#include <asm/mmu.h>
  40
  41#define CONSISTENT_OFFSET(x)    (((unsigned long)(x) - CONSISTENT_START) \
  42                                        >> PAGE_SHIFT)
  43
  44static u64 get_coherent_dma_mask(struct device *dev)
  45{
  46        u64 mask = ~0ULL;
  47
  48        if (dev) {
  49                mask = dev->coherent_dma_mask;
  50
  51                /*
  52                 * Sanity check the DMA mask - it must be non-zero, and
  53                 * must be able to be satisfied by a DMA allocation.
  54                 */
  55                if (mask == 0) {
  56                        dev_warn(dev, "coherent DMA mask is unset\n");
  57                        return 0;
  58                }
  59        }
  60
  61        return mask;
  62}
  63/*
  64 * This is the page table (2MB) covering uncached, DMA consistent allocations
  65 */
  66static pte_t *consistent_pte;
  67static DEFINE_SPINLOCK(consistent_lock);
  68
  69/*
  70 * VM region handling support.
  71 *
  72 * This should become something generic, handling VM region allocations for
  73 * vmalloc and similar (ioremap, module space, etc).
  74 *
  75 * I envisage vmalloc()'s supporting vm_struct becoming:
  76 *
  77 *  struct vm_struct {
  78 *    struct metag_vm_region    region;
  79 *    unsigned long     flags;
  80 *    struct page       **pages;
  81 *    unsigned int      nr_pages;
  82 *    unsigned long     phys_addr;
  83 *  };
  84 *
  85 * get_vm_area() would then call metag_vm_region_alloc with an appropriate
  86 * struct metag_vm_region head (eg):
  87 *
  88 *  struct metag_vm_region vmalloc_head = {
  89 *      .vm_list        = LIST_HEAD_INIT(vmalloc_head.vm_list),
  90 *      .vm_start       = VMALLOC_START,
  91 *      .vm_end         = VMALLOC_END,
  92 *  };
  93 *
  94 * However, vmalloc_head.vm_start is variable (typically, it is dependent on
  95 * the amount of RAM found at boot time.)  I would imagine that get_vm_area()
  96 * would have to initialise this each time prior to calling
  97 * metag_vm_region_alloc().
  98 */
  99struct metag_vm_region {
 100        struct list_head vm_list;
 101        unsigned long vm_start;
 102        unsigned long vm_end;
 103        struct page             *vm_pages;
 104        int                     vm_active;
 105};
 106
 107static struct metag_vm_region consistent_head = {
 108        .vm_list = LIST_HEAD_INIT(consistent_head.vm_list),
 109        .vm_start = CONSISTENT_START,
 110        .vm_end = CONSISTENT_END,
 111};
 112
 113static struct metag_vm_region *metag_vm_region_alloc(struct metag_vm_region
 114                                                     *head, size_t size,
 115                                                     gfp_t gfp)
 116{
 117        unsigned long addr = head->vm_start, end = head->vm_end - size;
 118        unsigned long flags;
 119        struct metag_vm_region *c, *new;
 120
 121        new = kmalloc(sizeof(struct metag_vm_region), gfp);
 122        if (!new)
 123                goto out;
 124
 125        spin_lock_irqsave(&consistent_lock, flags);
 126
 127        list_for_each_entry(c, &head->vm_list, vm_list) {
 128                if ((addr + size) < addr)
 129                        goto nospc;
 130                if ((addr + size) <= c->vm_start)
 131                        goto found;
 132                addr = c->vm_end;
 133                if (addr > end)
 134                        goto nospc;
 135        }
 136
 137found:
 138        /*
 139         * Insert this entry _before_ the one we found.
 140         */
 141        list_add_tail(&new->vm_list, &c->vm_list);
 142        new->vm_start = addr;
 143        new->vm_end = addr + size;
 144        new->vm_active = 1;
 145
 146        spin_unlock_irqrestore(&consistent_lock, flags);
 147        return new;
 148
 149nospc:
 150        spin_unlock_irqrestore(&consistent_lock, flags);
 151        kfree(new);
 152out:
 153        return NULL;
 154}
 155
 156static struct metag_vm_region *metag_vm_region_find(struct metag_vm_region
 157                                                    *head, unsigned long addr)
 158{
 159        struct metag_vm_region *c;
 160
 161        list_for_each_entry(c, &head->vm_list, vm_list) {
 162                if (c->vm_active && c->vm_start == addr)
 163                        goto out;
 164        }
 165        c = NULL;
 166out:
 167        return c;
 168}
 169
 170/*
 171 * Allocate DMA-coherent memory space and return both the kernel remapped
 172 * virtual and bus address for that space.
 173 */
 174static void *metag_dma_alloc(struct device *dev, size_t size,
 175                dma_addr_t *handle, gfp_t gfp, unsigned long attrs)
 176{
 177        struct page *page;
 178        struct metag_vm_region *c;
 179        unsigned long order;
 180        u64 mask = get_coherent_dma_mask(dev);
 181        u64 limit;
 182
 183        if (!consistent_pte) {
 184                pr_err("%s: not initialised\n", __func__);
 185                dump_stack();
 186                return NULL;
 187        }
 188
 189        if (!mask)
 190                goto no_page;
 191        size = PAGE_ALIGN(size);
 192        limit = (mask + 1) & ~mask;
 193        if ((limit && size >= limit)
 194            || size >= (CONSISTENT_END - CONSISTENT_START)) {
 195                pr_warn("coherent allocation too big (requested %#x mask %#Lx)\n",
 196                        size, mask);
 197                return NULL;
 198        }
 199
 200        order = get_order(size);
 201
 202        if (mask != 0xffffffff)
 203                gfp |= GFP_DMA;
 204
 205        page = alloc_pages(gfp, order);
 206        if (!page)
 207                goto no_page;
 208
 209        /*
 210         * Invalidate any data that might be lurking in the
 211         * kernel direct-mapped region for device DMA.
 212         */
 213        {
 214                void *kaddr = page_address(page);
 215                memset(kaddr, 0, size);
 216                flush_dcache_region(kaddr, size);
 217        }
 218
 219        /*
 220         * Allocate a virtual address in the consistent mapping region.
 221         */
 222        c = metag_vm_region_alloc(&consistent_head, size,
 223                                  gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
 224        if (c) {
 225                unsigned long vaddr = c->vm_start;
 226                pte_t *pte = consistent_pte + CONSISTENT_OFFSET(vaddr);
 227                struct page *end = page + (1 << order);
 228
 229                c->vm_pages = page;
 230                split_page(page, order);
 231
 232                /*
 233                 * Set the "dma handle"
 234                 */
 235                *handle = page_to_bus(page);
 236
 237                do {
 238                        BUG_ON(!pte_none(*pte));
 239
 240                        SetPageReserved(page);
 241                        set_pte_at(&init_mm, vaddr,
 242                                   pte, mk_pte(page,
 243                                               pgprot_writecombine
 244                                               (PAGE_KERNEL)));
 245                        page++;
 246                        pte++;
 247                        vaddr += PAGE_SIZE;
 248                } while (size -= PAGE_SIZE);
 249
 250                /*
 251                 * Free the otherwise unused pages.
 252                 */
 253                while (page < end) {
 254                        __free_page(page);
 255                        page++;
 256                }
 257
 258                return (void *)c->vm_start;
 259        }
 260
 261        if (page)
 262                __free_pages(page, order);
 263no_page:
 264        return NULL;
 265}
 266
 267/*
 268 * free a page as defined by the above mapping.
 269 */
 270static void metag_dma_free(struct device *dev, size_t size, void *vaddr,
 271                dma_addr_t dma_handle, unsigned long attrs)
 272{
 273        struct metag_vm_region *c;
 274        unsigned long flags, addr;
 275        pte_t *ptep;
 276
 277        size = PAGE_ALIGN(size);
 278
 279        spin_lock_irqsave(&consistent_lock, flags);
 280
 281        c = metag_vm_region_find(&consistent_head, (unsigned long)vaddr);
 282        if (!c)
 283                goto no_area;
 284
 285        c->vm_active = 0;
 286        if ((c->vm_end - c->vm_start) != size) {
 287                pr_err("%s: freeing wrong coherent size (%ld != %d)\n",
 288                       __func__, c->vm_end - c->vm_start, size);
 289                dump_stack();
 290                size = c->vm_end - c->vm_start;
 291        }
 292
 293        ptep = consistent_pte + CONSISTENT_OFFSET(c->vm_start);
 294        addr = c->vm_start;
 295        do {
 296                pte_t pte = ptep_get_and_clear(&init_mm, addr, ptep);
 297                unsigned long pfn;
 298
 299                ptep++;
 300                addr += PAGE_SIZE;
 301
 302                if (!pte_none(pte) && pte_present(pte)) {
 303                        pfn = pte_pfn(pte);
 304
 305                        if (pfn_valid(pfn)) {
 306                                struct page *page = pfn_to_page(pfn);
 307                                __free_reserved_page(page);
 308                                continue;
 309                        }
 310                }
 311
 312                pr_crit("%s: bad page in kernel page table\n",
 313                        __func__);
 314        } while (size -= PAGE_SIZE);
 315
 316        flush_tlb_kernel_range(c->vm_start, c->vm_end);
 317
 318        list_del(&c->vm_list);
 319
 320        spin_unlock_irqrestore(&consistent_lock, flags);
 321
 322        kfree(c);
 323        return;
 324
 325no_area:
 326        spin_unlock_irqrestore(&consistent_lock, flags);
 327        pr_err("%s: trying to free invalid coherent area: %p\n",
 328               __func__, vaddr);
 329        dump_stack();
 330}
 331
 332static int metag_dma_mmap(struct device *dev, struct vm_area_struct *vma,
 333                void *cpu_addr, dma_addr_t dma_addr, size_t size,
 334                unsigned long attrs)
 335{
 336        unsigned long flags, user_size, kern_size;
 337        struct metag_vm_region *c;
 338        int ret = -ENXIO;
 339
 340        if (attrs & DMA_ATTR_WRITE_COMBINE)
 341                vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
 342        else
 343                vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 344
 345        user_size = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 346
 347        spin_lock_irqsave(&consistent_lock, flags);
 348        c = metag_vm_region_find(&consistent_head, (unsigned long)cpu_addr);
 349        spin_unlock_irqrestore(&consistent_lock, flags);
 350
 351        if (c) {
 352                unsigned long off = vma->vm_pgoff;
 353
 354                kern_size = (c->vm_end - c->vm_start) >> PAGE_SHIFT;
 355
 356                if (off < kern_size &&
 357                    user_size <= (kern_size - off)) {
 358                        ret = remap_pfn_range(vma, vma->vm_start,
 359                                              page_to_pfn(c->vm_pages) + off,
 360                                              user_size << PAGE_SHIFT,
 361                                              vma->vm_page_prot);
 362                }
 363        }
 364
 365
 366        return ret;
 367}
 368
 369/*
 370 * Initialise the consistent memory allocation.
 371 */
 372static int __init dma_alloc_init(void)
 373{
 374        pgd_t *pgd, *pgd_k;
 375        pud_t *pud, *pud_k;
 376        pmd_t *pmd, *pmd_k;
 377        pte_t *pte;
 378        int ret = 0;
 379
 380        do {
 381                int offset = pgd_index(CONSISTENT_START);
 382                pgd = pgd_offset(&init_mm, CONSISTENT_START);
 383                pud = pud_alloc(&init_mm, pgd, CONSISTENT_START);
 384                pmd = pmd_alloc(&init_mm, pud, CONSISTENT_START);
 385                WARN_ON(!pmd_none(*pmd));
 386
 387                pte = pte_alloc_kernel(pmd, CONSISTENT_START);
 388                if (!pte) {
 389                        pr_err("%s: no pte tables\n", __func__);
 390                        ret = -ENOMEM;
 391                        break;
 392                }
 393
 394                pgd_k = ((pgd_t *) mmu_get_base()) + offset;
 395                pud_k = pud_offset(pgd_k, CONSISTENT_START);
 396                pmd_k = pmd_offset(pud_k, CONSISTENT_START);
 397                set_pmd(pmd_k, *pmd);
 398
 399                consistent_pte = pte;
 400        } while (0);
 401
 402        return ret;
 403}
 404early_initcall(dma_alloc_init);
 405
 406/*
 407 * make an area consistent to devices.
 408 */
 409static void dma_sync_for_device(void *vaddr, size_t size, int dma_direction)
 410{
 411        /*
 412         * Ensure any writes get through the write combiner. This is necessary
 413         * even with DMA_FROM_DEVICE, or the write may dirty the cache after
 414         * we've invalidated it and get written back during the DMA.
 415         */
 416
 417        barrier();
 418
 419        switch (dma_direction) {
 420        case DMA_BIDIRECTIONAL:
 421                /*
 422                 * Writeback to ensure the device can see our latest changes and
 423                 * so that we have no dirty lines, and invalidate the cache
 424                 * lines too in preparation for receiving the buffer back
 425                 * (dma_sync_for_cpu) later.
 426                 */
 427                flush_dcache_region(vaddr, size);
 428                break;
 429        case DMA_TO_DEVICE:
 430                /*
 431                 * Writeback to ensure the device can see our latest changes.
 432                 * There's no need to invalidate as the device shouldn't write
 433                 * to the buffer.
 434                 */
 435                writeback_dcache_region(vaddr, size);
 436                break;
 437        case DMA_FROM_DEVICE:
 438                /*
 439                 * Invalidate to ensure we have no dirty lines that could get
 440                 * written back during the DMA. It's also safe to flush
 441                 * (writeback) here if necessary.
 442                 */
 443                invalidate_dcache_region(vaddr, size);
 444                break;
 445        case DMA_NONE:
 446                BUG();
 447        }
 448
 449        wmb();
 450}
 451
 452/*
 453 * make an area consistent to the core.
 454 */
 455static void dma_sync_for_cpu(void *vaddr, size_t size, int dma_direction)
 456{
 457        /*
 458         * Hardware L2 cache prefetch doesn't occur across 4K physical
 459         * boundaries, however according to Documentation/DMA-API-HOWTO.txt
 460         * kmalloc'd memory is DMA'able, so accesses in nearby memory could
 461         * trigger a cache fill in the DMA buffer.
 462         *
 463         * This should never cause dirty lines, so a flush or invalidate should
 464         * be safe to allow us to see data from the device.
 465         */
 466        if (_meta_l2c_pf_is_enabled()) {
 467                switch (dma_direction) {
 468                case DMA_BIDIRECTIONAL:
 469                case DMA_FROM_DEVICE:
 470                        invalidate_dcache_region(vaddr, size);
 471                        break;
 472                case DMA_TO_DEVICE:
 473                        /* The device shouldn't have written to the buffer */
 474                        break;
 475                case DMA_NONE:
 476                        BUG();
 477                }
 478        }
 479
 480        rmb();
 481}
 482
 483static dma_addr_t metag_dma_map_page(struct device *dev, struct page *page,
 484                unsigned long offset, size_t size,
 485                enum dma_data_direction direction, unsigned long attrs)
 486{
 487        if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
 488                dma_sync_for_device((void *)(page_to_phys(page) + offset),
 489                                    size, direction);
 490        return page_to_phys(page) + offset;
 491}
 492
 493static void metag_dma_unmap_page(struct device *dev, dma_addr_t dma_address,
 494                size_t size, enum dma_data_direction direction,
 495                unsigned long attrs)
 496{
 497        if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
 498                dma_sync_for_cpu(phys_to_virt(dma_address), size, direction);
 499}
 500
 501static int metag_dma_map_sg(struct device *dev, struct scatterlist *sglist,
 502                int nents, enum dma_data_direction direction,
 503                unsigned long attrs)
 504{
 505        struct scatterlist *sg;
 506        int i;
 507
 508        for_each_sg(sglist, sg, nents, i) {
 509                BUG_ON(!sg_page(sg));
 510
 511                sg->dma_address = sg_phys(sg);
 512
 513                if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
 514                        continue;
 515
 516                dma_sync_for_device(sg_virt(sg), sg->length, direction);
 517        }
 518
 519        return nents;
 520}
 521
 522
 523static void metag_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
 524                int nhwentries, enum dma_data_direction direction,
 525                unsigned long attrs)
 526{
 527        struct scatterlist *sg;
 528        int i;
 529
 530        for_each_sg(sglist, sg, nhwentries, i) {
 531                BUG_ON(!sg_page(sg));
 532
 533                sg->dma_address = sg_phys(sg);
 534
 535                if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
 536                        continue;
 537
 538                dma_sync_for_cpu(sg_virt(sg), sg->length, direction);
 539        }
 540}
 541
 542static void metag_dma_sync_single_for_cpu(struct device *dev,
 543                dma_addr_t dma_handle, size_t size,
 544                enum dma_data_direction direction)
 545{
 546        dma_sync_for_cpu(phys_to_virt(dma_handle), size, direction);
 547}
 548
 549static void metag_dma_sync_single_for_device(struct device *dev,
 550                dma_addr_t dma_handle, size_t size,
 551                enum dma_data_direction direction)
 552{
 553        dma_sync_for_device(phys_to_virt(dma_handle), size, direction);
 554}
 555
 556static void metag_dma_sync_sg_for_cpu(struct device *dev,
 557                struct scatterlist *sglist, int nelems,
 558                enum dma_data_direction direction)
 559{
 560        int i;
 561        struct scatterlist *sg;
 562
 563        for_each_sg(sglist, sg, nelems, i)
 564                dma_sync_for_cpu(sg_virt(sg), sg->length, direction);
 565}
 566
 567static void metag_dma_sync_sg_for_device(struct device *dev,
 568                struct scatterlist *sglist, int nelems,
 569                enum dma_data_direction direction)
 570{
 571        int i;
 572        struct scatterlist *sg;
 573
 574        for_each_sg(sglist, sg, nelems, i)
 575                dma_sync_for_device(sg_virt(sg), sg->length, direction);
 576}
 577
 578const struct dma_map_ops metag_dma_ops = {
 579        .alloc                  = metag_dma_alloc,
 580        .free                   = metag_dma_free,
 581        .map_page               = metag_dma_map_page,
 582        .map_sg                 = metag_dma_map_sg,
 583        .sync_single_for_device = metag_dma_sync_single_for_device,
 584        .sync_single_for_cpu    = metag_dma_sync_single_for_cpu,
 585        .sync_sg_for_cpu        = metag_dma_sync_sg_for_cpu,
 586        .mmap                   = metag_dma_mmap,
 587};
 588EXPORT_SYMBOL(metag_dma_ops);
 589