drivers/base/dma-contiguous.c

   1 /*
   2  * Contiguous Memory Allocator for DMA mapping framework
   3  * Copyright (c) 2010-2011 by Samsung Electronics.
   4  * Written by:
   5  *      Marek Szyprowski <m.szyprowski@samsung.com>
   6  *      Michal Nazarewicz <mina86@mina86.com>
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of the
  11  * License or (at your optional) any later version of the license.
  12  */
  13
  14 #define pr_fmt(fmt) "cma: " fmt
  15
  16 #ifdef CONFIG_CMA_DEBUG
  17 #ifndef DEBUG
  18 #  define DEBUG
  19 #endif
  20 #endif
  21
  22 #include <asm/page.h>
  23 #include <asm/dma-contiguous.h>
  24
  25 #include <linux/memblock.h>
  26 #include <linux/err.h>
  27 #include <linux/mm.h>
  28 #include <linux/mutex.h>
  29 #include <linux/page-isolation.h>
  30 #include <linux/slab.h>
  31 #include <linux/swap.h>
  32 #include <linux/mm_types.h>
  33 #include <linux/dma-contiguous.h>
  34
  35 #ifndef SZ_1M
  36 #define SZ_1M (1 << 20)
  37 #endif
  38
  39 struct cma {
  40         unsigned long   base_pfn;
  41         unsigned long   count;
  42         unsigned long   *bitmap;
  43 };
  44
  45 struct cma *dma_contiguous_default_area;
  46
  47 #ifdef CONFIG_CMA_SIZE_MBYTES
  48 #define CMA_SIZE_MBYTES CONFIG_CMA_SIZE_MBYTES
  49 #else
  50 #define CMA_SIZE_MBYTES 0
  51 #endif
  52
  53 /*
  54  * Default global CMA area size can be defined in kernel's .config.
  55  * This is usefull mainly for distro maintainers to create a kernel
  56  * that works correctly for most supported systems.
  57  * The size can be set in bytes or as a percentage of the total memory
  58  * in the system.
  59  *
  60  * Users, who want to set the size of global CMA area for their system
  61  * should use cma= kernel parameter.
  62  */
  63 static const unsigned long size_bytes = CMA_SIZE_MBYTES * SZ_1M;
  64 static long size_cmdline = -1;
  65
  66 static int __init early_cma(char *p)
  67 {
  68         pr_debug("%s(%s)\n", __func__, p);
  69         size_cmdline = memparse(p, &p);
  70         return 0;
  71 }
  72 early_param("cma", early_cma);
  73
  74 #ifdef CONFIG_CMA_SIZE_PERCENTAGE
  75
  76 static unsigned long __init __maybe_unused cma_early_percent_memory(void)
  77 {
  78         struct memblock_region *reg;
  79         unsigned long total_pages = 0;
  80
  81         /*
  82          * We cannot use memblock_phys_mem_size() here, because
  83          * memblock_analyze() has not been called yet.
  84          */
  85         for_each_memblock(memory, reg)
  86                 total_pages += memblock_region_memory_end_pfn(reg) -
  87                                memblock_region_memory_base_pfn(reg);
  88
  89         return (total_pages * CONFIG_CMA_SIZE_PERCENTAGE / 100) << PAGE_SHIFT;
  90 }
  91
  92 #else
  93
  94 static inline __maybe_unused unsigned long cma_early_percent_memory(void)
  95 {
  96         return 0;
  97 }
  98
  99 #endif
 100
 101 /**
 102  * dma_contiguous_reserve() - reserve area for contiguous memory handling
 103  * @limit: End address of the reserved memory (optional, 0 for any).
 104  *
 105  * This function reserves memory from early allocator. It should be
 106  * called by arch specific code once the early allocator (memblock or bootmem)
 107  * has been activated and all other subsystems have already allocated/reserved
 108  * memory.
 109  */
 110 void __init dma_contiguous_reserve(phys_addr_t limit)
 111 {
 112         unsigned long selected_size = 0;
 113
 114         pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit);
 115
 116         if (size_cmdline != -1) {
 117                 selected_size = size_cmdline;
 118         } else {
 119 #ifdef CONFIG_CMA_SIZE_SEL_MBYTES
 120                 selected_size = size_bytes;
 121 #elif defined(CONFIG_CMA_SIZE_SEL_PERCENTAGE)
 122                 selected_size = cma_early_percent_memory();
 123 #elif defined(CONFIG_CMA_SIZE_SEL_MIN)
 124                 selected_size = min(size_bytes, cma_early_percent_memory());
 125 #elif defined(CONFIG_CMA_SIZE_SEL_MAX)
 126                 selected_size = max(size_bytes, cma_early_percent_memory());
 127 #endif
 128         }
 129
 130         if (selected_size) {
 131                 pr_debug("%s: reserving %ld MiB for global area\n", __func__,
 132                          selected_size / SZ_1M);
 133
 134                 dma_declare_contiguous(NULL, selected_size, 0, limit);
 135         }
 136 };
 137
 138 static DEFINE_MUTEX(cma_mutex);
 139
 140 static __init int cma_activate_area(unsigned long base_pfn, unsigned long count)
 141 {
 142         unsigned long pfn = base_pfn;
 143         unsigned i = count >> pageblock_order;
 144         struct zone *zone;
 145
 146         WARN_ON_ONCE(!pfn_valid(pfn));
 147         zone = page_zone(pfn_to_page(pfn));
 148
 149         do {
 150                 unsigned j;
 151                 base_pfn = pfn;
 152                 for (j = pageblock_nr_pages; j; --j, pfn++) {
 153                         WARN_ON_ONCE(!pfn_valid(pfn));
 154                         if (page_zone(pfn_to_page(pfn)) != zone)
 155                                 return -EINVAL;
 156                 }
 157                 init_cma_reserved_pageblock(pfn_to_page(base_pfn));
 158         } while (--i);
 159         return 0;
 160 }
 161
 162 static __init struct cma *cma_create_area(unsigned long base_pfn,
 163                                      unsigned long count)
 164 {
 165         int bitmap_size = BITS_TO_LONGS(count) * sizeof(long);
 166         struct cma *cma;
 167         int ret = -ENOMEM;
 168
 169         pr_debug("%s(base %08lx, count %lx)\n", __func__, base_pfn, count);
 170
 171         cma = kmalloc(sizeof *cma, GFP_KERNEL);
 172         if (!cma)
 173                 return ERR_PTR(-ENOMEM);
 174
 175         cma->base_pfn = base_pfn;
 176         cma->count = count;
 177         cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
 178
 179         if (!cma->bitmap)
 180                 goto no_mem;
 181
 182         ret = cma_activate_area(base_pfn, count);
 183         if (ret)
 184                 goto error;
 185
 186         pr_debug("%s: returned %p\n", __func__, (void *)cma);
 187         return cma;
 188
 189 error:
 190         kfree(cma->bitmap);
 191 no_mem:
 192         kfree(cma);
 193         return ERR_PTR(ret);
 194 }
 195
 196 static struct cma_reserved {
 197         phys_addr_t start;
 198         unsigned long size;
 199         struct device *dev;
 200 } cma_reserved[MAX_CMA_AREAS] __initdata;
 201 static unsigned cma_reserved_count __initdata;
 202
 203 static int __init cma_init_reserved_areas(void)
 204 {
 205         struct cma_reserved *r = cma_reserved;
 206         unsigned i = cma_reserved_count;
 207
 208         pr_debug("%s()\n", __func__);
 209
 210         for (; i; --i, ++r) {
 211                 struct cma *cma;
 212                 cma = cma_create_area(PFN_DOWN(r->start),
 213                                       r->size >> PAGE_SHIFT);
 214                 if (!IS_ERR(cma))
 215                         dev_set_cma_area(r->dev, cma);
 216         }
 217         return 0;
 218 }
 219 core_initcall(cma_init_reserved_areas);
 220
 221 /**
 222  * dma_declare_contiguous() - reserve area for contiguous memory handling
 223  *                            for particular device
 224  * @dev:   Pointer to device structure.
 225  * @size:  Size of the reserved memory.
 226  * @base:  Start address of the reserved memory (optional, 0 for any).
 227  * @limit: End address of the reserved memory (optional, 0 for any).
 228  *
 229  * This function reserves memory for specified device. It should be
 230  * called by board specific code when early allocator (memblock or bootmem)
 231  * is still activate.
 232  */
 233 int __init dma_declare_contiguous(struct device *dev, unsigned long size,
 234                                   phys_addr_t base, phys_addr_t limit)
 235 {
 236         struct cma_reserved *r = &cma_reserved[cma_reserved_count];
 237         unsigned long alignment;
 238
 239         pr_debug("%s(size %lx, base %08lx, limit %08lx)\n", __func__,
 240                  (unsigned long)size, (unsigned long)base,
 241                  (unsigned long)limit);
 242
 243         /* Sanity checks */
 244         if (cma_reserved_count == ARRAY_SIZE(cma_reserved)) {
 245                 pr_err("Not enough slots for CMA reserved regions!\n");
 246                 return -ENOSPC;
 247         }
 248
 249         if (!size)
 250                 return -EINVAL;
 251
 252         /* Sanitise input arguments */
 253         alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
 254         base = ALIGN(base, alignment);
 255         size = ALIGN(size, alignment);
 256         limit &= ~(alignment - 1);
 257
 258         /* Reserve memory */
 259         if (base) {
 260                 if (memblock_is_region_reserved(base, size) ||
 261                     memblock_reserve(base, size) < 0) {
 262                         base = -EBUSY;
 263                         goto err;
 264                 }
 265         } else {
 266                 /*
 267                  * Use __memblock_alloc_base() since
 268                  * memblock_alloc_base() panic()s.
 269                  */
 270                 phys_addr_t addr = __memblock_alloc_base(size, alignment, limit);
 271                 if (!addr) {
 272                         base = -ENOMEM;
 273                         goto err;
 274                 } else if (addr + size > ~(unsigned long)0) {
 275                         memblock_free(addr, size);
 276                         base = -EINVAL;
 277                         goto err;
 278                 } else {
 279                         base = addr;
 280                 }
 281         }
 282
 283         /*
 284          * Each reserved area must be initialised later, when more kernel
 285          * subsystems (like slab allocator) are available.
 286          */
 287         r->start = base;
 288         r->size = size;
 289         r->dev = dev;
 290         cma_reserved_count++;
 291         pr_info("CMA: reserved %ld MiB at %08lx\n", size / SZ_1M,
 292                 (unsigned long)base);
 293
 294         /* Architecture specific contiguous memory fixup. */
 295         dma_contiguous_early_fixup(base, size);
 296         return 0;
 297 err:
 298         pr_err("CMA: failed to reserve %ld MiB\n", size / SZ_1M);
 299         return base;
 300 }
 301
 302 /**
 303  * dma_alloc_from_contiguous() - allocate pages from contiguous area
 304  * @dev:   Pointer to device for which the allocation is performed.
 305  * @count: Requested number of pages.
 306  * @align: Requested alignment of pages (in PAGE_SIZE order).
 307  *
 308  * This function allocates memory buffer for specified device. It uses
 309  * device specific contiguous memory area if available or the default
 310  * global one. Requires architecture specific get_dev_cma_area() helper
 311  * function.
 312  */
 313 struct page *dma_alloc_from_contiguous(struct device *dev, int count,
 314                                        unsigned int align)
 315 {
 316         unsigned long mask, pfn, pageno, start = 0;
 317         struct cma *cma = dev_get_cma_area(dev);
 318         struct page *page = NULL;
 319         int ret;
 320
 321         if (!cma || !cma->count)
 322                 return NULL;
 323
 324         if (align > CONFIG_CMA_ALIGNMENT)
 325                 align = CONFIG_CMA_ALIGNMENT;
 326
 327         pr_debug("%s(cma %p, count %d, align %d)\n", __func__, (void *)cma,
 328                  count, align);
 329
 330         if (!count)
 331                 return NULL;
 332
 333         mask = (1 << align) - 1;
 334
 335         mutex_lock(&cma_mutex);
 336
 337         for (;;) {
 338                 pageno = bitmap_find_next_zero_area(cma->bitmap, cma->count,
 339                                                     start, count, mask);
 340                 if (pageno >= cma->count)
 341                         break;
 342
 343                 pfn = cma->base_pfn + pageno;
 344                 ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA);
 345                 if (ret == 0) {
 346                         bitmap_set(cma->bitmap, pageno, count);
 347                         page = pfn_to_page(pfn);
 348                         break;
 349                 } else if (ret != -EBUSY) {
 350                         break;
 351                 }
 352                 pr_debug("%s(): memory range at %p is busy, retrying\n",
 353                          __func__, pfn_to_page(pfn));
 354                 /* try again with a bit different memory target */
 355                 start = pageno + mask + 1;
 356         }
 357
 358         mutex_unlock(&cma_mutex);
 359         pr_debug("%s(): returned %p\n", __func__, page);
 360         return page;
 361 }
 362
 363 /**
 364  * dma_release_from_contiguous() - release allocated pages
 365  * @dev:   Pointer to device for which the pages were allocated.
 366  * @pages: Allocated pages.
 367  * @count: Number of allocated pages.
 368  *
 369  * This function releases memory allocated by dma_alloc_from_contiguous().
 370  * It returns false when provided pages do not belong to contiguous area and
 371  * true otherwise.
 372  */
 373 bool dma_release_from_contiguous(struct device *dev, struct page *pages,
 374                                  int count)
 375 {
 376         struct cma *cma = dev_get_cma_area(dev);
 377         unsigned long pfn;
 378
 379         if (!cma || !pages)
 380                 return false;
 381
 382         pr_debug("%s(page %p)\n", __func__, (void *)pages);
 383
 384         pfn = page_to_pfn(pages);
 385
 386         if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
 387                 return false;
 388
 389         VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);
 390
 391         mutex_lock(&cma_mutex);
 392         bitmap_clear(cma->bitmap, pfn - cma->base_pfn, count);
 393         free_contig_range(pfn, count);
 394         mutex_unlock(&cma_mutex);
 395
 396         return true;
 397 }