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