1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Contiguous Memory Allocator for DMA mapping framework 4 * Copyright (c) 2010-2011 by Samsung Electronics. 5 * Written by: 6 * Marek Szyprowski <m.szyprowski@samsung.com> 7 * Michal Nazarewicz <mina86@mina86.com> 8 * 9 * Contiguous Memory Allocator 10 * 11 * The Contiguous Memory Allocator (CMA) makes it possible to 12 * allocate big contiguous chunks of memory after the system has 13 * booted. 14 * 15 * Why is it needed? 16 * 17 * Various devices on embedded systems have no scatter-getter and/or 18 * IO map support and require contiguous blocks of memory to 19 * operate. They include devices such as cameras, hardware video 20 * coders, etc. 21 * 22 * Such devices often require big memory buffers (a full HD frame 23 * is, for instance, more than 2 mega pixels large, i.e. more than 6 24 * MB of memory), which makes mechanisms such as kmalloc() or 25 * alloc_page() ineffective. 26 * 27 * At the same time, a solution where a big memory region is 28 * reserved for a device is suboptimal since often more memory is 29 * reserved then strictly required and, moreover, the memory is 30 * inaccessible to page system even if device drivers don't use it. 31 * 32 * CMA tries to solve this issue by operating on memory regions 33 * where only movable pages can be allocated from. This way, kernel 34 * can use the memory for pagecache and when device driver requests 35 * it, allocated pages can be migrated. 36 */ 37 38 #define pr_fmt(fmt) "cma: " fmt 39 40 #ifdef CONFIG_CMA_DEBUG 41 #ifndef DEBUG 42 # define DEBUG 43 #endif 44 #endif 45 46 #include <asm/page.h> 47 48 #include <linux/memblock.h> 49 #include <linux/err.h> 50 #include <linux/sizes.h> 51 #include <linux/dma-map-ops.h> 52 #include <linux/cma.h> 53 54 #ifdef CONFIG_CMA_SIZE_MBYTES 55 #define CMA_SIZE_MBYTES CONFIG_CMA_SIZE_MBYTES 56 #else 57 #define CMA_SIZE_MBYTES 0 58 #endif 59 60 struct cma *dma_contiguous_default_area; 61 62 /* 63 * Default global CMA area size can be defined in kernel's .config. 64 * This is useful mainly for distro maintainers to create a kernel 65 * that works correctly for most supported systems. 66 * The size can be set in bytes or as a percentage of the total memory 67 * in the system. 68 * 69 * Users, who want to set the size of global CMA area for their system 70 * should use cma= kernel parameter. 71 */ 72 static const phys_addr_t size_bytes __initconst = 73 (phys_addr_t)CMA_SIZE_MBYTES * SZ_1M; 74 static phys_addr_t size_cmdline __initdata = -1; 75 static phys_addr_t base_cmdline __initdata; 76 static phys_addr_t limit_cmdline __initdata; 77 78 static int __init early_cma(char *p) 79 { 80 if (!p) { 81 pr_err("Config string not provided\n"); 82 return -EINVAL; 83 } 84 85 size_cmdline = memparse(p, &p); 86 if (*p != '@') 87 return 0; 88 base_cmdline = memparse(p + 1, &p); 89 if (*p != '-') { 90 limit_cmdline = base_cmdline + size_cmdline; 91 return 0; 92 } 93 limit_cmdline = memparse(p + 1, &p); 94 95 return 0; 96 } 97 early_param("cma", early_cma); 98 99 #ifdef CONFIG_DMA_PERNUMA_CMA 100 101 static struct cma *dma_contiguous_pernuma_area[MAX_NUMNODES]; 102 static phys_addr_t pernuma_size_bytes __initdata; 103 104 static int __init early_cma_pernuma(char *p) 105 { 106 pernuma_size_bytes = memparse(p, &p); 107 return 0; 108 } 109 early_param("cma_pernuma", early_cma_pernuma); 110 #endif 111 112 #ifdef CONFIG_CMA_SIZE_PERCENTAGE 113 114 static phys_addr_t __init __maybe_unused cma_early_percent_memory(void) 115 { 116 unsigned long total_pages = PHYS_PFN(memblock_phys_mem_size()); 117 118 return (total_pages * CONFIG_CMA_SIZE_PERCENTAGE / 100) << PAGE_SHIFT; 119 } 120 121 #else 122 123 static inline __maybe_unused phys_addr_t cma_early_percent_memory(void) 124 { 125 return 0; 126 } 127 128 #endif 129 130 #ifdef CONFIG_DMA_PERNUMA_CMA 131 void __init dma_pernuma_cma_reserve(void) 132 { 133 int nid; 134 135 if (!pernuma_size_bytes) 136 return; 137 138 for_each_online_node(nid) { 139 int ret; 140 char name[CMA_MAX_NAME]; 141 struct cma **cma = &dma_contiguous_pernuma_area[nid]; 142 143 snprintf(name, sizeof(name), "pernuma%d", nid); 144 ret = cma_declare_contiguous_nid(0, pernuma_size_bytes, 0, 0, 145 0, false, name, cma, nid); 146 if (ret) { 147 pr_warn("%s: reservation failed: err %d, node %d", __func__, 148 ret, nid); 149 continue; 150 } 151 152 pr_debug("%s: reserved %llu MiB on node %d\n", __func__, 153 (unsigned long long)pernuma_size_bytes / SZ_1M, nid); 154 } 155 } 156 #endif 157 158 /** 159 * dma_contiguous_reserve() - reserve area(s) for contiguous memory handling 160 * @limit: End address of the reserved memory (optional, 0 for any). 161 * 162 * This function reserves memory from early allocator. It should be 163 * called by arch specific code once the early allocator (memblock or bootmem) 164 * has been activated and all other subsystems have already allocated/reserved 165 * memory. 166 */ 167 void __init dma_contiguous_reserve(phys_addr_t limit) 168 { 169 phys_addr_t selected_size = 0; 170 phys_addr_t selected_base = 0; 171 phys_addr_t selected_limit = limit; 172 bool fixed = false; 173 174 pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit); 175 176 if (size_cmdline != -1) { 177 selected_size = size_cmdline; 178 selected_base = base_cmdline; 179 selected_limit = min_not_zero(limit_cmdline, limit); 180 if (base_cmdline + size_cmdline == limit_cmdline) 181 fixed = true; 182 } else { 183 #ifdef CONFIG_CMA_SIZE_SEL_MBYTES 184 selected_size = size_bytes; 185 #elif defined(CONFIG_CMA_SIZE_SEL_PERCENTAGE) 186 selected_size = cma_early_percent_memory(); 187 #elif defined(CONFIG_CMA_SIZE_SEL_MIN) 188 selected_size = min(size_bytes, cma_early_percent_memory()); 189 #elif defined(CONFIG_CMA_SIZE_SEL_MAX) 190 selected_size = max(size_bytes, cma_early_percent_memory()); 191 #endif 192 } 193 194 if (selected_size && !dma_contiguous_default_area) { 195 pr_debug("%s: reserving %ld MiB for global area\n", __func__, 196 (unsigned long)selected_size / SZ_1M); 197 198 dma_contiguous_reserve_area(selected_size, selected_base, 199 selected_limit, 200 &dma_contiguous_default_area, 201 fixed); 202 } 203 } 204 205 void __weak 206 dma_contiguous_early_fixup(phys_addr_t base, unsigned long size) 207 { 208 } 209 210 /** 211 * dma_contiguous_reserve_area() - reserve custom contiguous area 212 * @size: Size of the reserved area (in bytes), 213 * @base: Base address of the reserved area optional, use 0 for any 214 * @limit: End address of the reserved memory (optional, 0 for any). 215 * @res_cma: Pointer to store the created cma region. 216 * @fixed: hint about where to place the reserved area 217 * 218 * This function reserves memory from early allocator. It should be 219 * called by arch specific code once the early allocator (memblock or bootmem) 220 * has been activated and all other subsystems have already allocated/reserved 221 * memory. This function allows to create custom reserved areas for specific 222 * devices. 223 * 224 * If @fixed is true, reserve contiguous area at exactly @base. If false, 225 * reserve in range from @base to @limit. 226 */ 227 int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base, 228 phys_addr_t limit, struct cma **res_cma, 229 bool fixed) 230 { 231 int ret; 232 233 ret = cma_declare_contiguous(base, size, limit, 0, 0, fixed, 234 "reserved", res_cma); 235 if (ret) 236 return ret; 237 238 /* Architecture specific contiguous memory fixup. */ 239 dma_contiguous_early_fixup(cma_get_base(*res_cma), 240 cma_get_size(*res_cma)); 241 242 return 0; 243 } 244 245 /** 246 * dma_alloc_from_contiguous() - allocate pages from contiguous area 247 * @dev: Pointer to device for which the allocation is performed. 248 * @count: Requested number of pages. 249 * @align: Requested alignment of pages (in PAGE_SIZE order). 250 * @no_warn: Avoid printing message about failed allocation. 251 * 252 * This function allocates memory buffer for specified device. It uses 253 * device specific contiguous memory area if available or the default 254 * global one. Requires architecture specific dev_get_cma_area() helper 255 * function. 256 */ 257 struct page *dma_alloc_from_contiguous(struct device *dev, size_t count, 258 unsigned int align, bool no_warn) 259 { 260 if (align > CONFIG_CMA_ALIGNMENT) 261 align = CONFIG_CMA_ALIGNMENT; 262 263 return cma_alloc(dev_get_cma_area(dev), count, align, no_warn); 264 } 265 266 /** 267 * dma_release_from_contiguous() - release allocated pages 268 * @dev: Pointer to device for which the pages were allocated. 269 * @pages: Allocated pages. 270 * @count: Number of allocated pages. 271 * 272 * This function releases memory allocated by dma_alloc_from_contiguous(). 273 * It returns false when provided pages do not belong to contiguous area and 274 * true otherwise. 275 */ 276 bool dma_release_from_contiguous(struct device *dev, struct page *pages, 277 int count) 278 { 279 return cma_release(dev_get_cma_area(dev), pages, count); 280 } 281 282 static struct page *cma_alloc_aligned(struct cma *cma, size_t size, gfp_t gfp) 283 { 284 unsigned int align = min(get_order(size), CONFIG_CMA_ALIGNMENT); 285 286 return cma_alloc(cma, size >> PAGE_SHIFT, align, gfp & __GFP_NOWARN); 287 } 288 289 /** 290 * dma_alloc_contiguous() - allocate contiguous pages 291 * @dev: Pointer to device for which the allocation is performed. 292 * @size: Requested allocation size. 293 * @gfp: Allocation flags. 294 * 295 * tries to use device specific contiguous memory area if available, or it 296 * tries to use per-numa cma, if the allocation fails, it will fallback to 297 * try default global one. 298 * 299 * Note that it bypass one-page size of allocations from the per-numa and 300 * global area as the addresses within one page are always contiguous, so 301 * there is no need to waste CMA pages for that kind; it also helps reduce 302 * fragmentations. 303 */ 304 struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) 305 { 306 #ifdef CONFIG_DMA_PERNUMA_CMA 307 int nid = dev_to_node(dev); 308 #endif 309 310 /* CMA can be used only in the context which permits sleeping */ 311 if (!gfpflags_allow_blocking(gfp)) 312 return NULL; 313 if (dev->cma_area) 314 return cma_alloc_aligned(dev->cma_area, size, gfp); 315 if (size <= PAGE_SIZE) 316 return NULL; 317 318 #ifdef CONFIG_DMA_PERNUMA_CMA 319 if (nid != NUMA_NO_NODE && !(gfp & (GFP_DMA | GFP_DMA32))) { 320 struct cma *cma = dma_contiguous_pernuma_area[nid]; 321 struct page *page; 322 323 if (cma) { 324 page = cma_alloc_aligned(cma, size, gfp); 325 if (page) 326 return page; 327 } 328 } 329 #endif 330 if (!dma_contiguous_default_area) 331 return NULL; 332 333 return cma_alloc_aligned(dma_contiguous_default_area, size, gfp); 334 } 335 336 /** 337 * dma_free_contiguous() - release allocated pages 338 * @dev: Pointer to device for which the pages were allocated. 339 * @page: Pointer to the allocated pages. 340 * @size: Size of allocated pages. 341 * 342 * This function releases memory allocated by dma_alloc_contiguous(). As the 343 * cma_release returns false when provided pages do not belong to contiguous 344 * area and true otherwise, this function then does a fallback __free_pages() 345 * upon a false-return. 346 */ 347 void dma_free_contiguous(struct device *dev, struct page *page, size_t size) 348 { 349 unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT; 350 351 /* if dev has its own cma, free page from there */ 352 if (dev->cma_area) { 353 if (cma_release(dev->cma_area, page, count)) 354 return; 355 } else { 356 /* 357 * otherwise, page is from either per-numa cma or default cma 358 */ 359 #ifdef CONFIG_DMA_PERNUMA_CMA 360 if (cma_release(dma_contiguous_pernuma_area[page_to_nid(page)], 361 page, count)) 362 return; 363 #endif 364 if (cma_release(dma_contiguous_default_area, page, count)) 365 return; 366 } 367 368 /* not in any cma, free from buddy */ 369 __free_pages(page, get_order(size)); 370 } 371 372 /* 373 * Support for reserved memory regions defined in device tree 374 */ 375 #ifdef CONFIG_OF_RESERVED_MEM 376 #include <linux/of.h> 377 #include <linux/of_fdt.h> 378 #include <linux/of_reserved_mem.h> 379 380 #undef pr_fmt 381 #define pr_fmt(fmt) fmt 382 383 static int rmem_cma_device_init(struct reserved_mem *rmem, struct device *dev) 384 { 385 dev->cma_area = rmem->priv; 386 return 0; 387 } 388 389 static void rmem_cma_device_release(struct reserved_mem *rmem, 390 struct device *dev) 391 { 392 dev->cma_area = NULL; 393 } 394 395 static const struct reserved_mem_ops rmem_cma_ops = { 396 .device_init = rmem_cma_device_init, 397 .device_release = rmem_cma_device_release, 398 }; 399 400 static int __init rmem_cma_setup(struct reserved_mem *rmem) 401 { 402 unsigned long node = rmem->fdt_node; 403 bool default_cma = of_get_flat_dt_prop(node, "linux,cma-default", NULL); 404 struct cma *cma; 405 int err; 406 407 if (size_cmdline != -1 && default_cma) { 408 pr_info("Reserved memory: bypass %s node, using cmdline CMA params instead\n", 409 rmem->name); 410 return -EBUSY; 411 } 412 413 if (!of_get_flat_dt_prop(node, "reusable", NULL) || 414 of_get_flat_dt_prop(node, "no-map", NULL)) 415 return -EINVAL; 416 417 if (!IS_ALIGNED(rmem->base | rmem->size, CMA_MIN_ALIGNMENT_BYTES)) { 418 pr_err("Reserved memory: incorrect alignment of CMA region\n"); 419 return -EINVAL; 420 } 421 422 err = cma_init_reserved_mem(rmem->base, rmem->size, 0, rmem->name, &cma); 423 if (err) { 424 pr_err("Reserved memory: unable to setup CMA region\n"); 425 return err; 426 } 427 /* Architecture specific contiguous memory fixup. */ 428 dma_contiguous_early_fixup(rmem->base, rmem->size); 429 430 if (default_cma) 431 dma_contiguous_default_area = cma; 432 433 rmem->ops = &rmem_cma_ops; 434 rmem->priv = cma; 435 436 pr_info("Reserved memory: created CMA memory pool at %pa, size %ld MiB\n", 437 &rmem->base, (unsigned long)rmem->size / SZ_1M); 438 439 return 0; 440 } 441 RESERVEDMEM_OF_DECLARE(cma, "shared-dma-pool", rmem_cma_setup); 442 #endif 443