1 // SPDX-License-Identifier: GPL-2.0+
3 * Contiguous Memory Allocator for DMA mapping framework
4 * Copyright (c) 2010-2011 by Samsung Electronics.
6 * Marek Szyprowski <m.szyprowski@samsung.com>
7 * Michal Nazarewicz <mina86@mina86.com>
10 #define pr_fmt(fmt) "cma: " fmt
12 #ifdef CONFIG_CMA_DEBUG
19 #include <asm/dma-contiguous.h>
21 #include <linux/memblock.h>
22 #include <linux/err.h>
23 #include <linux/sizes.h>
24 #include <linux/dma-contiguous.h>
25 #include <linux/cma.h>
27 #ifdef CONFIG_CMA_SIZE_MBYTES
28 #define CMA_SIZE_MBYTES CONFIG_CMA_SIZE_MBYTES
30 #define CMA_SIZE_MBYTES 0
33 struct cma *dma_contiguous_default_area;
36 * Default global CMA area size can be defined in kernel's .config.
37 * This is useful mainly for distro maintainers to create a kernel
38 * that works correctly for most supported systems.
39 * The size can be set in bytes or as a percentage of the total memory
42 * Users, who want to set the size of global CMA area for their system
43 * should use cma= kernel parameter.
45 static const phys_addr_t size_bytes = (phys_addr_t)CMA_SIZE_MBYTES * SZ_1M;
46 static phys_addr_t size_cmdline = -1;
47 static phys_addr_t base_cmdline;
48 static phys_addr_t limit_cmdline;
50 static int __init early_cma(char *p)
53 pr_err("Config string not provided\n");
57 size_cmdline = memparse(p, &p);
60 base_cmdline = memparse(p + 1, &p);
62 limit_cmdline = base_cmdline + size_cmdline;
65 limit_cmdline = memparse(p + 1, &p);
69 early_param("cma", early_cma);
71 #ifdef CONFIG_CMA_SIZE_PERCENTAGE
73 static phys_addr_t __init __maybe_unused cma_early_percent_memory(void)
75 struct memblock_region *reg;
76 unsigned long total_pages = 0;
79 * We cannot use memblock_phys_mem_size() here, because
80 * memblock_analyze() has not been called yet.
82 for_each_memblock(memory, reg)
83 total_pages += memblock_region_memory_end_pfn(reg) -
84 memblock_region_memory_base_pfn(reg);
86 return (total_pages * CONFIG_CMA_SIZE_PERCENTAGE / 100) << PAGE_SHIFT;
91 static inline __maybe_unused phys_addr_t cma_early_percent_memory(void)
99 * dma_contiguous_reserve() - reserve area(s) for contiguous memory handling
100 * @limit: End address of the reserved memory (optional, 0 for any).
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
107 void __init dma_contiguous_reserve(phys_addr_t limit)
109 phys_addr_t selected_size = 0;
110 phys_addr_t selected_base = 0;
111 phys_addr_t selected_limit = limit;
114 pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit);
116 if (size_cmdline != -1) {
117 selected_size = size_cmdline;
118 selected_base = base_cmdline;
119 selected_limit = min_not_zero(limit_cmdline, limit);
120 if (base_cmdline + size_cmdline == limit_cmdline)
123 #ifdef CONFIG_CMA_SIZE_SEL_MBYTES
124 selected_size = size_bytes;
125 #elif defined(CONFIG_CMA_SIZE_SEL_PERCENTAGE)
126 selected_size = cma_early_percent_memory();
127 #elif defined(CONFIG_CMA_SIZE_SEL_MIN)
128 selected_size = min(size_bytes, cma_early_percent_memory());
129 #elif defined(CONFIG_CMA_SIZE_SEL_MAX)
130 selected_size = max(size_bytes, cma_early_percent_memory());
134 if (selected_size && !dma_contiguous_default_area) {
135 pr_debug("%s: reserving %ld MiB for global area\n", __func__,
136 (unsigned long)selected_size / SZ_1M);
138 dma_contiguous_reserve_area(selected_size, selected_base,
140 &dma_contiguous_default_area,
146 * dma_contiguous_reserve_area() - reserve custom contiguous area
147 * @size: Size of the reserved area (in bytes),
148 * @base: Base address of the reserved area optional, use 0 for any
149 * @limit: End address of the reserved memory (optional, 0 for any).
150 * @res_cma: Pointer to store the created cma region.
151 * @fixed: hint about where to place the reserved area
153 * This function reserves memory from early allocator. It should be
154 * called by arch specific code once the early allocator (memblock or bootmem)
155 * has been activated and all other subsystems have already allocated/reserved
156 * memory. This function allows to create custom reserved areas for specific
159 * If @fixed is true, reserve contiguous area at exactly @base. If false,
160 * reserve in range from @base to @limit.
162 int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
163 phys_addr_t limit, struct cma **res_cma,
168 ret = cma_declare_contiguous(base, size, limit, 0, 0, fixed,
169 "reserved", res_cma);
173 /* Architecture specific contiguous memory fixup. */
174 dma_contiguous_early_fixup(cma_get_base(*res_cma),
175 cma_get_size(*res_cma));
181 * dma_alloc_from_contiguous() - allocate pages from contiguous area
182 * @dev: Pointer to device for which the allocation is performed.
183 * @count: Requested number of pages.
184 * @align: Requested alignment of pages (in PAGE_SIZE order).
185 * @no_warn: Avoid printing message about failed allocation.
187 * This function allocates memory buffer for specified device. It uses
188 * device specific contiguous memory area if available or the default
189 * global one. Requires architecture specific dev_get_cma_area() helper
192 struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
193 unsigned int align, bool no_warn)
195 if (align > CONFIG_CMA_ALIGNMENT)
196 align = CONFIG_CMA_ALIGNMENT;
198 return cma_alloc(dev_get_cma_area(dev), count, align, no_warn);
202 * dma_release_from_contiguous() - release allocated pages
203 * @dev: Pointer to device for which the pages were allocated.
204 * @pages: Allocated pages.
205 * @count: Number of allocated pages.
207 * This function releases memory allocated by dma_alloc_from_contiguous().
208 * It returns false when provided pages do not belong to contiguous area and
211 bool dma_release_from_contiguous(struct device *dev, struct page *pages,
214 return cma_release(dev_get_cma_area(dev), pages, count);
218 * dma_alloc_contiguous() - allocate contiguous pages
219 * @dev: Pointer to device for which the allocation is performed.
220 * @size: Requested allocation size.
221 * @gfp: Allocation flags.
223 * This function allocates contiguous memory buffer for specified device. It
224 * first tries to use device specific contiguous memory area if available or
225 * the default global one, then tries a fallback allocation of normal pages.
227 * Note that it byapss one-page size of allocations from the global area as
228 * the addresses within one page are always contiguous, so there is no need
229 * to waste CMA pages for that kind; it also helps reduce fragmentations.
231 struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp)
233 size_t count = size >> PAGE_SHIFT;
234 struct page *page = NULL;
235 struct cma *cma = NULL;
237 if (dev && dev->cma_area)
240 cma = dma_contiguous_default_area;
242 /* CMA can be used only in the context which permits sleeping */
243 if (cma && gfpflags_allow_blocking(gfp)) {
244 size_t align = get_order(size);
245 size_t cma_align = min_t(size_t, align, CONFIG_CMA_ALIGNMENT);
247 page = cma_alloc(cma, count, cma_align, gfp & __GFP_NOWARN);
254 * dma_free_contiguous() - release allocated pages
255 * @dev: Pointer to device for which the pages were allocated.
256 * @page: Pointer to the allocated pages.
257 * @size: Size of allocated pages.
259 * This function releases memory allocated by dma_alloc_contiguous(). As the
260 * cma_release returns false when provided pages do not belong to contiguous
261 * area and true otherwise, this function then does a fallback __free_pages()
262 * upon a false-return.
264 void dma_free_contiguous(struct device *dev, struct page *page, size_t size)
266 if (!cma_release(dev_get_cma_area(dev), page,
267 PAGE_ALIGN(size) >> PAGE_SHIFT))
268 __free_pages(page, get_order(size));
272 * Support for reserved memory regions defined in device tree
274 #ifdef CONFIG_OF_RESERVED_MEM
275 #include <linux/of.h>
276 #include <linux/of_fdt.h>
277 #include <linux/of_reserved_mem.h>
280 #define pr_fmt(fmt) fmt
282 static int rmem_cma_device_init(struct reserved_mem *rmem, struct device *dev)
284 dev_set_cma_area(dev, rmem->priv);
288 static void rmem_cma_device_release(struct reserved_mem *rmem,
291 dev_set_cma_area(dev, NULL);
294 static const struct reserved_mem_ops rmem_cma_ops = {
295 .device_init = rmem_cma_device_init,
296 .device_release = rmem_cma_device_release,
299 static int __init rmem_cma_setup(struct reserved_mem *rmem)
301 phys_addr_t align = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
302 phys_addr_t mask = align - 1;
303 unsigned long node = rmem->fdt_node;
307 if (!of_get_flat_dt_prop(node, "reusable", NULL) ||
308 of_get_flat_dt_prop(node, "no-map", NULL))
311 if ((rmem->base & mask) || (rmem->size & mask)) {
312 pr_err("Reserved memory: incorrect alignment of CMA region\n");
316 err = cma_init_reserved_mem(rmem->base, rmem->size, 0, rmem->name, &cma);
318 pr_err("Reserved memory: unable to setup CMA region\n");
321 /* Architecture specific contiguous memory fixup. */
322 dma_contiguous_early_fixup(rmem->base, rmem->size);
324 if (of_get_flat_dt_prop(node, "linux,cma-default", NULL))
325 dma_contiguous_set_default(cma);
327 rmem->ops = &rmem_cma_ops;
330 pr_info("Reserved memory: created CMA memory pool at %pa, size %ld MiB\n",
331 &rmem->base, (unsigned long)rmem->size / SZ_1M);
335 RESERVEDMEM_OF_DECLARE(cma, "shared-dma-pool", rmem_cma_setup);