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Linux/kernel/dma/contiguous.c

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  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 
 10 #define pr_fmt(fmt) "cma: " fmt
 11 
 12 #ifdef CONFIG_CMA_DEBUG
 13 #ifndef DEBUG
 14 #  define DEBUG
 15 #endif
 16 #endif
 17 
 18 #include <asm/page.h>
 19 #include <asm/dma-contiguous.h>
 20 
 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>
 26 
 27 #ifdef CONFIG_CMA_SIZE_MBYTES
 28 #define CMA_SIZE_MBYTES CONFIG_CMA_SIZE_MBYTES
 29 #else
 30 #define CMA_SIZE_MBYTES 0
 31 #endif
 32 
 33 struct cma *dma_contiguous_default_area;
 34 
 35 /*
 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
 40  * in the system.
 41  *
 42  * Users, who want to set the size of global CMA area for their system
 43  * should use cma= kernel parameter.
 44  */
 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;
 49 
 50 static int __init early_cma(char *p)
 51 {
 52         if (!p) {
 53                 pr_err("Config string not provided\n");
 54                 return -EINVAL;
 55         }
 56 
 57         size_cmdline = memparse(p, &p);
 58         if (*p != '@')
 59                 return 0;
 60         base_cmdline = memparse(p + 1, &p);
 61         if (*p != '-') {
 62                 limit_cmdline = base_cmdline + size_cmdline;
 63                 return 0;
 64         }
 65         limit_cmdline = memparse(p + 1, &p);
 66 
 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         phys_addr_t selected_base = 0;
111         phys_addr_t selected_limit = limit;
112         bool fixed = false;
113 
114         pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit);
115 
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)
121                         fixed = true;
122         } else {
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());
131 #endif
132         }
133 
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);
137 
138                 dma_contiguous_reserve_area(selected_size, selected_base,
139                                             selected_limit,
140                                             &dma_contiguous_default_area,
141                                             fixed);
142         }
143 }
144 
145 /**
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
152  *
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
157  * devices.
158  *
159  * If @fixed is true, reserve contiguous area at exactly @base.  If false,
160  * reserve in range from @base to @limit.
161  */
162 int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
163                                        phys_addr_t limit, struct cma **res_cma,
164                                        bool fixed)
165 {
166         int ret;
167 
168         ret = cma_declare_contiguous(base, size, limit, 0, 0, fixed,
169                                         "reserved", res_cma);
170         if (ret)
171                 return ret;
172 
173         /* Architecture specific contiguous memory fixup. */
174         dma_contiguous_early_fixup(cma_get_base(*res_cma),
175                                 cma_get_size(*res_cma));
176 
177         return 0;
178 }
179 
180 /**
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.
186  *
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
190  * function.
191  */
192 struct page *dma_alloc_from_contiguous(struct device *dev, size_t count,
193                                        unsigned int align, bool no_warn)
194 {
195         if (align > CONFIG_CMA_ALIGNMENT)
196                 align = CONFIG_CMA_ALIGNMENT;
197 
198         return cma_alloc(dev_get_cma_area(dev), count, align, no_warn);
199 }
200 
201 /**
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.
206  *
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
209  * true otherwise.
210  */
211 bool dma_release_from_contiguous(struct device *dev, struct page *pages,
212                                  int count)
213 {
214         return cma_release(dev_get_cma_area(dev), pages, count);
215 }
216 
217 /**
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.
222  *
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.
226  *
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.
230  */
231 struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp)
232 {
233         size_t count = size >> PAGE_SHIFT;
234         struct page *page = NULL;
235         struct cma *cma = NULL;
236 
237         if (dev && dev->cma_area)
238                 cma = dev->cma_area;
239         else if (count > 1)
240                 cma = dma_contiguous_default_area;
241 
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);
246 
247                 page = cma_alloc(cma, count, cma_align, gfp & __GFP_NOWARN);
248         }
249 
250         return page;
251 }
252 
253 /**
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.
258  *
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.
263  */
264 void dma_free_contiguous(struct device *dev, struct page *page, size_t size)
265 {
266         if (!cma_release(dev_get_cma_area(dev), page,
267                          PAGE_ALIGN(size) >> PAGE_SHIFT))
268                 __free_pages(page, get_order(size));
269 }
270 
271 /*
272  * Support for reserved memory regions defined in device tree
273  */
274 #ifdef CONFIG_OF_RESERVED_MEM
275 #include <linux/of.h>
276 #include <linux/of_fdt.h>
277 #include <linux/of_reserved_mem.h>
278 
279 #undef pr_fmt
280 #define pr_fmt(fmt) fmt
281 
282 static int rmem_cma_device_init(struct reserved_mem *rmem, struct device *dev)
283 {
284         dev_set_cma_area(dev, rmem->priv);
285         return 0;
286 }
287 
288 static void rmem_cma_device_release(struct reserved_mem *rmem,
289                                     struct device *dev)
290 {
291         dev_set_cma_area(dev, NULL);
292 }
293 
294 static const struct reserved_mem_ops rmem_cma_ops = {
295         .device_init    = rmem_cma_device_init,
296         .device_release = rmem_cma_device_release,
297 };
298 
299 static int __init rmem_cma_setup(struct reserved_mem *rmem)
300 {
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;
304         struct cma *cma;
305         int err;
306 
307         if (!of_get_flat_dt_prop(node, "reusable", NULL) ||
308             of_get_flat_dt_prop(node, "no-map", NULL))
309                 return -EINVAL;
310 
311         if ((rmem->base & mask) || (rmem->size & mask)) {
312                 pr_err("Reserved memory: incorrect alignment of CMA region\n");
313                 return -EINVAL;
314         }
315 
316         err = cma_init_reserved_mem(rmem->base, rmem->size, 0, rmem->name, &cma);
317         if (err) {
318                 pr_err("Reserved memory: unable to setup CMA region\n");
319                 return err;
320         }
321         /* Architecture specific contiguous memory fixup. */
322         dma_contiguous_early_fixup(rmem->base, rmem->size);
323 
324         if (of_get_flat_dt_prop(node, "linux,cma-default", NULL))
325                 dma_contiguous_set_default(cma);
326 
327         rmem->ops = &rmem_cma_ops;
328         rmem->priv = cma;
329 
330         pr_info("Reserved memory: created CMA memory pool at %pa, size %ld MiB\n",
331                 &rmem->base, (unsigned long)rmem->size / SZ_1M);
332 
333         return 0;
334 }
335 RESERVEDMEM_OF_DECLARE(cma, "shared-dma-pool", rmem_cma_setup);
336 #endif
337 

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