1 // SPDX-License-Identifier: GPL-2.0+
3  * Contiguous Memory Allocator for DMA mapping framework
4  * Copyright (c) 2010-2011 by Samsung Electronics.
9  * Contiguous Memory Allocator
11  *   The Contiguous Memory Allocator (CMA) makes it possible to
12  *   allocate big contiguous chunks of memory after the system has
17  *   Various devices on embedded systems have no scatter-getter and/or
18  *   IO map support and require contiguous blocks of memory to
22  *   Such devices often require big memory buffers (a full HD frame
24  *   MB of memory), which makes mechanisms such as kmalloc() or
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
32  *   CMA tries to solve this issue by operating on memory regions
34  *   can use the memory for pagecache and when device driver requests
45 #include <linux/dma-map-ops.h>
61  * The size can be set in bytes or as a percentage of the total memory
68 static phys_addr_t  size_cmdline __initdata = -1;
76 		return -EINVAL;  in early_cma()
83 	if (*p != '-') {  in early_cma()
203  * dma_contiguous_reserve() - reserve area(s) for contiguous memory handling
204  * @limit: End address of the reserved memory (optional, 0 for any).
206  * This function reserves memory from early allocator. It should be
208  * has been activated and all other subsystems have already allocated/reserved
209  * memory.
222 	if (size_cmdline != -1) {  in dma_contiguous_reserve()
257  * dma_contiguous_reserve_area() - reserve custom contiguous area
258  * @size: Size of the reserved area (in bytes),
259  * @base: Base address of the reserved area optional, use 0 for any
260  * @limit: End address of the reserved memory (optional, 0 for any).
262  * @fixed: hint about where to place the reserved area
264  * This function reserves memory from early allocator. It should be
266  * has been activated and all other subsystems have already allocated/reserved
267  * memory. This function allows to create custom reserved areas for specific
280 					"reserved", res_cma);  in dma_contiguous_reserve_area()
284 	/* Architecture specific contiguous memory fixup. */  in dma_contiguous_reserve_area()
292  * dma_alloc_from_contiguous() - allocate pages from contiguous area
298  * This function allocates memory buffer for specified device. It uses
299  * device specific contiguous memory area if available or the default
313  * dma_release_from_contiguous() - release allocated pages
318  * This function releases memory allocated by dma_alloc_from_contiguous().
336  * dma_alloc_contiguous() - allocate contiguous pages
341  * tries to use device specific contiguous memory area if available, or it
342  * tries to use per-numa cma, if the allocation fails, it will fallback to
345  * Note that it bypass one-page size of allocations from the per-numa and
359 	if (dev->cma_area)  in dma_alloc_contiguous()
360 		return cma_alloc_aligned(dev->cma_area, size, gfp);  in dma_alloc_contiguous()
390  * dma_free_contiguous() - release allocated pages
395  * This function releases memory allocated by dma_alloc_contiguous(). As the
398  * upon a false-return.
405 	if (dev->cma_area) {  in dma_free_contiguous()
406 		if (cma_release(dev->cma_area, page, count))  in dma_free_contiguous()
410 		 * otherwise, page is from either per-numa cma or default cma  in dma_free_contiguous()
429  * Support for reserved memory regions defined in device tree
441 	dev->cma_area = rmem->priv;  in rmem_cma_device_init()
448 	dev->cma_area = NULL;  in rmem_cma_device_release()
458 	unsigned long node = rmem->fdt_node;  in rmem_cma_setup()
459 	bool default_cma = of_get_flat_dt_prop(node, "linux,cma-default", NULL);  in rmem_cma_setup()
463 	if (size_cmdline != -1 && default_cma) {  in rmem_cma_setup()
464 		pr_info("Reserved memory: bypass %s node, using cmdline CMA params instead\n",  in rmem_cma_setup()
465 			rmem->name);  in rmem_cma_setup()
466 		return -EBUSY;  in rmem_cma_setup()
470 	    of_get_flat_dt_prop(node, "no-map", NULL))  in rmem_cma_setup()
471 		return -EINVAL;  in rmem_cma_setup()
473 	if (!IS_ALIGNED(rmem->base | rmem->size, CMA_MIN_ALIGNMENT_BYTES)) {  in rmem_cma_setup()
474 		pr_err("Reserved memory: incorrect alignment of CMA region\n");  in rmem_cma_setup()
475 		return -EINVAL;  in rmem_cma_setup()
478 	err = cma_init_reserved_mem(rmem->base, rmem->size, 0, rmem->name, &cma);  in rmem_cma_setup()
480 		pr_err("Reserved memory: unable to setup CMA region\n");  in rmem_cma_setup()
483 	/* Architecture specific contiguous memory fixup. */  in rmem_cma_setup()
484 	dma_contiguous_early_fixup(rmem->base, rmem->size);  in rmem_cma_setup()
489 	rmem->ops = &rmem_cma_ops;  in rmem_cma_setup()
490 	rmem->priv = cma;  in rmem_cma_setup()
492 	pr_info("Reserved memory: created CMA memory pool at %pa, size %ld MiB\n",  in rmem_cma_setup()
493 		&rmem->base, (unsigned long)rmem->size / SZ_1M);  in rmem_cma_setup()
497 RESERVEDMEM_OF_DECLARE(cma, "shared-dma-pool", rmem_cma_setup);