/* * Contiguous Memory Allocator for DMA mapping framework * Copyright (c) 2010-2011 by Samsung Electronics. * Written by: * Marek Szyprowski * Michal Nazarewicz * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation; either version 2 of the * License or (at your optional) any later version of the license. */ #define pr_fmt(fmt) "cma: " fmt #ifdef CONFIG_CMA_DEBUG #ifndef DEBUG # define DEBUG #endif #endif #include #include #include #include #include #include #include #include #include #include #include #include #include struct cma { unsigned long base_pfn; unsigned long count; unsigned long *bitmap; unsigned int order_per_bit; /* Order of pages represented by one bit */ struct mutex lock; }; struct cma *dma_contiguous_default_area; #ifdef CONFIG_CMA_SIZE_MBYTES #define CMA_SIZE_MBYTES CONFIG_CMA_SIZE_MBYTES #else #define CMA_SIZE_MBYTES 0 #endif /* * Default global CMA area size can be defined in kernel's .config. * This is useful mainly for distro maintainers to create a kernel * that works correctly for most supported systems. * The size can be set in bytes or as a percentage of the total memory * in the system. * * Users, who want to set the size of global CMA area for their system * should use cma= kernel parameter. */ static const phys_addr_t size_bytes = CMA_SIZE_MBYTES * SZ_1M; static phys_addr_t size_cmdline = -1; static phys_addr_t base_cmdline; static phys_addr_t limit_cmdline; static int __init early_cma(char *p) { pr_debug("%s(%s)\n", __func__, p); size_cmdline = memparse(p, &p); if (*p != '@') return 0; base_cmdline = memparse(p + 1, &p); if (*p != '-') { limit_cmdline = base_cmdline + size_cmdline; return 0; } limit_cmdline = memparse(p + 1, &p); return 0; } early_param("cma", early_cma); #ifdef CONFIG_CMA_SIZE_PERCENTAGE static phys_addr_t __init __maybe_unused cma_early_percent_memory(void) { struct memblock_region *reg; unsigned long total_pages = 0; /* * We cannot use memblock_phys_mem_size() here, because * memblock_analyze() has not been called yet. */ for_each_memblock(memory, reg) total_pages += memblock_region_memory_end_pfn(reg) - memblock_region_memory_base_pfn(reg); return (total_pages * CONFIG_CMA_SIZE_PERCENTAGE / 100) << PAGE_SHIFT; } #else static inline __maybe_unused phys_addr_t cma_early_percent_memory(void) { return 0; } #endif /** * dma_contiguous_reserve() - reserve area(s) for contiguous memory handling * @limit: End address of the reserved memory (optional, 0 for any). * * This function reserves memory from early allocator. It should be * called by arch specific code once the early allocator (memblock or bootmem) * has been activated and all other subsystems have already allocated/reserved * memory. */ void __init dma_contiguous_reserve(phys_addr_t limit) { phys_addr_t selected_size = 0; phys_addr_t selected_base = 0; phys_addr_t selected_limit = limit; bool fixed = false; pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit); if (size_cmdline != -1) { selected_size = size_cmdline; selected_base = base_cmdline; selected_limit = min_not_zero(limit_cmdline, limit); if (base_cmdline + size_cmdline == limit_cmdline) fixed = true; } else { #ifdef CONFIG_CMA_SIZE_SEL_MBYTES selected_size = size_bytes; #elif defined(CONFIG_CMA_SIZE_SEL_PERCENTAGE) selected_size = cma_early_percent_memory(); #elif defined(CONFIG_CMA_SIZE_SEL_MIN) selected_size = min(size_bytes, cma_early_percent_memory()); #elif defined(CONFIG_CMA_SIZE_SEL_MAX) selected_size = max(size_bytes, cma_early_percent_memory()); #endif } if (selected_size && !dma_contiguous_default_area) { pr_debug("%s: reserving %ld MiB for global area\n", __func__, (unsigned long)selected_size / SZ_1M); dma_contiguous_reserve_area(selected_size, selected_base, selected_limit, &dma_contiguous_default_area, fixed); } } static DEFINE_MUTEX(cma_mutex); static unsigned long cma_bitmap_aligned_mask(struct cma *cma, int align_order) { return (1UL << (align_order >> cma->order_per_bit)) - 1; } static unsigned long cma_bitmap_maxno(struct cma *cma) { return cma->count >> cma->order_per_bit; } static unsigned long cma_bitmap_pages_to_bits(struct cma *cma, unsigned long pages) { return ALIGN(pages, 1UL << cma->order_per_bit) >> cma->order_per_bit; } static void cma_clear_bitmap(struct cma *cma, unsigned long pfn, int count) { unsigned long bitmap_no, bitmap_count; bitmap_no = (pfn - cma->base_pfn) >> cma->order_per_bit; bitmap_count = cma_bitmap_pages_to_bits(cma, count); mutex_lock(&cma->lock); bitmap_clear(cma->bitmap, bitmap_no, bitmap_count); mutex_unlock(&cma->lock); } static int __init cma_activate_area(struct cma *cma) { int bitmap_size = BITS_TO_LONGS(cma_bitmap_maxno(cma)) * sizeof(long); unsigned long base_pfn = cma->base_pfn, pfn = base_pfn; unsigned i = cma->count >> pageblock_order; struct zone *zone; cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL); if (!cma->bitmap) return -ENOMEM; WARN_ON_ONCE(!pfn_valid(pfn)); zone = page_zone(pfn_to_page(pfn)); do { unsigned j; base_pfn = pfn; for (j = pageblock_nr_pages; j; --j, pfn++) { WARN_ON_ONCE(!pfn_valid(pfn)); /* * alloc_contig_range requires the pfn range * specified to be in the same zone. Make this * simple by forcing the entire CMA resv range * to be in the same zone. */ if (page_zone(pfn_to_page(pfn)) != zone) goto err; } init_cma_reserved_pageblock(pfn_to_page(base_pfn)); } while (--i); mutex_init(&cma->lock); return 0; err: kfree(cma->bitmap); return -EINVAL; } static struct cma cma_areas[MAX_CMA_AREAS]; static unsigned cma_area_count; static int __init cma_init_reserved_areas(void) { int i; for (i = 0; i < cma_area_count; i++) { int ret = cma_activate_area(&cma_areas[i]); if (ret) return ret; } return 0; } core_initcall(cma_init_reserved_areas); static int __init __dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base, phys_addr_t limit, phys_addr_t alignment, unsigned int order_per_bit, struct cma **res_cma, bool fixed) { struct cma *cma = &cma_areas[cma_area_count]; int ret = 0; pr_debug("%s(size %lx, base %08lx, limit %08lx alignment %08lx)\n", __func__, (unsigned long)size, (unsigned long)base, (unsigned long)limit, (unsigned long)alignment); if (cma_area_count == ARRAY_SIZE(cma_areas)) { pr_err("Not enough slots for CMA reserved regions!\n"); return -ENOSPC; } if (!size) return -EINVAL; if (alignment && !is_power_of_2(alignment)) return -EINVAL; /* * Sanitise input arguments. * Pages both ends in CMA area could be merged into adjacent unmovable * migratetype page by page allocator's buddy algorithm. In the case, * you couldn't get a contiguous memory, which is not what we want. */ alignment = max(alignment, (phys_addr_t)PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order)); base = ALIGN(base, alignment); size = ALIGN(size, alignment); limit &= ~(alignment - 1); /* size should be aligned with order_per_bit */ if (!IS_ALIGNED(size >> PAGE_SHIFT, 1 << order_per_bit)) return -EINVAL; /* Reserve memory */ if (base && fixed) { if (memblock_is_region_reserved(base, size) || memblock_reserve(base, size) < 0) { ret = -EBUSY; goto err; } } else { phys_addr_t addr = memblock_alloc_range(size, alignment, base, limit); if (!addr) { ret = -ENOMEM; goto err; } else { base = addr; } } /* * Each reserved area must be initialised later, when more kernel * subsystems (like slab allocator) are available. */ cma->base_pfn = PFN_DOWN(base); cma->count = size >> PAGE_SHIFT; cma->order_per_bit = order_per_bit; *res_cma = cma; cma_area_count++; pr_info("CMA: reserved %ld MiB at %08lx\n", (unsigned long)size / SZ_1M, (unsigned long)base); return 0; err: pr_err("CMA: failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M); return ret; } /** * dma_contiguous_reserve_area() - reserve custom contiguous area * @size: Size of the reserved area (in bytes), * @base: Base address of the reserved area optional, use 0 for any * @limit: End address of the reserved memory (optional, 0 for any). * @res_cma: Pointer to store the created cma region. * @fixed: hint about where to place the reserved area * * This function reserves memory from early allocator. It should be * called by arch specific code once the early allocator (memblock or bootmem) * has been activated and all other subsystems have already allocated/reserved * memory. This function allows to create custom reserved areas for specific * devices. * * If @fixed is true, reserve contiguous area at exactly @base. If false, * reserve in range from @base to @limit. */ int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base, phys_addr_t limit, struct cma **res_cma, bool fixed) { int ret; ret = __dma_contiguous_reserve_area(size, base, limit, 0, 0, res_cma, fixed); if (ret) return ret; /* Architecture specific contiguous memory fixup. */ dma_contiguous_early_fixup(PFN_PHYS((*res_cma)->base_pfn), (*res_cma)->count << PAGE_SHIFT); return 0; } static struct page *__dma_alloc_from_contiguous(struct cma *cma, int count, unsigned int align) { unsigned long mask, pfn, start = 0; unsigned long bitmap_maxno, bitmap_no, bitmap_count; struct page *page = NULL; int ret; if (!cma || !cma->count) return NULL; pr_debug("%s(cma %p, count %d, align %d)\n", __func__, (void *)cma, count, align); if (!count) return NULL; mask = cma_bitmap_aligned_mask(cma, align); bitmap_maxno = cma_bitmap_maxno(cma); bitmap_count = cma_bitmap_pages_to_bits(cma, count); for (;;) { mutex_lock(&cma->lock); bitmap_no = bitmap_find_next_zero_area(cma->bitmap, bitmap_maxno, start, bitmap_count, mask); if (bitmap_no >= bitmap_maxno) { mutex_unlock(&cma->lock); break; } bitmap_set(cma->bitmap, bitmap_no, bitmap_count); /* * It's safe to drop the lock here. We've marked this region for * our exclusive use. If the migration fails we will take the * lock again and unmark it. */ mutex_unlock(&cma->lock); pfn = cma->base_pfn + (bitmap_no << cma->order_per_bit); mutex_lock(&cma_mutex); ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA); mutex_unlock(&cma_mutex); if (ret == 0) { page = pfn_to_page(pfn); break; } else if (ret != -EBUSY) { cma_clear_bitmap(cma, pfn, count); break; } cma_clear_bitmap(cma, pfn, count); pr_debug("%s(): memory range at %p is busy, retrying\n", __func__, pfn_to_page(pfn)); /* try again with a bit different memory target */ start = bitmap_no + mask + 1; } pr_debug("%s(): returned %p\n", __func__, page); return page; } /** * dma_alloc_from_contiguous() - allocate pages from contiguous area * @dev: Pointer to device for which the allocation is performed. * @count: Requested number of pages. * @align: Requested alignment of pages (in PAGE_SIZE order). * * This function allocates memory buffer for specified device. It uses * device specific contiguous memory area if available or the default * global one. Requires architecture specific dev_get_cma_area() helper * function. */ struct page *dma_alloc_from_contiguous(struct device *dev, int count, unsigned int align) { struct cma *cma = dev_get_cma_area(dev); if (align > CONFIG_CMA_ALIGNMENT) align = CONFIG_CMA_ALIGNMENT; return __dma_alloc_from_contiguous(cma, count, align); } static bool __dma_release_from_contiguous(struct cma *cma, struct page *pages, int count) { unsigned long pfn; if (!cma || !pages) return false; pr_debug("%s(page %p)\n", __func__, (void *)pages); pfn = page_to_pfn(pages); if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count) return false; VM_BUG_ON(pfn + count > cma->base_pfn + cma->count); free_contig_range(pfn, count); cma_clear_bitmap(cma, pfn, count); return true; } /** * dma_release_from_contiguous() - release allocated pages * @dev: Pointer to device for which the pages were allocated. * @pages: Allocated pages. * @count: Number of allocated pages. * * This function releases memory allocated by dma_alloc_from_contiguous(). * It returns false when provided pages do not belong to contiguous area and * true otherwise. */ bool dma_release_from_contiguous(struct device *dev, struct page *pages, int count) { struct cma *cma = dev_get_cma_area(dev); return __dma_release_from_contiguous(cma, pages, count); }