[deliverable/linux.git] / drivers / base / dma-contiguous.c

/*
 * Contiguous Memory Allocator for DMA mapping framework
 * Copyright (c) 2010-2011 by Samsung Electronics.
 * Written by:
 *	Marek Szyprowski <m.szyprowski@samsung.com>
 *	Michal Nazarewicz <mina86@mina86.com>
 *
 * 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 <asm/page.h>
#include <asm/dma-contiguous.h>

#include <linux/memblock.h>
#include <linux/err.h>
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/page-isolation.h>
#include <linux/sizes.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include <linux/mm_types.h>
#include <linux/dma-contiguous.h>

struct cma {
	unsigned long	base_pfn;
	unsigned long	count;
	unsigned long	*bitmap;
	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 int __init cma_activate_area(struct cma *cma)
{
	int bitmap_size = BITS_TO_LONGS(cma->count) * 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));
			if (page_zone(pfn_to_page(pfn)) != zone)
				return -EINVAL;
		}
		init_cma_reserved_pageblock(pfn_to_page(base_pfn));
	} while (--i);

	mutex_init(&cma->lock);
	return 0;
}

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);

/**
 * 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)
{
	struct cma *cma = &cma_areas[cma_area_count];
	phys_addr_t alignment;
	int ret = 0;

	pr_debug("%s(size %lx, base %08lx, limit %08lx)\n", __func__,
		 (unsigned long)size, (unsigned long)base,
		 (unsigned long)limit);

	/* Sanity checks */
	if (cma_area_count == ARRAY_SIZE(cma_areas)) {
		pr_err("Not enough slots for CMA reserved regions!\n");
		return -ENOSPC;
	}

	if (!size)
		return -EINVAL;

	/* Sanitise input arguments */
	alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
	base = ALIGN(base, alignment);
	size = ALIGN(size, alignment);
	limit &= ~(alignment - 1);

	/* 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;
	*res_cma = cma;
	cma_area_count++;

	pr_info("CMA: reserved %ld MiB at %08lx\n", (unsigned long)size / SZ_1M,
		(unsigned long)base);

	/* Architecture specific contiguous memory fixup. */
	dma_contiguous_early_fixup(base, size);
	return 0;
err:
	pr_err("CMA: failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
	return ret;
}

static void clear_cma_bitmap(struct cma *cma, unsigned long pfn, int count)
{
	mutex_lock(&cma->lock);
	bitmap_clear(cma->bitmap, pfn - cma->base_pfn, count);
	mutex_unlock(&cma->lock);
}

/**
 * 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)
{
	unsigned long mask, pfn, pageno, start = 0;
	struct cma *cma = dev_get_cma_area(dev);
	struct page *page = NULL;
	int ret;

	if (!cma || !cma->count)
		return NULL;

	if (align > CONFIG_CMA_ALIGNMENT)
		align = CONFIG_CMA_ALIGNMENT;

	pr_debug("%s(cma %p, count %d, align %d)\n", __func__, (void *)cma,
		 count, align);

	if (!count)
		return NULL;

	mask = (1 << align) - 1;


	for (;;) {
		mutex_lock(&cma->lock);
		pageno = bitmap_find_next_zero_area(cma->bitmap, cma->count,
						    start, count, mask);
		if (pageno >= cma->count) {
			mutex_unlock(&cma->lock);
			break;
		}
		bitmap_set(cma->bitmap, pageno, 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 + pageno;
		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) {
			clear_cma_bitmap(cma, pfn, count);
			break;
		}
		clear_cma_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 = pageno + mask + 1;
	}

	pr_debug("%s(): returned %p\n", __func__, page);
	return page;
}

/**
 * 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);
	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);
	clear_cma_bitmap(cma, pfn, count);

	return true;
}
Commit	Line	Data
c64be2bb MS	1	/*
	2	* Contiguous Memory Allocator for DMA mapping framework
	3	* Copyright (c) 2010-2011 by Samsung Electronics.
	4	* Written by:
	5	* Marek Szyprowski <m.szyprowski@samsung.com>
	6	* Michal Nazarewicz <mina86@mina86.com>
	7	*
	8	* This program is free software; you can redistribute it and/or
	9	* modify it under the terms of the GNU General Public License as
	10	* published by the Free Software Foundation; either version 2 of the
	11	* License or (at your optional) any later version of the license.
	12	*/
	13
	14	#define pr_fmt(fmt) "cma: " fmt
	15
	16	#ifdef CONFIG_CMA_DEBUG
	17	#ifndef DEBUG
	18	# define DEBUG
	19	#endif
	20	#endif
	21
	22	#include <asm/page.h>
	23	#include <asm/dma-contiguous.h>
	24
	25	#include <linux/memblock.h>
	26	#include <linux/err.h>
	27	#include <linux/mm.h>
	28	#include <linux/mutex.h>
	29	#include <linux/page-isolation.h>
446c82fc	30	#include <linux/sizes.h>
c64be2bb MS	31	#include <linux/slab.h>
	32	#include <linux/swap.h>
	33	#include <linux/mm_types.h>
	34	#include <linux/dma-contiguous.h>
	35
c64be2bb MS	36	struct cma {
	37	unsigned long base_pfn;
	38	unsigned long count;
	39	unsigned long *bitmap;
7ee793a6	40	struct mutex lock;
c64be2bb MS	41	};
	42
	43	struct cma *dma_contiguous_default_area;
	44
	45	#ifdef CONFIG_CMA_SIZE_MBYTES
	46	#define CMA_SIZE_MBYTES CONFIG_CMA_SIZE_MBYTES
	47	#else
	48	#define CMA_SIZE_MBYTES 0
	49	#endif
	50
	51	/*
	52	* Default global CMA area size can be defined in kernel's .config.
73678804	53	* This is useful mainly for distro maintainers to create a kernel
c64be2bb MS	54	* that works correctly for most supported systems.
	55	* The size can be set in bytes or as a percentage of the total memory
	56	* in the system.
	57	*
	58	* Users, who want to set the size of global CMA area for their system
	59	* should use cma= kernel parameter.
	60	*/
4009793e VA	61	static const phys_addr_t size_bytes = CMA_SIZE_MBYTES * SZ_1M;
4009793e VA	62	static phys_addr_t size_cmdline = -1;
5ea3b1b2 AM	63	static phys_addr_t base_cmdline;
5ea3b1b2 AM	64	static phys_addr_t limit_cmdline;
c64be2bb MS	65
	66	static int __init early_cma(char *p)
	67	{
	68	pr_debug("%s(%s)\n", __func__, p);
	69	size_cmdline = memparse(p, &p);
5ea3b1b2 AM	70	if (*p != '@')
	71	return 0;
	72	base_cmdline = memparse(p + 1, &p);
	73	if (*p != '-') {
	74	limit_cmdline = base_cmdline + size_cmdline;
	75	return 0;
	76	}
	77	limit_cmdline = memparse(p + 1, &p);
	78
c64be2bb MS	79	return 0;
	80	}
	81	early_param("cma", early_cma);
	82
	83	#ifdef CONFIG_CMA_SIZE_PERCENTAGE
	84
4009793e	85	static phys_addr_t __init __maybe_unused cma_early_percent_memory(void)
c64be2bb MS	86	{
	87	struct memblock_region *reg;
	88	unsigned long total_pages = 0;
	89
	90	/*
	91	* We cannot use memblock_phys_mem_size() here, because
	92	* memblock_analyze() has not been called yet.
	93	*/
	94	for_each_memblock(memory, reg)
	95	total_pages += memblock_region_memory_end_pfn(reg) -
	96	memblock_region_memory_base_pfn(reg);
	97
	98	return (total_pages * CONFIG_CMA_SIZE_PERCENTAGE / 100) << PAGE_SHIFT;
	99	}
	100
	101	#else
	102
4009793e	103	static inline __maybe_unused phys_addr_t cma_early_percent_memory(void)
c64be2bb MS	104	{
	105	return 0;
	106	}
	107
	108	#endif
	109
	110	/**
a2547380	111	* dma_contiguous_reserve() - reserve area(s) for contiguous memory handling
c64be2bb MS	112	* @limit: End address of the reserved memory (optional, 0 for any).
	113	*
	114	* This function reserves memory from early allocator. It should be
	115	* called by arch specific code once the early allocator (memblock or bootmem)
	116	* has been activated and all other subsystems have already allocated/reserved
	117	* memory.
	118	*/
	119	void __init dma_contiguous_reserve(phys_addr_t limit)
	120	{
4009793e	121	phys_addr_t selected_size = 0;
5ea3b1b2 AM	122	phys_addr_t selected_base = 0;
	123	phys_addr_t selected_limit = limit;
	124	bool fixed = false;
c64be2bb MS	125
	126	pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit);
	127
	128	if (size_cmdline != -1) {
	129	selected_size = size_cmdline;
5ea3b1b2 AM	130	selected_base = base_cmdline;
	131	selected_limit = min_not_zero(limit_cmdline, limit);
	132	if (base_cmdline + size_cmdline == limit_cmdline)
	133	fixed = true;
c64be2bb MS	134	} else {
	135	#ifdef CONFIG_CMA_SIZE_SEL_MBYTES
	136	selected_size = size_bytes;
	137	#elif defined(CONFIG_CMA_SIZE_SEL_PERCENTAGE)
	138	selected_size = cma_early_percent_memory();
	139	#elif defined(CONFIG_CMA_SIZE_SEL_MIN)
	140	selected_size = min(size_bytes, cma_early_percent_memory());
	141	#elif defined(CONFIG_CMA_SIZE_SEL_MAX)
	142	selected_size = max(size_bytes, cma_early_percent_memory());
	143	#endif
	144	}
	145
a2547380	146	if (selected_size && !dma_contiguous_default_area) {
c64be2bb	147	pr_debug("%s: reserving %ld MiB for global area\n", __func__,
4009793e	148	(unsigned long)selected_size / SZ_1M);
c64be2bb	149
5ea3b1b2 AM	150	dma_contiguous_reserve_area(selected_size, selected_base,
	151	selected_limit,
	152	&dma_contiguous_default_area,
	153	fixed);
c64be2bb	154	}
5ea3b1b2	155	}
c64be2bb MS	156
	157	static DEFINE_MUTEX(cma_mutex);
	158
a2547380	159	static int __init cma_activate_area(struct cma *cma)
c64be2bb	160	{
a2547380 MS	161	int bitmap_size = BITS_TO_LONGS(cma->count) * sizeof(long);
	162	unsigned long base_pfn = cma->base_pfn, pfn = base_pfn;
	163	unsigned i = cma->count >> pageblock_order;
c64be2bb MS	164	struct zone *zone;
c64be2bb MS	165
a2547380 MS	166	cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
	167
	168	if (!cma->bitmap)
	169	return -ENOMEM;
	170
c64be2bb MS	171	WARN_ON_ONCE(!pfn_valid(pfn));
	172	zone = page_zone(pfn_to_page(pfn));
	173
	174	do {
	175	unsigned j;
	176	base_pfn = pfn;
	177	for (j = pageblock_nr_pages; j; --j, pfn++) {
	178	WARN_ON_ONCE(!pfn_valid(pfn));
	179	if (page_zone(pfn_to_page(pfn)) != zone)
	180	return -EINVAL;
	181	}
	182	init_cma_reserved_pageblock(pfn_to_page(base_pfn));
	183	} while (--i);
c64be2bb	184
7ee793a6	185	mutex_init(&cma->lock);
a2547380	186	return 0;
c64be2bb MS	187	}
c64be2bb MS	188
a2547380 MS	189	static struct cma cma_areas[MAX_CMA_AREAS];
a2547380 MS	190	static unsigned cma_area_count;
c64be2bb MS	191
	192	static int __init cma_init_reserved_areas(void)
	193	{
a2547380	194	int i;
c64be2bb	195
a2547380 MS	196	for (i = 0; i < cma_area_count; i++) {
	197	int ret = cma_activate_area(&cma_areas[i]);
	198	if (ret)
	199	return ret;
c64be2bb	200	}
a2547380	201
c64be2bb MS	202	return 0;
	203	}
	204	core_initcall(cma_init_reserved_areas);
	205
	206	/**
a2547380 MS	207	* dma_contiguous_reserve_area() - reserve custom contiguous area
	208	* @size: Size of the reserved area (in bytes),
	209	* @base: Base address of the reserved area optional, use 0 for any
c64be2bb	210	* @limit: End address of the reserved memory (optional, 0 for any).
a2547380	211	* @res_cma: Pointer to store the created cma region.
5ea3b1b2	212	* @fixed: hint about where to place the reserved area
c64be2bb	213	*
a2547380 MS	214	* This function reserves memory from early allocator. It should be
	215	* called by arch specific code once the early allocator (memblock or bootmem)
	216	* has been activated and all other subsystems have already allocated/reserved
	217	* memory. This function allows to create custom reserved areas for specific
	218	* devices.
5ea3b1b2 AM	219	*
	220	* If @fixed is true, reserve contiguous area at exactly @base. If false,
	221	* reserve in range from @base to @limit.
c64be2bb	222	*/
a2547380	223	int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base,
5ea3b1b2 AM	224	phys_addr_t limit, struct cma **res_cma,
5ea3b1b2 AM	225	bool fixed)
c64be2bb	226	{
a2547380	227	struct cma *cma = &cma_areas[cma_area_count];
4009793e	228	phys_addr_t alignment;
a2547380	229	int ret = 0;
c64be2bb MS	230
	231	pr_debug("%s(size %lx, base %08lx, limit %08lx)\n", __func__,
	232	(unsigned long)size, (unsigned long)base,
	233	(unsigned long)limit);
	234
	235	/* Sanity checks */
a2547380	236	if (cma_area_count == ARRAY_SIZE(cma_areas)) {
c64be2bb MS	237	pr_err("Not enough slots for CMA reserved regions!\n");
	238	return -ENOSPC;
	239	}
	240
	241	if (!size)
	242	return -EINVAL;
	243
	244	/* Sanitise input arguments */
7ce9bf1f	245	alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
c64be2bb MS	246	base = ALIGN(base, alignment);
	247	size = ALIGN(size, alignment);
	248	limit &= ~(alignment - 1);
	249
	250	/* Reserve memory */
5ea3b1b2	251	if (base && fixed) {
c64be2bb MS	252	if (memblock_is_region_reserved(base, size) \|\|
c64be2bb MS	253	memblock_reserve(base, size) < 0) {
a2547380	254	ret = -EBUSY;
c64be2bb MS	255	goto err;
	256	}
	257	} else {
5ea3b1b2 AM	258	phys_addr_t addr = memblock_alloc_range(size, alignment, base,
5ea3b1b2 AM	259	limit);
c64be2bb	260	if (!addr) {
a2547380	261	ret = -ENOMEM;
c64be2bb	262	goto err;
c64be2bb MS	263	} else {
	264	base = addr;
	265	}
	266	}
	267
	268	/*
	269	* Each reserved area must be initialised later, when more kernel
	270	* subsystems (like slab allocator) are available.
	271	*/
a2547380 MS	272	cma->base_pfn = PFN_DOWN(base);
	273	cma->count = size >> PAGE_SHIFT;
	274	*res_cma = cma;
	275	cma_area_count++;
	276
4009793e	277	pr_info("CMA: reserved %ld MiB at %08lx\n", (unsigned long)size / SZ_1M,
c64be2bb MS	278	(unsigned long)base);
	279
	280	/* Architecture specific contiguous memory fixup. */
	281	dma_contiguous_early_fixup(base, size);
	282	return 0;
	283	err:
4009793e	284	pr_err("CMA: failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
a2547380	285	return ret;
c64be2bb MS	286	}
c64be2bb MS	287
7ee793a6 LA	288	static void clear_cma_bitmap(struct cma *cma, unsigned long pfn, int count)
	289	{
	290	mutex_lock(&cma->lock);
	291	bitmap_clear(cma->bitmap, pfn - cma->base_pfn, count);
	292	mutex_unlock(&cma->lock);
	293	}
	294
c64be2bb MS	295	/**
	296	* dma_alloc_from_contiguous() - allocate pages from contiguous area
	297	* @dev: Pointer to device for which the allocation is performed.
	298	* @count: Requested number of pages.
	299	* @align: Requested alignment of pages (in PAGE_SIZE order).
	300	*
	301	* This function allocates memory buffer for specified device. It uses
	302	* device specific contiguous memory area if available or the default
bb56d0dc	303	* global one. Requires architecture specific dev_get_cma_area() helper
c64be2bb MS	304	* function.
	305	*/
	306	struct page dma_alloc_from_contiguous(struct device dev, int count,
	307	unsigned int align)
	308	{
	309	unsigned long mask, pfn, pageno, start = 0;
	310	struct cma *cma = dev_get_cma_area(dev);
bdd43cb3	311	struct page *page = NULL;
c64be2bb MS	312	int ret;
	313
	314	if (!cma \|\| !cma->count)
	315	return NULL;
	316
	317	if (align > CONFIG_CMA_ALIGNMENT)
	318	align = CONFIG_CMA_ALIGNMENT;
	319
	320	pr_debug("%s(cma %p, count %d, align %d)\n", __func__, (void *)cma,
	321	count, align);
	322
	323	if (!count)
	324	return NULL;
	325
	326	mask = (1 << align) - 1;
	327
c64be2bb MS	328
c64be2bb MS	329	for (;;) {
7ee793a6	330	mutex_lock(&cma->lock);
c64be2bb MS	331	pageno = bitmap_find_next_zero_area(cma->bitmap, cma->count,
c64be2bb MS	332	start, count, mask);
7ee793a6	333	if (pageno >= cma->count) {
f70e3c4f	334	mutex_unlock(&cma->lock);
bdd43cb3	335	break;
7ee793a6 LA	336	}
	337	bitmap_set(cma->bitmap, pageno, count);
	338	/*
	339	* It's safe to drop the lock here. We've marked this region for
	340	* our exclusive use. If the migration fails we will take the
	341	* lock again and unmark it.
	342	*/
	343	mutex_unlock(&cma->lock);
c64be2bb MS	344
c64be2bb MS	345	pfn = cma->base_pfn + pageno;
7ee793a6	346	mutex_lock(&cma_mutex);
c64be2bb	347	ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA);
7ee793a6	348	mutex_unlock(&cma_mutex);
c64be2bb	349	if (ret == 0) {
bdd43cb3	350	page = pfn_to_page(pfn);
c64be2bb MS	351	break;
c64be2bb MS	352	} else if (ret != -EBUSY) {
7ee793a6	353	clear_cma_bitmap(cma, pfn, count);
bdd43cb3	354	break;
c64be2bb	355	}
7ee793a6	356	clear_cma_bitmap(cma, pfn, count);
c64be2bb MS	357	pr_debug("%s(): memory range at %p is busy, retrying\n",
	358	__func__, pfn_to_page(pfn));
	359	/* try again with a bit different memory target */
	360	start = pageno + mask + 1;
	361	}
	362
bdd43cb3 MN	363	pr_debug("%s(): returned %p\n", __func__, page);
bdd43cb3 MN	364	return page;
c64be2bb MS	365	}
	366
	367	/**
	368	* dma_release_from_contiguous() - release allocated pages
	369	* @dev: Pointer to device for which the pages were allocated.
	370	* @pages: Allocated pages.
	371	* @count: Number of allocated pages.
	372	*
	373	* This function releases memory allocated by dma_alloc_from_contiguous().
	374	* It returns false when provided pages do not belong to contiguous area and
	375	* true otherwise.
	376	*/
	377	bool dma_release_from_contiguous(struct device dev, struct page pages,
	378	int count)
	379	{
	380	struct cma *cma = dev_get_cma_area(dev);
	381	unsigned long pfn;
	382
	383	if (!cma \|\| !pages)
	384	return false;
	385
	386	pr_debug("%s(page %p)\n", __func__, (void *)pages);
	387
	388	pfn = page_to_pfn(pages);
	389
	390	if (pfn < cma->base_pfn \|\| pfn >= cma->base_pfn + cma->count)
	391	return false;
	392
	393	VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);
	394
c64be2bb	395	free_contig_range(pfn, count);
7ee793a6	396	clear_cma_bitmap(cma, pfn, count);
c64be2bb MS	397
	398	return true;
	399	}