/*
* 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));
/*
* 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);
/**
* 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;
}
